Hanbook For Rov Pilot Technicians

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HANDtsOOK FORRbV

PILOTITECHNICIANS By Chris Bell, Mel Bayliss and Richard Warburton

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pipeline pirLugh yet TheEMCplough PL2isthemostaclvanced p r o d u c eadn dh a sp r o v evde r ys u c t e s s fiunlo p e r a t r o n . Diverless Ioading anciunloadrng is provicled bycornprehensive pipehandling partof the equipment clesigned asan integral ploughScphisticated provides iontroiandinstrumentaiion p i p e l i n e t h e m a x i m uim l o r d u r i n t g h e t r enching lrotecti0n provirled Theequiprnei:t is withtheclassic operation. $MD tnaiensures stylehandling systen: safeandrapidcieploymcnt andrecovery.

TRAGKFfU lt EHIGI-E$ T h eE u r e k a v e h i c l ef o i -B T M a r i n ci s L r "; u i a r a n g eo f l i g h t w e i g hpto, u r e r f u v e h i 0 l edse s i g n e d a ln Lvj e r s a t i iter a c k e d a n d m a n u f a c t u r ebcyl S l \ 1 0f o r d i v e r l e s 0s p e r a t i 0 nT. h B S e vehicles canbefittedv;itha rangeof trenching ioois1oprovide

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US Disttibutor : MECCO Tel : (206)7884522 Fax : (206)7880639

Catt us now for further details. Tritech International Ltd' Tel: ++44224 744111 Fax : ++44224741771

US Distributor : MECCO Tel : (206) 7884522 Fax : (206) 788 0639

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Handbookfor ROVPilot/Technicians

@ Copyright

Handbook for ROV PilotvTechnicians, is the exclusivecopyright of the publishers and may not be reproduced in whole or part without the written permission of Oilfield Publications Limited.

Re-ordering

Additional copies of Handbook for ROV Pilot/Iechnicians nray be obtained by contacting OPL direct at thc address, telephone and fax numbers given at the foot of this page.

Frcilt co|er picture: 5lurysb! Engineeting Lttl's MRV is the latest :etterution of ROV and has an outstanding raLk recortl irt high speed survey, .nt\tnrctiotr, intervention and many other '-truriottt. M RV is of molulur r rtntrrut tiott :)tr offers simple configuration for depth .;:utgs of 2000 metres, up to 200HP atd a 5 :ttre through frame lift capacity. S.ngsbl Engineerhg Lttl !,: z s Larte. Kir kbymoors itle \;:rk YO6 6EZ !; ic p hon e: 075 I 13 175I TeleJiu : 075 I 13 I 388

This Book has been carefully preparetl from the best eri.^titrg sources of ittformation avai[able at the time of prepatution but O PL do trot guarantee lhe accuracy of the book nor of the limits, exteilt or position of aill cartographicreprcsentation delineated thercitl nor do OPL assume any responsibility or liability Jbr any relianu thereiin.

Homend House, PO Box 11,L.edburyHerefordshireHR8 1BN,England Tel: (01531)64563 Fax: (01531)634239

tsBN I 87094567 0

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As perfectionistswe are well awareof how importantit is to get all the piecesof the puzzleinto place,especiallywhenwe are talking aboutdifferent typesof cables.

We mAke y our pi cture g,'#";; fi*T,'Ht"#"r.Ti,, complet J

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\r\ Foreword Over the last 20 years or so, ROV Pilots and Technicianshave had to master more and more trades and skills. In these days of small operationsteams, working with ever more complex systems,usually far from home and 'the beach', they are expected to keep all of their equipment at I00"/" availability as well as use their special skills in navigating their vehicles safely and surely around all the hazards of thesea. All ROV businesseshave been built upon the professionalismof their Pilots and Technicians.As new successfuloperationsgeneratenew skills, this in turn prompts advancesin vehicle technology, and this continuouscycle of changemakes the life demanding and challenging.If there were any limits to the progressof ROV activitiesthey would be, in the end, set by the people who actually know and drive them. In this refreshing handbook, the authors have skilfully brought together a great wealth of practicalknowledgeand experienceof ROV operations,addressingall of the technical,operationaland managementdisciplinesin a clear and comprehensive manner, as well as including plenty of 'hard to find' technicalreferencedata. No matter whether you are a shore-basedmanager, operationssupervisor,system designer,interestedbystanderor actuallyat the sharpend "hands on the sticks", it should be kept closeby.

About Marcus Cardew MarcusCardewspent9 yearsat seaasa Navigator.He then spent2 yearsworking with mannedsubmersibles then 8 yearsastechnicaland operationsdirectorof Sub SeaSurveysbeforemovingto SlingsbyEngineeringastechnicaldirector.For the past10yearshe hasbeenrunninghis own business'systemTechnologies' in Ulverston, designingandmanufacturing a rangeof underwaterandvehiclesystems.

About The Authors

ChrisBellisaCharteredEngineerwll!twelveyearsexperienceaSanRoV of thepresentlv

Heh;$;";";il;;;ili.; superintendenr.

i"i tr'Jdevelopment

ROV trainingschemes' recosnised uet-naytissisaMernberofthelnstituteofNon-destructiveTestingwithextensive oncswlP Heleaches

in inrp""itJ"^oi'tuir.aaitl*;;nbn;rpectionexperience at all levels' courses approved FhiaseT

ElectronicsandHydraulic systemswith Richardwarburton is a specialistin ROV extensiveoffshoreexPerience'

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Acknowledgements The Authors are glad to acknowledgeand offer their appreciationto the following companies;all of whom haveofferedassistance with t1repreparationof this handbook. AshteadTechnolog5. Bowtech ProductsLtd BT (Marine) Ltd De Regt SpecialCableBV

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Hawke CableGlandsLtd.

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GrahamMills, OceaneeringLtd. MacArtney UnderwaterTechnologyA/S SlingsbyEngineeringLtd SystemsTechnologies TeesideValve and Fittings Co. Ltd. TSS (UK) Ltd.

ITTDTRT'TRO CONTROL SYSTEMSLtd * ROV BATHYMETRYUNITS I 45 Units deliveredI Digiquartzpressuresensorsand MesotechaltimetersI Fastupdate(6/sec)I Compact one-piecesubseaunit fits most ROVsI 24v DC power for subseaunit I Pitch/rolland conductiviryoptions

* VIDEO OVERLAYUNITS

* MULTIPLEXERS& CONTROL SYSTEMS I For ROVsand other remote control applicationsI 45+ systemsdeliveredI Upgrade/enhance old vehicles

* MINI MANIPULATOR

I Palor NTSC I Colour text andgraphicsI Mulri channel I Expandable

I 4 FunctionI 220vAC powered I Integratedpower unit and valvepackI Microprocessorcontrol I Completewith surface controller I Fitsmost small/mediumROVsI Put hydraulic power on electric vehicles

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I Desk top remote control I 8x 16and l6x 15matrrces

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I ValvepacksI Panand tilt units I ManipulatorslCamera booms I Actuators

tf,RPR0 conrnol sysrEMsLtd Unit 10,Wellheadscrescent TradingEstate,Dyce,Aberdeen,ScotlandAB2 oGA Tel:(44) 1224n2150

Fax:(44) t224n2166

DEDICATION

TheAuthorswouldliketodedicatethishandbookto:SueHamiliton SueJones Marion Else this manualwould without who'Shard work and timely assistance wives:their to and Produced

not have been

Pam Maria Belinda without which this and.patience for their Support,encouragement beenwritten.

book would not have

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Bibliography Underwater Inspection

Remotely OperatedVehiclesof the World

D Shon,M Bayliss E & FN SponLtd. r sBN 0- 419- 13540- 5 D Gallimore,A Madson OPL rsBN 1 87094559 X

An Introduction to ROV Operations

G Last,P Williams OPL rsBN | 81094523 9

PipelineRulesof Thumb Handbook

E W McAllister Gulf Publishing Co r sBN 0- 88415- 094- 1

SUT UnderwaterTechnologyVol18 No 2 On-site Testsfor UnderwaterVideo PictureQuality

RW Barrett,M Clarke, B Rav

SUT UnderwaterTechnologyVol 6 No 2 Snorrl SubseaControl System SUT UnderwaterTechnologyVol 15 No 4 Advancesin UnderwaterInspectionand maintenance SUT UnderwaterTechnologyVol 17 No 2 Application of a Remotely Operated ConstructionVehicle SUT An Introduction to Remoteiy OperatedVehicles Two Day Course 23-24February1994 BT (Marine)QualityManual ImplementingQuality ThroughBS5750

P Jackson,D Ashton Kogan PageLtd

r sBN 0749407972 The Quality ManagementManual

J Waller,D Allen,A Burns KoganPageLtd rsBN 0 7 49409037

ElectronicsTEC Level II

D C Green PitmanBooksLtd rsBN 0273018272

OptoelectronicLine Transmission

R L Tucker Heinemann Newnes rsBN 0 434919780

K J Bohlman Dickson Price Publishers

ElectronicsServicingVol I

rsBN0-85380-166-5 MTS OoerationalGuidelinesfor ROVs

r r r other useful reference books on underwater working from the offshore specialists An Introductionto ROVOperations

Remotely Operated Vehicles of the World This new book provides for the first time a complete and 'what's 'who's definitrve illustrated relerence to what' and who' in this hiqhly specialsed lield of underwater activity.

Thrsbook hasproved sopopularthatwe have recently had to commissionits first reprint, to satlsfythe steadydemand from readers who appreciateits clear easyto read formatand the substantialamountof informationit contarns.Much of lts contents.becausethe book's authorshave ltrst hand prrctrcal experienceinthe field, is simplynotavailable elsewhere,so if the factson ROVoperations ne rmportant to you order your copy now you won'tbe drsappornted.

l n a d d r t r o n1 oo r v r n g u p t o d a t e ' d n d h r g h l y d e t a i l e d lniormatrononevery ROV, including subseaploughs and other towed vehicles, it provrdes firll editonal listings of manufacturers, operators and vehicle development compilies too. Other sections cover equipmenvsystems manufacturing companies and thetr worldwide agents, product listings covering lights, cmeras, manipulators handlirg equipment, buoyancy, flotation umbilicals cables and connectors, motors, thrusters, nav/tracking, sonar and acoustics and ROV support vessels. There are also full dfectory listings of all compmies involved in ROV operations and underwater contracting including engineering and consultingr firms.

Pages:300 Price:i65 (inc p&p) Produa Order N": ROV/OPS

An Introduction to Diving Operations Offshore

'vessels If you ae already familiar with our of the world' series books then you'll know that we take their comprlalion ver\, senously Thrs book rs no exceptron. so if you are interested in subsea operalions and rn particular ROV's and thef related systems order you

A comlete overuiew of today's offshore industry drving technrques, equipment and operahons.

copy today. Paqes: 296 approximately Price: S95 (inc p&p) Product Order N": ROV,/W/ I

Pages:300 Price:965 (inc p&p) Product Order N": DIV/OPS

Ordering Ii you would hke to order any of thesebooksor would like a FfiEE copy of the OPL Cataloguelisting over 400maps,books, dtrectorresand databasescontactus at the addressgiven on the title page

10

HANDBOOK FOR ROV PILOT/TECHNICIANS

TABLE OF CONTENTS

ChapterL tChapter2 Chapter3 lChapter 4 "ehapter 5 uChapter6 tChap|erT Chapter8 Chapter9 'Chapterl0 Chapter 11 Chapter 12 "Chapter13 thapter14 Chapter15 Chapter16 {hapter17 Chapter L8 -Chapter19 Chapter20

Introduction.. OffshoreSafety Typesof ROVOiishoreStructures R o v A p p l i c a t i o n s. . . Systems ROV Ele-ctrical Equipment Test of Use ROV HydraulicSystems High PressureHydraulicF-ittings... ROV Hook-Up, Pre/PostDive Checks ... ElectricalMaintenance MechanicalMaintenance. EmergencyProcedures Comriuniiations UnderwaterVideo UnderwaterPhotography S e a ma n sh i... p y N a v i g a t i o n. . D r a g ,B u o y a n c& fifofing St
... 13 ..- l7 ... 31 ...... 39 ...47 .--... 79 Il7 131 167 l7I I75 I87 197 203 ..--. .. 207 .....- 213 - .- - .- 237 . . . . . . ;... . . . . . 2 6 9 . 299

APPENDICES containusefultechnicalinformation& Datasheets The appendices

11

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The [lnderwater World Comesto Houston, Texas January 16-78,1995

Man& Machine

Underwater

Smtrurtion ts$trcgtisn

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The combined annucrl conference of the Association of Diving Contractors and the ROV Committee of the Marine kchnology Society

hstallalion FiFclines HScs Hdfirms

D^n7n;7^;+- More than 1OO underwater contractors, industry and LXILLUI.L) suppliers equipment organizations will display the latest in new underwater services, products and capabilities.

ProgramI;,:? n:::J:Ttr1 ili=" f ff:J:?:fl??",:i

advari-cin g tec h nol o gy, ope rational experie nce, safety, regulations, commercial concerns and policy issues. Tl, -,- L- A Dinner Dance, Exhibitor's Reception and gala Lyen6 cocktail Party offer relaxed settinss to exchange information and review new ideas.

.,,,,hn1a Ct

Intervention is the nation's leading Underwater conference devoted to underwater technology. Over 3 , O O Oi n d u s t r y p a r t i c i p a n t s a n d t h e i r c u s t o m e r s w i l l b e there....Will you?

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Exhibit - ParticQtate . Attend at: tltcUl'$5 Gummittee contact Is reseiue lnlrginflmation

:Igffinluy

(713) e874808 Fax (713)987-4809 P.O.Box130937 USA Houston,TX 77219-0937

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i CHAPTER 1 INTRODUCTION 1.0.1 This ROV pilotflechnician Handbookhas beenwritten to compliment the 'the Associationof Underwgte-rEngineering.contractors (known as AODC) recognised RoV Pilotflechnician Inductidn and s[ills course,und ir the product or sJ"erar"years experience. running__such courses. It is intendedto be the first'in a seriesby the same authorsto include Handbooksfor: ROV Inspectors,ROV Systems/SurveyE"gi"irii and ROV Managersto include Offshore Superintendents.in addition to"being for the, now well establishedcourses,this handbookis likely to lggliredreading becomea ref'erence_ bookfor ROV SystemsOperatorsoffshore and others suih as Sub EnSineers and Manufacturers who may hdve an interestin the work of an ROV !9.a Pilotfechnician. The aim of this handbookis to presentconciselythe essential informationrequired py ROV Pilot/Techniciansin their everyday'workthat "*b1", thern to work both.to.fulyand effectively in the offshore induitri6s, in particutar,ttre petroleumand cable laying industries,but also the growth industriesof mine counter 1t911urys(MCM), anti-terrorismand drug interveniion. Much of the technologyof ROV design is_commonto all typgl whidh is reflectedin this handbookbylrre lrseor genericexamplesrarherthansp.ecific Boy types,where appropriut","-pllusising common featuresand the enablingtechnologiis. Practicaltixeicisesare.includedto allow the readerto practicethe mEthodsdesiribed in circumstanceswhere suitable equipmentand supervisionare available.This enablesthe handbookalso to be used tor the structuredtraining of personnelwho startedworking in this industry prior to the establishmentof the presenttraining programme. 1.0.2 A programmeof training.modules and assessment is now established and,clearly is foi trreptoifeaiue $Pyn in Figure l. The first hurdlethatmust be negotiated "*lttr ROV operatorto becomea Technicianor Engineer at,ititiesin Electrical Engineering,Electronics,Mechanicsand Hydraulics. It is not normalin the UK for studentsto receivethis breadthof training and it is thereforemore usual for them to havespecificskills,andto rely on-theIndirctionand Skills course(Module l) to introducethem to the essentials of the otherdisciplines.Thoroughcrosstrainingis then achievedthroughexperienceand attendancsoffurthernrodlles of traininsas careerspro.gress.At the time of writing it is expectedthat the AODC will beeina processto introducea 'Certificateof Conrpetenie'for ROV OperatorsbasJ"on both training.and experience,this will enablea'registerof competentoperatorsto be established, and may well prompt nrodificati-ons to this coursestructure.It is bglieye{' however,that thi.sproiesswill takea significantti-. ""J-th"t'ttrisianouoot wtll ttnd a placeas essential readingfor this scheme.A funhermodulebeinsa condensedversionof Modulesl, 7-and8 containingessential-.f.;t i;i"rmu?Jn rnuy then be offered for the experienced -operatorrequiriig updateclsafeiy inrormaiion as an essentialc.omponent.ofthe 'certifiaateof competeice' scheme. There are anumber ot recognisedroutesto becominga Technicianor Engineerand full detailsshouldbe the.Engineg.r^r.ng Council or other recogni"sed body, but ttrey inCfuOetfre ::,Yqll,ft9p tollowrng_ technical,cpalific.ations:Degrees,HNCor HND, city and Guilds and NationalVocationalQualificationsat le-vel3'or above. Cornplirirent.y pi*1ir.f experience,suchas apprenticeships, may be requiredin aclditionto these qualificationsbut wheresufficienirelevantexpiriencehasbeenobtained, this alone ..oy.bq acceptableto enrol for the ROV Pilot/TechnicianInductionanOStitti Courrr, which is the first srepto comperencyand to which this Hanclbookapplies

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r.0.3 Ttre aims of the ROV Pilot/TechnicianInduction and skills courseand this book are srmilar and are to ensurethat the TraineePilotflechnician has the essentialknowledge and skills to enablehim to work both safelyand effectively from his very first offshore tour of duty. This is essentialin the modernROV industry as the requirementfor lower costshasreducedthe crew sizesto the minimum, often only F^,oor three,and there is rarely an opportunityfor extra-numerarytraineesto be included. In addition we lay the foundationsfor future learningby explaining the principlesof the enablingtechnologiessuchas; 'O'rings, video cameras,telemetry and hydraulics. Our industry is practically basedand in this respectthis Handbook actsas a guide to practicalexercisesand an identificationof the skills required,these exerciseshould be adaptedto the training environmentand equipmentavailable. 1.0.4 The subjectsthat this handbookcover are wide ranging and diversemaking it necessaryfor the readerto have a graspof scientific fundamentalssuch as electricity, hydraulics,and photographyprior to readingit. There are many books available explaining thesefundamentalsand the readeris recommendedto familiarise himself with thesebeforetaking up this courseof study. 1.0.5 The technicallevelsdescribedare equivalentto the NationalVocationalQualification (NVQ) at level 3. The specificqualificationrecommended is the Engineering Training Authority (EnTra)NVQ Level 3 in EngineeringMaintenance,Electromechanicaloption,adaptedfor ROV equipment.In additionto technicalinformation, this handbookcontainsvaluableinformationon Offshoresafety,ROVs and their applications,Quality Assurancesystems,photography,seiunanship and many other subjectsessentialfor successfulROV operations. 1.1.0 Backgr
15

slowedsincetheoil pricefall of 1985andtherehavebeenmanyrecentcriticismsof itrr .Uifity of the offitoi. indutt.V 1o-{undfuture developments'Althoughmuchof ifr. i"rtrn"ofogyis ,o**on to all ROVs thesecriticismsarenot completelyfoundedas new deuelop"-entsareunderway,pafiicularlyin theareasof fibre optic telemetry' rrlgn OenniiiontV sysrems,Sens6rsandotherancillary.euuil,menl. -1\:t l" andfor interdiction anti-terrorism,-drug "*ffunaingmarketsin minecountermeasures, UnderwaterVehicles). AUVs (Autonomous t.L.2 classROV, The of ROV; The smallobservation Therearebasicallythreemainclasses sub-divided been have These Work classROV lna ttreTrackedvehicles/ploughs. into Low CostROVs(LCROVs)andHeavy,MediumandLight-workROVsTany U"in[proulAiAwittr a'surveyopiion._Ther6arecustombuilt ROVsfor particular applicitions,but ROVsateoftdnmodifiedto produce'hybrids'.For example vehictefor interventionanddrill suppo:t Sii";;bt E"gineerlngprovideda TR_OJAN ioi"i u'-oaltieA.,"riiloknown asCHALLENGERfo-rplatformInspectionR"!{IandMaintenance finMl, anda trackedversionfor cableiepairwork 5n9*l asROV vehiclethatis designed 128. This samecompunyno* providea state-of-the-art arounaflexibility knownastheMRV (Multi-RoleVehicle). Moredetailed . to ili: tY_f.f,tlient follow in later:.hapigrs: a"i.riptt""i of {OVi andtheirapplications has which industry, t"V fii". itt.t theROV industry.isi fascinatingmulti-disciplined of time,and.!p thepotentialfor eniovedrapidgrowitrin a relaiivelyshortperi-od "dhiii"".fi"u.R.tt to openup asit-matures.Centralto theabilityof theindustrytomeerfururechallenges'*itt6. theknowledgeandskillsof its personnel.It is hoped thatthis bookwill 6e ableto makea smallcontributionto these.

t6

CHAPTER 2

OFFSHORE SAFETY

2.0 Introduction The variousoperatorsin the North Seataketheir responsibilitiesunderthe variousActs of Parliament and Governmentlegislation very seriously. Before an individual is allowed onto any offshore worksite that worker must be medically fit and must hold a valid offshore survival certificate issuedby an approvedcenffe. Safe working practices are encouragedand it is mandatoryto wear the specifiedprotectiveclothing and equipment.Failure to comply would resultin dismissal. All new personnelare given a platform safety briefing on arrival which is specific to that platform or worksite. The operatorsrecognisethat offshore worksites can be dangerousplacesand thereforedo all they reasonablycan to eliminatethe dangers.As part of this safetyphilosophya permit to work schemeis adoptedgenerallythroughoutthe North Sea.,This schemeis outlined later in the handbookin more detail but in essencethe intention is to ensurethat alY work which is not of a routine natureis only undertakenwith written permission. This ensuresthat all safety considerationsare made before work commenCes.The Health and Safetyat Work Act alsoplacesan onusonto individualsto be safe themselvesand not to endangerwork mates. It is most importantthat offshore personneltake note of thesesafetyrequirements. 2.0.1 Legislation, Codes of Practice and Guidance Notes in the UK. Acts of Parliament: 1. Healthand Safetyat Work etc.Act I974Pwt l 2. Offshore Safety Act 1992 3. MineralWorkings(OffshoreInstallations) Act 1971 4. TerritorialSeaAct 1987 5. PetroleumAct 1982 6. Oil andGas(Enterprise) Act 1982 7. OffshoreSafety(ProtectionAgainstVicrimisation) Act 1992 Statutory Instruments:

SI 289 SI 308 SI 399 S I4 1 9 SI 486 SI 608 SI611 SI 679

sr 680 SI 702 SI 703 S I7 1 I SI 835 SI 840 SI9lO SI 923

(Construction The OffshoreInstallations and Survey) Regulations 1974 Well Control(Amendntent)1991 Health and Saf'ety(Diving Operations)at Work Applicationof StatutoryInsrruments (Life-savingAppliances)Regulations The OffshoreInstallations 1977 The Diving Operationsat Work (Amendnrent)Regulations1992 The OffshoreInstallations (FireFightingEquiprnent) Regulations1978 (Amendment)Regulations The OffshoreInstallations The SubmarinePipe-lines(lnspectors and Sifety) (Amendment) Regulations The OffshoreInstallations (Registrarion) Regulation s 1912 (Amendedby SI 679) The OffshoreInstallations (Managers)ReguIatiorr l9l2 (Amendedby SI 679) Asbestos(Prohibitions)(Amendment) Inspectors,etc. The Health and Safetyat Work etc. Act 1974(Application outsideGreat Britain) Order 1989 Asbestos(Prohibitions) Diving Operations Revokedby SI 1823)

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SI971 SI 978 SI 996 SI 1019 SI 1029 SI 1106 S I IZyZ S I 1248 S I 1289 S I 1331 S I 1333 S I 1398 SI 1443 SI 1513 SI I53l S I 1542

S I 1542 S I 167| S I 1672 SI tisg SI 1823 SI lB42 SI 1890 SI 1985 SI 2002 SI 2040

sr 2051 s I 2 11 5 sr2292

and Safety The OffshoreInstallations(SafetyRepresentatives i989 Regulations Comnrittees) IncludedApparatusor Works Diving Operationsat Work (AmendmenQ ^ ttre OffshoreInstallations(OperationalSafety,Health and Wetfare)Regulations1976 EmergencyPiPe-line\alve Preventionof Oil Pollution The Health and SafetyarWork etc. Act 1974(ApplicationoutsideGreat Britain) Order l9ll Control of Lead at Work Employer'sLiability (CompulsoryInsurance) SafetyZones Ionising Radiations Preventionof Pollution CompulsoryInsurance SubnrarinePiPelinesSafetY Control of Explosives The Offshoreinstallations(Logbooksand Registrationof Death) Regulations 1972 (Amendedby SI 679) ttr[ OffsnoreInstaliations(EmergencyProcedures)Regglations.1976 The OffshoreInstallarionsand PipelineWorks (First-Aid) Regulattons 1989 OperationalSafety,Health andWelfare and Life-SavingAppliances. The OffshoreInsiailations(Well Control) Regulations1980(Amended by SI 308) OffshoreSafety(Repealsand Modifications)Regu.latiols1993 The OffshoreInstallations(lnspectorsand Casualties)Regulations1973 (AmendedbY SI679) FreightContainers(SafetyConvention) SubnrarinePipelinesSafety (Amendntent) of Oil Pollution)(Amendment) The MerchantShipping(Prevention Order of Oil Polltrtion)(Amendment) The MerchantShipping(Prevention Regulations of Healthand Safetyat Work Regulations1992 ThEManagement Control of Asbestosat Work of Pollutionby Garbage) The MerchantShipping(Prevention Resulations

andapplyon or within SI lZ32 and SI 1019specificallyreferto fixed installations 500m of these.The otherregulationsand Codesof Practiceshouldbe usedas guidelinesand althoughnotln themselveslegalrequirementsfailure to follow an a court-asfaiiure to meet the recluirementsof the ippi"""O "ode coulcl6. .onrtru"d b_y_ will be govgrry{ Py ,lt. laws of that country UK the outside fiSnWn. Operations British Standards,Codesof Practice If in d=.oubt law. as UK *fti.fr -uy not be the same practice. working guide to saf'e good and UK legislationare a AODC Guidance Notes: AODC 016 AODC 032 AODC 036 AODC 033 AODC 051 AODC 060

CraneHooks RemotelyOperatedVehicle/Diver Involvement ROV Handling Systems(UK) Responsibilityfor UnderwaterInspection^ GuibanceNoie on the SafeandEfficient Operationof Remotely OperatedVehicles for working on High VoltageEquipment Sifety Procedures

18

N

AODC 061 AODC 062 AODC 063 AODC 064 DMAC 06

Bell BallastReleaseSystemsand BuoyantAscentin OffshoreDiving Operations Use of BatteryOperatedEquipmentin HyperbaricConditions UnderwaterAir Lift Baes Ingressof Water into U"nderwaterCylinders Chargedby Means of a Manifold System Code of Practicefor the SafeUse of Electricity Under Water RecommendationsThe Effect of SonarTransmissionon Commercial Divins Activities

Safety Notice 2193 CraneSling Hooks Used to Deploy EquipmentSub Sea AODC/DMAC Publicationsmav be obtainedfrom: AODC, 177AHigh Street, Beckenham, Kent,

UK, BR3lAH Governmentlegislationand StatutoryInstrumentsfrom: HMSO 2.0.2 Medical Fitness. The Offshoreoperatorsrequiretheir personnelto be medicallyexaminedby an approveddoctor. Thereis a prescribedform to the medicaland it is valid for:5 yearsfor workers under40 yearsof age. 3 yearsfor workers40 to 50 yearsof age. 1 year for workersover 50 yearsofage. The medicalincludesa dentalfitnessinspection. 2.0.3 Offshore Survival Courses There are variousapprovedoffshoresurvivalcentreswhich are authorisedto issue survival certificates.The centresoffer 3 and 5 dav survivalcoursesdesisnedto teach offshorepersonnelthe basicsof fire fighting, survival in the sea,helicopiersafetyand evacuationand generalfirst aid includingEAR and CCM. The 5 day coursecertificate is valid for 5 years. The 3 day courseis a refresherwhich lastsfor 3 or 4 years dependingon the individualoperator's recluiremenrs. Addressesof UK Centres: For generalinformation: CentralTrainingRegister, OffshorePetroleumIndustryTraining Board, Forties Road, Montrose, Angus, DD1O9 ET. RGIT, SurvivalCentreLtd., Aberdeen

19

7

2.L Responsibilities Under the Health and Safety at Work Ac(HSAWA) and the Offshore Installations (OperationaiSafety,Healtti and Welfare Regulations);StatutoryInstruments(SI) 1019. Th^eemployer has a responsibilityto ensurethe health,safetyand welfare of his "...suchinformation,instruction,ffaining and suPervisionas employeesand to provide to ensuretheseresponsibilitiesare properly discharged-The employer are^necessary..." must provid6 a written statementof his safetypolicies and procedureswhich must be freely available to employees.This statementis usually known as the Safety Manual. Empioyers also have a Orityto protect personsnot in their employlnent a1d;9lf; emptoyeapersonswho may be affectedby their operations.The Control of Substances Ha2ardousto Health Regulations1988(COSHH) requiresemployersto take the steps necessaryto minimise the risks arisingfrom the useof dangeroussubstances.These safetyand regulationsalsoplace a duty on the employeeto look after the health, "...full and proper make to working with and he may be himself and others welfare of facilityof other thing protective or personal equipment nreasure, useof any control he shall therein, any defects if he regulations and discovers provided-pursuant to these for safetyis of the employee The responsibility his employer...". ieport it forthwith to of awareness the employee's of paramount importance and evidence consideredto be of prinrary training. period of this must be demonstratedduring the trainee's 2.2 Attitudes Poor attitudestowardssafetyusuallycomefrom a belief that accidentswill only happen to other peopleand not to oneself. Experiencedoperatorswho havewitnessed accidents,oi nearaccidentsoffshoreareawarethat accidentscan and do happenand adjusttheir attitudesto"minimisetherisk of accidentsto thenrselves.A traineemust imaginebeingin the samesituationand be particularlycarefulto allow for any or instnlctions. The traineemust inexperience,asking wherenecessaryfor assistance for example,posingthequestion, imaginethe worstcasescenarioin all situations, "Wliat happensif that lifting wire parts?"and taking appropriatesafeaction. 2.3 Operational Safety Many factorscombinewhen operatingROVs which makethe potentialfor accidents greaierthan for most other forms of employment.The major onesare listed below.

2.3.1

Electric:al Saf'ety.

2.3.2

(HazardousAreas). ExplosiveEnvironments

2.3.3

Explosiveand RadioactiveSources.

2.3.4

MechanicalDevices.

2.3.5

High PressureHydraulicSystems.

2.3.6

Lifting and Deployingthe ROV.

2.3.7

Welding.

2.3.8

Gas Cylinders.

2.3.9

RestrictedAreas.

2.3.10

HelicopterOperations.

2.3.11

ProtectiveClothing.

20

\

2.3.12

Use of Tools.

2.3.13

Good Housekeeping.

2.3.t4

Working with Divers.

2.3.15

The Natureof the Sealtself.

2.3.16

EmergencyProcedures.

Thesefactorswill be examinedin more detail in the following paragraphs. 2.4. Electrical Safety ROVs usually operatewith high voltagesto reducethe current down the umbilical and hencethe umbilical size. This fact coupledwith the natureof the offshorework environmentdictatesclosescrutinyof materialsusedin electricalinstallationsin order to avoid possibletoxic effectsin confinedspacesshouldan electricalfire occur and the harshconditionslequire that a high degreeof skill and safeworking practicesgo into the installations.It is obviousthat if we are to operatewith high voltagesin a wet environmentthereis a very real risk of electricshockand that precautionsagainstthis must be taken. Theseprecautionsfall into threecategories:peisonalprecauiions; passiveprotection_and activeprotection. Personalprecautionsconsistof applying good work practicesand housekeeping methds and usingcorrecrprorectivectoitiirig anO tools- Passiveprotectioncan be providedin 5 ways-.Active protectionmay bd providedby eithera residualcurrbntdevice(RCDior a line in.sulationmoniior(LlM). 2.4.1 Personal Precautions

1. 2. 3. 4. 5.

6. 7. 8. 9.

only work on electricalsystemsif you aresureyou know what you aredoing. Be absolutelysurethatthe groundconnectionis madethroughthe umbilicalto theROV. Connectan additionalexternalgroundsnap when the ROV is on deck. Wear rubberglovesif handlingthe umbilicalduringoperations. Ma]<esurethat inexperiencedpersonnelstandwell clearduring operationaland maintenanceprocedures. Do_notallow personneland tools to becomedisorganisedduring maintenance and repair proceduresor take shon cuts due to operationalpressures. Wheneverpossiblestandon a rubbermat. Know the first aid for shocktreatmentand the medicalevacuiitionproceduresof the vessel. All metersnrustbe suitablyrarede.g.l0tn V a.c.or 5000V a.c.

2.4.2 Passive Protection Piq fo"l of protectionis providedby the useof: adequateinsulation;providing a fixed barrierusingprotectiveclothing;usingshieldingand suitabreearrhing. 2.4.2.I Insulation The primary meansof providing passiveprotectionagainstshockis by insulationof the power systemand the applianceit serves.Insulationis lesseffectiveunderwaterthan on dry land becausea defectat any point might allow currentto flow in the water and part of this currentnray be interceptedby the submersibleor say a diver. The effectivenessof insulationas a meansof protectionmay be improvedby using two layersof insulationwith a conductingscrbenin betweeh.Two defectsire the-nneeded to constitutea risk. The first defectcan be detectedby continuouslymonitoringthe

21

insulationlevelbetweentheconductingscreenandtheload,andbetweenthe screenand failureof both causesimultaneous theoutercasing.Entry of watercould-however 'O'ringsand suchas sealingarrangements sectionsof insilation,consequently if doubleinsulationis to be more pressurebalanceterminationsshouidbeinCorporated effectivethansingleinsulation.

, t' | - _ - l

c t I

IsolatedEarth

Figure 2.I IsolatingTransformer Insulationshouldbe further improvedby supplyingthe load via an isolating transformer. This electricaldevice isolatesthe supply current from the load therefore making it impossiblefor a fault to eafih in the supplycausinga problemon the load side. The w6ole of the electricalsystemincludingthe transfonnersecondarywinding and all the appliancesare thusinsulatedfrom eafih. It is thenpossibleto makecontact with any point on the secondarycircuit without receivinga shock. This prevents,for example,tontactwith a cranewire from the surface,the leg of a stee.lplatform or a ship'shull from fornting an earthreturn path and therebycreatinga hazard..If a first defectis not rectified,contactwith the circuit or the occurrenceof a seconddefectmay causecurrentto flow througheitherthe ROV or a diver. This can be avoidedby incorporatingan activeproiectiondevicefor detectingthe fir.stdefect. The whole of the circuit: transformer;secbndarywinding; connectedcableand the load shouldhave a to earth. high insulationresistance

22

Current Carrying Conductors

Figare2.2 Double Insulation with a Conductins Screen 2.4.2.2 Fixed Barrier When electricalequipmentrequire^s directcontactwith seawaterto functioncorrectly e..8.an impre-ssed curent anodea fixed barriercan be installedto keep the ROV or diver a specificsafedistanceaway from it. This barriershouldbe non-metallicand non-conducting if possible.In additionto suchequipment,high-powerfixed installations e.g.cablesandnrotorscan feedlargecuirentsinto the waterif a fault occurs. Again fixed barrierscan be usedto keep the ROV or a diver at a safedistance. The safedistancecan be reducedby incorporatingan impedancein the starpoint to earthline of the supplyto limit the fault curent. Careshouldbe takento en.surethat all protectivedeviceswill function at the low level. A fault currentlimit of 1 amp is recommendedby the AODC Codeof Practicefor the SafeUse of Electricity L-nderwater. 2.1.2.3 Protective Clothing An1'practicewhich limits the flow of currentthroughthe body is beneficial.Rubber gJovesshouldbe worn and shouldhavea cuff to give the wriit areasomedegreeof protection.Wheneverhandlingthe ROV umbilicalthesetypesof gloveshouldbe $orn. 2.1.2.4 Shielding equipmentmay be enclosedwithin a conductingshieldto preventcurrent Jhe el_ectrical frromflowing into the water. Where a shieldis fitted it shouldbe suitablvconnectedto canh. to preventa dangerousvoltageby an internalfault. Protectivescrbensshouldbe sonsrructedflom high conductivitymaterialand havelow resistance joints, otherwisea fault current-flowingin the screencan producea dangerousvoltagegradientover its externalsurface.However,thisdeficiencycan be gr.eatlyreducedby the useof a

LJ

double screen.The conductingscreen,the externalscreenin double screenedsystems should also be in contactwith the water to restrict the voltage difference betweenthe screenand the surroundingwater. 2.4.2.5 Suitability of Earthing On any unit which operatesat a voltagewhich is higherthan the unprotectedsafelimit the conductive stmctureor frame shouldbe connectedto earth to dissipateany fault current. The connectionshouldhave a low impedanceto minimise any rise of voltage on the conductive structureor frame, and sufficient mechanicalstrengthto prevent accidentalbreakagewhen the equipmentis operatedwithin the statedlimits. The connectionshouldbe throughpurposedesignedconductorsin the power cables. The earth return path can be augmentedby an areaof baremetal, even corrodedsteelwill do, in contactwith the water; such an ilrangement can be many times more effective than normal earth leads. 2.4.3 Active Protection This form of protectionincorporatesdevicesinto the circuit which cut off the supply would a shortcircuit situationoccur. 2.4.3.L Residual Current Devices (RCDs) Commonly usedRCDs have a typical operatingtime of 15 to 25 ms. The trip currents of RCDs shouldbe selectedto be as low as possibleconsistentwith freedomfrom accidentaltripping which is inconvenientand can be dangerous.A trip currentof 30 mA at 20 ms. hasbeenfound to be suitable.

Figure 2.3 ResidualCurrentCircuit Breaker Any imbalancein the curents flowing in the positiveand neutralwindings trips the breaker.In a real devicethereis oftenonly one turn as shown.The breakeris held'on'

24

I

by magneticforces.The magneticcircuitis designed sothatonly a smallcurrentis neededto diverttheflux to analternativepathandreleasethearmature. Gonsumer's Load

Test Resistor

Test Button

-l-

Current Transformer

Trip Mechanism

Ph

N

SuPPIY

Figure 2.4 ResidualCurrentCircuit Breaker Type2 This type works in a similar mannerbut illustratesthe situationwhen an earthis included. 2.4.3.2 Line Insulation Monitors(LlM) A line insulationmonitor (LIM) may be usedto monitor the insulationlevel of an umbilical cableas it entersor leavesthe waterand any developingelectricalleakagewill be detected.A readout of insulationlevel shouldbeprovided with warningsof iow levelsif appropriate.In order to usean LIM as part oi an activeprotectiondeviceit shouldbe connectedto a circuit breakerto give suitableoverall systenloperating characteristics. 2.4.3.3 Toxicity of Materiats In the eventof a fire or even seriousoverheating,many commonly usedelectrical materialsgive off noxious and toxic fumes. aiit is oiten necessary to work in -cables confinedsp€c_es offshoreit is importantalwaysto uselow-toxicity and other materials.Full guidanceon the selectionof suchmaterialsis given in the AODC Code of Practicefor the SafeUse of Electricity Underwater.

25

2.5 Installation Practice portable and fixed electrical To maintain the integrity of all fomls of protection, staffshould

b8;'s"j;ii i;;il';;d 9v'ory4tll:l:f.i onlvsuchusedshould should equipment equipment electrioal or rewrrng,anoanytemporary #"il;il.tuli;;" usl ofElectricitv Safe the ihecode'oinittl.Jror #;6 #;;;;Jil;Gal"

should equipment Underwater.Con,.u.io.rr"$."SUfe ioiuna"t*ater electrical should staff Comrietent functions. toispecifii staffin writingascompetent authorise and hazards of the aware be and proceduies befamiliar*itt prope,TniiatLatibn shouldbemadefor Frequentilt!::"-,ont work' underwater to problemsparticular of^equipment. on cabresandfoiany gen^eral.deterioration ;;G; iiens of mechanicar of the test insulation i-;orporatedwith the6 minthly if;J#;;ffi;;;;-b" Ir uiuully completedto fulfil insurancerequirements' il;iii;;i;tri.tr 2.6 Batteries to beelectricallv'safe''As in many In thepastbatterieshaveusuallybeenconsidered asa reserveor back-up' casestheyarenot usedas?-nrim* p";;; t;;;.", Uutrather ln practice. batteriescan it"quently r*t*O ti"m el6aricalsafetyassessments. ;il;; them' using care'shouldbe takenwhen ;;;G;"".y r"at irur*as andconsiderable are discharged a limited life andwhen primarycetts(non-iectarg"uUf"batteriei)hav-e prinrary be can cells of nororiousror proouJ'i"n;;?;;;;ilp*d"cts. Short-circuitin'I piovided' tfton-.itcuiiptot..tionino'ld be andadequat. hazardous potentially arenomiallyofhigherpowerthanprimary r"rrr-t...t uigeaute'batte.ies) |;;;"dfi qpplyiIn additlon,however,thereis an cells,sothesameb;;ffr;;;;*nJuiiont andrecharging' dutit'tgdischarge ;;;i;r*; hazardfrom hydrogengar"sptod^uced a properly in surface the on out iifrorfA iormitty 5. t..i'tutg"d $iil;""ff ventilatedarea. 2 . 6 . t Su b me rg e dB a tte ri e s facilities'thecharge recharging arerequiredto havesubmerged If fixedinstallations extrac-ellsmaybe a"'etilt, a' shouldbelimitedto a levelbelowthegassing,roTtug., Wheredevices capacitv' batterv thirequii6d requiredto attaintfr. *otf.tng uottage-inO '"il be taken should care o^tioen. anO pt""r!J'i;;;h;,".;mUiiation"of ft* htd-''ten malfunction and e'iectrolyte the ro prevenrou.r.nu.iii;;iri;h ;t;y f"uat".'^"y?uet of anexplosiveor toxicgasmixture a baiteryconrpafiment, ;ii;; i."ii.. If wa-terinters wa.tertight' shouldbeconrpletely Batterycompartntents .Fuses *uV t. proOuced. and batteries the to possible as close as compartment battery shouldbefittedin the shouldbeencapsuLrr.Jio;iru.niublownfusefrom igniting,h"_p?.1:r-b^l,.P91ottn equrpment in battery-powered ;;;;ph;r; in iire.ontpu.ttn"nt.Thestateof batteries shouldbehandledwithcaution'Sincea Batteries shouldbechecki;;iG;r;. shockanda state,.a, batterycannotU" turn"i tii it tonttitutes'evenin alow-charge by metaltools.Electrolytesqtilageor carryUu-,1tt, if accideniaiyitrort-circuited Wherethereis any overcanutroproUOJ;i.;6g;puttt ftoniu highpotenti.al,te'rrinal'connections flexibleelectrical p"r.iuiiirv oi ietatiue*ou"*Enibetweenbatte-riei, shouldbe used. 2 . 7 E x p l o si veE n vi ro n me n ts shouldcomplyrvith of ROV'semployed.offshore In UK waters,thehandlingsystems 1976 Regulations Welfare) Hedlth'and fbli"*tional Safety, theOffshorernstatialions offshore an on, or of' means by from, SI 1019which.dll-; ily'activity (asdefined) locatedin hazardous aiadiusof 50bm. Thisrelatesto equipment o, Utfii,1 installation ;'...r;y to bedangerof likely is itt"te p;Jof theinsiutluionin which areasdefinedas; liquid.""' frc,-itie ignitionof gas,vapourof volatile Ft. o. explosion

26

The Pilotffechnician must thereforebe awareif he is working in a hazardousareaand suitableprecautionsmust be takenwhich might includethe following: 2.7 .I No smokingor nakedflames. 2.7 .2 Hot work permit may be requiredwhen working on the ROV 2.7 .3 Control and workshopcontainersmay needto be approvedfor electrically hazardouslocation by being configured to meet the requirementsfor purged enclosures.Altematively explosionproof componentsand intrinsically safe devicescan be usedinside thesecontainers,but the former is preferred.For further infomration on the requirementsof purgedcontainersrefer to the AODC OperationalGuidelinesfor ROV's page 126. 2.7 .4 Winch slip ring, junction boxesand terminationsmay needthe following modifications: i) explosionproof boxes,rigid metal conduit. ii) pressurisethe electricalsystemwith safegas. iii) fill the existing sysremwith oil. 2 .7 .5 Use explosionproof electricmotorsfor winchesand cranes. 2.7 .6 Deck cablesmay not meetthe requirementsfor steelarmouringthereforea cage deployedsystemmay be required,altemativelythe vehiclenray only be operatedwhen a hot work pemrit hasbeenissued. 2.8 Explosive Handling Explosivesare usedextensivelyduring someROV operations.It is imperativethat the personalsafetyprecautionsfor handlingexplosivesare adheredto. The work itself will be under the direct control of a qualifiedexplosivestechnicianwho will follow a written procedureand apply safeworking practices.The role of the ROV must be fully understoodand the work itself must be detailedin writine. A common safetv requirementfor this typeof work is to inrposea radio silince as it is possiblefor radio transmissionsto trigger sontetypesof detonator. 2.9 Mechanical Devices Thrustersand manipulatorson ROVs can be very powerful and may not behaveas expected.An electricalfault, for examplecancausea normallyplacid manipulatorto oscillateviolently due to a phenomenaknown as positivefeedback,causingimmense damage. It is importantto standclear of theseduring pre/postdive checksor whenever the vehicleis operatedon deck. For exampleit is importantto be surethat the systemis powere{ down beforeputting a handinto thrustersto clear obstnrctionsor for any other work of this nature. 2.10 Hydraulic Systems. ROV hydraulicsystemsoperatetypicallyat 200 Bar (3000p.s.i.)and,shoulda loose fitting causea leak for example,seriousinjuriesmay be caused.It is important thereforethat all personnelworking on the hydraulicsystemshouldbe qualified and have attendedthe relevantsafetyseminars,and that non-essential personnelstandwell clear of ROVs wheneverthe hydraulicsystemis underpressure.The work areashould be isolatedwith signsin lettersat least5 cm high stating;"DANGER HIGH PRESSURETESTING''.

),7

2.11. Lifting and Deploying the ROV seanor3j lifting h.eavyloadswith Many ROV Pilot/technicianshaveno experience_at of lifting time. The procedures first cranesor ruggersprior to goingoffshorefor the a represent can and operation the of anddeployii! tfre-nOVarEcrucialto the success Procedures conscientiously. and correctly ""iy gi.uit aietyhazardif not implemented toriifting equipmentand ROV deploymentmethodsarecoveredin the seamanship awareof secrionoTthisirandbook.Theobj6ctivehereis to makethepilot/technician to enableshim to assist procedures ih. tirkr that areinherentduring[aunch/recovery safelywi-thoutexposingtiirirsglfor othersto danger.At thetime with theseprocedures by relevantauthoritiesto determinethemostsuitable of writing itudiesareundenway Curreltpractisgas.laidout in AODC 036 (Revl) systemtestprocedures. deploymEnr "Theinitial andPeriodiiExamination,TestingandCertificationof ROV Handling is: Systems" Initial and period examinationand test of ROV launch and recovery systems.

a

i)

As New/Installed: Manufactureto a recognisedCodeof Standard' or s Standard Specification. B uild to Manufacturer' and Verify compliancewith NationalRegulations. 2. Staticload braketest at 1.5 x SWL. Functiontestat 1.25x SWL. 3. 4.Bothteststoincludeanyadditionalequiprilentwhich rnay be fitted to the ROV. NDT to be carried out on critical items. In Service: 1. Visualexaminationandfunctiontestat SWL' 2. Staticload brakeresrat 1.5x the weight at be lifted in air. NDT to be carriedout on critical items. 1.

ii)

b.

Initial and PeriodExaminationandTestof ROV Lifting Cable/TVire Rope and Terminations. i) 1. Z.

ii) 1. 2. 3.

As New/Installed: Verify compliancewith NationalRegulations. Load testto 1.5x SWL. In Service: Functiontestat SWL as an integralpart of the Lifting Systemandvisualexamination Staticload testat 1.5x SWL. umbilicalsshouldbe testedas above Electro-mechanical and re-terminatedat leastonceevery 12 months.

Theseshouldbe verified with the relevantauthorities(DnV, Lloyds etc.)on each mobilisationas standardsvary. 2,ll.l

Precautions i) ii)

Be awareof rigging safetyin generaland wear the appropriatesafety clothing i.e. safetybootsand hard hats. Do notitand behihdtuggersetc.Thete havebeenmaly nastyaccidents offshorewherebythe wlres havepartedand personnelhavecaughtthe fit guardsto tuggers. whiplash.If necessary

28

I iii) iv)

v) vi)

Practicelaunch/recoveryproceduresfrom a fixed platfbrrn before attemptingthem at seaand make surethat all the personnelinvolved are fully awareof their roles. ROV's can weigh typicallyaround1 Tonne. When this weightis lifted from a moving platform it representsa significanthazardtherefore;keep the lifting pennantas shortas possible,do not standbetweenthe ROV and any fixed structure,and handlethe ROV at arrnslengthto avoid it trappingany pafi of the personif the lifting mechanismshouldbreakor sliP. Do not leanover the sideof the ship and be awareof the locationof life savingequipment.It is wise to practicethe man overboardprocedurein fine weatherconditions. Tie all the equipmentdown and stow it correctlyduring periodsof heavy weather.

2.L2 Diver Observation ROV's have sufficient power to crushdivers or to dras them fror.r.r their worksite shouldthe umbilicalsbeconreentangled.Thereforeth! following precautions mustbe takenwhen working with divers. 2.I2.1 Precautions i) iD iii) iv)

Establishcommunicationswith the diving superuisorand be preparedto turn off the ROV power immediatelyon his instruction. Fit guardsto the thrusters. Whereverpossiblework down currentof the diver and take careto keep the umbilicalsapart. Use rlinimal thiustercontrols.

Reference:AODC GuidanceNote RemotelvOoeratedVehicleiDiver Involvement. (AODC 32) 2.13 The Nature of the Sea The hazardsof the seaarecoveredin the chapteron seamanshipso sufficeit to sayhere do not underestimatethe inherentdangersof wind, wavesand tides. 2.14 Teamwork and Communications Efficient and effectiveteamworkandclearand concisecomnrunications areessentialif ROV operationsare to be safeand competent.Theseskills are emphasisedthroughout the industryand theirinrportance cannotbe over-sffessed. Effectivecommunications must extendto the ship'sor platform'screw or any othergroupconcernedin any offshoreoperation. It is importantthat everyoneconcernedknows when the ROV goes into the water,when it comesout and whatit is doing. Similarlyit is essentialthe ROV crew all know their taskand what is requiredto conlpleteit. Finally it shouldbe noted "core that Safetyis a theme"throughoutthis book and will be found to be so on any recognisedtraining course.

29

= F

. . . other useful reference books on underwater working from the offshore specialists An lntroductionto ROVOperations

Remotely Operated Vehicles of the World Thrsnew book provrdesfor the first time a completeand

'what's 'who's definl'iive Lllustrated reference to what' and who' in this highly specLaiised field of underwater actlvrty

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In addrtion to gtivrng'up to date'and hrghly detailed lnformation on every ROV, includinq subseaploughs and other towed vehicles, it provides full editorial [strnqs of milufacturers, operators and vehicle development companies too. Other sections cover equipment/systems manufacturing compades and their worldwide agents, product listings coverrng lights, cmeras, manipulators hildling eguipment, buoyancy, flotation umbilicals cables and connectors, motors, thrusters, nav/tracking, sonar and acoustics md ROVsupportvessels. There ae also full directory listinqs of all companies involved in ROV operations and underwater contracting lncluding engineering and consulting fims.

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An Introduction to Diving Operations Offshore

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Ordering Il you would like to order any of these books or would irke a FBEEcopy of the O P I C a l a l o g u cl i s t i n g o v c r 4 0 0 m o p s .b o o k s , directories and databases contact us at the address given on the title page.

30

I

CHAPTER 3 TYPES OF ROV 3.0.0 Introduction 3.0.1 For the purposeof this book the term ROV shall meanan unmannedvehicle with a communicationandpower link to the surfaceby meansof a tetheror umbilical. ROVs are classifiedin the "Guidancenote on the safeand efficient operationof remotelyoperatedvehicles"(AODC 051 February1989)into five classes:-Class1 PureObservationVehicles,Class2 Observationwith Payloadoption Vehicles,Class 3 Work classvehicles, Class4 Towed or bottomcrawlingvehiiles, and class5 Prototypeor Developmentvehicles. In fact ROVs are a continuumof types and capabilitiesfrom simple video camerasto 'flying bedsteads'with any number of options, highly sophisticatedwork and surveyvehicles,bottom crawling vehiclesand specialone-offs. Any attemptto classifyall thesepossibilitiesleadsto confusionat the boundarieshowever,in this chapterwe will list and describesomewell known exampleswithin theseAODC classifications.Due to the ever growing number of typesand manufacturers this list is by no meansexhaustivebut servesto demonstrate the rangethat is available. J.0.2 Figure3.1 showsthe systemcomponentsfor a RCV 225 system. The basicsystem componentswill vary in their physicaldimensionsbut are comrnonto all ROV systems. They are;the PowerPackor PowerDistributionUnit (PDU), the control consulor operatorcontrol Unit (oCU), the SonarControlunit (SCU), the winch and FiandlingSystenr('A'Frame),the launcher,Garage,or TetherManagernent System(TMS), and the vehicleitself. Handling System

Power Pack

Figure3.1 ROV SystemComponents

Figure 3.1 ROV SystemComponents vehiclesinclude;The DeepOceanEngineering 3.1.0 Class1 PureObservation phantomand the BenthosMiniROVER. Theseare theoreticallyphysicallylimited to pure video observationrasksalthoughtheyhavemore recentlybeenmodified.with (CP) ih. fit-"nt of grabbersto accompliJhretrieval tasksor calTy.CathodicProtection 300. Phantom a 3.3 Figure and probes. FigurJ3.2 showsa MiniROVER

Figure3.2 Benthos,MiniROVER Mk II

Phantom300 Figure3.3 DeepOceanEngineering,

I

3.2.0 Class2 ObservationVehicleswith a PayloadOption include;the Hydrovision OffshoreHyball, the SeaeyeSurveyor,the PerryTritech Sprint,and the Bofors UnderwaterSystems/Sutec SeaOwl. Thesearevehiclescapableof carrying additionalsensorssuchas stills cameras,cathodicprotection(CP) measurement systems,additionalvideo cameras,sonarsystemsand wall thicknessor flooded memberdetectionsystem. A class2 systemshouldbe capableof operatingwithout lossof its originalfunction when carryingat leasttwo additionalsensors. Figure3.4 showsan OffshoreHvball and Fieure3.5 showsa SeaeveSurvevor.

Figure 3.4 Hydrovision,Hyball

Figure3.5Seaeye, Surveyor -')-')

3.3.0 Dia.blo'thePenyTritechSuper Vehiclesinclude;theHydrovision Class3 Workclass Trojan slingstvEngineering's OfT;h;;;;;pioneerand;;il;;;,;nd Scorpio,SubSea with fitted be to largeetioultt andMulti RoleVehicle(MRV). fn.r"*fticfes aie ind manlpulatiye Class fot"int"*tntion toot, and/orspecial 3^s$'. sensors additional to tools and sensors .upu'Uiiii'ufn*i"g add.itionil 3 vehicleswill havea multiplexing spare have will also be operatedthroughihe uehicle-sVste* The umbilical vehicleshave workclass "q"igpg* to allow ;;;i;;ii'^.yr""o conductors at Hp) to op€rate leastonethrusterin sufficientpropulsivepower(typicallyut f"u'it'SO ".ttiiui iii..tiont ylilst carryingadditional eachof the longituOiirf, rri#f-a 3'8 showtheSuper eig"i" :'Oifto*t" niuUfo-'figyt9t.3.'7,& toolingpackages. 3J.1showtheTrojanincludinga Scorpioincluding,1'fpii"it'.""t"r, iig"i"tl.rO-AandFigure3'13showstheMRV' ,h-"'Pi;.;; detaileddrawing,Fi';"i;3.it;h";t

Figure3.6 rllgg:"':lglPhP*

SCORPIS

ww{wfrffafn,irl{;i&

figure :7-F...y Tritech Inc, SuperScorpio

I E -,.

Figure3.tl Perry Tritech Inc, SuperScorpioPilotsC
?ROIAil

Trojan Figure3.9 Slingsb,v Engineering,

35

${*nipul*ttlrs TlX,*l5t*f*.i,

..,r,,,.,'''

H-r.draulis* RlecirieallX l**t:xrries l.:nrliliL'lti Tsriiii:l* l:.lilast

Figure 3.10 Slingsby Engineering Ltd' Trojan Detailed Schematic

Figure3.1I Subsea OffshoreLtd, Pioneer

Figure3.12 Slingsby Engineering, Multi Role Vehicle(MRV)

36

3.4.0 Class4 Towedor BottomCrawlingVehiclesinclude;Soil MachineDynamics(SMD) ROV 128and SMD'sModular EurekaTrackedVehicle,SlingsbyEngineering's Plough. Towed Vehicleshaveno or little propulsivepower off the seabedand are generallycapableof limited manoeuvrability.They travelthroughthe waterby the haulingactionof a surfacecraft or winch. Bottom crawling vehiclesmove primarily by exertingtractionforceson the seafloor via a wheelor track systemalthoughsome 'swim' limiteddistances.Figure3.l3 showstheEureka,Figure3.14 may be ableto s h o w st h eR O V 1 2 8 .

Figure3.13 SoilMachineDynamicsLtd, Bott
System Figure3.14 SlingsbyEngineering, ROV 12ttCableBurial/Retrieval 3.5.0 hereastheyarebeyond vehiclesarenot featured Class5 Prototype or Development 'Remotely read Operated is recornmended to thescopeof his book. Thereader (OPL) ROV's. Vehicles listing of availlable for a full anddescription of theWorld'

37

I

I CHAPTER 4

OFFSHORE STRUCTURES

4.0 Introduction Offshore oil and gas are the most important naturalresourcesto be discoveredin Britain this century. They are a vital commodityproviding energyand chemicalsto industry and providing revenueto the exchequer.Therehasbeenan enorrnousfinancial incentivefor the oil companiesto ventureoffshore,acceptingthe high risks involved, in order to exploit thesereserves.Sincethe first licencesfor North Seaexploration were issuedtn 1964over 112productionplatformshavebeeninstalled;which demonstrates the growth of the industryin this geographicalregion. World-wide there has beensimilar gowth in regionswhich have similar depositsof oil and gas. 4.0.1 Exploitation of Reserves In the searchfor oil the usualprocedurefollows a setpattern. Initial surveysare undertakenusing seismictechniqueswhich producedatafor interpretationby expert geologists.When a likely areais pinpointedwildcat explorationrigs aredispatchedto the areato testif thereare any reservesby drilling deepinto the seabed. If oil or gas reservesare found further pre-productiondrilling is undertakento determinethe extent of the reservesand provewhetherfull productionis viable. Oncecommercialviability is provenproductionfacilitieseredesignedand installedalong with all the infrastructure that goeswith offshoreoil field developmentsuchas,for exanrple,sub-seapipelines, underwatermanifold centresand offshoreloadinefacilities. 4.1 Offshore Structures Structuresoffshorecome in a variety of shapesand sizesand in a variety of materials. Productionplatformscan be of steelconstructionor of concreteand someof the steel platformsfloat and are tetheredin placeby cables. Thereare underwaterconstructions suchas wellheads,manifoldcentres,emergencyshutdown valveigloosand linear block manifolds.Therearemany hundredsof kilonretresof sub-seapipelines. 4.1.1 Steel Platfornrs It shouldbe rememberedthat offshorework is expensiveand thereforeproduction platformsare designedwith a view to doing all the fabricationashoreand minimising the work involvedin installationandrepairandmaintenance.In the main,production platformsare of steelconstructionand aredesignedto be easilyinstalledand maintained.Thereare severalvariationsof designfor this type of installationbut the majority areof the piled structuraltype. Someof the variationsare;tensionedleg platforms(TLP),jack-upplatformsand semi-submersible anchoredproduction facilities. 4.1.1.1 Piled Steel Production Platforms An exampleof this typeof structureis the BrentA Platfomrin ShellExpro'sBrent Field. Somefacts aboutthe nlatform are of interest. a)

Substructure Waterdepth. Productioncapacity Jackettype Numberof legs Numberof piles Weightof jacket

14m gas 100,00b/d oil and 2OOmmscfd Self floating steelconstruction 6 32 skirtpiles 14,225tonnes

39

Weightof piles b)

7 ,316 tonnes

superstructure Height of deck above sealevel Deck area Deck construction Deck Weights: Facilitieson deck ModulesandequiP.

21.7m 2,300m2 Plategirder 1,507tonnes 2,354tonnes 14,762tonnes.

^-*

Figure 4.1 BrentA

40

4.1.2 Concrete Gravity Platforms An exampleof this type of platform is CormorantA in Shell Expro'sCormorantfield. These than the steelplatforms and are not piled into the sea -1,. structuresare more massive " l. Hence the genericterrn gravity" for this type of structure.Again somefacts are of interest.

a)

Substructure Waterdepth

150m

Productioncapacity 60,000b/d oil and 30 mmscfd gas 1,000,000bbls Storagecapacity Caissonshape Square 57m Caissonheight 4 Number of legs Weightin air 294,655tonnes

b)

Superstructure Heiehtof deckabovewater

23m

Area of deck Deck construction Weights:Deck Ecluipment within deck Modulesandequip.

4.200m 2 Box girder 5,834tonnes 3,593tonnes 19,011tonnes

Figur e 4.2 CormorantA

41

4.1.3 Single Buoy Moorings World-wide there are a number of different variationson this type of loading facility. An exampleof an offshoreSBM which was initially usedby Shell Expro in the Auk oil field was the ELSBM (ExposedLocation SingleBuoy Mooring) and when in useit was located approximately 1 nautical mile from the Auk A platform. It was kept in place by 8 anchors,eachweighing 15 tonnesplacedin a 3000 foot diametercircle. The anchorcablewas 3" studchain. The mooring hawsersand the hoseswhich carriedthe oil to the tankerswere carried on large reels in the superstructureof the buoy.

Figure 4.3 Auk FieldELSBM

42

I

4.1.4 Pipelines There are thousandsof kilometres of pipeline laid on the seabed world-wide and although at first glancethesestructuresappearto be simple they are in fact just as carefully designedas all other types of offshore structureas the diagram, figure 4.4, of a typical field joint indicates.

SheetMetalCladding

Concrete Weight Coat Re-inforcement

FieldWeld

BitumenWrap or Dope Coating

Circumferential cuts in concreteto minimisedamage when pipe bends duringlaying

FieldWeld is covered with Black Bitumen underthe Sheet MetalCladding

PipeDiameterup to 36" WallThickness5/a"- 11/q"

Figure 4.4 Typical Pipe Joint 4.2 Loading of Offshore Structures Whatevertype of offshorestructureis consideredthe mannerof its reactionto the loadingimposedon it in servicewill be similar. The reactiondependson the properties of the materialsusedfor any particularstmctureand as an illustrationa brief descriptionof the propertiesof elasticmaterials shouldprove helpful. 4.2.1 Yield Stress When any componentis loaded,the materialinitially behaveselastically. This means that when the load is removed,the componentreturnsto its original size and shape. This will continuewhile thecomponentis in use,unlessthe yield load is exceeded. Yield stressis thereforethe stressat which the materialwill no longerbehavewholly elastically. If the loadingis continuedbeyondthe yield point, the materialwill deform and someof that defbrmationwill be pemranent.Therefore,if a structureor part of it is dentedo'r bent,it has beenloadedabovethe yield stress. 4.2.2 Ultimate Tensile Strength (UTS) If loadingis continuedwell into this region,it reachesa maximum value known as the ultimatetensilestrength(o urs ) . Attemptsto load beyondthis value will resultin the materialfailing by ductile fracture.Ductile fracturecan be identifiedby a largeamount of local deformationin the region of the fracture.

43

4.2.3 Brittle Fracture Brittte or fatigue fracture is by crack propagationwithout noticeablelocal deformation in the region of the fracture. Becauseof this lack of visible deformation, allY technique which cin assistin making it easierto detectcracks needsto be considered,and this needhas beenone of the riain driving forces behind the developmentof the science of for ductile and brittle fracturesee non-destructivetestins.For tensileteit characteristics Figure 4.5 -2 Fracture600 MN m i.0olostrail Glassfibre

UTS+00 MN m

Fracture30% strain

Stress o MN m-2

Strarn

Figure 4,5 for TensileTest Characteristics Ductile and Brittle Fracture 4.3 Stress Concentration It hasbeenfound that in a contponentunderload wherethereis a changein shapejust stressis very much higherthan elsewherein the locally at that changein shape,^the quantified by the strbssconcentrationfactor (K1 ) which is is This eTfect co-ponent. the rltio of maximunt stressat the changein sectionto the averagestress.This was first developedby ProfessorInglis when studying the causeof the formation of cracks from the .oinert of hatchcoveri in the decksof merchantshipsat the beginningof this cenrury. The effect of this is bestshownby consideringthe simpleexampleof an elliptiial hole in a flat plate. The flat plateis loadedin tensionin one directiononly with a stress,o, and in theplateis an ellipticalhole as shownin Figure4.6. The plate is so large that the loss of areadue to the cut-outcan be neglected.At the edgeof the cut-out at point A the stresswill be higherthan the averagestresso by an amountgiven by the Stressconcentrationfactor K1 suchthat the stlessat A = omax.= K1X O . The valueof K1 for this caseis given by the equation: K1=la2a b

44

E

Figure 4.6 Load on a Flat Plate with an Elliptical Hole It is worth examiningthis equationis a little more detail.Fig.5.7 showsthe variation of K1 with the shapeof the hole. It will be noticedthat the shapeof the cut-outand its positionin the stressfleld is important. The longer and thinnerthe cut-out (or defect) the largerthe stressconcentrationfactor K1 and hencethe higherthe maximum stressat the tip of the defect. The positionof the cut-outor defectin the stressfield is important.If the long sideof the cut-outis at right anglesto the maximum stress,the stressconcentrationfactor is higherthan if it runs in the directionof maximum stress. An awarenessof the fact that stresses are higherat changesof shapealertsthe inspector to areasmost at risk from crackingby fatigue. As thereis seldomsufficienttime to inspectthe whole sffucture,this knowledgeleadsto a more effectiveinspection programme. Someof the changesin shapethat will give rise to stressconcentrations and hencelead to increasein stresses in the strictureare: a b d e f g D

Nodejoints; Cut-outsin members; Holesin drilling templates; Weld profiles(unlessgroundflush with the parentmetal); Weld defects; Corrosionpits; Marks on the surfaceof the materialcausedbv accidentaldamaseor bad workmanship.

i3o

Figure 4.7 Variationof Stressconcentration As a crack grows, the value of K1 will increase.Becausethe value alb increases,this is sometimesiefened to as sharpeningthe crack.One of the standardengineering. emergencyremedialproceduieswhln a crack hasbeendiscovered,is to drill a hole at itre tlfi of ine crack,oflen referredto as crack blunting of -stopping..The ryasonfor this cun be understoodbecausethe stressat the tip of the crack will be high. Furthel gio*tfr of the crack will increasethe valueof K1 to an even highervalue (for a long thin J1ipr., this can be greaterthan 10). The drilling.of thehole.atthe tip.of the clack redirceithe high lodal stressat the tip of the crack,making the crack lesslikely to propagate,i.e. grinding out cracksreducesthe a/b ratio.

46

\

CHAPTER 5 ROV APPLICATIONS 5.0.1 Introduction The last ten yeiushavewitnesseda slow demisein the offshorediving indus0ry broughtabout,at leastin part,becauseof theresearchanddevelopmentput into makingsafer,morereliable,bettertooledandcosteffectiveRemoteOperated Vehicles(ROVs). CunentlyROVs areemployedon manysub-seataskswhich were formally undertakenby divers,suchasgeneralplatforminspectionsand seabed scour surveys.Reducinghumaninterventionon manyunderwatertasksalsoreducesrisk of injury or worseto personnelthis is a furthercompellingreasonfor reducingthe numberof diversoffshoreandcountriessuchasNorwayhavea governmentpolicy to legislateagainstall diving on newprojectswithoutdispensation.It is the intentionof this chapterto discussthe mostcommontaskscarriedout by ROV'stheseinclude:/ PipelineInspection '/ Drill Support r PlatformInspection Intervention I CableLaying I Construction ROTV Mine CounterMeasures Anti-tenorism/Drugenforcement l

5.1.0 PipelineInspection The annualinspectionof pipelinesin theNorth Seaformsthe bulk of ROV operations during the summermonths. CurrentlyROVs operatefor periodsof up to 70 hours virtually non-stopandthe latestacoustictechnologyrecordsdetailsof thepipeline's integrity with greataccuracy.Thesefactors,alongwith improvementsin subsea video camerasmeanthat ROVs aretheprimepipelinesurveymethod. 5.1.1 Normal VehicleFitment A standard'Workclass'ROVwill normallyhavethefollowing equipmentand sensors: Thrusters Front andBack SIT Cameras Lights RangingSonar Manipulator

47

PanandTilt Mechanism EmergencyAcousticTransPonder EmergencyHigh IntensityFlashingLight Gyro Compass Power,Control,Instrumentation HydraulicPowerPack VehicleDepthSensors Vehicle Altimeter 5.1.2 Additional Fitment Specificto PipelineSurvey In additionto the abovea'surveypackage'willbefitted specificallyto enablethe of a Pipelinesurveycontract. This vehicleto meetthe specificationr6quirements packagewill usuallyinclude: Twin boomswith full colourvideoandadditionallighting Still camera camera Possiblystereo/photogrammetic Strobelights for still c:uneras SidescanSonar Pipetracker SubBottom Profiler CurrentDensityMeter/ContactCP Probe TemperatureandSalinitySensors AcousticResponder Odometer This surveyequipmentis explainedin the following paragraphs. 5.2.1 Twin Booms Prior to undertakingpipelinesurveywork an ROV will be fitted with twin booms, thesearefitted to eachsideof thevehicle. Theseboomsaredeployedandadjusted, hydraulically,oncethevehicleis at theworksiteandon thepipeline. Colour usually -czuireras lights will be attachedto eachboom. Thesecanbe andthe associated video individualtypositionedto achievethebestview of eachsideof t!9 pipe._!he type andmodelbf video camerawill vary andthesearedescribedin Chapter15 UnderwaterVideo. The lights will be of variableintensity. The maximumpower will dependon a numberof factorswhich areoutlinedin Chapter15 also. As a.guide, however,at least1000Wattsof poweroutputwill normallybe requiredto obtainthe correctlighting from a distanceof 1 meterfrom thepipe.

48

Responder

Transponder

0.25metres

l-

0.6metres

Responder( 0 m , 0 m )

Flower Pot

BathyUnit

/

I

\ Transponder

0.72metres

I

-ptpETRACKER

\Additional

Equipmenr

* BathyUnit

Lights -+

ColourCamera

,/ Survey Sled

-rrditionalEquipment='ont and RearSit Cameras S--:lls Stereoor Photogrammatic S:ob€

Figure5.1

49

D.H.SS.PROTIIER

DIYE OOI

AN9TE 035DEG START

DATE I.I.92

ANGTE I45 DEG STOP .|.8 gTtPslzl DEG

59-59-23

Tlill

AUTOilAnC 00 SEc

I43OM/S SOUNDYEI.OCITY ttP HORTZ

l.2M

HEADON PORT

VTRTSEP

,OsM

'TBDHEADON

looolNo oFF

SilIDHIAD HIGHER

L

L

6 t

'.

?

sr l

k a

lD

"":-"''"

9r. ,

o

'T

!

,

'

J

\

i

i.

"ir. .-:. '.rLC-r

n"'

.l

i

,l

irr.

:.r

gl,d.ilr*, I l..r*irp4r.r

,6r.';;$

r. a r .o *q;-1 .;1:r!-tr;'!!rrl'l.

Figure 5.2

50

nigry."5.1 illustratesthe varioussurveykit anachedto an ROV during a typical pipelinesurvey. 5.2.2 Stills Camera The stills camerawill usuallybe fitted to thepan andtilt mechanism,andmay be eithera mono,stercoorphotogrammetictype-.Thesecamerasare explainedinthe C..hapte1 l6.UnderwaterPhotogqphy. Wiitr tfrestills cameraattachedto the pan and tilt mechanlsqphotographscan6e takenfrom variousanglesasthe Rov is' manoeuvredalongandaroundthepipe andan indicationof *re field of view will be obtainedfrom the video ciuneraon tfie samemechanism. 5.2.3 SideScanSonar Sidescansonaris a.particulartypeof sonarthattransmitsin a sidewaysdirection enablilg.aplal 9f tle seabedtopographyto be plottedasrheROV nivels alongthe pipe. This enablesthe positionof topogaphicalfeatures anddebrissuchasbou-lders or trawlergearto be recordedrelativeto tlie pipe. 5.2.4 Pipetracker Pipetrackersusuallyoperateontheprinciplesof magnetism,hence,they areusually known as 'magneticpipetrackers'.An exdmpleof th-isis theTSS 340 wtrictris in commonuseoffshore Thesearefitted to ROVs to locateandtack ferromagnetic pipg 9rd cables. They usea passivesensingtechniqueto give the operatorirelative positionof thepipeor cable. somemodelshavea'SEARCH'and'StctgAtuRe ANALYSIS'mode which_allows anyfield anomalyto be pinpointed,anda full signatureanalysismadeifrequired. Pipetackershavea p^arti^cularly usefulrole in trackingpipe thatis buriedandtherefoiecannotbe foilo*ed visualiv andversionsare in useto follow andlocatefaultsin buriedtelecommunications cabl6. 5.2.5 sub Bottom Profiler and rrenching Profiler (DHSSprofiter) The Dual HeadedScanningSonar(DHSS)Profileris an acousticdevicethat enables a profile of the seabedto beobtained.It accomplishes this by steppingtwo (onepositionedon eachsideof thev:ehicle;fromihe ddtwira horizontal transducers to the verticaldownwardsposition. Thedistancesfrom eachheadto the seabedor otherfeatureis recordedasa sonarreturn. The DHSSProfileris essentialfor determiningthe^'Depth of Burial' of a pipeline,thedepthof a Eenchor the lengthof a 'Free-span'.A 'free-span' is an unsuppbrted lengthof pipelinewhich may be citical if thereis ?ny Possibilityof movemen[of thepipe. figtird 5.2 illustratesa cross sectionalview of-p1peanqseabedrecordedfrom a profiler system.Modernprofiling sonarcanbe usedfor both subbottomandtenching applicaiionsandareavailableiri both singleheadedanddual headedmodels. 5.2.6 Current DensityMeter/ContactCp probe A CurrentDensityMeter andContactCP (CathodicPotential)Probeare usually attachedto the manipulatorfor useon exposedareasof pipelineor anodes.Thb principlesof operationof theseis that they monitorthepotentialto corrodeof any glposeametalon the pipelineandtheeffdctiveness of anodes.The CurrentDeniity Metermeasuresthe CurrentDensitywhich indicatesthe CP coverandthe Contact'Cp Probemeasuresthepotentialof theexposedmetalwith referenceto the silver/silver chloridehalf cell in mv andis expectedto be within the following ranges: Unprotectediron andsteel

-500to -650mV

Cathodicallyprotectediron andsteel

-800to -900mV

5t

I : l

-1000to -1050mV

Zinc (Anodes)

The contactCP probeis usedbecauseit is inconvenientto maintainan earth with the pipe on a movingvesselasis requiredwith the Proximityprobe conne,ction which is normallyusedfor platforminspections. but full The aboveinformationis to enablethePilot to havea basicunderstanding informationincludingcalibrationmethodsis includedin the CSWIP3.3uROV inspectorscourseandhandbook. 5.2.7 Temp and Salinity Sensors Thesemeasurethe temperature andsalinityof the waterduringoperations.Often thesearecombinedwith an accuratedepthfiansducerto form a Bathymetricsystem. 5.2.8 Acoustic Responderffransponder/Pinger An acousticdevicewill be attachedto the top of thevehicle. Therearethreegeneric types:Pinger- This repeatedlyemitsshortpulsesof acousticenergyat a set frequency.This canbecontinuousthroughoutthedive or canbe initiatedin the eventof a powerfailureto thevehicleto enablethe crewto locateit and effect an emergencyrecovery. Transponder- This emitsshortpulsesin responseto interrogationfrom the will haveits own codeand vesselor othertransponders.Eachtransponder manytransponders canoperatetogethereachrespondingto its own code receivedacousticallyandbeingdisplayedby individualsymbolson the PositioningReference(HPR) System. surfacedisplayof the Hydro-acoustic Responder- This is similarto theTransponder exceptthat it respondsto an elecffonicsignalsentthroughtheumbilical. This is'moreaccuratethanthe transponderbecausethereis only a oneway propagationof acousticenergy throughthe water. Calculationof throughwaterrangeandbearingsis subject to errorsdue to variationsin soundvelocitiesdueto variationsin the waters density,temperature andotherbathymetricconditions. Thesedeviceswill allow the surfacevesselto trackthe vehicleandrecordthe position of the ROV relativeto thevesselasthe surveyprogresses. 5.2.9 Odometer The Odometeris a devicemuchlike thewheeleddevicesthat Surveyorspusharound to measuredistances.For ROV applicationsthesearetypically usedto measurethe distanceof an areaof damagefrom thenearestFieldjoint andto measurethe depth producesignalstansmittedthrough andextentof the damageitself. Potentiometers the umbilical to the surfaceto indicatethenumberof turnsof thewheelandits displacement. 5.3.0Additional Instrumentation Required for PipelineSurvey. In additionto the equipmentfitted to thevehicleit is necessary for navigationand controlpurposesto haveadditionalsystemsotherthanthosealreadyoutlinedabove.

52

5.3.1 SurfaceNavigationSystem The surfacevesselwill constantlyfack its positionwith the aid of radio beaconsor satellitenavigationsystems.Examplesof radio systemsare;Decca,Sylledis,and Pulse8. Theserequireland or platformbasedffansmittersto accuately (Usuallywell within I meter)positiontheshipusuallyin termsof 'Northings'and'Eastings'. It is becomingmorecommonrecentlyto positionthe surfacevesselwith GPS(Global PositioningSystem)Satellites.Theseareupdatingquickerandbecomingmore accurate.Dependingon the Globalareathe surfacevesselis in, the particularsystem in useandthe numberof satellitesin usethe accuracycanbe between+/- 50m at worse+/- 10masthe norm and+/- 2m at best. 5.3.2 Telemetry System This systemenablesconffol,instrumentation, sensor,andpossiblevideo signalsto be communicatedbetweenthe surfacevesselandthevehicle. Eitherelectrical conductorsor opticalfibresareusedto carrythe signalsin digital form. Fibre Optic telemetryhasthe following advantages overconventional'HardWired' telemetry:a)

A higherupdate(Baud)rate

b)

No electricalinterference

c)

Negligiblesignallossthroughthelengttrof the umbilical

Fibre opticshavethe disadvantage that thefibresmaypart andmay consequentlybe moredifficult to join or re-terminatein the field. Thepaft of the telemetrysystem that switchesthe informationonto theline in sequence is known asthe multiplexer. It is preferableto usea fibre optic telemebry systemfor pipelinesurveywork due particularlyto the very largevolumeof datathat is requiredto be ransmittedto the surfaceand the enhancedvideoqualitythat is possible. 5.4.0 Drill Support This sectionoutlinesthe variousstagesof thedrilling prograrnmeandindicatesthe areaswherethe vehiclecanprovidevaluableassistance.Beforethe programme commencesthe operationscontrollershouldadvisethe drilling supervisorof the capabilitiesof the vehicleandwhereit canassistthedrilling operation.Thereis a tendencyto underestimatetheassistance thatan ROV canprovideto a dritling operation.For this reasonan overviewof the taskshasbeengiven,thesewill be explainedlaterin the chapter. 5.4.1 OverviewTasks Generaltasksto assistwith the overalloperationwill include: a)

Surveysiteand seabedprior to spudding-in.

b)

Acousticbeaconplacementandrecovery.

c)

Guidanceof packagesandtools.

d)

Observationandguidanceduringcritical drilling sequences.

e)

A-X ring replacement.

f)

EmergencyBOP or packagerelease.

53

g)

Debrisremoval.

h)

Recoveryofdroppedobjects.

D

SettingWellheadcharges.

j)

Guidewire cuttingandreplacement.

k)

Settingguidepostcuttingshapedchange.

5.4.2 Drilling Programme The following sectionoutlinesa typicaldrilling prograrnme.At eachstageof the is given. drilling operationa brief descriptionof thevehiclesassistance Vehicle Programme

Drilling Programme 1)

Rig on site

Surveysiteand seabed prior to'spudding-in'.

2)

Drilling to set30" casing

Placemarkerbuoys to assistin well relocation.

3)

30" casingstab-in

Observerelativepositionof casingto hole. Adviserequired directionto move. Use sonarto providedistanceof casingto markerbuoy andadvisewhen readyto stab-in.

4)

30" casingcementing

Monitor cementoperationand checkbulls eyeon guidebase.

5)

Drilling to set18 5/8" casmg

Observeenffy to guidebaseand assistby pushingif required.

6)

18 5/8" casingentry

Observeentryto guidebaseand assistby pushingif required. ObserveBOP latching operation.Checkbulls eye and ball joint inclinometeron stack. Carryout full inspectionof stack, lower marineriser packageand riser/conductor.

7)

Drilling to set 13 318" 9 518"7" conductors

At this point in the programme thevehiclechangesfrom an activeto passiverole. It is that regularchecks recorrrmended on the stackare carriedout and the distanceanddirection of the beaconto the stackcrosscheckedby sonar. Othertask requirementswill dependlargely on theproblemsencountered during the drilling progranrme andcouldvary from locatingand recoveringdroppedobjectsto

54

ffi" ;ilTf:ff I'*ii:,l',*"'ffi The programmeoutlinemayvary dependingon thetype of well, or rig andthe depth beingdrilled. A copy of the actualwell programmewill be availablein the drill supervisorsoffice. 5.4.3. Liaison with Drilting Staff It is preferablethat beforemobilisationthedrilling supervisor(s) and sub-sea engineer(s)arecontacted.Not only to outlinethe assistance thevehiclecanprovide but alsoto verify the equipmentinstallation,the typeof stackin useetc. A greatdeal of time canbe savedat this stageandpossibleproblemareasironedout. Also, it is worthwhilepresentingoptionalequipmentsuchastheemergencystackreleasepanel andA-X ring replacementsystemsothat fitting requirements, configurationand positioningcanall be verifiedin advance.A very usefulpreparationis to paint tools andequipmentthat areto be usedunderwaterwith white markingsto enablethemto be moreeasilyseenby the vehiclesvideocameras. 5.5.0 Blow Out Preventer(BOP) This is a safetydeviceinstalledat the top of the well thatcantypically be 10 metres in heightandweigharound150Tonnes. 5.5.1 Functionsof BOP Shoulda drill stringreachan areaof pressurethatis higherthanthe hydraulicheadof pressureexertedby thedrill mud thena blow out or'kick' will occur. This resultsin an unconfolled blow out of mud followedby oil or gas. The BOP allowsthe well to be shutoff whilst heaviermud is pumpeddowntherebybringingthe well under control. 5.5.2 Operationof the BOP The BOP containsoneor morepairsof ramsmadeof steelor toughrubber. Shoulda blow out occurthenthe ramsarehydraulicallyclosed.Therearetwo kinds of rams Pipe(choke)andshear(kill). The kill ramscut throughthedrill pipe andsealoff the well. Chokeramscloseandsealaroundthedrill pipe. Both ramsareheld in place, onceactivated,by hydraulicpressure.Oncethis taskhasbeencompletedheavier mud is pumpeddownthe flow andchokelinesto the drill stringbelow therams whilst the drilling operationsandBOPareshutdown until thepressuredue to the headof mud is greaterthanthe pressurefrom the gasor oil in the formationthereby stabilisingthe situation 5.5.3 Taskson a Blow Out Preventer a)

Checkkill line connector

b)

Inspectslip joint, flex joint andhoses

c)

Guideline replacements

d)

Align riserinto BOP

e)

Checkconnectionof productionconffol systems

0

Manuallyover-ridinghydraulicconnectorfor lifting BOP

55

g)

ChanginggasketbetweenBOP andconnectorhousing

h)

GuidingBOP into placein wellhead

D

of transponders Deploymentandreplacement

5.6.0 DetailedTasksDuring Drilling Operations for the varioustasksthe The following area possiblesetof detailedprocedures vehiclemay be requiredto cary out duringthe drilling operationsoutlinedabove. do not Drilling suiport Task Proceduresa.redescribedin detail herebecause.they appearlnany of our otherHandbooks,whereas,o,nlygqoleryi_eyof inspectionTasks is includedastheyareincludedin detailin the CSWIP3.3uROV Inspectors Handbook 5.6.1 Seabed Survey a)

t9 F lury.I"d. This is normallydone Locatethe centreof the ar-ea usinga mini beaconandtherig/shipHydro-acousticPositioning ReferenceSystem(HPR).

b)

Carryout a 3600sonarsearchandenterthe relativepositionof any targetson the log sheet(seeFig. 5.3).

c)

Locateandidentify any significanttargets.Notethe dimensionsand composluon.

d)

Passthe informationto thedrilling supervisor.(seechartFig. 5.3)

5.6.2 PlaceMarker Buoys The reasonfor placingthesebuoysis to allow easyre-locationof the hole after the reducetime requiredfor the 30" casingstab-in. 36" bit is withdrawnandconsequently a)

Make up two markers.Theseshouldbe singleanddoublewhite paintedGrimsbyfloatsattachedto suitableweightsby approximately 5 ft of line. (one200 mm dia...metalGrimsbyfloat givesabout4 kg uplift).

b)

Prior to the field stringbeingrecoveredlaunchthe vehicleandplace the markerbuoysusingsonarat thepositionsindicated.SeeFigure 5.4

NOTE: c)

The doublebuoy shouldbe placeddueNorth of the stringandthe singlebuoydueSouthfor easeof orientation. Ensurea video hookup with the bridgeandthedrill floor is functioning. Recoverthevehicle.

56

Date: Vessel:

DiveNo:

Tape No:

Seabed Survey

Location:

Note: The Centre Axis is the Soud-in Location

t

Figure 5.3 DrillString

-/

t l

- t t -

tt ll t l

It

Seabed

L_J

l

Figure5.4 57

(

5.6.330" CasingStab-in 1)

Whenthe 30" casingis 2 to 3 joints from the seabedlaunchthe vehicle.

2)

Descendon the casingandwhenat the basecarryout a sonarscanfor the Grimsbyfloats.

3)

Passthe relevantdirectionsto thebridge. It is betterto agrcebeforehandon the procedurehereand it is that-"goto" directionsaregiven. i.e. movethe casing30 suggested feeton a headingof2700.

NOTE:

4)

with boththe buoysandthe baseof Oncevisualcontactis established the casingin view the vehicleshouldremainon a constalt hga{ingeitherto lhe North or Southof thecasing.This will enablethe bridge to work from a knownorientationandmakethe final adjusfinents to bring the casingbetweenthe 2 buoys. necessary

5)

Whenthe casingis betweenthebuoysthevehicleshouldcloseup on onesetof buoysandindicatetheNorth or Southmovementrequiredto centralisethe iasing. It shouldbe notedthat while not usuallyobvious the hole diameterai the seabedis approximately6 ft andprovidingthe orderto stab-inis givenwhenthecasingis abovethe hole it will gravitateinto the hble (a hundredfeetof peneffationis_possible. iryithouttherebeinga hole). It is possiblefor thevehicleto puqh,the. casingover the hole andthis is ofteneasierthanmovingthe wholerig by adjustinganchortensions.In orderto accomplishthis the vehicle havda locatingframeattachedandthe casingshouldbe marked s6oul-
6)

While the casingis beingfed in thevehiclecanstandbyon the seabed until the guidebaseis inposition (normally5 ft abovethe seabed). The baseshouldbe checkedto ensureit is level and,if required,the bull's eyecanberecovered.

NOTES: 7)

To allow removalof the unit on oneoccasion.anold A-X ring was weldedto a guidebaseandthebull'seyefitted to this After checkingthe guidebasemonitorthe stringto casingunlatching operationandrecoverthevehicle.

5.6.430" CasingCementing 1)

thelaunchtime. to determine Liaisewith thedrill supervisor

2)

The vehicleshoulddescendon the riserandtakeup a positionup currentof the guidebaseto preventtheobscuringof the visibility.

3)

Checkthe cementis over spillingaroundthe guidebase.Usuallythe excessvolumeallowedis 100- I507o.

NOTE:

It is quitedifficult, especiallywhereonly monochromevideo is used, to diflerentiatebetweenmud,in filland cementhoweverwith practise it is possible.

58

4)

When-thesupervisoris satisfiedwith thecementingoperationrecover the vehicle.

5.6.5 Drilling to setthe 18 5/8" Casing 1)

Whenthe 30" casinghasbeencementedthe bit will be loweredto drill for the 18 5/8" casing,3-4joints off the guidebaselaunchthe vehicle.

2)

Monitor thepositionof thestringto guidebaseanddirect asnecessary.

3)

Assistby pushingthe stringinto the guidebaseif required.

NOTE:

4)

The deeperthe seayater depththeeasierit is for the vehicleto push the stringinto position,but thePilot shouldbe wary during strong currents. Whenthe sning is in positionrecoverthevehicle.

5.6.6 l8 5/8" CasingEntry The procedurehereis similarto thatoutlinedfor the30" casingstab-in. 1)

Whenthe casingis within 3 joints of the guidebaselaunchthevehicle.

2)

Assistir.tgujdilg thecasingto theguidebase,by pushingif required. The casingis fed in until it is approximately4 te€tabovethe b6ttomof the.permanent_guide base.Monitor the sring beingdetachedfrom the casing( a left handthreadconnectsthetwo).

3)

It is normalto fit the stackat this stage.Checkwith the supervisoron the time spanaq{ basedon this it maybe worthwhilekeepingthe vehicleon standbyon the seabed.

4)

Monitor the stacklatchingoperation.Dependingon how modern the rig is thiswill be an 18_ 3/4" 10,000psi unit or 20 3/4" 2000psi stack. In thelattercasea 30 5/8" 10,000psi unit is fitted at a later stage. Verify the degreeof tilt on the bullseyes.

5) 6)

Checkthe angleometer(s) on theball joint (wherethe lower marine riserpackagejoins the BOp).

7)

Cany out a full inspectionof the stack. Ensuresonarreflectorand beaconarmsarein thecorrectpositionandthatno oil leaksor damage is apparent.

8)

Ascendon theriser/conductor andinspectthis andhoselinesfor damageandsecurityof attachment.

5.7.0 PossibleTasksRequirements The following-tasksoccurlraphazardly duringthecourseof drilling operationsand may be carriedout only infrequently.

59

5.7.1 A-)VV-X Ring Replacement(Hydraulicallyoperatedunits only) The metalgasketwhich sealsbetweenthe guidebaseandtheBOP is usuallycalled the V-X ring andthe gasketthat sealsbetweentheBOP andtheLower Marine Riser Packageis usuallyknown asthe A-X ring. If thesefail two choicesareoPe! to the supervisor:roundtrip the stackandeffectthechangeout on surfaceor lift the stack clear,ejectthe A-X ring andhavethevehicleplacea newring in the guidebase. The methodchosenwill largelydependon thedepthof seawaterandconsequentlythe procedurefor a vehicle roundtrip time for the stack. Howevertherecommended changeout is listedbelow. 1)

with the instruction Fit the A-X ring carryingframein accordance supplied.

2)

Checkout the system,fit the A-X ring in positionandlaunchthe vehicle.

3)

Descendon the riserandmoveinto thepositionover the guide baselBOP.

4)

Exactpositioningof thering in the guidebaseis critical so ensurethat the self centringframeis levelprior to ejectingthering. When satisfiedthat thepositioningof thevehicleis correctoperatethe verticalthrusterpot to give60Voof down thrustandactuatethe A-X ring tool.

5)

Ascendclearof theguidebaseandvideotheunit in position.

6)

Monitor the stackreplacement andstandbywhile it is latched.

7)

Liaisewith the drilling supervisorandrecoverthevehiclewhen appropnate.

5.7.2 EmergencyBOP or PackageRelease This taskwill only be requiredif the stackor marineriserpackagecannotbe hydraulicsystemsfail. conventionallyreleasedi.e. if theprimaryandsecondary However,it only needsonesuchfailurewith worseningweatherconditionsto back-upsystem,which canbe independently validatethe needto havea separate operated.The emergencystackreleaseandlowerpackagereleasepanelsmustbe premountedon the stackandplumbedinto theexistingsystem.The following procedure could be usedwhenthis taskis undertaken. 1) 2)

Fit the emergencystackreleasepanel tool to the manipulator. "hot line" to the quick connect and fit this Fit the rig supplied to the tool. Allow a reasonableamount of slack to allow for the manipulator rotation before taping the hose to the vehicle. (NB ensure the tape can be broken after hose is connectedto panel).

3)

Launch the vehicle and descendon the riser. Once at the stack go to the appropriatepanel and turn off the valve

4)

Insert the quick connect into the guide cone and ensurea positive lock before releasingthe hose.

6L)

I

5)

Oncethe hoseis connectedadvisethedrilling supervisor,breakfree of the tapeholdingthehoseto thevehicleframeandstandbyto monitor the unlatching.

6)

Whenhe stackis unlatchedrecoverthevehicle.

5.7.3 Debris Removal Smallitemsof debrisor transponders may beremovedby thevehiclewithout assistance simply by takinghold of it with the manipulatorhowever,wherelarge, heavyobjectssuchasdroppedlengthsof drill stringrequiremovingassistance from the drill floor will be required. 5.7.4 Recoveryof Large Dropped Objects This taskmay crop up from time to time andthe item canvary from a drill stringto a completestack. As the vehicle'slift capabilityusingthe manipulatoris in the orderof 90 kg it will often be necessary to attackhooksor slings. This is a common-sense taskandthe following guidelinesarepresented asa guideonly. 1)

Liaisewith the necessary personnelto determinethe exactshapeof the object(s),its approximate weightandsuitablelift attachmentpoints.

2)

Basedon the informationsupplieddecideon the methodof recovery, i.e. slings,singlehook,net,multiplehooksor stringdeployedretrieval tool.

3)

While the slings,wire ropes,hooksor stringdeployedretrievaltools arebeingfashionedandloweredlaunchthe vehicleandlocatethe object. Mark the positionrelativeto the well headandstandbyfor toolsto be lowered.

4)

Attachthe recoverytool andensuretheobjectis lifted clearof the seabedbeforerecoveringthevehicle.

NOTE:

It is goodpractiseto ensurethatthevehiclealwaysremainsabovethe objectbeinglifted in casethe lifting deviceshoulddisengageandthe objectfall ontothe vehicle,the speedof lift shouldbe variedif difficulty in achievingthis is experienced.Clearthis point with the rigger/chargehandprior to thelift commencing.

5.7.4 SettingWellheadChargm This will normallybe caniedout from a shipafterthe well hasbeenpluggedand abandoned andtherig hasmovedlocation. The primarytaskof the teamwould be to locateandmark the Wellheadthenfollow theexplosiveexpertsdirectionfor placing the charge.It is recommended thattheROV Supervisoris awareof all the necessary precautionsfor handlingexplosivesandthattheexplosivesexpertgivesa safetytalk to the teamprior to mobilisation.This talk shouldcoverthe methodandprocedures for placinganddetonatingthecharge. 5.7.5 Guide Wire Cutting/Replacement Wherea guidewire systemis usedthevehiclemay berequiredto cut andreplacea wire. It shouldbe notedthatthe standardrig equipmentcannormallycarry out this taskwithout assistance by usingthe remaining3 wires. However,whereequipment

6l

I

5)

Oncethe hoseis connectedadvisethedrilling supervisor,breakfree of the tapeholdingthehoseto thevehicleframeand standbyto monitor the unlatching.

6)

Whenhe stackis unlatchedrecoverthevehicle.

5.7.3 Debris Removal Smallitemsof debrisor transponders may beremovedby thevehiclewithout assistance simply by takinghold of it with the manipulatorhowever,wherelarge, heavyobjectssuchasdroppedlengthsof drill stringrequiremovingassistance from the drill floor will be required. 5.7.4 Recoveryof Large Dropped Objects This task may crop up from time to time andthe item canvary from a drill string to a completestack. As the vehicle'slift capabilityusingthe manipulatoris in the orderof 90 kg it will oftenbe necessary to attackhooksor slings. This is a cornmon-sense taskandthe following guidelinesarepresented asa guideonly. 1)

Liaisewith thenecessary personnelto determinethe exactshapeof the object(s),its approximateweightandsuitablelift attachmentpoints.

2)

Basedon the informationsupplieddecideon the methodof recovery, i.e. slings,singlehook,net,multiplehooksor stringdeployedretrieval tool.

3)

While the slings,wire ropes,hooksor stringdeployedretrievaltools arebeingfashionedandloweredlaunchthe vehicleandlocatethe object. Mark the positionrelativeto thewell headandstandbyfor toolsto be lowered.

4)

Attachtherecoverytool andensurethe objectis lifted clearof the seabedbeforerecoveringttrevehicle.

NOTE:

It is goodpractiseto ensurethatthe vehiclealwaysremainsabovethe objectbeinglifted in casethe lifting deviceshoulddisengageandthe objectfall ontothevehicle,the speedof lift shouldbe variedif difficulty in achievingthis is experienced.Clearthis point with the rigger/chargehandprior to the lift commencing.

5.7.4 SettingWellheadCharges This will normallybe carriedout from a shipafterthe well hasbeenpluggedand abandoned andtherig hasmovedlocation. Theprimarytaskof the teamwould be to locateandmark theWellheadthenfollow the explosiveexpertsdirectionfor placing the charge.It is recommended thatthe ROV Supervisoris awareof all the necessary precautionsfor handlingexplosivesandthatthe explosivesexpertgivesa safetytalk to the teamprior to mobilisation.This talk shouldcoverthe methodandprocedures for placinganddetonatingthecharge. 5.7.5 Guide Wire Cutting/Replacement Wherea guidewire systemis usedthevehiclemay berequiredto cut andreplacea wire. It shouldbe notedthatthe standardrig equipmentcannormallycarry out this taskwithout assistance by usingtheremaining3 wires. However,whereequipment

6l

necessitates theuseof thevehiclepossibleguidelines failure or othercircumstances for this taskarelistedbelow. 1)

Launchthe vehicleanddescendto theguidebase.

2)

Cut anyremainingwire protrudingfrom the post. This shouldbe cut ascloseaspossibleto thepostandthe stubfed insidethe post.

3)

Placelatchreleasetool overexistinglatchandlift unit clear.

4)

Locatethe new wire and grip immediatelyabovethe latch, the closer the better.

5)

Manoeuvrethe vehicleinto positionabovethe postandplacethe cone of the latchover thepost.

6)

Releasethe wire, maintainposition,raisethe manipulatorandbring it to force down quickly andsharplyontothe latch. This is necessary guide post. latch the loaded which holds the to clip backthe spring

7)

Whensatisfiedthe latchis in positionandconnectedto the guidepost checkthis by tuggingon the guidewire.

8)

Monitor the latchwhile tensionis appliedfrom the surfaceandwhen this hasbeencompleted,recoverthevehicle.

5.7.6 SettingGuide PostCutting Charge if a posthasbeenbadlybentanddoesnot allow re-installation This may be necessary of the stack. As no shapedchargesarecarriedthefirst actionwill be to contactthe baseand iurangefor the charge(s)andan explosivesexpertto be sent. Checkwith the drilling supervisorthat the leadtimesquotedby baseareacceptable.On receipt of the charge(s)the actionto be takenis asfollows: 1)

Discusswith the explosivesexpertthe procedureto be followed for placlp the charge.Usevideopreviouslytakgnto-highlight any. significantareasof damageto enablehim to decidethe bestposition for the charge.

2)

Whentheprocedureis settledsatisfactorilyensureeachmanis aware of his role andlaunchthevehicle.

3)

Locatethe bentpostandplacethecharge.Video the placementand havetheexplosivesexpertverify it is correctlypositioned.

4)

Recoverthe vehicleanddetonatethecharge.

5.7.7 Drilling Support (General) The abovesectionis by no meansexhaustiveandwill not be relevantto every situation. It is true,however,thatROVs arethe normalmethodof providing underwatersupportfor drilling operations.It is goodpracticefor at leastone member of the ROV crew (usuallythe Supervisor)to remainon thedrilling rig for a number of wells to allow him to becomefamiliar with particularmethods,aspractised,in what is, undoubtedly,a specialised areaof ROV operations.

oz

5.8 Platform Inspection Legislationrequiresall offshoresfuctureshavea valid certificationof fitness renewedonceevery5 years. Oil companiesmayhavetheir sffucturesinspectedon an annualbasis,eachyearlyinspectionis collatedin orderto applyfor the 5 year 'Certificateof Fitness'.It is not theintentionof this sectioniodiscussplaform inspectionin detailasit is a specialised areathatis describedin detailin the CSWIP f.:g.$OJ InspectorsHandbook/Course andis normallyrequiredto be carriedout by qualifiedpersonnel.The intentionis to highlightthe areaswhereROVs play a key role. 5.8.1 GeneralVisual Inspection (GVI) is normallyundertakenon platformsannuallyby 9eneralYisual In_spectign ROVs. The ROVs usedfor platforminspectionwill be observationclasscompleie with tetherqanqgeqentsystemsoperatingfrom eithera dive supportvesseloi from {e^nlatform itself. _Typicaltypesof ROV usedfor this purposeinclude;the Seaeye 600, the OffshoreHyball andthe Sprint. The itemsthat will be inspectedincludetherisersandconductorswhich areof particularco_ngern astheycarrytheHydrocarbons from thewells andawayfrom the platforms. Otherkey itemsto be inspectedwill includethe anodes,the members, welds,the mudmatsandotheritemssuchasclampsandpile guides. The ins_pection will beplannedfrom the'Workscope'provided by theclientandwill normallyincludethefollowingtasks:1)

Assessing amountof marinegrowthdeposits

2)

Locatingdebris

3)

Locatingareasof generaldamageto structuralcomponents

4)

Coatingcondition

5)

Cathodicpotentialmeasurements usingthe proximity silver/silver chlorideprobe(CPP)ar anodesandotherarbasof inierest.

6)

The conditionandintegrityof clamps

7)

Relativemovementbetweenclampsandrisers

8)

Floodedmemberdetection

9)

Mudmatsurveys

10)

Inspectionof the spoolpieceandsealine flange

11)

Anodecondition

Resultsareloggedeitherby computersystemsor on datasheetsandthesetogether with video tapesform the inspectionreportrequiredby the client. Oncethe leneral completedthena closevisualinspectionmay be required. Islal inspectionhas.been This is normally.carried-out by diversbut ROVs arebeingd-eveloped tliat arec'apable of carryingout thesetasks.

63

r 5.8.2 CloseVisual Inspection Closevisual inspectionis carriedout whendefectshavebeenhighlightedby the generalvisual inspectionor asrequiredby the workscope.Work classvehiclesmay becomeinvolvedin this part of the inspectionin thefollowing ways: 1)

Cleaningof weldsandremovalof marinegowth usingrotatingwire brushesor waterjets. Waterjets canbe eitherhigh pressure(HP) or Low Pressure(LP) andmay be sandentained. It is extremely importantto adhereto anypeftinentsafetyregulationswherehigh pressurewaterjetting is beingutilised. In generallow pressurewater jetting will be sufficientto removelooseor soft marinegrowthprior to ultrasonicfloodedmemberdetectionor wall thicknessmeasurement. High pressurewaterjets will be usedwherea baremetalfinish is requiredprior to weld inspectionor crackdetection.

2)

Photographyof anomalies.If the anomaliesarelargethey may be photographed duringtheGVI but closeusing'stand-offphotography up photographyusingspecialNDT or Photo$ammeticcameraswill be requiredfor weld or crackphotography.

The practiceof Non DesffuctiveTesting(NDT) involvesthetestingof weldsand membersby ultrasonic,elecffo-magnetic andradioactivemethods.Thesetasksare normallyca:riedout by diversbut morerecentlyspeciallyadaptedtooling packages haveallowedwork classROVsto carryout thesetasks. 1)

Floodedmembertesting- The ultrasonicor radiographictestingof a memberto determineif wateringresshastakenplace.

2)

Wall thicknessmeasurement- The ultrasonictestingof a memberto determinethewall thickness.

3)

(MPI) - Theinspectionof a weldsfor MagneticParticleInspection ink. This coilsor prodsandfluorescent defectsutilisingmagnetising by methodis usuallyundertaken by diversbut hasbeenaccomplished ROV.

4)

ACFM andACPD aretwo methodsof finding weld defectsmore suitedto ROVs astheelectronicprobesaresmallerthanthe equipment methods requiredfor MPI. The probesuseelectronicallysophisticated to detectdefectsthat arebeyondthe scopeof this book.

is constantlyincreasingandit is The involvementof ROVsin platforminspection quitefeasiblethat the wholeinspectionprogrammewill becarriedout by ROVs in the nearfuture. This is particularlysoasweld inspectionsarebecominglessfrequent asweld defectpredictabilitybecomesbetterunderstoodandROVs andthere operatorsarebecomingmorecapable.This is dueto technicaladvancesand improvedoperatorstandards with the emergence of theCSWIP3.3uROV Inspectors qualification. raining coursesand 5.9.0 Interventiontools The main impetusfor ROV Intervention hascomefrom the fact that a fully equippedROV supportvessel(ROVSV)will costbetween1/3rdand 1/10thof the costof a dive supportvessel(DSV), ROV interventionis thereforeconsiderably cheaper.In Norway,NorskHydroisTOGI andOsebergDevelopmentProjects representimportantmilestonesfor remoteintervention.Thesewerethe first projects in which therewereprimary operationson the subseainstallationswhich were

o4

I I

carriedout solely by RoV. Until this point, ROV underwaterinterventionon pennanentinstallationshad beenrestrictedto back-upand override tasksin casethe prime actuationsystemsfailed. With the increasedreliability and availability of ROV systems,suchoperationscould be much more cost effective. Typically such operationsinclude opening and closing valveswhere the operationcan be planned some time in advanceand are not part of the installation control system operated automaticallyor via the seabed umbilical. 5.9.1 Norway Norway has taken a lead in remote intervention becauseexploration and production operations are occurring in ever increasingwater depths and are already at and beyond the reasonablypracticaland economicdepthsfor manneddiving (around350 to 400 metresor 1150to 1310feet). In addition ii is consideredsocially unacceptable in Norway for people to be taking the risks associatedwith deepdivingoperatiohs. 5.9.2 Other Areas Of The World Other parts of the world are also making progresswith the developmentof diverless interventiontechniques.Theseinclude areasof the world where explorationand p:oduction are moving into water depthsbeyond the capacityof saturationdiving. Operatorsin the Gulf of Mexico have set many recordsfor suchactivities. In particular,Shell have drilled in 2,292 metres(7 5I7 ft) of water from the drill ship 'Discoverer SevenSeas'with underwaterinterventionsupportprovided by an OceaneeringHYDRA 2500 ROV. Shell are also bringing theii Auger leg platform (TLP) on streamin 872 metres(2,860ft) of water. In Brazil, Pero6ras aie operating subseacompletion'stied back to productionsystemsin over 1,000metresdepth. 5.9.3 Methods of Interventions There are threemain methodsof carrying out remote intervention:the Remoterv QperatedTool (ROT), the Remotelybpirated Vehicle (ROV) and the Remoteiy OperatedMaintenanceVehicle (ROMV). 5.9.3.1 The Remotely Operated Tool System(ROT) This is a developmentof existing drilling interventiontechniqueswhere tools are deployed,via guide wfes, lowered from the surface. Once landedat the work site, the_toolcan carry out its specific tasks. Usually suchtools are controlled by separate umbilical cablesfrom their topsidecontrol station. ROTs can deploy and operate larger and heaviertool systemsthan would be consideredusing ROV methods. Also the tool is securelylocked into the installation,providing a firm basefor precise operations. The tools can be usedto recoverand replacelarge components,suchas c.ontrolpods and valve inserts. ROTs havehigh reliability and are very task specific, they are also designedto requirevery little operator'skillt. Rors are limited by water depthfor guide wire operation,the needfor a more sophisti^cated supportvesselwith theIncreasedassociatedcosts. Also thereis always a risk of the tool 'dropping',and damagingthe subseaintervention. 5.9.3.2 Remotely Operated Vehicle (ROV) ROV operationsare normally low-force, or more correctly, low mass. This is not to say that high forcescannotbe generated,only that the ROV tools are individually smaller. Typically a rangeof interventiontools could include; a subseaROV winch, an interfacesystemto a valve, a seriesof tool to remove covers,accessvalve inserts, 'elevator' an to recoverthe removedcomponents,tools to inspectand clean inside valve insert bodies,sealsurfaceinspection,cleaningand refacing tools etc. The tools

65

canbe fitted to the ROV or canbe loweredto seabedin a sepiuatebasket,$ey are andthenhandledin turn fittea wittr buoyancymaterialto reducetheir in-water^weighi LVG [OV. ttt" t6ols areusuallyjob specific,but often.ianbe usedto address severalsimilar tasksin differentlocationsgiving costsavings. the surfacesupportvessel The ROV tool spreadis oftencheaperto build and^operate, ROV DP sripportvessel,ofteirmakingtlg.o.pglatignlcfeaper r* GJorril"rdil.ty thanwith ROTs. Car6fUdesignwith guidesandlatchesto eitablishthe tools in the canbe usedto minimise ;Ai did-;niuna i*olving-automad'coperationsthereafter repeatability. thl operatorskill requirementandensure 5.9.3.3 RemotelyOperatedMaintenanceVehicle (ROMV) The third methodis whereeffectivelyan ROT is deployedinto a subseainstallation, wherethe tool canmovewithin the itructureandcarryout severaltasksandis known of this is the asi remotely operatedmaintenancevehicle(ROlVlV). An_example. Snorre the shows 5.5 figg: Productionsys-tem. Sugnf"roleirm'SnoneSubsea andROMV module control iu6r.u productionsystem.Figure5.6 showi the manifold system conEol subsea end eff6cterwhich ii usedto rlcover andreplaceall typesof modules.

'@* 't/.-2-

3 '

'V"i ''/,'

,e Umbilical Porches

Figure5.5 production system subsea Snorre

66

, 4

'

ROMV End EffectorNo. 2 ExternalCan

\

\

ROMV Guide Sleeves and Latch Receptacles

PressureComoensator

Clamp Halves

<

z \

Hex Drivel-:-

- --G Torque Wrench

HydraulicCouplers InductiveCouplers Mounting Base --'

Figure5.6 Manifold conffolmoduleandROMV endeffector 5.9.5 Typical intervention tasks by ROV a) Pull-in andconnectionusingan ROV asthe solemeansof operating the Pull-in connection(PIC)tool andotherpull-in methods.-see Figure5.7 b)

Inspectionandcleaningby ROV tools. SeeFigure5.8

c)

ROV supportfor Blmote OperatedTool Packages.seeFigure5.9 which showsan MRV with purposebuilt interventionpac[ageadded at therearfor Mobil.

d)

Electricalandhydraulicconnectorcleaningby customRov toors.

e)

Electricalcableinstallationtooling.

f)

Controlsystemfor a seriesof ROTs

s)

ROV in_tervenliolpanelsfor hydraulic"hot stab"operations.See FigIIg 5.I0_whichshowsa Tronic mini c-E conneitorandreceptacre andFigure5.11whichshowsa subsea treewith stab-inpanel.

h)

Remotecrackdetectionandsizingby ROV.

i)

ROV basedwelding. SeeFigure5.12

j)

ROV baseddredging.SeeFigure5.13

o/

The aboveserveto illustratethe rangeof ROV interventiontasks,andis-notintended to be exhaustiveasthis is a speciauiedareaof work with teamsof tool design specialistsemployedby all the majorROV Contractors'

Figure5.7 ROV Flow line Pull-in

TRITON

Figure5.8 Cleaning ROVStructural

Figure 5.9 MRV With ToolingPackage

Figure5.10a TronicC-EMini Connect

.T'BAR ROVPLUG RECEPTACLE MOUNTED BULKHEAD

Figure510b ToleranceTo Misalignment TronicC-E Mini Connedtor

Figur e5.ll TreeWith Stab-InPanel Subsea

71

FrictionWeldingTool

Figure5.12 ROV BasedWelding

:i

AlternativeDump ...;1/ Line to Surface ..iJ"

Line Dump to Seabed

ii

\:.

Figure5.13 ROV BasedDredging

72

5.10.0Telecommunications CableLaying Telecommunications Cablelaying is a world wide operationcarriedout by companies suchasBT (Marine)andCableandWireless(Marine)whichis increasingin frequencyas the telecommunications revolutiongatherspace. Similar methodsare usedin the offshoreoil industryfor layingcontrolumbilicals,flow linesand pipelines. 5.10.1GeneralOperations In generaloperationsa work classROV may be requiredto cruryout the following duringthecablelayingoperarion: 1

Prelay survey - The surveycarriedout beforethe cableis laid to assess thereliefof the seabed.

2

Touchdown monitoring- The ROV is requiredto observethe point at whichthecablemakescontactwith theseabed.This enables engineers to determineif the tensionof thecableis correctduringthe lay downprocedure.

3

Postlay survey - The surveyingof thecableoncelaid,this task resembles thatof a pipelinesurveyandis to ensurethatthecableis laid correctlvon the seabed

5.10.2Burial Oftenthecableor controlumbilicalis requiredto be buried.This is likely to be requiredin shallowareaswherethereis a likelihoodof trawlingor similaractivities d.utrugilgthecable. This is achievedin oneof two ways; a ploughis towedbehinda shipwhichploughsa ffenchandpositionsthecablein it, or a Trencherwhichis a trackedROV createsa trenchwith waterjets andlaysthecablein it. In bothcases afterthecableis placedin thetrenchnormalseabedactionis lift to fill thetrench. 5.f03 EurekaTrenchingSystem theEurekatrenchingsystemanda SMD ploughareshownin chapter f1r exampl^e_of 3; Typesof ROV. 5.10.4Modular PloughSystem ligury 5.14showsa descriptionof theModularPloughSystemtakenfrom theBT (Marine)datasheet. 5.10.5Submersible TrenchingSystem Figure5.f 5 s_hsys a descriptionof the Submersible trenchingsystemsimilarly operatedby BT(Marine)andtakenfrom theirdatasheet. 5.10.6Summary hereis intendedasan overviewof cablelayingequipment. lh9-information_presented ' laying_is, however, a specialised areaandalthoughthetechnologyis !ab]e fundamentally similarto all ROVs,dueto theirlargesize(oftenseveri[Tonnes)they tend.tobe operated_by large_r crewsof typically7 men for 24 hourcoverage.They will be; a teamleader,two Senioroperatbrsoi shift supervisorsandtwo o=perators per shift..P]oqgh.s andtrenchers areoperatedfrom dedicafedsupportvesselswith heavy launchfacilitiessuchas'A' framesat thesternof thevessel.in bothcasesprofiling

73

and bathymerricsonar(seechapter19) are usedto ensurethat the cable is being laid in the trench and is entering the machine at the correct angle due to the very poor visibility experiencedduring theseoperations.Detectioncoils are positioned-oneach side to aid location of buried cable and responderbeaconsare attachedto enable the 'track' the plough or trencherwith its' HPR system. surfacevesselto 5.11.0 Construction have been Specially adaptedtrencherssimilar to the one describedin 5.10 prev^io-up was the good of this example A work. bed construction adiaptedio undertake sea platform concrete_storag.e the central wall around building of a round concretebarrier (Norway). of full A description Phillips Petroleum in the E-kofiskfield operatedby joumal (SUT) Technology this project is describedin the SocietyOf Underwater 'UndlerwaterTechnology'Volume 17 No.2 1991. It is sufficient to statehere that such projectsare possibleby adaptingtrencherswith suchthings as; seabed levelling tools, debris collection rakesand scrapercollection tool. 5.11.1 General Construction Work Generalconstructionwork usually involves the installationof steeljackets. Theseare floated off a bargeand lifted into position on the seabed by a Derrick Barge. Typical ROV taskson suchinstallationsinclude the following:i)

Pre installationseabed survey

ii)

Placing transpondersand positioningthejacket

iii)

Checkingthe mud mats

iv)

Monitoring the pile driving and depthof penetration

v)

Monitoring the cementreturnsat seabed for pile cementing

vi)

Diver Observation

vii)

Postinstallationsurvey

Particularcare must be taken with regardto safetywhen undertakingthesekinds of constructionoperations.Care must not only be takennot to harm divers that may be in the water but deck work must be done with careas many dangerousoperations suchas heavy lifting, welding and cutting will be taking place. 5.12.0 Remotely Operated Television(ROTV) A good exampleof an ROTV systemis the FOCUS (Fibre Optic Controlled UnderwaterSystem)400Inspector. This is a versatile,stable,controllable,towed sensorplatform. The modular designapproach permitsdesignsto depthsof 6000m 'box kite' design with cable lengthsof up to 10000m. The innovative hydrodynamic lends itself to carrying a multitude of sensors.Theseare commonly fitted with video cameras,obstacleavoidancesonar's,side scansonar,soundvelocity probe, still cameras,lights, pan and tilt units and transponders.Everything in fact that a pipeline survey ROV might carry except the thrusters. ROTVs can offer a cost effective answerto pipeline surveywork. ROTV Pilots, however,needfast reactionsas ROTV surveys are often faster (around 2 knots) than normal ROV survey (around U4 - U2 knot). Control is accomplishedthroughcontrol foils at the sternof the vehicle. Figure 5.16 showsthe FOCUS 400 performancecurves. 5.-13.0Other applications

74

Other applicationsinclude the military useof ROVs for Mine CounterMeasures. This is a specialisedareawhere the ROVs in use are requiredto be; reliable,quiet with a minimal magneticsignature. ROVs are being widely usedby customsofficials and the police to counterterrorismand drug smugglingwhere attachmentsmay be found on the undersideof vessels.Headlinegrabbingapplicationsinclude the survey of the Titanic and the MV Derbyshire. Other more romantic applicationsinclude the dredging for gold off South Africa and the harvesting of Pearls off Japan. There are as many applicationsof ROVs as man can imagine,and it has to be true that there will be many more in the future as the explorations of the oceansis still consideredto be in its infancy.

.aut.,iauii,u:3t iut::a::

MPS CablePlough

&Fe$r

-

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Figure5.14

75

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tr' $ I

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77

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Chapter 6 Electricalprinciptes 6.1 Introduction In order to be able appreciatethe Rov Electrical systemthoroughly, a basic understandingof the Flectrical principles is essential.The first iption of this chapter concentrateson revising theseprinciples so they can be applied when carrying out maintenanceon any system. 6.1.1 Voltage and Current In order to understandthe natureof electricity and the basic electricalpropertiesof materials,a knowledge of the structureof atoms is required. All materialsare madeup of atomsand all atomscontajn tiny particlescalled electronswhich orbit a centralnucleus.

electron

+

c

+nucleus

I

@/ Figur e 6.1 Electronshave.anegativechargewhile the nucleushasa positivecharge.Like charges repel while unlike chargesattracteachother,thereforethe negativeeleitronsare attractedto the positive nucleusand are held in orbit. In conductors,electronsare not tightly held to their atomsand may break free and move from one atom to another.TheseTree'electronsnormally move aroundrandomlv.

,/

'free'

t

,/

metal

t @ +

-{ electrons 'e--Vg

of

^r@

Figure 6.2 If thesefree electronsaremadeto flow in the samedirection,the resultis an electric curTent.

19

metal 'free'

@+

electrons

@+ @+

@+

Figure 6.3 Insulatorsare materialsin which electronsare strongly bound to their atoms and there may be few free elecftons.It is thereforedifficult for current to flow. (For example, glassand rubber.) Free electronscan be made to flow in one direction in a conductor by applying a positive chargeto one end and a negativechargeto the other. The positive chargeat one end will attractfree electronswhile the negativelychargedend will repel electrons. Currentis the numberof electronspassingany one point in a conductorin one second. In other words applying a potential difference (or voltage) acrossa circuit will causea current to flow. The PotentialDifference createsa force, known as Electro-Motive Force which gives rise to current flow. The size of the current will dependon the size of the voltage and also the amount of resistancein the circuit. The symbol for currentis I, it is measuredin amps. The symbol for voltageis V, it is measuredin volts. The symbol for resistanceis R, it is measuredin ohms. 6.1.2 Resistance and power Resistanceis an oppositionto currentflow that givesrise to power being dissipatedand work being done.The power may be dissipatedin the form of light, heator motion. Figure 6.4 illustratesa simpleelectricalcircuit involving the basicelectricalprinciples.

Directionof Current Power Distribution ,/ istance

VoltageSource

Figur e 6.4 a potentialof charge,theunitsof whichare In this situationthecurrentsourcedevelops thattherewill be a dropin potentialacrossthe calledvolts.It followstherefore to heat,light or motion. resistance dueto someof theelectricalenergybeingconverted

80

6.1.2.1 Relationship between voltage, current, resistancerandpower Thereis a mathematical relationshipbetweenvoltage,curent andresistance. OHM's Law statesthatthecurreniin a circuit is dlrectlyproportionalto thevoltage andinv.ersely proportionalto theresistance. Thesequantitiesarelinkedby the following equation. VOLTAGE = CURRENT x RESISTANCE (V=IR) Poweris the amountof work thatcanbedonein a standardunit of time (1 second). Electricalpoweris expressed in unitsknown aswatts. Onewatt represents thepower usedwhenoneampereof currentflows dueto anElectromotiveForie (EMF) of'1 volt. Poweris relatedto Voltage,CurrentandResistance by thefollowingequation. POWER= (CURRENT;z x RESISTANCE P=I2R POWER= VOLTAGE2/ RESISTANCE P=V2lR 6.1.3 Electromagnetism Figure64 showsanelectricculrentflowingthrougha conductor produces a magnetic aroundthe conductor,thedirectionof whichdependson thedireciionof current-flow.

-+

conductor+

I

direction of magneticfield


conductor+

I direction of magneticfield Figur e 6.5 If theconductoris formedinto a coil anda currentis passedthroughit, a magnetic &F p producedwhich is similarto rhatof a barmagnet. This is knownasanelectromagnet.

8l

F bar magnet

Figur e 6.6 by:The magneticfield is increased I 2 3

increasingthenumberof loopsin thecoil increasingthecurrentthroughthecoil usinga ferrouscore

6.L.4 Electric motors

Directionof Rotation Figure 6.7 Figure6.7 showsthe basicactionof anelectricmotor.If a current9?:ryingconductor is placedin a magneticfield theconductorwill movein a rotationaldirectionthatis uponthedirectionof currentflow. In practicea motoris made!p_gf dependent of coils woundon a former.The interactionbetweenmagneticfield and thousands electricalcurent is strongerallowingthemotorto developa greatertorque. 6.1.5 Direct current Figure6.8 illusratestherelationshipbetweenvoltageandtime.In this situationthe currenthasconstantmagnitudeanddirection.

82

I

Figur e 6.8 6.1.6 Alternating current Figure6.9illustrates therelationship between voltageandtime.In thissituationthe curent variesin magnitudeanddirection.Thecurrentvariesbetweena positivelevel anda negativeleveloyera periodof time.Thetime takenfor onecompletecycleis knownasthe periodictime, andthenumberof cyclesthatoccurin onesecondis termedthe frequency. It followsthereforethat:

FREQUENCY=

I T where1= periodictime The advantageof altematingcurrent over direct currentis that it is possibleto transformalternatingcurrent by meansof either a 'stepup' or 'stepdown' transformer.

+V max+V

time

max-V

Figur e 6.9

83

F !

As thecoil rotatesit'cuts'the Figure6.10illustrateshow AC. currentis generated. linesof magneticflux resultingin currentb-einginducedinto theconductor.This is knownas singlephaseAC current andis commonlyusedfor domesticsupply. Direction of induced

Externalpowersource coupledto coil mechanically providesrotation

Directionof Rotation Figur e 6.f0 6.1.7 Transformer action A transformeris a devicethat transfersAC energyfrom onecircuitto anotherwithout therebeinganyelectricalcontactbetweenthetwo circuits. in section6.1.3.If anAC Transformers operateaccordingto theprinciplesdiscussed cwrentis appliedto a conductorthentheresultingmagneticfield will build up and of thecurrent.If thisconductoris collapsein sympathywith thevaryingmagnitude placedin closeproximitywith anotherconductor thenthemagneticfieldwill inducea aremadeup of coilsof In practicetheconductors currentinto thisconductor. secondary wire knownas primary andsecondarycoils . Figure6.11 illustrates theactionof thetransformer.

PFIMAfr ! SECONOAFYCOILS WOUNOON THE SAME CORE

Figur e 6.11 Therelationshipbetweentheprimaryvoltageandthe secondary voltageis dependent on thenumberof turnson thecoils.Figure6.10illustrates the stepup andstepdown transformer.The outputvoltageis directlyproportionalto thenumberof turnsin the coil. Theexampleshowsaninputvoltageof 115VACto a coil with 1000turns. The secondary coil has2000turnsandanoutputof 230VAC.

84

Example: RATIO OF PRIMARY COL TURNSTO SECONDARy= I : 2 INPUT VOLTAGE =200 VOLTS. Therefore

2x.200 =400VAC SecondaryVoltage ' l 6 . 1 . 8 R el a ys Figure $q!y-q areelectricalswitchesthatoperateon theprincipleof electromagnetism. 6.12illustrates a simplerelaycircuii. The diagramshowsthecontactswhentherelayis in its de-energised state.In this state tley.arereferredto asbein_g normallyopenor irormallyclosed.Whencrrrent is applied via thecontrollingcircuittherelaybecomes energised andthecontactschangeto th'e oppositestate.Thisin turnconnects thehighvoltagesourceto themotor.

RELAYCONTACT

MOVING ARMATURE

HIGH.VOLTAGE HIGH-CURRENT POWERSOURCE

220 VAC

N.C.

I

I n.o.

CONTROLLING CIRCUIT

6VDC

REI-AY

I

CONTROLLED CIRCUIT

J

I

RELAYCONTAST

MOTOR

LOW.VOLTAGE LOW-CURRENT POWERSOURCE

F igur e 6.12 6.1.9 3-Phase electricity betweensinglephasecurent andrime.The ftgult 6.8illustratedtherelationship disadvantage of singlephasecurreniis thatit is noi suitablein situations wherea high powerfactoris required. Figure6.13illustrates theprinciplesof generating 3-phase electricity.Threecoilsare >et . 120.de_grees apartresultingin threeseparate phaiesof currentU6inginducedinto eachcoil. It canbe seenthereforethatthephasesarealsooffsetfrom eich otherby 120

85

of turns,thisbeingoneof In practiceeachcoil is madeup of man^y.thousands degtees. current. generated the of magnitude the thjmain faitors thatinfluences

A

tI I

, Red,Yellow and Blue coils Figure 6.13 6.1.10 Transformer configurations 3 Phasetransformersare normally connectedin either Star or Delta configuration dependingon their specificrequirements.Figure 6.14 illustratesthe two modesof connectlon. Phase1

Conductors

Neutral

Phase2 Phase3 Delta Confi

Star Configuration Figure 6.14

It can be seenthat in the starconfigurationthat the threewindings have a common return line as opposeto the deltaconnectionwhereno return is present.With star I

86

transformersthe line insulation is only required to withstand the phasevoltage and not the full outputvoltage.Also two choicesof load voltageare availablebetweJnthe windings if the neutralline is used. The main disadvantageof the star configuration is the transformersbehaviourwhen harmonicsof the fundamentalfrequency exist in the secondarywindings. The_deltaconfiguration doesnot suffer the samedisadvantagesas the star configuration. In this situation the closed form of the delta piovides a path for the harmonicsto circulate and preventsthem flowing into the power system. The most commonconfigurationon ROV systemsis a star/deltaSivitchingMechanism. In the delta mode the output is ungrounded,the groundingof one phasewill not seriouslyeffect the operationof the power systemas the fault cunent hasno direct return path to supply. If the output was in star then a fault current would have a direct seareturnpath to the supply.Another advantageof this configuration is that any unwantedharmonicsarepreventedfrom propagatingthroughthe power system.It is usual practice to employ a srar/ deltaconfiguraiion in the power supply. tnitially star configurationprovidesa low startup currentfor the electricmotor, oncerunning at operatingspeedthe systemswitchesto deltaconfigurationwhich runs more effiiiently. 6.1.11 Power supplies The mainparts of-a power supply unit (PSU) are a transformer,rectifier, smoothing circuit and a stabilisingcircuit(seefigure6.15).

rectifier

smoothing

tabilising d.c . output

rnput Figure 6.f5 a) The transformer

The transformertak€san ac input voltage(e.g.mains)and 'steps' (converts) it to the.required voltage.A transformeimaylherefore be step-up'or'stepdg*L'dependingon the turnsratio betweenthe secondaryand the primary windings. b) The rectifier The transformeroutputis an ac. voltage.This is then convertedto a dc voltageby the rectifier,howeverthis is not a steadydc voltageand as suchis not suitablefor many applications. c) The smoothingcircuit Most equipmentandelectroniccircuitry requirea constantand steady supplyvoltagein orderto operate.This circuit smoothesthe rectifiei output to give a steadydc voltage. d) The stabilizingcircuit Becauseof internalresistance,the dc outputof a PSU or batterydecreases from a maximum as the currentdrawn increases.The greaterthis decrease. the worseis saidto be the regulation of the supply.

87

Figure6.16illustratestheeffectof currentloadingon a powersupply.

d.c. output voltage REGULATION CURVES

load current Figur e 6.16 thisproblemensuringtheoutputvoltageremains circuitovercomes Thestabilising constant. RESISTANCE

t-

)

F D

z

Circuit Action. As the culrent drawn by the load increasesthe current and a constantvoltageacross throughthe diode decreases R1 is maintained. Figure 6.17 aZ.enerDiode is incorporatedinto the Figure 6.17 illustrateshow a deviceknown as 'clamps ' the output voltage at the de.siredlevel The diode circuit. the of oufrut stage regirdlesiof the externalloading. It is not ihe intention of this sectionto dwell on the ciicuit theory of theseelectricaldevicesas there are mlny text books availablethat cover the subject{uite adequately,but to provide sufficient information to cross-traina mechanicalitilotflechnician to be ableto assistan Engineerwith electricaltasks.

88

Aux 240 V

Deployment

UMBILICAL Figure 6.18.

89

6,2 Introduction To The System It canbe thebasiclayoutof atypicalRqy s_ys!gq. In chapter3 figure3.1illustrates Tether winch, umbilical , seenthatthe systemis comprisedof a surfaceunit, Systemandvehicle.It is theintentionof thissectionto discussthebasic Management of theseindividualunits. principlesof operation 6.2.1 Surface Unit thesurfaceunitof a typicalworkclassROy (SELMulti Roll Figure6.18illustrates VJtricte).Thereis onemainpowerinput whichmay be suppliedfrom thevesselor generator.An auxiliaryinputof 24AVis alsoprovided installationor from a customised asa domesticsupply. The maininput,typically440VAC,is fed via a junctionbox to themainPower to thefollowingmainunits. DistributionUnit.Poweris thendistributed a) PurgeSystem. b) DeploymentCrane. c) Winch PowerPack. d) Stepup Transformer. e) ControlConsole.

6 . 2 . 1.1 P u rg e System The purge systemprovidesa pressurisedsafeareathus enablingthe us of non-zone relatedequipmentin the control cabin and winch junction box. When the systemstartsup a fan pressurisesthe cabin to 0.75 milli Bar, this is monitoredby the PurgePanelfor a period of twenty minutes.After this period, should no problemsoccur then the vehicle systemwill be switchedon. During operations, shouldcabin pressurefall below 0.25 milli Bar then the Purgesystemwill automaticallyshutdown the system.It follows thereforethat if the vesselor installation is in a situationwhereinflammablegasis presentthe positivepressureinsidethe cabin will preventthe gasintruding,if the pressurefalls then the power will be cut off preventingany electricalarcingoccurringand causingan explosion. 6.2.1.2 Deployment Crane The cranehydraulicpower pack consistsof a 3-Phaseelectricmotor, the power for which is takenfrom the PDU. 6.2.1.3 Winch Power Pack The winch power pack operateson the sameprincipleas the crane.A 3-PhaseElectric motor is directly coupledto a hydraulicpump. The motor receivesits'power from the PDU 6.2.1.4 Step Up Transformer The stepup transformeris suppliedwith 440VAC which is convertedto a suitablelevel as to overcomeline lossesin the umbilical. Typical surfacevoltagesfor ROVs are as follows:

90

a) RECONIV I60VAC

b)scoRPro1100vAC c) HYDRA 1800VAC d) RCV 1s0950VAC e) MRV 33OOVAC 6 . 2 . 1 . 5 C o n tro l C o n so te Thecontrolconsolehousesthe surfaceelecronicscontrolinstrumentation anddisplays thevehiclesensorinformation. a) Surface electronicsand control instrumentation Thesurfaceelectronics processes thesignalsreceivedfrom thevehiclesprimary controls(e.g.joy-stick,manipulator mastercontrol).Theprimarycontrols producga varyingdc voltagethatmayvary proportionallybetwebn t5v depending on thesystem.Thesesignalsari:algititizedandmultiplexedbefore beingtransmitted downtheumbilicalto thevehicleelectronics. Section6.3in thischapterlooksat multiplexingin moredetail. Figure6.19illustrates thebasicprocess of controlandinstrumentation.

AnalogueSignal Umbilical \ Surface Interface

overswitch DigitalSignal Figur e 6.19 Theremoteboxis a replicationof theprimaryflying controlsandenables thedeck officerto steertheROV awayfrom thevessejoi installation duringthelaunch procedure into a safedivingposition.Oncein positionthecontrolisrevertedbackto themaincontrolsin thecontrolcabin. Thejoy stickpotentiometer is simplya variableresisrorthatproducesa proportional analogue voltage.There.isoneporenriometer for eachplanebf rhejoy-siicli. The surfaceinterfaceunit amplifiestheanaloguesignafto a suitablet6vetto beapplied to themultiplexer(mux)unit.

"

b) Sensorinformation Chapter5, section5.2.2discusses thevarioussensors thatmavbefoundon a typical$OV. Thevehicleelectronics incorporates a'two way iata link'which allowsdatato betransmitted to thevehicle-from thesurface,asis thecasefor

9l

the control information,and from the vehicle to the surface,as the information from the sensors.

is the casefor

(e'g' The sensorsconsistof transducersthat convertsone form ofenergy is in energy electrical The energ.y. pressure,rcmperatureo. u"our,ir; i"iii.tti.ul in the tranqmitted and the form or ri *ui.gue signal trriii converte{ tg &-gitat signat.rn" r"nror infoniation is displayed to the samemann"; u;ih;;;ntifi pilot on the control console. 6.2.1.6 Switch On Procedure It is important when switching the systemon to follow the correct procedure' a) ConsolePower b) Vehicle Power c) HYdraulicPower can occur' If this procedureis not followed complicationswith the systemstelemetry electronics surface the Slave^princip.l9, Master / The telemetry systemworks on the on being rhe masterand thevehicle being the slave.tf ttrev6trict: tly:l:t^:Yll:l* and is enabled slave the whereby arises before the consolepo*"t then the sitiation and can receiving no ro*-und f.o* the surfacemaster.This is an undesirableeffect the system the down powering When fruJto p-ossibledamageof the telemetry sy{em.. Order' procedureshould be followed in Reverse 6.2.I.7 Display Unit As well as housingthe vehiclecontrol systemthe surfaceunitis rel"u{1!^t1{3laf monltors uiO.o unOsensorinformation.The systemincorporatesa numberof vtdeo sensors-asrequired' -circuit. ;[i"h ;r; capableoib.ing switchedvideo camerasand boardsin All the Programm.e. niugnostics S.if h;;; sysre;; ROV Some computer surface a then the systemare continuallymonitored,Ihoulda fault occur relevantcircuit allows the operato.;;G througha programmewhich will locatethe board. 6.2.2

Winch SYstems

Most winches All ROV systemsrequirea systemto-deploythe vehicleto the work site' as opposeto ar. "i..tt"-ttydraulic and are designedtocontrol the lengthof umbilical depth,and ohvsicallvliftine the vehicle.When submergedthe vehiclecontrolsits own

iliffi"fr^iir.;';ilil;

outof liftsthevehicle tothecrane atiached il;-fis meChanism

is thewater.There."-r*" i,i.eptionsto thisin whichcasea morepowerfulwinch lifting umbilical' fittedwith a speciallydesigned Figure6.18showsthemainunitson a typicalwinch'. togetherby sliprings' two junctionboiesconnected ffr? iyrrc. incorporates 6 . 2 .2 .1F i xe d Ju n cti o n B ox

to theumbilical' Thefixedjunctionbox is a two wayjunctionboxthatpasses.power uia"o rtgnlutfrom theumbilicalanddatasignalin bothdirections.

92

6.2.2.2 Rotating Junction Box Therotatingjunctionbox,asthe nameimpliesis attachedto themaindrumof the winchandcarriesout thesamefunctionasthefixedjunctionbox. On systemswherefibre opticsareused(seesection6.4) therotatingjunction box may housefibre optic transmitters andreceivers.This overcomestheproblemscausedwhen transmininglight energyfrom a fixedjunctionbox to a rotatingjunctionbox.The signalpassingbetweenjunctionboxesremainselectricalwhichis morecompatiblewith theslip ring assembly. 6.2.2.3 Slip Rings The slip ringsprovidetheinterfacebetweenthefixedjunctionbox andtherotating junctionbox. Figure6.20illustratestheoperationof theslipring.

_ WINCH MOUNIING

Qr?-,!qA-I irr \rlv!!3

?f PQ!E& S|GN{ & FrBEROqrC PASSI5

IO ROIATINC JUNCIION8OX

OFTIONAI PRESSURT CCMPTNSAiOR'

M O D E LI ? 6 ELECTRICAL SUP

I sEt oFllrL

l

Figure 6.20 The unit consistsof a numberof contactsknown as brushes(one brushper conductor) mountedon a centralcore which is staticand directly connectedto the fixed junction box. The core is mountedin a cylinder which is free to rotateand is directly coupledto the winch drum. Insidethe cylinder thereis anothersetof contactsthat make physical contactwith the brusheson the staticcore.It follows thereforethat electricalcontinuity is maintainedat all timesduring the rotationof the winch drum. The slip ring in Figure 6.20 alsoincorporatesa fibre optic rotaryjoint which allows light signalfrom the static junction box to passthrougha prism network which in turn directsthe light onto a lens. The lens then convergesthe light onto a receptorin the rotary sectionof the joint before it is sentdown the umbilical. It becomesobviousthat the efficient functioningof the whole systemis dependenton the integrity of the slip rings and for this reasonthey are manufacturedto a high degreeof quality. Correctmaintenanceis crucial,an outline of which is referredto ln chapter11.

93

6.2.3 Umbilicals The umbilicalprovidestheelectricallink betweenthesurfaceandtheROV Umbilicals -uy U" armouieddependingon whethertlreyarerequiredto lift thevehicleout of the Thefifling streirgthis providedby a steelwire *ui", duringtherec6veryo"peration. of this natureareheavyandrequire Umbilicals ttre rlmhtical. *iup tttit srirrounds dedicatedwinches. a typicalumbilicalfor a workclassvehicle. Figure6.21illustrates

Fibre Optic Bundle

Amrour

Power Conductors Coaxial

Quads

F i g ur e 6 . 2 1 6 . 2 . 3.1T yp e s o f co n d u ctor of thefollowingconductors: Thisumbilicalconsists In thiscase4 eachphasebeingspreadover4 conductors. a) 16Powerconductors, actasneutralline. conductors pairs'.Thetwistedpaircarry of two wirescalled'twisted b) 4 Quads.A quadconsists For thisreasonthetwistedpairsare theteiemerysilnalsanddataup from thesensors. to profectthe signalfrom extemalinterference. screened c) I FibreOpticbundle.Thesefibresmay be usedto carryvideoor anyform of digital signalasrequired. d) 2 CoaxialCables.Coaxialcableis normallyusedto carryvideosignalfrom the vehicleto thesurfaceunit.

o,l

The Quadsand coaxialsare shieldedby a copperbraiding.If this was not the casethe high voltagesin the power conductorswould leadto severeinterferenceand comrption of the data signals. It should be noted that if fibre optic bundlesare incorporatedin the umbilical, because of their delicate structure,they are usually placedin the centreto minimise breakagedue to bendingof the umbilical. The conductorsareenclosedin a plasticsheathingwhich providesinsulationand protection. This would be a standardumbilical and would not be suitableto lift the vehicle.By coveringin armourthe umbilical is then given its lifting capabilities. 6.2.3.2 Safety Factors During launchand recoveryoperationsthe umbilical is often waveringat headheight.If extremecare and attentionis not exercisedat all times then severeinjury or even death can occur to carelesspersonnel.It is the responsibilityof the ROV teamto make everyone awareof thesedangersduring the launch / recoveryperiod. 6.2.3.3 Umbilical Breakdown Conductorswithin the umbilical can breakdue to excessivetensionor severetwisting or bending.Faultsof this naturecan lead to long periodsof down time and the pilot shouldalwaysbe awareof the umbilicalsstateduring diving operations. The maintenanceand repairof umbilicalsis coveredin chapter11. 6.2.4 Garages And Cages Many ROV systemsemploy a Earageor cagewhich housesthe vehicleduring the launch/ recoveryprocess.In this situationthe vehiclewill be protectedfrom possible damagewhilst passingthroughthe 'splashzone'. Small ROVs are limited at what depththey can work due to the drag factor of long lengthsof umbilical. This problemis overcomeby deployingthe vehicle in a garage, 'swim' in orderto onceat the working depththe vehicleonly hasa shortdistanceto reachthe work site.By working from the garagethe largedrag factor hasbeen eliminated. The garageemployswhat is known as a Tether Management System (TMS). The TMS controlsthe paying out and reelingin of the umbilical during the diving operation. The TMS is controlledby the pilot from the control cabin.The TMS control signals passdown an armouredlifting umbilical in the sameformat as the ROV control signals. They are then processedin the TMS electronicsbonle and usedto control the appropriatehydraulicvalve.The ROV umbilical is housedon a hydraulicallycontrolled drum. From this the umbilical passesthrougha systemof guidesand rollers that maintainthe correcttensionon the umbilical whilst paying out and reelingin. A pan and tilt camerais alsofitted to the systemto aid the pilot when latchingand unlatchingthe ROV.

95

YDRAULIC power

OPTICS ruNCTION BOX

PORT FLOAT TANK control

PRESSURE SENSOR

umbilical

power control

STARBOARD FLOAT TANK

SONAR SCANNING I.JNIT

UMBILICAL TERMINATION Figur e 6.23

96

6.2.5 Vehicle Electrical System Figure6.23illustrates rhebasicelectricalunitsof theROV 6 . 2 . 5 . 1 U mb i l i ca l T e rmi n a ti on The umbilicalis terminatedin anoil filled junctionboxwhichis compensated (see chapter8). The signalsareroutedthroughiedicatedsubseaconnectors to therelevant unrts. 6.2.5.2 Hydraulic Power Unit (HpU) P{* phasepowel is suppliedto anelectricmotorwhichis directlycoupledto the hydraulicpump.on some. sysrems thepowersignalmaypassthroughd stepdown transformerprior to-reaching themotor.Whentfrehydrduiicpowerii switcliedon at thesurfacea controlsignalis sentvia the systemsdaiacommunication link an activates a relayandappliesthepowerto theelectriimotor. 6.2.5.3Port float tank Theactuallayoutof theelectronicsfor ROVsvariesfrom vehicleto vehicledepending on.itsworkscope. For examplean ROV thatis intendedfor mainlysurveyoperations" will possiblyhave.anextrapressure vesselincorporated into its d6signto ho'use the necessilyelectronics. This particularexampleof ROV incorporates two float tanks.The telemetrycircuits alongwith theporv-er suppliessensorcards,andgyrowill be housedin this tank.The port ?.ndstarboardfloat tanksareelectricallyconi.ectedasthemainsystempower suppliesalsosupplytheequipment in thesiarboard floattank. 6.2.5.4Starboard float tank Thestarboard tankmayhousetheelectronic circuitsthatcontrolthesurveyequipment. Thisexampleillusratesthesona-r scanassembly powerbeingderivedfrorirthe starboard float tank.TheremayalsobepowerJuiplieshousEd in hereto drivevarious otherpiecesof surveyequipmentsuchasprofileis,pipetracker or sidescan units. 6 . 2 . 5 . 5Op ti cs j u n cti o n b o x junc_tion Theoptic.s boxis a unit thatis commonto mostworkclass/largeinspection classvehicles.It is simplyanoil filledjunctionbox thatmaydistributeioweito the vehicle,lights, compass andothersensors. Thediagramilluitratesthetypicalsituation in whichthepowerfor eachlight.comes in on a commoncable(typicatiytZOVeCper light),it is thendistributed to variouslampssituatedaroundttre'vetricte. 6 . 2 . 5 . 6 V e h i cl e l i g h ts Thenumberof lightson ROVsvariesconsrderably anddepends on thenumberof cameras fittedandthetaskto becarriedout.Theoperationis standard andconsistsof a relayor Powgrcontrolmodulededicated to eachdmp. Therelaysare'switchedby controlsignalsfrom thesurfaceandonceenergised cbnnectpo*e. to therelevanriamp. 6 , 2 . 5 . 7T h ru ste r co n tro l u n i t Thehydraulicoperationof thethrustercontrolunit (TCU)hasbeendiscussed in Chapter8. Theunitreceives a varyinganalogue signalfiom theServoDriver Cards housedin themainelectronics bottleor in thJcase5f figu.e6.7. theportfloat tank.The servodrivercardconsistof.agroupofamplifiersthatbdostthecontrblsignal to a suitablelevelto drivetheservbvalveiin theTCU.

91

6.2.5.8 Hydraulic control valves (HCU) The hydraulic operationof this unit hasalsobeendiscussedin chapter8. This unit receiGs analoguesignal of a positive or negativepolarity dependingon the direction that the manipulator limb or pan and tilt unit is required to move. 6.2.6 Auto control functions The task of flying the ROV is made easierby the inclusion of Auto Control functions into the vehicie efectronics.Thesefunctions normally include Auto Heading and Auto Depth. 6.2.6.1 Gyrocompass The auto headingfunction operateson a similar principle to a shipsauto pilot in the sensethat it willremain on a pre-determinedheadingso long as the function remains selected. 'mass' spinningon an axis. If The ROV is fitted with a Gyroscopewhich is basicallya a right angleforce is appliedto a gyroscopethen the unit will ry to.exertan eqtraland oppbsitefbrce in ordei ihat it may ieturn io its cenral axis. In practice the gyro is pbweredby an electric motor an
98

resulting'error'signalis appliedto the vertical thrusterwhich actsin sucha way as to counteractthe changein depth. Auto functions in their simplestform require the pilot to switch the device on at the surface.The vehicle.istotallycontrolled-bythe auto functionin this stateand the pilot has to physically switch the device off to iegain control. More complex systemsillo* the pilot to make fine adjustmentusing trim confols. 6.2.6.4 Trim

controls

Trim controls allows the pilot to apply a control signal to the ROV from a sourceother ,h.T ltt jgystick. The sourcesare usually in the form of a single turn potentiometer which maintain a fixed control signal to ihe vehicle as oppose-tothe pilot determined signal from the joystick. The commonesttrim controls arb: a) Forward / Reversetrim. (cruise control) b) VerticalUp /Down trim c) Lateral Port lStarboard trim The principleof operationis the samefor eachtrim in that the potentiometers'add'a signalto th9 main input gonrol signal.They are usefulwhen flying the vehicle into a currentor if the vehicleis being subjectto a crosscurrent.fne pilot can usethese controlsto make the flying operationlessstrenuous poq: systemshaveheadingtrims which can be usedin conjunctionwith the auto headingand enablesthe pilot to makefine adjustmentto the-directionof the vehicle. 6.2.7 Sensor functions It is essentialthat the vehiclesoverallconditionof operationis constantlymonitoredin order to minimise unnecessary breakdowntime. The following items are monitored. a) Oil Temperature. b) Oil Pressure. c) Oil level. d) Water ingress. e) Water ingressto connectors. The sensorsoperateon a similar plnciple in that a transducermonitors the pressureor temperatureand convertsthis to a DC voltage.Thesesignalsare multiplexed and travel on the vehicles'up'datalink. The water ingresssensorsare locatedin the pressurevesselsand usuallyconsistof two contactslocatedat the-lowestpoint of the veisel. Any water ingresswili shortthese contactstogetherand form an electricalcircuit. The resistancebetweenall the conductorsthat areattachedto the relevantsubsea connectorsis also monitored.If wateringressiontakesplaceat the connectorthen the resistancewill fall and provide a readoutat the surfaceunit. The resistances mav be displayed9n alq charton the surfacedisplayand arecommonly termedIRs. fhey may be AC or DC dependingon the circuit b6ingmonitored.

99

Telemetry

6.3 6.3.1

Introduction

Section 6.2 of this chapterdiscussedthe basic electrical units and various sensorsthat are found on ROV systems.It alsodiscussedthe methodby which the vehicle is controlled from the surfaceunit. It is now necessaryto look at how control and sensorinformation is transmitted betweenthe surfaie unit and the vehicle. The systemthat carriesout this task is commonly known as the Telementry System. Analogue Signals

6.3.2

Analogue signalsvary continuously with time and assumeany amplitude level within the limitations of the electroniccircuitry. It is thesetypes of signalsthat are produced by the potenriometersin thejoystick control. Figure 6.24 showsa typical o-utput signal,in analogueform from a controljoystick. It follows that the output from the joystick potentiometermust be transmittedvia the umbilical to the thrustercontrol -circuitryon the ROV. During this processthis signalwould be subject!g ling losses and disiortiondue to the physicalpropertiesof the conductorsin the umbilical. +5V

ALOGUESIGNAL.

I

l]*+I U lI

Y

-5V \ JOYSTICK POTENTIOMETER.

Figur e 6.24 6 . 3 . 3 D i g i ta l S i g n a l s theyhavetwo discreetlevels,one asareanalogue Digitalsignalsarenot continuous levelis a constantpositivevoltageandtheotheris zerovolts. Figure6.10 showsan thata simpleon/offsignalwill still be exampleof a digitalsignal.It followstherefore, it to lihe lossesanddistortionbut will however,beeasierto re-shape'once susceptible signalis converted hastravelledthroughtheumbilical.For thisreasontheanalogue 'word',a particularoutputvoltagelevelat the into a 'train'of digitalpulsesknownasa joystickwill havea dedicated digitalcode: ATOD CONVERTER. ANALOGUE SIGNALIN.

rLnr DIGITALSIGNAL OUT.

Figur e 6.25

100

i

6.3.4

Line losses

Line lossesis a condition that effectselectrical signalswhen they are transmitted through conductors. Physical propertiesof metal conductorsare such that they will absorbsomeof the signalbeing passedthroughthem, thusresultingin line loss. 6.3.5

Time Division Multiplexing

So far we have discussedthe use of digital signalsto transmit the control information for the ROV. In practice however, the transferof information for all thrustersand sensorsis a continuousprocess.Ideally eachthrusterand sensorwould require an individual conductorin the umbilical thus allowing a constantstreamof data passing betweenthe vehicle and the surfaceunit. However, this would lead to the overall diameterof the umbilical being large and thereforeimpractical. To overcomethis problem the telemetry systemmakesuse of Time Division Multiplexing (TDM). Insteadof eachfunction having a dedicatedconductor,they in fact sharetwo conductorsknown as a 'twistedpair'. In order to overcomethis problem the analogue signalsareconvertedto digital signalsprior to being transmittedthroughthe umbilical. Figure 6.26 illustratesa very simpletelemery system.

fL ,lFo

ShieldedTwistedpair Word I Cardsin SurfaceUnit l. MotherBoard- PowerSupplies 2. ND ConverterBoard 3. Timing/ProgramBoard 4. MIIX Board

MF Sync

Word2

ch3-16

Figur e 6.26 6.3.6 Twisted Pair Two wires twisted together,one wire is dataup link, the other a datadown link. The wires are protectedby a shieldknown as a screen.

t0l

6.3.7

Programme MicroProcessor

circuit controls the switching operationof the The programmemicroprocessor 'rn

1 gpgnifirst,followed.byMUX ;;ldpi"?;; rttunn"ri. otherwordsrvrUxCtrannet 'words', eachwordcontaining cttanief2, androon. Thiswill resultin a trainof digital informationfrom differentfunctionson the system'

6.3.E Main Frame SynchronisingCircuit 'receive'circuitscandistributeeachword to therelevant In orderthatthe telemetry ;"ltipl.;;; cttanneta iyictrionisationpulsehasto be addedto-qcfr glounof words' Main Frame This is addedat thebeginningof thegioupandtheqn-d-py-lh" will contain64 syqlgm MUX "hannel a'64 F# r*u-pi" Cir;?;. S;;.-i;i;i"g a'frame'.The systemwill transmitmany *"oiar; theseaie collectivelyknown^as givesrise to a constantflow of controland This of framesLurryi"rond. thousands in theform of a alongthetwistedP-arr is ransm'itted rinioi information.Information 'frame'.Datafrom eachfunctionis allocated a "timeslot"in thisfiamethusallowmg 'frame' ttr" .onrtuntt ansfeiti informationfrom all functions.Figure6.11 showsa oi i *ords, eachword containsdigitalinformationfrom I particular ;;;fiG function:firlr pto""rr it Ging carriedout thoisandof timesa secondtherebyallowing uit"n.sametime. In practicethereis onewordperchannel. -uny functionito "f.* 6 . 3 . 9 M u l ti p l e xe r C i rcu i t (Mux Cir cuit) 'channels' Themultiplexercircuitis simplya collectionof electronicswitchesknownas conrrolinformationto passon to theline. The switchesoperate thatallow^data Itfollows thattheoutputfrom the by a microprocessor. i"qi*rii"ffy unO3r. controtteO j;y-;iirfp"ientiomerer mustbe trinsmittedviatheumbilicalto thethrustercontrol losses signalwouldbe subjectt-o.Jing thi^s "#*iii"g on the ROV.Duringthisprocess umbilical. in the anddistortiondueto thephysicalpropertiesof theconductors of n_umber Multiplexe.,yrt"-i *uy "6ntuin'8,i6, 32 or 64channels {epelding9l l!: lnto a incorporated functibnsbeirigincorpoiatedinto thesystemandarevery often singleIC. 6 . 4 F i bre Op ti cs 6 . 4 . 1 In tro d u cti o n has,overtheyearssteadilyimproved.Thelasttwentyyearshas Line transmission dramatically- seenrevolutionaryinnovationssuchasdigitalisatibnandoptoelectronics ROV that^the recently Ifisonly p"6nology of datitransmission. ind cosreffective uii"i of transmission in the transmission data i;d"rrty trastiiae useof OpticalFibre telemetryandvideosignals. 6 . 4 . 2 T h e o ry makesuseof theoriesthathavebeenknown Theprinciplesof opticalfibretransmission from whenit passes how a light beambehaves to manfor centuriel.Fig 6,27illustrates light of beam a when that onemediumto unoih"r6f diffrr.nt densities.It danbe seen the light is reflectedback is directedut u tru"tp**t medium(glass),althoughs^ome-of i;t" rh" &ginatlng medium(air),a h-ighp.oponionof thelight will passinto that medium.

102

IncidentRav

nl (air) n2 (glass)

q = Angleof refraction 0 = Angleof Incidence Figure 6.27 6.4.3

Refractive Index

Refractive index refers to the optical density of a material. It is a direct proportion betweenthe velocity of light in a vacuum to the velocity of light in the material. Velocity of light in vacuum Refractiveindex = Velocity of light in medium.

=n

The refractive index is given the symbol n. 6.4.4

Snells Law

Willebrord Snell put forward a theory that claimed that the sine of the angle of refraction(0 ) dependedupon the sineof the angleof incidence(0 ). He claimedthat the ratio of the sineof angleof incidenceto the sineof the angleof refractionis a constant.

Sin0=n! Sind=n2 Wherenl andn2 aretherefractiveindicesof thematerialthroughwhichthelight is passing. ugh a glassblock. trig O.Zashowsho

n2(glass) nl(air)

Figur e 6.28

103

l

areparallelthen( 01 ) mustbeequalto ( 02). Because theglass/airboundaries

n2 (glass) Light source

Figur e 6.29

Figure6.29showsthe situationin whichlight is passingfrom a denseto a lessdense m#ium i.e.glassto air.Inthis situationn2is greaterthann1 andthereforetheangleof refraction(0 ) is greaterthantheangleof incidence(0). the If theangleof incidenceis increasedstill furtherthenwe canseein figure6.29_that will point light the At this exceed90 degrees. angleofiefracrionwill eventually becomeTotally Internally Reflected.

cri tical angle

:

nl (air) Figure 6.30

It is the principlesof Total InternalReflectionthat is madeuseof in the transmissionof light throughan optical fibre. The glasstube actsas a guide for the light beam,as the light is rapped iniide the glass,then any bendsthat occur in the glassare insignificant. Itls necessaryhoweverto surroundthe glassin a cladding,the refractiveindex of which is slightly lessthan the glass,in order to minimise dispersionand thereforeany significantlosses. Note: The angle of incidencethat causesthe angle of refraction to be greaterthan 90 degreesis known as the critical angle and is roughly 42 degreesfor glass,with a refractiveindex of 1.5.

104

n1 (cladding)

n2 (fibre)

n1 (cladding) Figure 6.31 Fig 6.31 showsa situationin which the light beamis totally internallyreflectedthrough cladded fibre. 6.4.5 Light Transmitters In order to convert electricalenergyto light energyan Optoelectronicsemi conductor suchas a Light Emitting Diode (LED) or laserdiode is used. Note: Light that is emittedfrom an LED is quite safeto the nakedeye, howeverlight emitted from a laserdiode is potentially lethal and greatcare must be exercisedwhen using suchdevices. Fibre

GG

Active Reeion

+p

Silicon Dioxide

n contact n typeGaAs typezinc(diffused GaAs)

Gold Heatsink

Figure 6.32 Figure 6.32 showsthe typical constructionof an LED The applied electrical signal gives rise to the Gallium Arsenideprod'ucing"excited" electronsthat travel from the p type to the n type material.During this processthey producelight energy,a processknown as SpontaneousEmission. 6.4.6 Advantages and Disadvantagesof LED and Laser Diode 1) LED's are cheaperto manufacturethan laserdiodes. 2) Laser diodes have a greateroptical power and can work at higher temperaturesthan LED's. 3) Laserdiodesare sensitiveto overloadcurrents,when they are requiredto operate continuouslythey can produceunfavourablethermalcharacteristics.

105

6.4.6 Receiversand Photodiodes A photodiodeconvertslight energybackto electricalenergy.Theyaresimilarto LED's in the fact thatthephotons(light energy)giveriseto theflow of currentbetween theP-Njunction. 6.4.7 Types of Fibre Therearetwo typesof fibre commonlyavailable,SteppedindexandGradedindex fibre. 6.4.7.1 SteppedIndex Fibre As previouslystated,propagationalongpathsis possibleoncethe incidentray has reachedthecriticalangle,(approximately Howeverthis situationgivesrise 42 degrees). in attenuation to anincrease losses. anddispersion By makingthefibre coreextremelynarrow(approximately 50 micrometres),and enclosing it in a claddingof refractiveindexwhichis only slightlylessthanthatof glass,we cannot only reducethecriticalanglebutalsoreducelosses. A fibreconstructed in thismanneris knownasstepindexfibreandis suitablefor short distancetransmissions asfoundin ROV umbilicals.

106

Outerl-ayer

Cladding

Buffer Protective Coating

Figure 6.33 Steppedindex Fibre 6.4.7.2 Graded Index Fibre rn.9aiy$vantage sJgpindexfibreis thatthebandwidthof transmission is limiteddue 9f to thedifferentopticallengthsca,usg$ by thevarious lengthsat whichrigrrtis piopagare. This canbeovercomeusiig gradedinoi:xriure. Gil;ii;jex fibre dif?ersfi.Lmstep indexfibre in thefact thattfiJcoresrefractiveindexa.r*ui"r paraboticatt/*iirr iaaiar distance. Themainadvantage of using.graded indexfibre is thelow refractiveindexat thecenrre of thefibre. Thisis usefurtinl" ."rpiing ttresharpiti*r*o beamof anLED with thefibre.

t07

Figure 6.34 Graded index Fibre 6.4.8 Fibre Optic Connectors That available. It is nottheintentionof thischapterto list all thefibreopticconnectors coveredin theappendixsection. is adequately an opticalfibre for re-terminating Howeverit is essentialthattheconectprocedure breakdowntime. connectionis followedin orderto minimiseunnecessary a STRATOSSS430-01 for assembling Thefollowingsectionlaysdowntheprocedure in manyof Slingsby incorporated is This type of connector bundle. fibre opti-c to a fibre optic systems. Ltd ROV Engineering 6.4.9 Umbilical Optical Termination - Vehicle opticalfibre of theStratosSS430-01 relatesto theassembly Thefollowingprocedure coated jacket secondary 900mm fibre opticbundlecontaining connectorto a figtrt required: will be followingequipment fibres,withinanumbilicalcable.-The controlled); a Heatcuringjig (temperature

r 08

b Stratostool kiu c Micropolishec d OpticalCableFaultl,ocator(OTDR); e Connectors, leadsandsplicesasrequired; f Hot air gun; g Disposable syringes, 5ml and lml; h Stratossyringeneedle; g I9g syringeneedle; h Scalpel; It will alsobe necessary to havethefollowingmaterials: a ConnectorStratos S5430-011.0 b Heatshrink sleevingRaychem Atum3/1,612,I2/4 and1/16"RNF 100or similar: (isopropylalcohol) c Solvents2-propanol (or paintstripper) Dichloromethane White spiritor trichloroethylene d EpoxyResinEpo-tek 360 e SpiralCableWrap3mm f AbrasivePaper360grit wet anddry g AbrasiveFilm30mm,12mmand3mm 6 . 4 . 9 . 1 P ro ce ss In stru cti o n s a Switch on the heatcuring jig and serro 95 deg. C. b PrepareEpo-tec360 resin as follows: i. Draw up the requiredvolume of resin (part A), into the 5 nrl syringe (allow 0.5 ml per plug) noting that the calibrationdoesnot includethe volume containedin the nozzle.Withdraw the plunger further to leave an equal volume of airspaceabovethe resin. ii. Draw up the correspondingvolume of hardener(part B), (mix ratio 10:1 by volume) into the 1 ml syringewith the 19 g needle,ensuringthat there are no air bubblesand that the needleis full when making the measurement. iii. Inject the hardenerinto the resinby enteringthe needleinto the syringe through the nozzle.Mix the resin and hardenerby blocking the nozzle and shakingthe syringeuntil an evencolour is achieved.Pay particular attentionto the material which may becometrappedin the nozzle. iv. Degqsthe material by holding the syringe nozzleupwardsand expel all the air abovethe resin. Cover the nozzleand draw a vacuum by withdrawingthe plunger.Repeatthis operationuntil only a few large

t09

v. vi. vii. viii.

viii. ix.

x.

xi.

xii.

xii.

xiii.

xiv.

bubblesform. Wipe the syringe nozzleand fit the Stratosneedle.Leave the resin to standfor ten minutesbeforeuse. The pot life of the mixture is approximatelyeight hoursat room temperature. Strii, 500 mm of sheathfrom the fibre optic bundle and remove the tape wrap and filler compound. Cut the centrestrengthmemberapproximately50 mm from the cut end of the sheath. Place 100 mm length of l2/4 heatshrinkon the bundle and temporarily positionout of the way, by sliding along the cable. Placeonto eachfibre in the following order: (a) 50 mm length of Atum 6/2; (b) 100mm lengthof Atum 3/1; (d) 150mm lengthof RNF 100-1/16" (e) Stratosnut (female threadtowards end of fibre); (0 Crimp sleeve(shoulderedend first if applicable); 'No-Nik' tool (or similar) Strip 50 mm of coatingfrom the fibre using avoidingdamageto the fibre. fibres in dichloromethaneto remove the remaining Immers6the ex--posed wipe the fibre with a cleandry tissue'(,If qsing If necessary buffer. paint stripper,rembveiesidueby wiping with tissuesoakedwith 2propanol). Thd barefibre is very susceptibleto damageand contamination,do not touch or leaveexposedfor any longer than necessary. Checkthat the plug is clear by sightingthrough,if not, removewhite plasticcap andthen replacethe cap and re-check,luppo1 the crimp sleeueat ihe end of the coatingand assemblethe plug, guiding it carefullyover the fibre and onto the crimp sleeve,up to the shoulder. Crimp flug in position:Placethe plug in the smalljaws. Operaqqte lever-tohotd ttie plug (do not crimp yet). Pushthe crimp sleevefully into the plug. Crihp the plug without moving the plug.,sleeveor fibre. Oncethe crimping operationhasstarted,it cannotbe aborted. Using the cleavingtool, touchthe fibre flush with the face of the mountingcap and removethe excessfibre by bendingit away from the scratch. Excessiveforce when scratchingthe fibre will displaceor damagethe fibre inside the piug. Using the back of Cscalpelbladeand the thumb as a lever,carefully removethe white plasticcap.Removethe cap without twisting. Examinethe end of the plug to checkthat the fibre is centralizedbetween the balls,then fit the mouldedsiliconereservoircap. Do not attemptto refit the mountingcap afterremoval.If the fibre is trappedbetwbena pair of balls,or outsidethem,carefully depressone of llie balls with the tip of a scalpelto allow the fibre to return to the centre.Do not touch the fibre. Expel the air and a few drops of resin from the syringe to ensurethe noizle is clear. Hold the plug assemblyvertical with the reservoir upwardsand drop 2-3 dropsinto the reservoir,taking carenot to touch the fibre. Cleanthe needleand insertit into the injectionhole in the plug body. Withdraw the plungerto suckthe resin into the noseof the plug, if -.y air entersthe stringe remove the needlefrom the plug and expel the air beforecontinuing.Inject resin slowly into the plug until it reachesthe top of the reservoir,tip out resin andrepeatuntil threecycleswith no bubUteshave beenobierved. Removethe needlefrom the injection port and sealthe hole with the plasticplug. Wipe away any tracesof resin from the plug body.

110

xv.

xvi.

xvii.

xviii.

Check the temperatureof the curingjig is 95 deg. C. +/- 5 deg. C. Clamp the plug(s) in the heatingblotk.-Take care to avoid trapping the plasticplug. Do not move the reservoir,which, if moved, will-allow resin to contaminatethe noseof the plug. Allow the resin to cure until 1.5 to 2 mm of curedresin is visible abovethe plug (curedresin is a red/brown colour). Remove the plug and allow to cool to room temperature. Carefully twist and pull off the reservoir.Wipe away the remaining liquid resin. The cured resin should not be allowed io extend furthEr than 3 mm nor should it be left for more than eight hours before removing the reservoir,otherwise,difficulty will be experiencedin removing the reservoir without causingdamageto the potting in the plug nose. If the reservoir appearsto be stuck, cut through with side cutting pliers 2-3 ryy abovethe plug nose,and peel off the-remainingsilicone moulding.Do not exert any sidewaysforce on the resin, which could resultin damageto rhe fibre within the plug. Removetheplasticplug.

6.4.9.2 Potishing a Using 360 grit paper,sandoff the proruding resin until the 3 balls arejust visible. b Polish the plugs using Stratgstools with 3M abrasivefilms in the following order: i. Tool number 491with 30mm film (green) ii. Tool number 492with l2mm film (yellow) iii. Tool number 493 with 3mm film (pink) c Thoroughlywash the plug to removedebrisfrom previousoperationsand rinse throughthe polishing lool. Blow off excesswater and assembl6the plug into the tool and securewith the collar nut. Wet the glassplateand abrasivefilm ind-placethe film ol th9 plate..Floodthe surfacewith water and polish the plug using a figure of eight or circular motion progressing.across the film suih that the abrlsiue i-susei for one pass only. Keep the film wet during polishing. d Light pressure.onlyis requiredon the tool; when cutting is completea decreasein resistanceto motion will be apparentand no track will be left on the abrasive.Rinsethe tool underrunning water and removethe plug. e Removeabrasivefilm and rinse off debris,storefor further use,(an A4 sheetof abrasivehas sufficienrareafor the polishingof 6 plugs). f Repeatthe operationusing the tools and abrasivesin the order listed in 6.4.9.1. To avoid damageto other plugs,ensurethat the final polish with the pink film is complete. g Dismantleandrinse the tool and,plugin waterthenre-assembleand polish againwith the final tool until no further material is removed.Dry the plug using a bleanpiper ' towel payingparticularattentionto waterremainingih the nut and fii the white protectivecap.

ill

6.4.9.3 Finat Assembly and Testing a Test eachplug using the OTDR with at least50 m launchlength.Typical loss betweentheiwdtypeJof fibre will be 2 dB to 4 dB althoughthe systemwill operate with higher losses. testinstrumentsrecordsshouldbe kept of b When using light-source/power-meter finding and re-terminating,allowancefor fault when referenfe measuredvaliesTor made at 3 dB&m (850 nm) or 1 dB/km (1300 nm)' be should shorteningof the cable c Slide the 1/16" heatshrinkup to the backof the plug and shrink doyn tu\ing carenot to overheatthe fibre. Slide the'3/1heatshrinkovefthe crimpedend of the plug allowing 1 to 2 mm for Stratosnut movementand shrink down. Slid-ethe 6/2 heatshrinkonto the plug over the previouslayer to the sameposition and shrink down. d Identify fibres with numbersleevesover the plug body, ensuringthat thenumben co-incide"atboth rop and bottomof the umbilical by referenceto the wiring diagramor discardedumbilical end. e Wrap the fibres,from the sheathonto the large heatshrink,with the 3 mm Spirawrap as far as the plug body. f Lay the fibres backinto the helix of the bundleand positionthe heatshrinkover the end of the sheathprojecting50 mm beyondthe end and shrinkdown. Beforemakingconnectioni,ensureplugsand couplersareclean.If dirty, cleanwith a papertowel soakedin 2-propanol. 'O'ring on the outboardsideonly. This is to ini couplersarefitted with an internal underpressure. allow thi connectorfacesto free flood with oil thusavoidingcollapse 'O' ringsremoved. Couplersmountedinsidejunction boxesshouldhaveboth internal 6.4.10 Umbilical Optical Termination ' Surface The following procedurerelatesto the assemblyof StratosST optical fibre connectorto coatedllres, within an a tightjacketfibre optic bundlecontaining900mmsecondary in 6.4.9with the laid out as will required be The'same equipment cable. umb-ilical no 1 ml micropolisher; the with is recluired rubber-mat a differences: following to have necessary also be It will is required. nor scalpel, needle, syringe,lgg syringe thefollowingmaterials: includingwhite nylon crimp sleeve; ST-MC-128(or ST-LC-121t) a ConnecrorSrratos RNF 1fi)or sinrilar Atum 612and 1214,1116" b HeatshrinksleevingRaychem (isopropylalcohol) c Solvents2-propanol Dichloromethane(or paint stripper) White spirit or trichloroethylene 353 ND d Epoxy ResinEpo-tek e SpiralCableWrap3 mm f AbrasiveFilml2 ntm, 3 ntnt, and 1 mm

t12

6.4.10.1ProcessInstructions a Switch on the heatcuring jig and set ro 90 deg. C. b PrepareEpo-tek 353 ND resin as follows: i. Open the sealedsachetand remove the 'squish Pack'.Inspectfor damage. ii. Remove the dividing sealbetweenresin and hardenerby pulling the pack on either side,do not attemptto slide it as this may puncture the pack. mix the two componentsby kneadingrhe pack gently with the fingers until the colour is uniform and no streaksremain. iii. Removethe plungerfrom the syringe,cut the corneroff the squishpack and transferthe resin into the syringe, avoiding trapping air. iv. Degasthe material by holding the syringe nozzleupwardsand expel all the air abovethe resin. Cover the nozzle and draw a vacuum by withdrawingthe plunger.Repeatthis operationuntil only a few large bubblesform. Wipe the syringe nozzleand fit the Stratosneedle.Gave the resin to standfor ten minutesbeforeuse. The pot life of the mixture is approximatelyfour hoursat room temperature. v. Strip 500 mm of sheathfrom the fibre optic bundle and remove the tape wrap and filler compouni,. vi. Cut the centrestrengthmemberapproximately50 mm from the cut end of the sheath. vii. Place 100 mm lengthof l2l4 heatshrinkon the bundleand temporarily positionout of the way, by slidingalongthe cable. viii. Placeonto eachfibre to be terminated(in the order shown): (a) 50 mm length of Atum 6/2 b) 100mm lengthof Atum 3/l (c) 150mm lengthof RNF 100-1/16" (in oil filled junction boxesonly - in dry boxesuseboot supplied with plug trimmedto suit coatingdiameter) ix. x.

xi.

x.

xi.

(d) Crimp sleeve(for ST-LC-128- white end first) Strip 50 mm of coatingfrom the fibre using 'No-Nik' tool (or similar) avoidingdamageto the fibre. Immersethe exposedfibre in dichloromethane to removethe remaining buffer. If necessarywipe the fibre with a cleandry tissue.(If using paint stripper,removeresidueby wiping tissuesoakedwith 2propanol). The bare fibre is very susceptibleto damageand contamination,do not touch or leaveexposedfor any longer than necessary. Check that the plug is clearby sightingthrough,thenfully insertthe syringeneedleinto the backof the plug and inject until a beadof resin aPPears throughthe otherend of the plug. Removethe syringewhilst still injectingto leaveresinin the backof the plug - approximatelyhalf fill the receplacle. Supportthe crimp sleeveat the end of the coatingand assemblethe plug, guiding it carefullyover the fibre and onto the crimp sleeve,as far as it will go without forcing it. Maintain light pressureuntil any excess resin flows out; carefully wipe resin off without moving the plug. Crimp plug in position:placethe plug in the smalljaws. Opeiatethe lever to hold the plug (do not crimp yet). Pushthe crimp sl-eeve fully into the plug. Crimp the plug without moving the plug or sleeve. -Ue Once the crimping operationhasstarted,it cannot aUorteO.

113

xii.

xiii.

check the temperatureof the curingjig is 90 deg. c. +/- 5 deg. c. ettow the resin to cure until the Clamp the plu!(s) in the heatingUtoct<. red/browncolour' plug is a beadbf resin on the end of the (Approximately20 30 minutei dependingupon ambienttemperature). Remove the plug and allow to cool to room temp€rature. Using the cleavi-ngtool, touch the fibre flush with the beadof resin and remo..rethe excessfibre bv bending it away from the scratch' Excessiveforce when scratchingtlie fibre will damagethe fibre inside the Plug.

6.4.L0.2 Polishing a Examine the end of the plug for exposedfibre and, if necessary,lightly polish with dry 12 mm film to removethe glassonly. b Fit the plug into the polishingtool. c Placethe rubbermat on the glassplate.Wet the mat and12 mm film and placeon the mat. Flood the surfacewith witer anOtlgtrttypolish the plug using a figurg of eight or circular motion progressingacrossthe film iuctr that the abrasiveis usedfor one pass only. Keep the film-wet du-ringpolishing.Regularlyexaminethe plug face until only a thin film of resin in the centreof the face remains. d Removethe mat from the glass.Wet the glassand 3 mm film and continuepolishing. Light pressureonly is requirddon the tool. Regularlyexaminethe plug face until no resin is visible on the ceramicfaceof the plug. e Repeatthe operationfor the remainingplugs. To avoid damageto the otherplugs,ensulethat the final polish is complete. 6.4.10.3 Final Assembly and Testing a Test eachplug using the OTDR with at least50 m launchlength.Typical loss betweenthe two typesof fibre will be 1 dB to 2 dB althoughthe systemwill operate with higher losses. testinstrumentsrecordsshouldbe kept of b When using light-source/power-meter measuredvalies-for referencewhen fault finding and re-terminating,allowancefor shorteningof the cableshouldbe madeat 3 db&m (850 nm) or I db/km (1300 nm). c Slide the l/16" heatshrinkup to the back of the plug and shrink down ta\ing carenot to overheatthe fibre. Slide the-3/1heatshrinkup to the back of the plug and shrink down. Slide the 6/2 heatshrinkonto the plug over the previouslayer and shrink down. Ensurethe final layer doesnot foul the sprungsleeveof the plug. d Identify fibres with numbersleevesover the plug body, ensuring.that.thenumbers correspondat borh top and bottom of the umbilical by referenceto the wiring diagram or discardedumbilical end. e Wrap the individual tubesfrom the sheathonto the heatshrinkwith the 3 mm Spirawrapas far as the plug body. f Lay the fibres back into the helix of the bundle and position the I2l4 heatshrinkover the end of the sheathprojecting50 mm beyondthe end and shrink down. ensureplugs and couplersare clean.If dirty, clean with a Before making conne^ctions, papertowel soakedin 2-ProPanol.

u4

6.4.1J Optical Time Domain Reflector (OTDR) The OTDR is probablythemostcommonpieceof testequipmentusedin the maintenance of ROV opticalfibre systems. (i.e.loss This instrument is usedfor measuring performance, attenuation transmission versesdistance)in situationswherefibreshavebeenrepaired. Theoperationof OTDRsmakesuseof theprinciplethatthetime takenfor a pulseof light beingtransmittedandthusreflectedcanbe measured.It is thereforepossibleto locatefaultsover a knownlengthof fibre. Figure6.12illustratestheprincipleof operation.

115

6.5 Fibre Optic Safety Guidlines systemwhich containsa Laser This ROV systemincludesa fibre optictransmission r.p"Ut" "f iititting harmfulradiationat a wavelengthnot visibleto thehumaneye. The to ensurethe safetyof all personnel. foitowing guideliriesmustbe understood 1) Never Look Directly Into a Laser Beam from a bulkheadfitting or a fibre tail whenthelaseris switchebon. Protectivecoversand/orshieldingshouldbe used to preventthispossibility. wherenecessary checking. 2) Never Use Optical Viewing Instruments(ie microscopes).when suitable 6r opticalpower.'TheROV systEmwill havepowermetersandlight sources for checkingthecontinuityof anopticalfibre link. 3) Never Inspect Polished Connectorsor Terminations beforeensuring^that the laseris switchedoff andthe ROV OCU Power is IsolatedandLocked Off at the PDU. Whenhandlingfibre opticcablethefollowing safetyinformationshouldbeunderstood by all personnel. "SharpSafe" 1) Never CasuallyDiscardGlassFibre Shardsalwaysusethe box suppliedwith eachsystemfor properdisposal. 2) Never LeaveSpareFibre Loose,alwaysensurethat spareor disusedfibres aresealedandprotectedwith heatshrink. 3) Wear SafetyGlasseswhenhandlingthe exposedendsof tetherandumbilical cablescontainingopticalfibres. on all junctionboxesand 4) Ensure"Laser Warning" Labelsaredisplayed S. s andtermination g fibre-opticconnection containin enclosures

l16

CHAPTER 7 USE OF TEST EQUIPMENT 7.0 Introduction It cannotbe emphasised enoughto theROV Pilotflechnicianjust how importanrit is to havea thoroughunderstanding of the basictestequipmentivailable. hi general, thevastarrayof settingson a multimetercanbeoff iutting to thenovicetedhnician andconfusiontendsto arisewhenthenewoperatoriails tdappreciate the basictheory behindthevariouselectricalquantitiesbeingmeasured. 7.1 ElectricalQuantities Thequantitiesandqualitiesthatareof interestto thetechnicianare: 7.1.I

VOLTAGE AC/DC

7.1.2

CURRENTACDC

7.1.3

RESISTANCE

7.1.4

CONTINUITY

7.t.5

INSULATION

The theoryof thosevariouselectricalquantitiesthataremeasurable is discussed in chapter6. 7.2 MeasuringVoltage The unit Volt refersto thepotentialof electricalchargeat a givenpointin a circuit with respecltg 0v or groundasit is commonlyknovin. Dep"ending on the iystem being.tested thevoltagemay.be AC or DC. T[rediagrambtilowsh?wsu iyp'i"ur situationwherevoltageis b-eing measured: +10V

10kohms

5V with respect to ground

10k ohms

uv (grouno)

Figure7.1

t17

7.3 Measuring Current As with voltage, curent may be AC or DC and care must be taken to ensurethat the meter is at thJcorrect settin!. tt may be necessaryto re-insert the positive meter lead is a movement of electrical (red) in another socket for cirrent rneasurement.Current'broken' and the meter be must circuit the and therefore a circuit iharge through below shows an The diagram measurement. correct the in to obtain inseied s&ies measuring: example of current

/s\

Meter inserted in seriesinto circuit

Figure7.2

7.4 Measuring Resistance Measuringresistanceis quite straightforward as the meter hasonly one serof ranges as opposedto voltage. When measuringresistanceit is important to switch off the equiphent that is being tested. Any componentsthat are being testedshouldideally be out of circuit. This is due to the fact that surroundingcomponentsmay be in parallel with the componentbeing testedand will in effect producea lower resistance value. 7.5 Continuity Testing When carrying out fault diagnosiscontinuity testingtendsto be one of the commonest test procedurescarriedout by the technician. The test indicateswhetheror not there is an electricalconnectionbetweentwo relevantpoints in a circuit. In the ROV industrv industrycontinuity continuitv testing testins is predominantly oredominantlvusedin order to test subseacablesfor conduciorbreakage.Moit multimetershave a dedicatedswitch settingfor continuity testing. This position is indicatedby a symbol depicting a diode and an audio tone. The diagram below indicatessucha symbol. Figure 7.3. Provided thereis lessthan a certainvalue of resistance(variesfrom meter to metel, e.g.. 50 ohms, 100 ohms).This meansit may not operateon a long length of cable.

118

->F- ,r)) Figure7.3 On placingthetestleadson therelevantpointsin thecircuit,a bleepingsoundwill be heardif continuityis present.The testcanalsobecarriedout by settingthe meterto resistance.Obviouslyif continuityis presentthemeterwill readcloseto Ohms. The disadvantage of thismethodis thattheoperatorhasto physicallylook at themeteras opposedto just hearinganaudiotone.

7.6 Insulation Testing Insulationtestingis probably the most common form of test carriedout in the ROV industry. Subseacablesand connectorsare under constantstressfrom factors such as high subseapressure,vibration and corrosion. Thesefactorscan lead to a break down in the insulation betweenthe conductorswhich will eventuallylead to a short circuit. For this reasonit is important to regularly test the insulationresistancebetweenall conductorsin a cable. The test meter usedis known as a Megger Meter. It is impofiant to appreciatethat by just measuringthe resistancewith an ordinary multimeter we could not determinehow the cable would perform in a realistic situationi.e. carrying high voltages.By using a Megger Meter we in fact apply a high voltage e.g. 500v and measurethe resistanceat the sametime. In practicethe meter has two test leadswhich may be fitted with crocodileclips in order to ensure the safetyof the operator. The meter can be set to measurein excessof 200 Megohms,when connectedup the operatorpushesthe test button which appliesthe vo-ltage.The resistanceis indicatedby a moving needle,a cable shouldideally have infinite resistancebetweenits conductors.The following precautionsshould be noted when using Megger Meter: 7.6.1 Disconnectall cablesfrom any electroniccircuitry. 7.6.2 Do not touch probe conductorswhen carrying out meggertest. 7.6.3 Always dischargecableswhen testis completed.Adjoining conductorswill have capacitivepropertieswhich may storecharge. 7.7 Types of Meter There .ue two typesof meter commonly availableto the engineer. (a)

ANALOGUE METERS

(b)

DIGITAL METERS

7.7.1 Analogue Meters Analoguemetersusually incorporatea pointer which can move over a scaleand can, within limits, assumeany readingi.e. theycan indicatecontinuouslyany magnitude of voltage or current.There are many typesof instrumentsthat fall into this category, but the most common is the moving coil meter.

119

t

Figure 7.4 The moving coil meter consistsof an aluminium former which is pivoted at eachend so that it is?ee to roratein a magneticfield. Fine copperwire is wound aroundthe former through which cunent is passed.The magneticfield is producedby.shaped perrnanent magnets,the magnetic circuit is completeg bV I cyliryler of .soft iron, so ^that is therefore, only a nariow gap remains through which the coil swing.s. Tt_r_e-.coil is When current positioned in a mafn6tic field of uniform strengthand direction. the of magnitude. through the-coilit takesup a position dependingupgn the fassed 'current. The-movingcoil meter usesthe principlesof the electric motor which is coveredin chapter6 of this book. Obviously the accuracyof this meter dependson userinterpretationof pointer position. To reducereading€rror a narrow needleis usedand the scalefitt-edwith a mirror. The user simply aligns the needlewith its reflection.The magnitudeof currentthat can be measureddependson.theresistance of the coil. In order to measurelargercurrentsa resistoris connectedin parallel with the coil, this is known as a'shunt'resistor.The moving coil metermay alsobe used as a voltmeter by connectinga resistorin serieswith the coil, the resistoris known as a multiplier. With the aid of an internal.batterythe moving coil meter is.capableof measuringresistance.For electronicservicingwork a meter that is capableof measuringall electricalquantitiesis used,this is known as an Avometer. 7.7.1.1Multipliers. This sectiondiscussesthe principlesof using a multimeter to measurevoltageby incorporatinga multiplier iesistor. In this examplethe meter has an internal resistance of lkQ and a full scaledeflectionof 40pA. This simply meansthat the meter needle will be deflectedacrossthe full rangewhen a currentof 40pA is passedthrough it.

Figure7.5 Max voltage= 1kC)x 40PA V= 0.04V V= 40mV Thereforethismeterin its 'raw'statecouldonly readup to 40mAor 40mV. If we wish to readhighervoltagesor culrentswe needto adaptthecircuit. capability,resistorsin Placingresistorsin serieswill increasethevoltagemeasuring capability. parallelwill increasethecurrentmeasuring

120

Example:If the abovemercrwasto measureI Volt, whatseriesresistance wouldbe required? Totalresistance musrequal;

1 volt/40pA= 25ke 1 R = V/I )

Therefore a24kQ resistoris requiredin serieswith the lkQ resistanceas shown in figure 7.6

Figure7.6 This is termeda multiplier and enablesuseof the meter as a voltmeter. 7.7.1.2 Shunts In order to read culrent, a parallel or shuntresistanceis requiredin circuit. Example: rf we wish the samemeterto read 1OmAf.s.d.,what valueof shunt resistanceis required?

1 = (10mA) - (a0pA)= 9.96mA V=40uAxlkO=40mV R =V/[ R = 40mV/9.96mA R = 4.02C1

121

Example: What value of shuntis requiredto makea 40pA, 10kQ meterread1A f.s.d.?

I =1-40pA I = 0.999964 V=IxR V=40pAx10kO V = 0.4V = 0.4VI 0.99996A Shuntresistance = 0.4 c) Shuntresistance 7.7.2 Meter loadingeffect Theprocessof usingshuntsandmultipliersmeansthatour metershavea sp-ecific is conditionalon valuefortach voltagerangeon themeter.Thisresistance resistance therangein useandis normallyquotedin kQ /V e.g.an AVO Model 8 has20 kC)^/ on boththeac anddc voltageranges.This meansthaton the lV rangethemeter while on the 5V rangeit has5 x 20kQ =100kf) . systemhas20kQ resistance, smallvoltagesacrosshighresistance's. This hasseriousimplicationswhenmeasuring Example: What voltage shouldbe measuredin the circuit below and what voltage would be measuredassumingthat the meter is an AVO 8 (20kO f/) on the 5V range?

122

Figure7.9

Expected voltage: 5 V Measuredvoltage: Meterresistance = 5 x 20kCl = 100kQ Totalcircuit.resistance=(1 /I20kO+ I / 100kQ)+ l20kQ thereforeit follows that 54.5kQ+ 120kQ= 174.5kQ Currentdrawn =

10/ l74.5kQ = 57.3LrA

Voltage acrossmeter -- 57.31tAx 54.5kQ = 3 . 1 5V 7.7.3 Digital Meters Digital metersgive a direct readout that is free from human eror. The instruments have no moving partsand are generallylessexpensivethat analoguemeters. a b

a l'

e

s lf

a a a a a a a o

a o a a

o

.

a a a a o a

Figure7.10

t23

The diagram aboveshowsthe typical layout for a digit on a meter. Each segment may be representedby four lighi emitting diodes(LED's). The LED's emit light when a suitablevoltage is appliedto them. 7.8 Safety Precautions a) Check Test Leads for damageto insulation. b) Always setmeter to highestrangebeforetaking reading. c) Ensurevoltage being measuredis within rangeof meter. d) Removeany jewellery beforeworking on live equipment. e) If possiblealwayswork with somebodyelsepresent. f) If possiblecarry out measurementusing only one hand. 7.9 Oscilloscope The cathoderay oscilloscope(CRO) is a measuringinstrumentin which the deflectionof an electronbeamdisplaysan appliedvoltage. An electronbeamis directedthrough a vacuum on to a face plate that is coatedwith fluorescentpowder. When the electronbeamstrikesthe face plate it producesa spot of light on the screen. The oscilloscopeincorporatesa systemof platesthat, on applicationof a voltage,deflectsthe electronbeameither horizontallyor vertically. The resulting movementof the spot of light can now be usedto measurethe applied input voltage. The deflection systemincorporatestwo setsof platesknown as X and Y plates,the X platesprovide horizontaldeflectionand the Y platesvertical deflection. If the input to the deflection systemis rapidly varying , persistenceof vision will make the moving spotof light on the faceplateappearas a continuousline. 7.9.1 Advantagesof the oscilloscope a) Low inertia of electronbeampermits the measurementof rapidly changinginput waveforms. b) The deflectionalong two axis allows a graphicaldisplay of voltage againsttime. c) Oscilloscopeshave a very high input impedancewhich preventsthe circuit under test becominsloaded. 7.9.2 The basic system All ROV systemswill have an oscilloscopeincludedin the tool kit, many different types are in existence,however,the principlesof operationare the samefor all models. The oscilloscopeconsistsof threebasicblocks. Theseare : a) A cathoderay tube (CRT). b) Vertical deflection system( Y Plates).

124

t

c) Horizontal deflection system( X Plates). 7.9.3 Cathode Ray Tube (CRT) The CRT containsan electrongun that consistsof a cathodethat when heatedemits electrons. The electronsare acceleratedtowards the face plate by electrodesthat also regulate the intensity of the beam. It follows therefore thdt theseelectrodesdetermine the brightnessof the traceon the display. The electronbeamis focused_byan electronlens. The electronlens achievesfocusing by either electromagneticcoils or field shapingelectrostaticelectrodes.Most oscilloscopesuseelectrostaticallyfocusediubes.

ELECTRON LENS ELECTRON GUN

cathode X deflection

r

intensity focus

Figure 7.ll 7.9.4 Yertical deflection system The vertical axis is usedto measurethe magnitudeof the input voltage and normally requiresa voltage of between20 and30 vofts to producea full scale-cleflection of the electronbeam. An amplifier and attenuatornetwork allows a wide rangeof input signals_tobe measured,the attenuatorhaving a switchedrangethat is rn'anually controlled.

125

face plate coated in

phosphour

The oscilloscopescreenis thereforegraduatedwith a fixed numberof centimetre squares,each squarerepresentinga fixed voltagelevel dependingon the settingof the VOLTS /DIV control. The Y gain control is normally variable and allows the operator to make a wave form occupy-afixed numberof squares.This function becomesuseful yhgn Ising a dual traceoscilloscopeand comparisonof two input signalsis required. A dual trace oscilloscope,as the nameimplies, has two electronbeamsthat are independently deflectedallowing two signalsto be displayedat once. 7.9.5 Horizontal Deflection System In order to give a voltage againsttime display the spot must be made to sw^eepfrom left to right acrossthe display. This is achievedby applying a ramp wave form to theX plaies. The ramp wave form is commonly known as a sawtooth wave form and is generatedby an oscillatorcircuit within the oscilloscope.

fly back

Blankingperiod

sweeptlme

Figure 7.12 The rising edgeof the SAWTOOTH givesrise to the spot moving acrossthe display. The sharpfalling edgerepresentsthe spotreturningto the left hand side of the display tfly back'period. During this period the electrongun is tumed off and is known as the and thereforeonly the left to right traceis displayed. The sawtoothis generatedby an oscillatorknown as a timebaseoscillator.This oscillator can generatedifferent sweepspeedstherebyaltering the time it takesfor the spot to sweepacrossone squire. The timebasecontrol determinesthe output of this oscillator and is calibratedin TIME / DIVISION.

t26

7.9.6 Oscilloscopeprobes Oscilloscopeprobesare usedto detectthe actua_lsignal,they have fine metallic tips that allow measurements of signalsto be madefronivarious componentson a cir&it board. The probe is connectedto the oscilloscopevia a screenedcable.For this reasonthe an eafth clip which must always be attachedto a suitableearthpoint on the lldg.ttut clrcult. It is also.necessaryto calibrate the probe before use in order to compensatefor thebuilt in reactance.This is achievedby connectingthe probe to tfi" rqu6r.i*uu" gutlYt of the oscilloscopeand altering the _adjustmeitscr6* on the acd;i probe. This is adjusteduntil the squarewave has a unifonn shapeas shown in rigure zlti--

TNCORRECT

CORRECT

INCORRECT

Figure7.13 7.9.7 Oscilloscope controls. figurg 7.4 illustratesthecontrolson a typicaldualtraceoscilloscope.It is not the intentionof this chapterto discusseuery'function aviilableastheyarenot normally requiredfor thebasictestprocedures cdrriedout on anROV syrte-. Uoweveithe maincontrolsthatarenecessary areoutlinedbelow. 1) POWER ON / OFF: Turns oscilloscopeon and off. Operating condition is indicatedby an LED. 2) X POS: Controlshorizontalposition of trace. l0) TIME / DIV: Selectstimebasespeed. 16) INTENSITY: Intensitycontrol for fface brightness. 17) FOCUS: Focuscontrol for tracesharpness. 19) CALIBRAToR: o.z.v peak to peak squarewave outpur for calibrationof testprobe.

r27

20) coMPoNENT TESTER:Enablesa wide varietyof electrical to be testedby connectingajack plug.into th.e.CTsocket components into the groundsocket.Theresultingdisplay connection in earth and of thecomponent.Thedisplayscanis normally integrity the indicates manual. oscilloscope in the be found 2l) Y POS:Controlsverticalpositionof trace. 24) VOLTS/ DIV: Selectssensitivityin eithermV /Cm or V / Cm. 26) DC - AC - GD: Selectsinputcouplingto eitherDC,AC or

:

,tt"='".

lll\ *-ll 1

;5

d o , ir 9o ?r

in

I

"T-'l d -

OU

-T-l "Ll :l

ifl.;G$(I

ilnFZAi*

r!\\4 ; 6>==t?r V/ -:\

EEO //\ r

.\J/.

'-' .\J,

Figure7.14

i t28

l

I

7.9.8 Typical usesof oscilloscope Oscilloscopesdo not come into everydayuseas do test meters,however in certain situationsthey becomeessentialto the technician. Typical testsare as follows. a) Monitoring of video signalduring either calibrationof cameraor fault finding on the video sysrem.(Seechapter15). b) Monitoring of telemetrysignalduring fault finding procedure. Telemetry signals,being digital signalsare best suitedto being measuredwith an oscilloscope. It is not possibleto interpreteachdigital pulse,however it is sufficient to be able to stepthrough a circuit and determineif telemetrysignalis present. This enablesthe technicianto be able to fault find to board level or if necessaryto componentlevel. 7.9.9 Measuring Amplitude of a Signal The amplitudeor, signallevel as it is commonly known can be determinedby making useof the screengraticule. By altering the VOLT/DIV control then we can ielect a suitablescalein order that the level of signalcan be determined.For exampleif the VOLTIDIV is set to 2Y|DIY then in the exampleshown the peak to peak voltageis 6V.

2V per division

Figure7.15 TypicalvoLTiDIVISIoN sertings mayrangefrom 5 voLTS /DIVISIoN to SmV/DIVISION. 7.9.10Summary It is not the intentionof thischapterto discusseveryfunctionavailableon oscilloscopes. Therearemanytypesavailableandthe technicianwouldberequired to readtheoperators manualfor theparticularoscilloscope he/sheintendsto uie. However,the basicprinciplesdiscussed in this sectionapplyto all oscilloscopes.

t29

7.10 Self Diagnostics Many ROV systemsnow incorporatea surfacecomputerthat carriesout a self diagnosticspiogra-*e. This ehablesthe operatortb monitor signalsat various points in the system. A typical self diagnosticsprogrammeis includedin the_HydrovisionDiablo ROVThe lollowing pagesare availablein a typical data display system. a) Multiplexer information: Up link and down link data for each channelc-anbe displayedshowingeachindividual data'bit'. When a function is operatedthe datacan be seento vary accordingly. b) Main display: This pageis normally displayedduring diving operationsand providesttre pilot with vehicle heading,vehicle depth, pitch and roll, oil pressureand temperature. c) Thruster demand and gain: The amountof thrusterpower that is being usedis displayedgraphically. Also the thrustergain is displayed as a percentage,it is possibleto adjustthe gain to suit the conditions during the dive. are displayed d) DC voltages: The DC voltagesat the control outputs 'null' the trim both digitally and graphically. It is also possibleto controls to zero volts in order to eliminate thrusterspin when no input is receivedfrom the joystick. It can be seenthat it is possibleto diagnoseareasof faults without touching the ROV. This can make the faulf finding procedurelesstime consuming The softwarealso allows the operatorto re-programmemultiplexer channels,for exampleif someextra equipmentis to be fitted io the vehicle a channelcan be set up without any physical re wiring taking place.

130

CHAPTER 8 HYDRAULIC SYSTEMS 8.1Introduction Vehiclesare,aspreviouslystateddividedinto threeclasses. SeqotgJV__QPerated pJe.ball,WorkclassandLarge InspectionCiass. The lattertwo arenormally dedicatedto work tasksandpipelineinspections.Dueto thephysicalsizeof tlie vehicleandthe weightof the.equipment fitted to theRov, thefower/sizedeveloped by the thrustersis critical to their operation.For this reasonmanufaciurers makeuse of hydraulicsastheir sourceof power. 8.2 Hydraulic Principles Hydraulicscanbedefinedasthe transmission of powercreatedby pushingon a c.onfinedliquid. Figurg8.1 illusratesa simplehydraulicpress,cirrying o"utexactly the sametaskasa mechanicallever. A forceof iOtUis aplpUea to a pision of an area of I squareinch, the pressureis definedasForceper Unit area,or: Pressure=Force/Area Thenit followsthata pressure of l0lbs per squareinchis developed in thefluid throughout.the container.By_simple caltuhtionwe canseethat^the pressure developedin the containerwill in fact supporta loadof l00lb suppoitedon a piston areaof 10 squareinches. In comparisonwith the mechanicallevei, we canseethat exactlythe sametaskcanbecarriedout by a fluid basedsystem.

3. This pressurewill supporta 100lb. weightif this is a 10sq. in. piston.

An input lorce of 10lb.on a one squarc inch piston

r I

I

vl

.l/ 2. developsa prcssure of 10 pounds per squarc inch (psi)thrcughout the container.

INPUT 4. The forcesarc proportional to the piston arcas. 10tb. 1 sq. in.

=

100tb. 10sq. in.

A. SIMPLEHYDRAULIC PRESS

Figure8.1

l3l

OUTPUT

A basichydraulic systemrequiresa pump to developthe oil pressure,a valve to control the flow of oil to the actuator,which in turn carriesout the work required by the system.Figure 8.2 illustratesa basicsystemof this nature.

2. Llneecarrytho llquld to actuaton whlch arc pushed to causea mechanlcaloutPut to movea load.

TORESERVOIR 3. Someactuaton openle ln I stralghtllne (llnearactuatoF). Theyarc calledcyllndon or ram8. They arc ugedto llft vuelght'exerl force,clamp,etc. A. LINEAR ACTI'ATOR

Figure8.2

132

I

8.3 Advantagesof Hydraulics Hydraulic systemshave severaladvantagesover non-fluid basedsystems. 8.3.1 Variable Speed The speedof the actuatoris dependenton the volume and flow rate of the oil being suppliedto it. This can be achievedby either using a flow conffol valve, or by alteringthe deliveryof the pump, i.e. how much oil the pump suppliesto the actuator over a given time. 8.3.2 Reversible It is possibleto reversea hydraulicactuatorinstantaneously without causingany damageto the system. A directionalcontrol or reversiblepump providesthe reversingcontrol,whilst a pressurerelief valve protectsthe systemfrom excess pressure. 8.3.3 Overload Protection A pressurerelief valve protectsthe systemfrom excesspressurebroughtaboutby an overloador torque,force in the actuator. For exampleshould an ROV thruster becomefouled and seized,thenthe flow would ceaseand the pressurebuild up. The pressurerelief valve will activateand allow the oil to flow back to the tank, thus protectingthe systernfrom damage. 8.3.4 Stalling If an electricmotor stallsduring an operationdue to overload,it is likely that a fuse will blow, thuspreventinginstantre-start.If a hydraulicsystemstalls,thenthe PressureRelief Valve will divert the oil backto tank for the periodof time that the systempressurerentiiinsin excessof nomtal working pressuie.Once normalpressure is resumedthe systemwill continueto operateas normal. Stalling, therefore,does not posethe sameproblenrin a hydraulicsystem,as it doesin a purely electricalor mechanicalsystem. 1. In thls posltlonof the dlrcctlonalvalve.. .

2. pump dellr/ery18dlrcctedto the cap end of the ryllnder. 3. The plston rcd extends.

DIRECTIONAL VALVE

Figure8.3a

133

4. Exhaustoll ls pushedout ot the rcd end and dlrccted to the tank.

5. In anotherPosltlon'oll ls dlrcctedto the rcd end of the cYllnder.' .

6. the Pletonrod rctracts.

I I !

Exhaustollfrom the cap end ls dlrcctedto tanx' 8. -' The rcllef valveProtectsthe iwt". bYmomLntarllYdlvertlng ir6w to tank durlng reveelng' anO*rt en Plston|s stalledor

lil,pi-ii6,iaot strcke.

Figure 8.3b

8.4 Pressure Pressureiscreatedwhenevertheflowofliquidi'1.::Y:'g..Thismaybebrou.ght with anapplied in thepiping'or thepiestnceof anactuator load aboutbv a restriction An 80001b oil pressure. i;;;; "i'; efiect tiie illi;r;;;..; 8.4 Figure road. of tt00PSIPressure'Force inchpisto' t;";;t;;;;;;"it bv a 10sqLrare srrnnorted a' ;'d"Ar;;.;6 ii *.,t't y thefoll-owi ng formul Pressure= &Isg Area Pressure= f(l0llD 10Sqin Pressure= 800PSI

I t f o l l o w s t h a t i f t h e l o a d i s u n c r e a s e pu" d t h eit"n spitton' o i s t h eTheForce p l e s s u rand e . FPiston igureS.4(B) theeffect"1" f..t on the t'ti"* illusrrares sanle'Howevertheoil flow prrrr"#iJtuintih" s9 and unchanged remain the flowis 10 Area o"*p output passses thepiston;';;t;il's-s'ir19"i fi;;il;minute.t*l: overal] The to *ou" thepiston' *-OlS"guff9"r'prl i;[;;; then Lallonsimins t6adwill movemuchslower' Effectis thattfr" pi.to"riuii,ii"i"fJ* ttre

134

I

1. Theforceis 8000tb. and. . .

2. the arcais 10sq. in,

3. The pressur€equalsForce+Arca equals8000lb.+10sq. in. = 800psl. A. NO LEAK IN SYSTEM

Figure8.4a

gpm arelost thrcugh 4. ,19-112 a leak.. .

5. the oil not lost muststill raisethe piston.

6. Thusthercstill is an 8000lb. forceon the oil and pressureis maintained.

B. LEAK IN CYLINDER Figure 8.4b

135

8.5 Flow As discussedin the previous section,it is pressurethat gives the actuatorits force. However, it is the flbw of oil that gives thb actuatorits movement,flow is createdby the actionof the pump. 8.5.1 Measurementof Flow There are two ways in which flow can be measured. Velocity - The averagedistancethat the oil particlestravel per unit and time. Units - Feetper secondor metresper second Flow Rate - Is a measureof the volume of fluid passinga given point in a given time. Units - gallonsper minuteor litresper minute 8.5.2 Flow and PressureDrop In order for liquid to flow, theremust be a stateof unbalancedforce to causemotion. when fluid flows througha pipe of uniform diametertherewill alwaysbe slightlyless pressuredown streamwittr ieipect to the pressureup streanr.This is due to friction in lhe pipeline,and must be takeninto accountduring the designof the system.Figure 8.5 illustratespressurewith respectto flow througha unifornl pipeline.

1. Prcssureis maximum herebecauseof lhe heightol llquid.

4. Succeedinglylower levelof liquld In these pipes is a measurc

2. Pressurcis zerc her€ as the llquid llows out unrcstrlcted.

3. Frlctionin the pipe drops prcssure fiom maximum to zerc

Figure8.5

8.6 Hydraulic Calculations By applyingthe basiclaws of physicsit is possibleto determinethe main components requiredby a hydraulic system. 8.6.1 Determining Pipe Size By applying one of two formulasit is possibleto calculatethe size of hydraulic lines required. If gpm and velocity is known, it is possibleto calculatethe cross Sectional Area of the flow line. Cross SectionalArea =

( squarefeet)

gom x 0.3208

Velocity(fps)

N.B. fps - feet/second

The Velocity in fps can be calculatedby usingthe formula:

(fps) velocity

=

3.r17ffiea

8.6.2 Work and Power Work is carriedout whenevera force actsthrough a distanc:e. i.e. Work = Force x Distance e.g. A 10lb load is moved througha distanceof 5 feet. ThereforeWork = 10lb x 5 feet Work Done = 50 ftllb In practicewe must takeinto accountthe rateat which work is done. This is referred to as power. Porver = .Ee.tgg-E-Di$ltglgg or Work Time Time 8.6.3 Horsepowerin a Hydraulic System One horsepoweris describedas being power requiredto lift 33,0001b,1 foot in 1 as gallon/minute, minute. In a hydraulicsystemspeedand distancearerepresented and force is representedas pressure. Horse Power = gpm x P.S.I x 0.0005tt3 Horse Power = gpm x Psi x 0.583

1000 or hP= SP1IIJ-ESI t7t5 We can now calculatethe exacthorsepowerof a systemusingthis formula,however this formula assumesthat the systemis 1007aefficient. In practicea typical hydraulic systemis only about 807oeffrcient. For this reasonwe have to calculateon effective horsepowerto compensatefor losses. The equationis as follows:-

137

hp = gpmxPSIx0.000583 hasto bemodifiedto approximately hp=gpmxPSIx0.0007. N.B. 0.000583is approximately80Voof 0.0007. Thushorsepower cannow berepresented h.p=gallonsxpAUXdE minutes Sq Inches As I gallon- 231Cubicinches l 2inches- lfoot Power

=

sallon minute

x e1!in3 gallon

x

Pounds in2

x

12in

= 231 ft lb l min t2 This givesthe equivalentmechanicalpowerof one gallon per minuteflow at 1 PSI of pressure.We can expressthis as a horsepowerby dividing by 33000foot poundsper minute.

++ rtrb/ min 33000

= 0.0005tt3hp

ft lb / min

hp 0.0005t13 Thus 1 gallonper nrinuteflow at I PSI ecluals 8.6.3 Horse Pnwer and Torque Torque can be defined as a rotating or twisting force. There are two torque - power formulasmost commonlvused.

Torque=63025xhp rpm

hp = fgrgue-:rlpxq 6302s

8.7 BasicHydraulicSystem Figure8.6 showsthe basiclayoutof the hydraulicsystemof a typicalWorkclass ROV. It is the intentionof this sectionto discussthe variouscomponentsthat make up the system.

138

:

2. C a a t

{ t ;

-9:

g 9 e , 6 :

:> e 6

a 7

9 : - i

4 =

9.: 6 q

,

,3

z o a o

o I a

o t o o I

= I

3? ol

:< 5 r

t

t, I !

I

i< z:

t

rt : <=

c

e {

; o t 6

i O

ir t:

> r

ig

F i

f

ffiHlill :

:

:

9

3

F = : i : r i 6 : ' * : : ;

Figure8.6

r39

8.7.1Hydraulic Pump The hydraulic pump is directly coupledto an electric motor and convertsmechanical energyinto hydraulic horsepower.The principle of the operationis that an increasing volume is generatedon the intake side and a decreasingvolume (with increasing pressure)on the outputside. 8.7.1.1 Pump Displacement The flow capacityof a pump can be defined as the displacementper revolution, or in cubic simply the outputof oil in gallonsper minute. Displacementis expressed inchesper revolution. 8.7.1.2 Pump Delivery The delivery of the pump is dependentupon two factors:a) Load Conditions b) Drive Shaft Speed The pump will actuallydelivermore oil thanit's specifiedrating,if it is runningunder no-loadconditions. It follows thereforethat the deliverywill reduceunderexcessive load conditions. The amountof oil beingdeliveredis alsodependentupon the speedthat the shaft the drive turns. In orderfor the pump to performaccordingto it's specifications, motor must operateat the correctspeed. 8.7.2 Types Of Pump The most commontypesof hydraulicpump found in industryare positive pump deliversspecificamountsof pumps. A positivedisplacement displacement in fluid per revolution,strokeor cycle. Thesepumpsmay be of fixed displacement, have adjusted. to be parameter, internal components this certain orderto adjust Somepumpshavethe facility to vary the sizeof the pumpingchamberby adjusting pumps. externalcontrols,thesepumpsareknown as variabledisplacenlent

t40

8.7.2.1ExternalGear Pump 4. Outlet pressuneagainst teeth causesheavysideloadingon shafts as indicatedby arrows.

3. and forced out of prcssure port as teeth go back into mesh.

OUTLET

D R I V EG E A R

2. Oil is carriedaround housing in chambers formed between teeth, housingand side plates. .

INLET

1. Vacuumis createdhere as teeth unmesh.Oil enters from rcservoir.

Figure8.7

As the teethof the two gearsun mesha partialvacuumis created,thus,drawingoil into the unit. The oil becomestrappedbetweengearteeth,and as the teethmesh togetherthe oil beconrespressurised.Gearpumpscan be ntountedin tandem,or throughdrive which allows separate inlet andoutletparts,thus,creatingtwo separate isolatedsystems,possiblywith two differenttypesof hydraulicoil. Thls systemdoes occurin certainROV systems,typically wherethe nranipulatorhydraulicsystemis isolatedfrom thenlrin system. C A M R I N GS U R F A C E

8.7.2.2VanePumps 2. is carriedaround ringin pumpingchambers.. .

ECCENTRICITY

PUMPING CHAMBERS

A side load is exerted on bearings because of pressureunbalance.

SHAFT

ourLErI

|NLET€>

.*+L

1. Oil entersas space betweenring and rotor increases.. .

3. and is discharged as space decreases.

CASTING

141

of a The,unit.consists Figure 8.8 illustratesthe operatingprincipleof the v?1e: puqq. 'thrown'againstthe outer sldttedspindle. The slotscontainmoveablevaneswhich are casingoi the pump body. The eccentricityof the spindleis suchthat a vacuumis then the oil creatJdon the infdt siOi, and as the volunie betweehthe vanesdecreases, they casing, the with contact in constant pressureincreases.Due to the vanesbeing from further extend they then down, ire subjectto constantwear. As the vaneiwear is necessary. their slotsand eventuallyreplacements The vanepumpscoverslow, mediumand high volumelangesand.can operateat i,p t,i fOoo pSr. T'heyare highly elficient with a low noise level and a long ;;;;t;;; life. 8.7.2.3 Piston Pumps Pistonpumpsare contmonlyusedon ROV's and operateon the principlethat.whena pistonin u bor. rerracrsit diaws fluid in and when-itmovesout it expelsfluid from ihe bore. The secondtype of pistonpunlp: Thereare two typesof pistonpunlps: a) Radial Piston Pumps g.gl. RadialPistonPumpsconsistof a cylinderblock insidea reitctiotlring' (seefE are housed.The The cylinder blockcontainsboresin which free moving pi.stons pistons aresubjectto. the it.spins, as way that a in such is offset block cylinder into the. cylinders.As the is drawn fluid nloue out, pistons As the force. clntrifugal the pistons then rirtg decreases, reaction and block s:ylincler thg distancjbetween process' in fltrid the forcing out centre move in towardsthe

.ENTERLTNEx.--.1

C Y L I N D E RB L O C K

CASE

PISTONS

CYLINDEB

R E A C T I O NR I N G

Figure8.9

t42

b) Axial Piston pumps Figure 8.1-0showsa.simpleaxia! pump. The cylinders rorareparallelto the axis of rotationof the cylinder block. Th-eswashplate is at an anglethat determinesthe length of thepiston stroke. The larger the strokeis, then tFe more oil is drawn to the bore and the larger the displacemenibecomes. The ports are arrangedso tha^tas the pistonspassthe inlet, they are drawn back and as they passthe outlet they are forced out. The displacementof ihe pump is determined by the numberof pistonsand the length of the sttoke. VALVEPLATESLOT

2.and are forced back in at outlet.

PISTONSUB.ASSEMBLY

DRIVESHAFT

OUTLET PORT

lNLET PORT

SWASHPLATE

SHOEPLATE (RETRACTOR RtNc) CYLINDER BLOCKBORE

' i,:*"1'",:':liffi:, ... Figure8.10

in sucha waythatoil is allowecl pasrthepistonringsand lotg pistonsaredesigned into thecasingto facilitatelubrication of internalbearings.Forthisreasontherehas to be a part,knownasa casedrain,to allowoil backto ihetank. 8.8 Hydraulic Valves Introduction a.basic.layout for anROV hydraulicsystem.It canbe seenthat ligut" 8.6illustrated thethrustermotorswill requireavariableflow speedanddirection,in orderto meet theirrequirements. Themanipulators containlinearactuators, whichrequi.eonly a variabledirection,burnomtallyody a constant flow rate.

143

8.8.1 Directional Valves Directional valves feature in the ROV Hydraulic systemin more than one form. They have the ability to start,stop and control the direction of fluid flow. 8.8.1.1 Classificationof Directional Valves Directional valves are classifiedaccordingto certaincharacteristicsas listed below:a) Number of flow paths e.g. two way, threeway. b) Actuation method e.g.mechanical,pneumatic,electrical c) Internalvalve element e.g.Poppet,spool,piston,ball d) Size- Sizeof flangeor part connections e) Connections- Pipethread,straightthreador flanged 8.8.1.2Check Valve Checkvalvesfeaturein almostall hydraulicsystemsincludingROVs Basicallythey allow the flow of fluid in only one direction. Figure 8.11 showsa checkvalve servingas an in line one way valve. A springholds thi poppetin the nonrrallyclosedposition. Fluid pressureforcesthe poppetagainst the Spiiirg,thusallowing flow in the appropriatedirection. When the pressureceases, the poppetretulnstctits seatand preventsany undesiredback flow of oil. Typical UsesOn ROV As on many hydraulicsystems,a checkvalve is often useddirectlyafterthe pump to preventbaik flow of oil, in the eventof excessivepressurebuildingup in the system. SEAT

BALL(ORPOPPET)

FREEFLOWALLOWED AS BALLUNSEATS FREEFLOW

FLOWBLOCKEDAS VALVESEATS

F i g u r e8 . l l

r44

NOFLOW

8.8.1.3 Trvo Way Directional Valves Two way directionalvalvesare commonly found in what is termedthe Hydraulic, Control Unit (HCU). This unit consistsof a'bank' of two way directionalvalves, which control devicessuchas manipulatorarms,and camerapan/tilt units. The H.C.U generallyoperatesat a lower pressurethan the thrusterhydraulic system, typically 1000- 1200PSI. As previouslymentioned,the H.C.U may be completely isolatedfrom the main system,by incolporatingtwo directly linked gear pumps into the system(seesection8.7.2.I) STATICOIL

VALVE CLOSED otLouT A

I otLtN

DrREcroN ffi O\E OILOUT

DIRECTION TWO Figure8.12 8.8.1.4Actuationof DirectionalValves Thereareseveral methods generally usedin industryto actuate thespoolmovement. Theyinclude,pneumatic, mechanical andelectrical actuarion.TheROV industry makesuseof electromagnetism, andtheparticular valveis knownasa solenoid valve.

t45

i

ENERGISED COIL

P \

ARMATURE

lSED DE-ENERG colL.

SPOOL Figure 8.13

Fig 8.13 showsthe solenoidvalve in an energisedstate,by applyinga voltage,the coil becomesenergised,moving the pin againstthe spool. Normally solenoidvalves containsprings,that centralisethe spooloncethe coils arede-energised. 8.8.2 Servo Valves The servovalve is a directionalvalve that is capableof being infinitely positionedto providecontrolof the amountof fluid suppliedto the actuator.ROV's make useof lhesedevicesto meet the requirementsof the thrustermotors, which are requiredto run at variablespeedand in eitherdirection. 8.8.2.1Principlesof Operation ServoValve:Figure 8.14 showsthe principleoperationof a Electrohydraulic IONOUE MOTOF ANO SERVO VALV€ ARE IN SINGLE UNIT I

I I

MECHANICAL OF HYDRAULIC

ACTUATOR MO/ES AT COiITROLLED SPEEDTO CONTROLLED POSITION

I

II

MECHANICAL OFIHYDFAUL(

FEEOBACK DEVICETELLS SER\IOv LvE IF OESIRED

o_1 l^E199.!Iv

Figure8.14

r46

A control signal,which may compriseof an analogued.c voltage is feed to an amplifier, which booststhe signal. This analoguevoltage will representthe initial output from the joystick control. The electricalsignal is appliedto the torque motor, which is mechanicallycoupledto a spool that controls the fluid rate of flow. If follows thereforethat the load will move at a rate proportionalto the electrical input signal. A feed back loop may be incorporatedinto the system,whereby an electrical signal is appliedfrom the load to the servoamplifier. This feedbacksignal is comparedwith the original input signal,and any resultingerror is fed to the torque motor, which reactsin sucha way as to cancelthe error. 8.8.2.2 Torque Motor Figure 8.15 showsthe basicoperationof the torquemotor. ARMATURE

SUPPORT TUBE FLAPPER PERMANENT MAGNETS

FEEDBACK SPRING

Figure8.15

PERMANENT MAGNETS

The unit consistsof a flapper,pivoting on a flexible supporttube. The flapper is coupled to armature,which is encasedin a permanentmagnet. Each armatureis surrbundedby electricalcoils to which the conrol signal is applied. On application of control sighal the armaturesare shroudedby a magneticfield, the strengthof which is proportionlalto the input signal. This magneticfield gives rise to the movementof the armaturesand thereforethe pivoting of the flapper. The flapper is mechanicallyconnectedto the spool as illustratedin the_single.stage servovaive (Fig 8.16). It follows that the spoolwill move proportionallyto the input signal and thus createa fluid flow of equalproportion. 2. causesspooltoshifta distanceproPortional to electricsignal. VALVE BODY

hLECTRICAL CONNECTOR

TORQUEMOTOR

SPOOL

1. Deflectionof motorarmatuc

PRESSURE

MECHANICAL CONNECTION

Figureft.16 8.8.2.3 Two StageSp
148

1. Whentorquemotor movespilot valveto left. 6. Sleevefollows pifotspool and cuts off flow whendesiredmain spoolpositionis reached.

3. Supply prcssureis openedto port'4". . .

PILOTSTAGE SLEEVE

LINKAGE FULCRUM (vARtABLE)

2. largeend of spool rcceivesincreasedcontrol pressurleand spool moves to right.

TOROUEMOTOR ARMATURE

cotLs

2A SPOOL ENDAREA

CONTROL PRESSURE MAIN SPOOL

4. and port "8"

1A SPOOL ENDAREA

Figure8.17(a)

t49

7. Ratioof main spoolto pilot spool movement is adjustable.

5. Feedbacklinkage transmitsspool movementsto sleeve

3. Controlpressune is presenthereand at smallend of mainspool.

2. In neutral,large pilot end is blocked at pilot valvein the staticcondition.This pnessune= 1/2control pressure(Pc). PILOTSTAGE SLEEVE

FULCRUM LINKAGE (vARTABLE)

PILOTSPOOL SUPPLY PRESSURE

ARMATURE FEEDBACK MAINSPOOL 1. l.argespool end areais twice the area of oppositeend which is subjectto control pressune at all times.

CONTROL PRESSURE

4. Controlpressuneholds mainspool stationary againstoil trappedat oppositeend at 1/2(Pc). PcxlA=1l2Pcx2A

Figure 8.17 (b)

150

E

The principleof operationis similar to the single stagevalve, exceprthat the flapper is mech.anically_ connectedto.a pilot spool, which coitrols the main supply spooi.^It should be notedin this casethat the feedbacklink from the main spoofioitt.i flapper is mechanical. The most common type of servovalve usedon ROV's is the MO'dF, the specificationsand port configuration are availablein the appendixsectionof this book. 8.9 Hydraulic Actuators 8.9.1 Introduction The.h.ydraulicactuatoris the unit responsiblefor convertingthe energystoredin the fluid into mechanicalenergy. They compriseof either motors,or rams; motors providing rotary motion for thrusters,rams producinglinear motion for manipulators and camerapan and tilt function. 8.9.2 Hydraulic Rams Figure8.18 illustratesthe typicalconstructionof a hydraulicram/cylinder.

ROD ENDHEAD RODEND PORT

COLLAR CUSHION

OPTIONAL AIRVENTS (FORBLEEDTNG ArR FROMCYLTNDER)

RODBEARING

PISTONSEALS CAP END HEAD ENDPORT

RODSEAL RODWIPER PLUNGER CUSHION BODY

STATIC SEAL

Figure 8.18 The^operatig!of the cylinderis basicin the fact that oil is cleliveredto eitherport via the Solenoidvalve, and.thepressureactsup on the piston,rnovingit in the appropriatedirection. The pistonrod is connectedto the 'linrb'of-a manipulatorfor exampleand transfersthe movementof thepistonrod to the lirnb.

r5l

Figure8.19 illustratesthe variouscylindermountingmethods

TAPPED MOUNT

FLANGE FLANGE RECTANGULAR RECTANGULAR MOUNT-BLINDEND MOUNT-RODEND

SOUAREFLANGE MOUNT-BLINDEND

CENTERLINE LUGMOUNT

SOLIDFLANGE MOUNT_RODEND

SOLIDFLANGE MOUNT-BLINDEND

SIDELUGMOUNT (FOOTMOUNT)

MOUNTTRUNNION RODEND

MOUNTTRUNNION INTERMEDIATE

T R U N N I OM NO U N T BLINDEND

TIE ROD EXTENDED MOUNT-RODEND

TIEROD EXTENDED MOUNT-BLINDEND

TIE ROD EXTENDED MOUNT-BOTHENDS

CLEVISMOUNT

MOUNTWITH CLEVTS BEARI SPHERICAL

Figure8.19

152

The main componenrsof the limb are as follows. a) Seals' The sealbetweenthe pistonand the cylinderwalls is critical for efficient operation. The sealsmly qg manufacturedfrorncast iron or more commonly rubber. If thesefail, then 'gre_ep.' will occur when the actuatoris on load. This is cauied by oil by-passingthe seal. Iris important to ensurethat the rubber material is compatibie with the oil, as the rubber may perish. The integrity.of the rod sealis of upmostimportance,as this preventsingressof dirt, or seawater into the actuator. Rod sealsmay be manufacturedfrom rub6er or teflon. The rod sealmaterialmust be compatiblenoi only with the oil, but in the caseof ROVs in the seawater. b)-.Cylinder Cushions- The cylindercushionsare situatedat eitherend of the cylinder, in order to slow down-themovementof the piston at the end of it's stroke. If this was not the case,the piston would hammeragain.stthe end cap and suffer possibledamage. c) Ports ' The externalopeningsto the cylinderallowing oil to and from the cylinder as appropriate. 8.9.3 Hydraulic Motors 8.9.3.1Introduction Motor is theterm given to an actuatorthat providesrotaryrnotion. All motorsare commonin the fact thatpressurejs exerted-onpiston,vanesor gearswhich are directlycoupledto an ourputshaft. The motor that we areconcernedwith most in the ROV industry,is the axial piston motor. For this reasonit is this motor that we will baseour information. 8.9.3.2 Perf
153

d) Starting Torque - The startingtorclueis the torqueretluiredto startthe load of theoreticaltorque. turning. Once againit is consideredto be a percentage e) Speed- Speedis therotationalvelocityat a specificpressurethat the motor can mainlainwithout sustainingdamage.It is a funciionof volumeof deliveredfluid and displacement. f) Slippage- Slippageis the leakingof fluid acrossthe motor without any work takingplace. 8.9.3.4 Axial Piston Motors Axial pistonmotorsareprobablyone of the commonesttype found on ROV systems. They fall into the classof High Speed,Low TorqueMotors. Figure8.20 showsthe constructionof a typical in line axial pistonmotor. 5. As the piston passesthe Inlet,it beginsto rcturn into its bore becauseol the swashplate angle. Exhaustlluid is pushed into the outlet port.

4' The pistons,shoe plate, and cylinderblock rotate together.The drive shafl is splinedto the cylinderblock.

3. The piston thrust is transmittedto the angled swash plate causing rctatlon.

PISTONSUB. ASSEMBLY OUTLETPORT

INLETPORT DRIVESHAFT

SHOERETAINER PLATE

2. Exerts a force on pistons,forcing them out of the cylinderblock.

Figure11.20

154

Fluid pressureacts up on the piston endswhich transmitthe pressureto the swash plate. The angle of the swashplate is suchthat a rotationalmovementis developed. The torqueof the motor is proportionalto the area,numberof pistonsand the angle at which the swashplate is positioned. The motors may be of fixed displacementor variable displacement.The variation of displacementis brought aboutby externally adjustingthe angleof the swashplate. 8.10 Contamination Control 8.10.1 Introduction It can be said that about 707aof hydraulic breakdownsare due to contaminationof hydraulic fluid. Contaminationcan be defined as the presenceof solid particlesin the hydraulic fluid. It is essentialthereforeto try and minimise this occurrencein the best possiblemanner. 8.10.2 Effect of Contamination on System The following factorshaveto be takeninto accountwhen looking at how contaminationeffectsthe system. a) Purposeof Hydraulic Fluid To Cool and dissipateheat Contaminationfornrsa sludgeon the reservoirwalls and thuspreventseffectiveheat transfer. - To Transmit Power restrictsthe flow of oil to Contaminationblockssmallorificesand consequently relevantunits. - Lubrication This can leadto disastrousconsequences. All hydrauliccomponentshavetolerances which allow a certainamountof oil to flow throughthem for lubrication. For example, a certainamountof oil passesthe pistonrings in the axial motor in order to lubricatethe shaftbearings.Build up of contaminationin the cylinderswill prevent this and leadto possibleseizingof the shaft. b) MechanicalClearances The clearancebetweenhydrauliccomponentscan be definedas follows. - 5 micrometersfor high pressureunits - l5 to 40 micronreters fbr low pressureunits Note - one micrometeris one millionth of a meter.

r55

Figure 8.21 showsthe typicalclearancevaluefor varioushydrauliccomponents ln.

pm

Gearpump (Pressureloaded) Gearto side plate Geartip to case

1t2-5 1t2-5

0.00002-0.0002 0.00002-0.0002

Vanepump Tip of vane Sidesof vane

1t2-1' 5-13

0.00002-0.00004 0.0002-0.0005

Pistonpump Pistonto bore(R)" Valveplateto cylinder

5-40 112-5

0.0002-0.0015 0.00002-0.0002

Servovalve Orifice Flapperwall Spoolsleeve(R)" Controlvalve **Orifice*-'

0.005-0.018 0.0007-0.0025 0.00005-0.00015

130-450 18-63 14 - l --

Figure[1.21

c) Modesof Failure the particlesthatbringaboutcontamination varyin size.It is thisfactthatdetermines degreeof failurein a hydraulicsystem. - CatastroPhic Failure jammingacomponent.Forexamplea particlemay largeparticles BroughtuUout'Uy nAgJU"t*een rhetedth'ofthetwo crowi wheelsin the motor. This wouldcause immobilised. of themotorandresultin theROV beconring .".frpf.t. seiuure - IntermittentFailure mayprevent suchaSreliefvalves.Thecontantinant Thismayoccurin conrponents backto dy.Pp p.op".ly a1dthevalvewouldtemporarily Itr" popp"tfrom re-seat'i,lg resumed. be will is flushedaway,normaloperation tun[. R'ssoonastheconffimin'ant - DegradationFailures This by fine contaminants. iuitui.r arecausedby erosionof components Oegra-aa?ion failureoccursif not checkedby a processmay contlnueuntil catastiophic (See 12). chapter procedure. maintenance 8.10.3Summaryof Contaminants in theROV thevariouscontaminants Thetableshownin tig tt.22summarises hvdraulicsvstems.

156

Contamlnant

Character

Sourceand Remarkr

Acidicby-products

Corrosive

Breakdownof oil. May also arisefrom water{ontramination of phosphatg-€st€r fluids.

Sludge

Blocking

Breakdownof oil.

Wator

Emulsion

Alreadyin fluid or introducedby system fault or breakdown of oxidation-inhibitors.

Air

Soluble

Effectcan be controlled by anti-toamadditives. Excessair due to improperbleeding, poor s!€tomdesignor air leaks.

Insoluble Othsroils

Misciblebut may r€acl

Use of wronglluid for toppingup, etc.

Grease

May or may not b€ miscible

Fromlubricationpoints.

Scale

lnsoluble

Frompipes not prop€rly cleanedbeforeassembly.

Melallicparticl€s

lnsoluble with catalylic action

May be causedby water contamination, controllable with anti-rustadditives.

PaintflakEs

lnsoluble, blocking

Abrasiveparticles

j

Painton insideof tankold or not compatibl€ with fluid.

Abrasive and blocking

Airborneparticles(remwewith air tilter).

Elastomeric partlcles

Blocking

SealbrEakdor'vn. Checkfluid,compatibility of sealdesign.

Sealingcompound particles

Blocking

Sealingcompounds shouldnot be usedon pipojoints.

Sand

Adhesiv€ particles Lintor fabric threads

Abrasiveand blocking

Sandshouldnot be usedas a fillerfor manipulating pipebends.

Blocking Blocking

Adhesives or jointingcompounds shouldnot be usedon gask€ts. Onlylinhlreeclothsor ragsshouldbe usedfor cleaningor plugging dismantled components.

Figure8.22

r57

8.10.4 Prevention of Contamination Low Pressure As a generalrule ROV's incorporate-2filters into the systenl.thev are after the located is Filtei SuctionFilters and High PressureFilter. The Low Pressure b" that particles tank and before th" ;;";i *tti.ft isaeiigneA to removeany T.u{ lmplles name the as suckedfrom the tank byihe pump. High pressurefilters, removesany conraminationift".itr. pu-b on the high pressureside. Figure 8.23 illustratesa typicalhigh pressurefilter 5. Bypassvalve oPens if filter is too clogged to Pass lullflow.

2. flowsdown aroundcarlrldge.. .

CARTRIDGE r

BODY

3. through filterlng

mediumto center of houslng.. .

Figure[1.23 is It is nottheintentionof thischapterto go intodetailon filter changingasthat Maintenance' amplycoveredin chapter12on Mechanical 8.11 HydraulicFluids requiredfrgm a hydraulicoil' It hasbeenmentionedpreviouslyabouttheproperties of whichoils shouldbeusedin the tio*.u.. it is usefuiL'i,uu.anappreciation theROV is working. which in elviionment i'i,.* io suittheparticular 8.11.1Viscosity to flow, or aninverse of a fluidsresistance Viscositycanbedefinedasa measure whichoil is usedin determines that viscosity of its fluidir'. it is generally measure is low, a fluid that viscosity its then Ii canneisaiaif i nuiOfio*s easiiy, ;ily$;. doesnotflow easilyis saidto havehighviscosity'

158

8.11.f.1 Choosingthe Right Viscosity One has to make a compromisewhen choosingoil of the optimum viscosity. A high viscosity oil is desirabl6for maintaininga sealbetweenmating surfaces,however thereare disadvantages. - High resistanceto flow - High temperaturecausedby friction - InCreasedpower consumptiondue to friction - Sluggishoperation - Air becomeseasilytraPPed. If we overcomethesefactors by using a low viscosity oil, the following problems may occur. - ExcessiveInternal Leakage - Pump efficiency decreases,slowing down actua.torspeed. - Brea'kdown of oil film betweenmoving parts givesrise to frictional wear. 8.11.1.2Measurementof Viscosity th.eflow rateof oil at a The viscosityof a given oil can be determinedby measuri.ng and hasbeen given tempeiutute."Thisvalueis termedthe KinematicViscos^ity (lSO) for a varietyof oils at by the InternarionalStandardsOrganisation Eatalogued different temperatures. Figure 8.24 illustratesthe ISO figuresfor oils at 40oC'

rso ViscositY Grade

fsovc2 tsovc3

tsovcs tsovcT tsovclo

tsovcls

KinematicViscositYLimits Midpoint KinematicViscositY cSt at 40oQ cSt at 40oC

2.2 3.2

4.6 6.8 10

1s

fsovc22 tsovc32

22 s2

lsovc46

46

tsovc6s

68

tsovcl00 tsovcl50

100 150

tsovc320

320

t s o v cl 0 0 0 1 0 0 0 t s o v cl s0 0 1 5 0 0 Figure8.24

159

l' From this we seethat one must bearin mind the conditionsthat the ROV is required to operate. For examplewhilst working in the Arctic regions-alow viscosity oil is required,e.g. ISO VG 30. When working in hotter climate-s,for examplg-T fg Eaitern wa6rs, the vehiclemay requireoils of viscosityof aroundISO VG 10. Typical Oils are as follows:

BP ESSO SHELL TOTAL

HLP 10 NUTOH10or UNVISJ13 TELLUS RIO OTTELLUSTIS AZOLLAVGlO

8.12 Manipulators 8.12.1 Introduction Constantimprovementin technologyhavegiven rise to ROVs carrying out more and more subseatasksthat were at one time reliantsolelyupondivers. In order to carryoutthesetasks,ROVs haveto be fitted with roboticsarn1s,commonlyknown as manipulators. All nranipulatorswork on a master/slaveprinciple, the pilots control being the masterand the manipulatorbeingthe slave. Manipulatorscan have anythingup to nine functions. 8.12.2 Principlesof Operation 'eyeball' equippedwith classare_ Manipulatorsare found on all classesof ROV - small would be to carry a purpose for exarnple their manipulators, function electronic single where complex, rnore become in the tasks vehicles increase size, As Probe. CP manrpulators reason For this required. are manipulators more functional strongerand of this natureare hydraulicallypowered. The functionsare nornrallyonly recluiredto operateat a flxed rateand therefore solenoidvalveswill be usedto cont}olthe flow of oil. Norr.nallyeachfunctionwill haveits own dedicatedvalve, which will be one of a seriesof identicalvalves, collectivelyknown as theHydraulicControlUnit or H.C.U.

160

Figure8.25showsthelayoutof theSlingsbyEngineering Ltd TA009SevenFunction Manipulator. CJ) -l

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on the master Figure8.26showsthelocationof therelativefeedbackpotentiometers andslavearms.

t

Figure 8.26

POTENTIOMETER LOCATIONDIAGRAM SLAVVMASTER ARM

162

8.1,2.37 Function Manipulator The TA009 Manipulator consistsof two main groupsof componentswhich constitute a basic7 function, closedloop positionalfeedbackmasterslavemanipulatorsystem. The Master Arm and its associatedpower supply and amplifiers are the minimum componentsrequiredin the masterarm gfoup. (SeePictorial SystemAssembly). The SlaveArm, Valve Pack,Positive CompensationSystem,UnderwaterCable Assembly and SlaveElectronicsUnit are the minimum requiredcomponentsin the slavearm group. (SeePictorial SystemAssembly). The systemis designedto be capableof operatingin a variety of installation situations. Typically, a remotepiloted submersible,or mannedsubmersible configurationmay be usedas the TransporterPackage. A numberof productoptionsto the basicmanipulatorare available. Among theseare:A. B. C. D. E. F. G. H. I. J. K. L.

ContinuousWrist Rotate Tool Grip Jaws ForceFeedback Tool Lock Mechanism FreezeFacility ParallelJaws Self ContainedMultiplexer. 8th FunctionExtender basedcontrol Teachand RepeatMicroprocessor HydraulicPowerPack SpecialTooling Interface DebrisCutters.

The sevenfunctionsavailablein the standardsystemare,as configuredin the human arm. 1. 2. 3. 4. 5. 6. 7.

ShoulderSlew (left/nght) Shoulderup/down Elbow pivot (left/nght) Forearmrotate Wrist Pivot (left/right) Claw rotate Claw open/close

163

The following is a brief overviewof the systemoperation..It is describedwith the assumptiontfr'ata basic systemand freezefacilityare-fitted in a modern Type ROV. Otherinstallationswould operatethe samein principle. The motion of the manipulatoris governedbythe masterarm systemwhich.is a scaled-downversion ofihe slaveirm (underwaterarm). Each position feedbackjoint, on both masterand slavearms,has a 5 kilohm servopotentiometermountedon it, the spindleof which is directly coupledto the motion of the joint itself. Refer to the mechanicalassemblydrawingsfor further details. Thus,to takea parricularjoint, a signalis availablefrom both the masterand slave arms and theseare nominally pre-alignedat the commissioningstageto corer the samelength of travel on the potentiometers,and henceto give nominallythesame have+- 5V d.c. betweenthe terminals.Some voltage.ing", as all potentiometers variaiion e*ists in the forearmrotate,claw rotate and claw open/closefunctions as the masterarm is configuredwith rotary actuationpotentiometersand the slavearm with linear actuationpot6ntiometers.The electronissystemsperform gain adjustmentto ensurematchingof voltageswings,in theseparticularcases. controlbox, the Both masterand slavesignalsarefed to the vehicleelectronics 'Freeze'control card and the surfacemasterarni signa-isbeing carriedvia the optional sysremor vehicledatl link. The controlbox electronicsperformsa compal.son b'etweenthe two signalsand if an errorexistsbetweenthe two, suppliesa drive signal to rherelevanthydiaulicseruovalve (proportionalcontrolvalve)in the slavearm. This servesto diive the slavearm joint to the requiredmasterarm position, tltg electronicscontrolrnonitoringconlinuouslyand progressivelyreducingthe drive signaluntil the two arm signalscorrespond.Atth.is point, the slavearm and master ar-mare in the samepositidn,for that particularjoint. Taking all sevendegreesof freedomrogerherand all operatingat ihe sametime (if recluired)this meansthat whateverp6sitionor attitudeis takenup by the masterarms,within the mechanical of the systenl,the slaveamr will be driven until it asstlnlesa constraint.s g posit iott. correspottdin 'freeze'switch is released,the electronicscausethe slavearnl to track slowly, over A A a 10 secondperiod,to any new positionthat the masterarnt ntay.have.adopted. power to hydraulic switch to is used and hydraulicisolatevalve is fitted io the system the arm.

r64

Figure8.27showsthe capabilitiesof the SlingsbyEngineeringLtd 9 Function Manipulator.

TA33-9FunctionMaster/Slave Manipulator

Slave

s\ r$

R c l a to n

i.

Roiatron

340' Rotalron

\

.^- -. ': *./ / \,

..,

Master

I

':

3.10!'\>/../ Potat,on

90'

,l

\-

t . ,i\

./ts,

-x-

\'. \

\ /

s-:. ia.

165

l

1

i ..i

Figure 8.27

TA33- OperatingEnveloPe

Specification S h o u l d e-r U p / D o w n 190" S h o u l d eSr l e w L

1M

A
Elbow 1'10" ForearmRotation 340" UpperWristPitch 80" WristYaw +15" -65' LowerWristPitch 80" ClawRotation OPtional 340".Continuous RotationTorque 108.Nm B0ft.lb. ClawOpen/Close 1 . 5 1 " , 12 M 1 S O m (m6 i n . ) M a x i m u mR e a c h 1 7 5 m( 6 9i n ) MaximumLiftat FullBeach 3 a k g( 7 5 l b) H y d r a u l iS c upplY 1 3 8 1 2 0b6a r( 2 0 0 0 i 3 0 0p0s . i . ) 29 p m . Weiohtof SlaveArm BBk6 (193lb.)InAir. 56 kg (123lb.)ln Waier Weiqhtof Installation k g ( 1 5 4i b . )I nW a t e r 0 . 5 h 4 l i O [ g Q 4 2 t b . I) nA i r . 7 0 1M

Figure 8.28 Sice elevalion

TheTA33is a ninefunctionmasierislave primarily forsubsea designed rnanipulator vehicles, operated useon mannedor remotely for in almost being use u'ell as suitable as environment. anyhostile dexterity TheTA33offersunrivalled withtheruggedness essentialfor combined rr 9cr mr nr wt(og

cJ vrv rrehs c o 2 r : n e r : l i n n qi v . H i r :v rv l, ii vr ' ' ' i, r r v '

:e n , ri iv

the arm servicelinesrun tryithin electrical possibility the of damage avoid lo s'iructure orsnaggrng.

subsea as a generalpurpose Designed suited theTA33is particularly manipulator, tasks and inspection cleaning to dif{lcult whereaccessis limlted, on structures s u c ha sw e l d e dn o d a l j o i n t s . of theproven TheTA33is a development nowaccepted manipulator, TA9sevenfunction master/slave slandard industry as theof-fshore of a hastheadvantage system,and therefore back-up sparesandtechnical wellestablished service.

8.12.4 Conclusion This chapterhasprovidedan overviewof hydraulictheoryand the components of the systemis coveredin commonlyfound in ROV systems.The maintenance chapter12.

166

CHAPTER 9 PRESSURE FITTINGS 9.0 Introduction work classRovs alr makeuseof hydraulicpo-wer.Thehydraulicsystemsthus pressure fittings to.oitnr.t together the highpressurepipe work and !!!t-ovea,use hosesusedto connectto-gether thevariouscomponents.High pressurefittings are produced bvseveral diffErent manufacturer t ait swic ii6ki;;ig"ffi -?" u rangeof re-usablefittingsthatarevery?opular gr{".d["* the indusny. These fittings will be usedro ilustrate-therypesoftitrinls availablel 9.1 Selecting Fittings Beforeanv fittins is selectedthetubeoutsidediameter mustbeknownandthefitting threadsiz6musti'e either,ttritGaloingw *ork, o.,nurct ia to existingfittings where modificationsor mainteii:: is required.1-te ne*i conriJrruoon is the working pressure. Forhvdrauric

systems thii may. F;r.i,-on il0'db;;.i.'ffi';;?ltiig musrbeableto withstand thispressure #itf,tut Gfi;;;."""'

ur"o

9.1.1 Thread Size Due to designconsiderations therearea numberof differentthreadsizesandtypes available.The threadmaybetafred;rparallel a)

Japergdthreadsaredesignedsothata pressure-tight sealis madeon the threads.when usingthese a seaiantsuchasv" stripTeeze eI" eeL or swak lypes is required.Thesearemanufaft*ra io gs ;1:'*

b)

Parallelthreadsareused.where a pressure-tight sealis not madeon the threads.The sealis usually_maae'elttreimetit-to-*"tat "i *id, a gasket againstthefaceof the.femitepun.irtiie maybe3 "*iul;;; on the sealing:urangement all being'coveredby BS 2779. i)

Thefirst variationis a Mareparallerwith Bonded Gasketseal. In thiscase_ a compositewasher,"i"uffy metalandelastomer,is usedto.sealagainit thefaceor ttrJ remdreport. A machined taperdirectlybehindthemarethreadc"nt is trr" gast"t.-----

ii)

one variationis theFemaleparalrel.This typeseals againstthe " faceof thefemaleport metal-to-metal oi *itr, u gurt"tl---"-

iii)

The third variationis theFemaleparalel Gauge.A gasket, meta] or fibre, is usedinsidethefemalepon uguinrta flat surface.The lating palejgTpgrynt exertsa load"fth. t;k;;";.li;;;. co.nnection. BS 1780(19g5)is anadditionuf ip".in;;r.;"f"; this type.

Therearea numberof differentthreadsusefor hydraulic applicationssomeof themore usualtypesare:a

AmericanStandardpipe Thread(NpT)

b

AmericanStandardUnified Thread

c

rso7/1

d

rso228/r

to/

e

BSP

f

BSPT DIN

h

JIS

i

BSPP

9.1.2 Pressure Rating It canbe statedwith confidencethat Swagelokfittings areall ratedto the maximum working pressureof standardtubing. In their literaturethey statethat Swagelokfittings providea leakproof sealon all tubingconnections.The onusis, however,on the individual to ensurethat he selectsthecorrectlyratedfitting for thejob in hand. 9.2 The Swagelok System to all manufactured components, Thesefittings arecomprisedof four precision-made very stringenttolerances andunderrigid qualityconffolprocedures.The consistency is ttrereasonthatSwagelokcanbe so andqualityof thesematchedcomponents "fit purpose". are:for Thefour components confidentin their being The nut The backfemrle The front femrle The body Specialcoursesandtrainingis providedby Swagelokon demandto teachthecorrect andsafeuseof their fittings. A selectionof Swagelokfittings areshownin Figure

168

9.3 Advantages of Tube Fittings The reasonsfor concentrating on thesetypesof mechanical pipe fittingsin this chapter are:Tubefittingsareeasierto installttranthreadedpipe Labourcostscantresignificantlyreduced is eliminated W.ldirg,with the assoliatedsp6cialprocedures, No specialisttoolsarerequired

Figure 9.1

r69

CHAPTER 10 ROV HOOK UP, PRE/POST DIVE CHECKS f0.0 Introduction It is the intentionof this chapterto outlinethe mobilisationof a typical ROV systemand discussthe principlesbehindthe pre and postdive routine. As.$9 nameimplies the pre andpost dive checkstakeplaceimmediatelybeforethe vehicleis deployedand as soonas it arrivesback on deck. It cannotbeemphasised enoughhow importanta task the pre and postdives are. They form an integralpart of the plannedmaintenanceprocedurein the fact that they identify any malfunclion immediatelyand can thereforeminimiseany vehicledowntimb. For this reasonit is importantthat a standardroutineis laid down in the form of a checklist that is made availableto all Rov personnel,especiallynewcomersto the system. Becomingcompetentat carryingout a pre andpost dive checkis a skill that develops only with practice. It is importantto includeeveryitem on the list and a very imponant point is to be totallyawareof the fact thatthehydraulicshavea limitedrunningtime in alr.

l0.l ROV Hook Up ROV hook up basicallyrefersto themobilisationpro<;edure thattakesplaceat the beginningof the of the contract,the taskusuallytakesbetweentwelvs and twentyfour hoursdependingon the classof vehicleandthe natureof theiob. Mobilisationtakesp!'rceinitially in the baseandwill involvetestingthe system, carryingout a full inventoryof sparesand consumablesand selectinga suitablecrew to suit the natureof the operation.Oncethis hasbeencarriedout the systemwill be transported to the vesselor installationby supplyshipor helicopterdependingon the classof ROV beingused. The actualpositioningof theconuolcabin,workshop,winchandcranerequiresa certainamountof liaisonwith theauthorities on boardas therearemanv safetvfactors that haveto be takeninto account. Oncein positionthe ROV teamcan startto connectup the appropriatecablingbetween therelativeunits. l0.t.l

Deck Cabling

Deck cableis atmoured,zonetwo ratedcablethat carriesthe necessarysignalsbetween the controlcabin,winch and wortshop. Typicalexar.nples of thesecablesareas follows:a)

Main power cableto supplythe winch andcranepower packs.

b)

Domesticpower supplyto the workshop.

c)

Cableto route power, control,video and optical fibre signalsfrom the control cabinto the winch fixedjunction box.

d)

If necessary any purgehosesbetweenall the units.

e)

Communication link betweencontrolcabin,winchnndcrane.

0

Vesselor rig supplyto thepowerdistributionunit.

t71

possibleand once r.nanner During this procedurethe cableswill be routedin the safest necessary' "gui" Ef.r" iiuiron with the vesselor installationcrew will be During.the The umbilical is alsoconnectedto the ROV during this procedure. looseconductorsbeing "."rp"".iion ttrenOV is dir.onnr.t"d from the rlmbilibal,the r"ru.!O to the winch which hasa dedicatedtravellingcontainer' quite 1ime., Once in locationthe conductorsarefeconnected,a taskthat can.be ^,rs the operatton in the stage final The in use. system the on depending ;;;;g -unA "nruring that ai1the equipmenti=nthe contiol cabin is hooked testingof the ,ytp. up colrectly. winch' workshop Once the testshavebeensatisfactorilycompletedthe control cabin, and requireto inspected are welds and craneare weldeJto ttredeck.ontompietion the be certified before the operationscan proceed' 10.2 Pre and Post Dive Checks system'It can Fisure 10.1illustratesa typicalpre andpostdive checkIist for a Scorpio or defectscan faults any the whole systemand therefore il;'h;;h*ktinciude ;""# be identifledimmediatelY. not sufferedany The list beginswith integritychecksthat ensurethat the vehiclehas not worked loose' has physicaldamageo. ittui?nVequipmentthat is fitted to the vehicle the ROV' Thesechecks.nuv oiio riigfrify d.p"nding on what equipmentis fitted to is alsoincludedin thelist. It may be the casethatthe It canbe seenthata generator power and therefore systemis working "i " iftip that does.t''oittuu" a suitablesourceof If this is thecasethenit is the the ROV .o-puny ii ;q;il"4 to supplya-generator. responsibilityof the teamto etlsureits safeoperation' The once the integrity checksarecornpleteit is safeto PoYel up the ROV. with a comms haidwire via is officer deck pitot iind communicationOei*eenlne functions b:i.?:.o,l1g^the pilot will The officer. deck -i"-pt'one treadseiur"JUyil. elltctent An ' vehicle the observing officer deck from the control cabin whil.stthe pack is not methodof communicationis essentialto ensurethat the hydraulicpower takestime to *nning for too tong ,i periodin air. Cood communicationprocedures 14. in Chapter Oeuitofi,the basicititis of which arediscussed that the During the dive checksit is the responsibilityof the deck officer to ensure ha.vg the right to by'. near p*.du.. doesnot endangergy petsonnelwho may be Jley risk. at vehicle rhe interceptanyone*ho irr"lir"el tir be puftingthemselvesor

172

SCORPIOPRE AND POSTDIVE CHECK LIST Post Dive No:

Date

Submersible:

Pre Dive No:

Post

Dare Vehicle Integrity Checks Pre frame meetrom damase

Post JENERATORCHECKPre

)ost VEHICLEPOWERON Pre

Fuel level

Flux gateto SLAVED

cables & connectors secure

Water level

Leak locator to OPR

Podsuaps,caps & PlugsOK

Anti-freeze correct

Resetcable twist ind.

KELLUM & Pennenr corrcct

off

Oil ievel

Fixed buoyancy& BallastOK

Thruster& propscorrect

on

Depth ind. to zero

Generator running

Auto depth to MAN

Record running hrs

Auto hdg to MAN

Manipulatorsecure& correct

Veh lts check

Cable cutter secure& correct Pan & Tilt & carncracorrect on

WINCHCHECKS he

Post

Lens cover -

off

Video system check

Oil level in reservoir

Sonar svstem check

Resetfootagectr

Power ON - HYD.

Lights secure

Brake operation

Check HYD Dressure

Sonar correct,comp full

Buoy'cy floats ready

Hyd.TermSecurc& 80%full

Comms working

ThrustersfunctionsOK

Hyd. Fill Vv & Drain Plug OK

Startwinch

Pan& Tilt OK

Hyd. motor securc

Test all functions

Manipulator OK

HYD temp(100F max)

Hyd. Conps (x27)807, full

Tools function OK

CMNECHECKS

TCU oil ind full. & cao securc

Oil level in reservoir

HYD - OFF HDG - OK with ship?

TCU Vv closed& cappcd HCU oil ind. full, cap secure

Hook & ShacklesOK

Climb/dive rate ind - 0

Umb. Terrn. OK & Comp 807o

[)ost

Optics J/B comp diaphm full Xenon flashersecure

Pre

Lifr wLe OK

Pitch ind veh atirude

Startcrane fest all functions

Ancillary eqpt check

Emergencypinger secure off

Still camera& flashsccure

on

)osI

VEHICLEPOWERON Pre

SonardynetransrxrndcrOK

PowerON - OCU

Ancillary eqpt. litted & secure

Hyd.Wng Lt ON

BALL-AST FITTED kg

ADDITIONAL BUOYANCY

1 0 . 3 D i ve L o g s

Leak indicator test lts

kg

PowerON - Veh

EmrgyPingertestOK off

Xenon flasher

CheckRCU

Figure 10.1

The pre dive and post dive log sheetsare retainedby the companyand contribute towardsthe recordsthat arekept regardl_ng vehicle'shistory Another importantlog lfq is the ROV dive log. The dive log recordsatt the eventsthat oicur from the momentt[e Rov leavesthe deck until the momentit comesback again.By carryingout this processit is possibleto keeprecordof the total numbeiof hoursthai th-evehicle has beenoperatingas well asrecordingspecificeventsthatoccurduring thedive.Fig. 10 2 illustratesa typicaldive log.

| /-')

tn

DIVE LOG SUBMERSIBLE DIVENO:

DATE:

OPERATIONTEAM

SHIP/P[-ATFORM

SUBMERSIBLE

SEASTATE

JOBNO.:

CHARTER:

Sheet of WIND: LAT.:

LOCATION:

IONG:

Ops Controllcr I Surface Officer

DIVETASK:

Pilot

EXTRA EQI.IIPMENTFTTTED:

Observer

BOTTOMCONDITIONS:

Winch aran"

No.: \rlDEorAI,E

)eck

Time

Video counter

Evenl

Figure 10.2

I utveouRmoN'

CHAPTER 11 ELECTRICAL MAINTENANCE. ll.0

Introduction

A plannedmaintenanceprocedure(PPM) is, in the long term a cost effectiveway of ensuringthe efficient operationof the whole system. tTppV were not in place then breakdownwould eventuallyoccurand leadtotime consumingremedialriaintenance during which the vehiclewould be on DOWN TIME. Down Time refersro the time that the systemis eff-ectivelyoff hire due to breakdown. Adhering to 3 PP{ is the respon_sibility of all ROV personneland all pracrices shouldbe suitablylogged. well organised procedurewill reflect the systems .A fogging^the overallperfor_ma1ce and will, in certalnsituatioiJ aid technicianin locatingfiults. Maintaining.the log.isnormallytheresponsibility of the SubEngineeras he forks solely.withthat particularsystemas opposedto certainpersonne'i who are contractors and will constantlybe moving betweendifferent systems.The Sub Engineerwiil ensure.thatthe log.sarekept up to dateand compil-eany 'handover'doiumentationthat is requiredto be given to the new teamon cre*^change. A certainamountof time may be dedicatedeachday to carryingthe routine maintenance.It is the intentionof thischapterto outlinethevaliouselectrical maintenancetasksthat nray be carriedout as part of the maintelrance procedure. ll.l

C a b l e s , C o n n e c t o r sa n d p e n e t r a t o r s

As-a.general rule the vehicleelectronics tendsto be a very reliablepartof the system. All the circuitsarehousedin watertightpressure vesselsand requirblittle main"tenance. Howeverthe connectors andcablesthat-interlink the variouspressurevesselsare exposedto the harshenvironnlentand eresusceptible to danrageand wear. For this it is imperative that the technician be fully awilre of the"correcrmethodsof Ieasg.lt handlingandmaintaining suchdevices. ll.l.l

C o n n e c t o l . sa n d P e n e t r a t o r s

Connectorsand penetratorsfbrm the interfacebetweenthe internalelectronicsof the ROV and the externalcablinginterconnects the variouspressure vessels.The efficient operationof thesedevicesdepe.nds on their ability to preuentwateringressto the currentcanying conductors.Figure 11.0illustraiesa-typicalconnecto-r and penetrator unrt.

LockingSleeve Lockinq

Penetrator

Contacts Conductors

Figure11.0

175

11.1.1.1 Penetrators The penetratorforms the interfacebetweenthe intemalelectroniccircuitry and the connector.Penetratorsare normally manufacturedfrom high quality stainlesssteeland mating are boltedor screwedinto the actualpressurevessel. The sealbetweenthe two 'O'Ring this of integrity facesis createdby a rubber'O'Ring and it is the degreeof that preventswater ingressto the pressurevessel. The numberof internalconcluctorsand thereforecontactscan vary betweenone and anythingup to seventydependingon the requirementsof the interconnection.The ,onturtr"u." normally gold phtedto ensurei ttigtt degreeof electricalconductivity..All conductorsand contids arechemicallybonded-intoa syntheticrubbermatrix which to watel ingress. offersa high degreeof insulationandresistance penetratorsand connectorsaremanufacturedin eithermale or femaleconfigurationand of this handbook. a list of the many availabletypesareincludedin the appendices ll.l.l.2

Connectors

Connectorseredirectly attachedto the cableand haveinternalconductorsand contacts The nray havea locking sleeve nlan.er as in penetrators. that are bondedin the .sa,rle of the lockingsleevehoweveris purpose niain The unit. that addsto rherigidity of the during.. the.penetrator of pulledout beingaccidentally ro prevenrthe con"necrbr not createdby the are ih6 sealing_properties that opirations. It is importantto-realise eventual and to damage lead will only tightening over i
t76

ll.l.2

Theory of Operation

$Su1e I 1.1 illustratesthe principleof operationof a singlepin connectormating with a female penetrator.

Internalconductor

Male connector

Syntheticrubber

'O'ring

Bulkhead Figure ll.l The diagramillustratesa typical connector/ penetratorconfiguration.It can be seenthat thereis a taperedshoulderlocatedat the baseof the contact.-Thisforms part of the connectorsyntheticbody and it can be seenthat when the connectorand penetratoris matedthen a sealis createdalongthe faceof the shoulder. It follows thai as the vehicle increases in depththenthe surroundingwaterpressurewill increase.This hasthe effectofforcing the rubbersealingfacEstogetherandthus,increasingthe sealing effect. It is imperatjvethereforethat the integrityof the sealingfaceslsmaintainEdat all timesas any breakdownwill resultin waterineiess.

177

11.1.2.3 'O' Ring Seals O Rings operateon n similar principleto the connectorsand penetrators.They form a mechanicalsealwhich is illustratedin f i g u r e1 1 . 2

4 Water pressure

Air inside vessel

+ =+

'O'ring Un-distorted a). Natureof

'O' ring

at shallowdepth

Water pressure

Air inside vessel

----+>

+ +

b). Natureof 'O'rirtgat depth F i gur e ll.2

mis shapen increases theO Ringbecomes It canbeseenthatastheexternalpressure andis forcedinto thegapbetweenthetwo surfaces.It followsthereforethata greater sealexistswhenthevehicleis at greaterdepths,howeverwhenworkingin shallow depthswateringressmayoccurif thetwo facesarenotfirmly boltedtogether.

178

11.1.3 Maintenance of connectors, Penetratorsand 'o' Rings. The efficient_operation of sub seaconnectorsis totally dependenton how well they are maintained.It cannotbe emphasised enoughhow importantit is that the correct methodsare usedwhen carryingout connector/ peneratormaintenanceas failure to do so may result in many hoursof unnecessarybreakdown. lf.1.3.1

Connectors and Penetrators

Whenevera connectorand penetratorare unmatedthe following procedureshouldbe followed. a) Inspection of contacts. Electricalcontactsare susceptibleto corrosion. A defectof this nature would indicatethat therehasbeena possibleingressof water througha faulty or improperlymatedconnectoi. Contactsmay also becomeirisaligneddue to the connectorbeing'forced'duringthe matingprocess. Contactsshouldalsobe inspectedforevidenceo-f'arcing'.eriing occurswhen the contactis improperlymatedin the femalerecepttcle, this givesrise to the current jumping'acrossthe gap and causingthe contactto burn. b ) l n s p e c t i o no f s y n t h e t i c r u b b e r . The rubbershouldbe inspectedfor evidenceof wateringress.Any sign of nloistureon the rubbersurfaceis unacceptable and the problem shouldbe addressed imrnediately.The possiblecausesof wateringress are inrpropermatingof the connectorand penetrator,rubber beconringmis-shapen due to over tighteningof the lockingsleeveand, in exttemecasestherubberbecomingcrackedor perished.In exffeme casesof waterlngressan electro-chemical reactionmay takeplace resultingin a depositfomringaroundthe sealingface.s. c) O Ring Seat. Connectors thatnrakeuseof an O Ring to createthe sealrequirethe O Ring to be thoroughlyinspectedwhenbverthe unit is un-mated.The O Ring shouldbein-spected for obvioussignsof damage,lack of integrity and perishing.It is not uncommonfor an O Ring tobe mislaidand-the unit reassembled withoutthe O Ring beingin place. For thisreasonit is imperativethat the technicianchecksthat it is Correctlyin positionbefore assernbly. 1I.1.3.2.

Assembly Procedure

Oncethe aboveinspectionhasbeencarriedout the following procedureshouldbe undertakenwhen assemblingthe connectorand penetrator. a) The contactsand sealingfacesshouldbe cleanedwith a suitable electricalsolventcleanerin orderthat all tracesof dirt areremoved. It to useQ Tips in order ro removeany tracesof din Tay b9 ne^cessary fronr the o Ring groove.on somevesselsor installatibns theremav be a sourceof compressed air availablewhich canassistin the cleaninebf theconnector.

179

b) Oncethe contacts,connectorand peneffatolarecleanit is necessary ro lightly greaserhe connecror.It is normalpracticep apply a thin fild ofSiticon Grease to the maring parts in order to provide lubrication. If this was not carriedout then the mating partswould becomedry and difficult to un-mate. The excessiveforce that would haveto be appliedto un-matethem would lead to possible damageor distortionof the unit. c) The connectolshouldbe matedto the peneffator,taking greatcare as to align the two mating unitscorrectly. Most connectorshavea locating lug tliat preventsany riisalignment iating pla9e.-Som.econnectorsand with one pin, calleda.polarisingpin, of penetratorsare manufacture-d biffe.ent size which assistsin correctlocation.In this situationgreatcare must be takenas to correctlyalign them. Figure I 1.3illustrates connectorsof this nature.

Polarizingpin

Flangefbr captivating lockineSleeve

o@o@o @o o@

/@ o\

o o o

o @ @

o @

12 way connector

/ way connector

Figure 11.3

180

d) When adjus.tingthe locking sleevegreatcaremust be takento preventover . tightening. If this occursthen the connectoris liable to warp thus'destroyingthe sealingproperties. It.is thereforeonly necessaryto hand tighten the lockiig sleeve and no attemptshouldbe-m1{g to use spannersor sffapwren*ches.Occasiona'ilyit may be necessaryto usea tool of this natureto undo a connectorlocking sleeve. This is becausethe unit may havebeensubjectto extremepressureand thil hashad the effect of tighteningthe connector.It may also be the casethat the connectoris somewhat inaccessibleto the handan a tool is requiredto releasethe locking sleeve. f 1.f.3.3.

Greasing

It is importantto fully appreciatethe reasonbehindapplyingSiliconeGreaseto sub-sea connectors.As previouslystatedit is usedpurely as a lubricantand doesnot createthe seal. There are many misconceptionsthat exist ttnoughoutthe industry,someclaiming " that if a largequantityof greaseis appliedthenthe grJateris the sealingeffect of the c

Excessivegreaseallows pathfor waterintrusiorr

I

I

t

t Grease

Figure Il.4 Figure 11.4illustratesthe effectof over greasing,in this situationthe gleaseprevents the connectorand p€neffatorfrom matinf coneclly. The greaseactualiyallows a path for water,thatmay be underpressure, tolccess the conta6ts. ll.2

Sub-Sea Cables

Sub-seacablesareespeciallydesignedto withstandexcessivelyhigh pressuresto which.theyare.subjectedto in their working environment.They ari manufacturedfrom a resilientsyntheticrubberthat offers a higli degreeof protectionand electrical insulationto the conductorswithin. Sub-ieacibles containvarying numbersof conductorsdependingo.nthe specifictask. It must be statedhoweier that if they do not fall into a structuredmaintenance procedurethenthey arevery susceptibleto faiiure and consequent breakdownof the system.

181

F ll.2.l

Possible Cable Defects

The following defectsare likely to occurwithout regularmaintenancetaking place. a) Breakdown of outer sheathing. During operationsthe cablesareconstantlyexposedto drag causedby the movementof the vehiclethroughthe water. If they are not properly secured cablesmay then they becomesusceptibleto wear.In extremecircumstances becomesnaggedon a manipulatoror even suckedinto a thruster. To overcomethli problemit is-importantto ensurethat all cablesare securely fastenedwith Ty- Rapsto the vehicleframe. In someextrembcasesthe insulationmay perishcausingthe rubberto crack and exposethe conductorswithin. For this reasonit is importantto inspectall cableson a regularbasis. b) Breakdown of internal conductors. Extremecablemovementcan alsoleadto the conductorswithin the cable breakingdown, particularlynearthe connectorswhich tendsto be the most sensitivepoint. Once againit is possibleto detecttheseoccurrencesby regular testingof the cable. 11.2.2 Testing Sub Sea Cables In order to monitor the integrityof the internalconductorswe can measurethe insulationbetweeneachone usinga MEGGER METER. This hastheeffectof betweeneachconductorwhilst connectinga high.voltageto measuringthe resistance the condultors.(seechapter7 Use of TestEquipment).Ideallythe insulationshouldbe howeveringressof moisturecombinedwith either infinite betweenconductors, connectoror conductordamagecanleadto an insulationbreakdownthat will require repair to be canied out. NOTE: WHENEVER AN INSLLATION TEST IS CARRIED OUT THE CABLE SHOULD ALWAYS BE DISCON}{ECTEDFROM THE PRESSUREVESSELSOR ANY ELECTRICAL CIRCUITRY. 1 1 . 3 M a i n t e n a n c eo f U m b i l i c a l s to bothfatigueandoverloadingwhichcaneventuallylead to Umbilicalsaresusceptible the breakdownof the internalconductors. Thesefactorsmay arisefrom poor piloting techniqueswhich may leadto the umbilical becomingtwistedor kinked. Damagemay of the umbilical during the launchandrecovery alsooccurdue to mismanagement process.When the vehicleis passingthroughthe splashzonethe umbilical may tend to 'slack' isnatch'due availablewhilst latchingand un-latching. to therebeinginsufficient havingto carryout what is known as a in R.O.V. team All thesefactorscanresult the lengthy and tediousprocess,howeverit RETERMINATION. Retenninationcan be a 'down procedure in to order minimise the vehicle is importantto follow the correct time'. of a typicalarmoured The following sectionsoutlinethe processfor there-termination umbilical.

182

11.4. Cable Splicing { stlylqiolmay often arisein which a sub-seacablerequiresrepair to be carriedout in the field. This may be due to insulationbreakdown be^tween the internalconductorsor in extremecases,the severingof the cableby a thruster.In eithercasethe cablecan be re-joinedusing.eitherth.equick splicemethodor the long splicemethod. Normally sparecableswill be availableand the damagedone can be instantlyreplacedwith a serviceableone. In this casetime will allow the damagedcabletobe iepairedusing the long splicemethod. Howeverit may be the casethat the repairrequires'immediate attention,in this casethe quick splicemethodwould be used.

ll.4.l

Long Splice

The long sp-licemethodmakesuseof speciallymanufacturecl potting compoundsto form arigid, water tight joint. It is the settingtime of suchcompotindstliat restrictthis -?llod long..I periodsof maintenance.Figuie 11.5.illustraresthe procedureof cable splicingby this merhod. ll.4a. Staggeringof joints Solderedioint

Sub-sea cable ll.4b Potted joint

183

It can be seerrthat the coresof the cableare staggeredwherethey arejoined in order to coming mainrainunifonn thickness.Staggeringalsopieventsthe solderedjoints from 'heat into contactwith one another. Each solderedjoint is normally coveredwith shrink'to add to the insulatingproperties.Oncethis stagehasbeencompletedthe cable agent.The cableis then coresand the outsideinsulatiodis cleanedwith a degreasing poured. is potting into which compound the mountedin a mould Thereis a wide variety of potting compoundsavailable,eachhaving slightly different the compoundsis the specificdepthrating and properties.The main difference-between ^the guaranteedlife spanof the compound. Oncethe compoundhasbeenpouredinto the mould thejoint requiresto be left to setfor approximately[l to 10 hours. L1.4.2 Short Splice The initialjoining togetherof theconductorsis the sarnefor the shortspliceas it is for with this methodis the fact that no form of potting the long splice. The only dit-ference tape compoundis used. Insteadan insulatingrubbertapeknown as self amalgamating is used.When the tapeis stretchedit actuallybondswith itselfto form a strong waterproofjoint. The tapeis woundaroundthe conductors,startingfrom the centreof the conductorsand workingoutwards.Betweeneachlayerof tapeit is common practiceto coateachlayerwith a resinthatsetsandfonns an electricallyinsulatingand waterproofcoatingover the tilpe. ll.5

Sub Sea lanrps

of this theprinciples The qualityof Subsealightingis crucialto all ROV operiitions, in chapter16.For thisrensona correctntaintenance subjecthavebeendiscussed procedure is essentillif thisclualityis to be upheld. The mostcomlnonproblemthatoccurswith subsealightingis the burningout of the actualfilament. Therearea varietyof lanrpsavailableto the indusffy,the main differencebeingthe powerrating. They aremountedin a housingwhich offers in which to operate.It follows thereforethat protectionand a watet'tightenvironmerrt 'o'ring whenevera lamp is which requiresto be inspec:ted seal the housingcontainsan maintained. Lampsmay burn out due to one or nroreof the following retlsorts. a) Wateringressto the lanrpconnector. 'o'ring b) Breakdownof the sealallowingthe actuallamp to become exposedto seawater. c) Mis handlingof thelarnpduringinstallation. d) Beingoperatedfor too long a periodin air. If wateringresstakesplacewithin the lanrpconnectorthenthe connectorshouldbe the cableshouldbe undoneand thoroughlyinspectedfor darrrage.If necessary replacedwith a serviceable one. 'o'ring If the sealbreaksdown thenit to shouldbe replaced,if waterdoesmakecontact with the lamp connectors thena shortcircuitis likely to occuras well as corrosionand breakdownof the actualcontacts.

184

It is imperativethat the lampsare not touchedduring installationas moisturefrom the 'hot spots'onthe bulbs surfacethat can causethe glassto crack. For skin can lead to this reasonthe bulbs are suppliedsurroundedby a pieceof foam that shouldbe usedto hold the lamp duringinstallation. It is importantto realisethat sub seabulbsrequireto be watercooled. Shouldthey be run in air for too long thenthey may overheatand bum out. During dive checks thereforethe lamps shouldonly be operatedfor a few seconds.

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185

CHAPTER 12 MECHANICAL

MAINTENANCE

12.0 Introduction Throughoutthis handbookattentionhasbeenconstantlydrawn to the necessityfor a plannel maintenanceprocedure.So far we havediscussedmaintenanceas regardto the blectricalsideof the RO, it is now the intentionto discussthe routinemaintenance proceduresthat shouldbe carriedout on the mechanicalunits of the ROV. It follows ihereforethat this chapterwill concentratelargelyon the maintenanceof hydraulic systems,the basicprinciplesof which havebeencoveredin Chapter8. Maintenanceof hydraulic systemsis carriedout on the basisof how long the system hasbeenoperating,this informationmay be obtainedfrom the Sub Engineerslog book 'hoursrun'meter that may be incorporatedinto the control console. or an Each unit will have a specifiedperiod of time that it can operatefor, after which it will be requiredto be removedfrom the systemand serviced.As a generalrule.theunits that requireto be servicedwill be swappedfor a serviceableone.The actualservicing may.requirespecialisttestequipmentand will thereforebe sentashoreto a suitable servicingengineer. However,it is the responsibilityof the ROV teantto ensurethat the day to day runningof the systemis maintainedandthatif any unitsareto be removed, they are done so in the correctmallner. l2.l

Hydraulic Oil Level

The function of hydraulicoil is initially to transferenergythroughoutthe systemand thus give rise to work beingdone by the actuators.[t alsoprovideslubricationand cooling to certainmoving components.It is imperativethereforethat the fluid be maintainedat alt optirrum level at all timesotherwiseseriousdetrimentaleffectscould takeplacethroughoutthe systenr. l2.l.l

Loss Of Pressure

The toralenergythat is presentin the hydraulicfluid is nradeup of potentialenergyand kinetic energy. The potentialenergyrelatesdirectly to the systempressureand it due to leakagethenthe energystoredin follows thatl? the opiimum oil level decreases in the fact that systempower will be evident lost. This will become fluid will be the in controllingthe vehicle. difficulty pilot may experience and the reduced L2.1.2Lack Of Lubrication In extremesituationsthe optimumoil level may be reducedto suchan extentthat insufficientlubricationtakesplace. Situationsmay arisewherecertainhigh speed may seize.This may be the casewith thepump which contains components componentssuchaspistons,gearwheelsand bearings.Insufficientlubricationof thesecomponentscould leadto excessiveheatbeing generatedand eventualseizure thusresultingin systemfailure. 12.1.3 Sea Water Ingress Shouldthe situationarisewherevirtuallyall the systemsoil is lost thenthis will result to flush the in the ingressof seawater. If this shouldoccurit will becornenecessary whole systemout with freshoil. existingoutsidethe system The ingressof seawateris causedby a positivepressLlre if this shouldoccurit can leadto suchproblemsascorrosion with respectto the.inside, within the system.

187

Any ingressof water to the systemcan be detectedby drainingoff a sampleof oil from the lowestpoint , theoil will haveemulsifiedand will havea'milky' appearance. 12.1.4 Determining The Oil Level As a generalrule the oil level is monitoredvia the systemselectronicsand is displayed at the surfaceunit. A transduceris mountedon the systemwhich producesan electrical signalproportionalto the oil level, this is passedvia the systemtelemetryto the surface. Shouldthe oil fall below a certainlevel an alarmwill be activatedindicatingto the operatorthat a leak nray be present.Normally therewill be two alarms,the first being activatedat 660/oof the total oil level. This alarmmay be over-riddenand will allow the operatorstime to rec:overthe vehiclebeforecompleteoil lossoccurs. The secondalarm will be setto activateat a much lower value,for exarnple337o,this alarm cannotbe over-riddenand will causethe systemto completelyshutdown. The oil level can also be monitoredwhen the vehicleis on deck by noting the positionof the compensators. 12.1.5

Compensation

As a generalrule the ROV hasseveraljunctionboxeswhich,when subjectto extreme pressurewould probablyimplode. This is overcomeby filling eachbox with pressurised statichydraulicoil. The internaloil pressureis nraintained by a pistonthat is exposedto the externalseawaterpressure.The pistonis directlycoupledto the oil systemvia a springthatmaintainsthe oil pressureat 3 to 5 PSI abovetheexternalsea waterpressure.It follows thatthe pressureinsidethejunction box is positivewith respectto the externalseawaterpressure, thuspreventingthe inrplosionof thejunction box. This methodof conrpensation is appliedto the main hydraulicsystenr.Shouldan oil leakoccurthe internalpositivepressurewill give riseto the oil beingforcedout as opposeto seawatel beingallowedin. As theoil leveldropsthe alarnrswill be activated and the operatorscan recoverthe vehicle,hopefullybeforeiiny seawaterentersthe system. Whilst the vehicleis on deckit is possibleto nronitortheoil levelby notingthe position piston. It is conrnronpracticeto nronitortheoil levelsthroughout of the compensator the systenrin this mannerduringthe pre and postdive checks.(seeChapter10). 12.1.6 Oil Filling The frequencyof which the systemrequiresfilling with oil dependsuponthe leakage factorof thevarioushydraulicunits. Howeverthe methodfor filling the system remainscommonfor all ROVs. It is commonpracticeto fill the systemat the lowest point in orderto minimisethe trappingof air. The systemis filled from a pressurised containerwhich hasa dedicatedhydraulicfitting to coupleto theoil inlet. Beforeconnectingit is vital to ensurethatthe filler point is thoroughlycleanin orderto minimisethe ingressof dirt into the systenr.Many systemsnrakeuseof 'quickfit' connectorswhich simply snapon to theoil inlet. This minimisesthe useof spanners a n dc o n s e q u e n tsl yl v e st i m e . 12.1.7 Air Bleeding Wheneverthe systemis filled with oil it is necessary to bleedair out of the system. This is normallydonefrom the highestpoint in the system.Howeverit may be the casethat therearevariousbleedpointsaroundthe systernlocatedin the appropriate positions.The bleedpointrnayconsistof a capthat when slackened allowsthe trapped air to escape.The bleedpoint shouldremainin this stateuntil oil flows freelyfrom the fitting. It may be necessary to bleedthe systemon a regularbasisespeciallyif a major oil changeor refit hastakenplace.

188

12.1.8 Oil Filter Change Oil filters shouldbe changedwheneveran oil changeis carriedout. Most filters require the elementto be changedand thereforea spareshouldalways be kept in stock. Th^e operatorsshouldneverbe temptedto run the systemwithout a filter elementas this could lead to major breakdowndue to contaminationof the maior units. Before changingthe filter or any unit for that matterit is importantro drain the systemoil as the posltlvepressure wouldresultin a largelossof oil. 12.1.9 Dielectric Oil As previouslymentionedall junction boxesare oil filled, howeverthejunction box may houseconductorsor transfomrersthat would not be compatiblewith siandardhydraulii oil. In this caseit is necessary to usean oil thatis inert. bielectric oil hashigh' insulatingpropertiesand is usedin suchenclosures.This oil is sometimescilled transformeroil and is c^ompensated in the usualmanner. It is importantthat the insulationpropertiesof the oil is constantlymonitored,this can be doneby draininga sampleof the oil front the enclosureand checkingfor signsof water.In the caseofthe tlectric motor the insulationis monitoredelecrricilly, in ihis casea resistancereadingis displayedat the surfaceunit andgivesan indicationto rheintegrityof thedielectricdil. 12,2 Component rvear It is commonpracticeto.havespecialisedengineerscarry our the servicingof individual hydraulicunits. The.taskmay iequirethe useof specialistecluipment and"skillsthat doesnot fall within the requirements of the Rov personnel.'However, a basic understandilgq{ which conrponents aresusceptib]e to wearcould help the operatorin the diagnosisof basicfaults. We will now coirsiderrheconrponents of the basic hydraulicunitsthatareproneto wear. 12.2.1 Hydraulic pumps and motors HydraulicpqnJp.s itnclntotorscontaineithergears,vanes or pistonswhich arerequired to.operate at high speeds.Irt eachcasethe principleof operationrelieson fine tolerances betweenthechanrberwall andthemovingcomponent,any increasein these tolerances can leadto lossof systempressurein thelase of pumpsandreducedpower and excessive'case'pressurein the caseof motors. Pumpsand motorsaredesignedin ;uc.!.a way.thata certainamountof oil is allowedpassedihe pistons,vanesor g"utr to facilitatelubricationof.the bearingsand shaftseals. For this ieasonit is possibieto measuretheoutputof the casedrainover an intervalof tinte,and,by consultingthe manufacturersdata,de,tem-Line the integrityof the internalconrponents.For eximple if the oil is in excessof the s.pecifications it would indicatethat thepistonrings werewom therebyallowingexcessoil into the casechamber. Another cgrymox problem that can ariseis wearingof the shaft seals.This is evident by a visualcheckof the systemwhilst on deck. SJalshavea specifiedworting life as statedby the manufacturer,howeverthis can be drasticallyredircedif the systeirsoil becomescontaminated.If any seals_are everremovedthey shouldalwaysbe inspected for damageand any signsof breakdown.

r89

L2.2.2 Hydraulic valves and Valves generallycontainminute componentsthat areresponsiblefor the flow rate oil. For this reasontheir operationis dependenton 'ht - , dr""6;;nydrautic ileanlinessof the sysr; oil and the environmeniin which they havebeenserviced. Typical faults that iould arisefrom blockagescould be:a)

Blo,ckedrelief valve leadingto systemoperatingat reduced pressure.

b)

Blockagein solenoidvalve leadingto malfunctionof manipulator flnction.

c) Blockagein servovalve leadingto eithercompleteloss of oil flow to thrusteirlotor or reductionin runningspeed' 12.2.3 Hydraulic rams The operationof hyclraulicrantsdependstotally on th€ integrity.of the internaland can leadto leakageacrossthe piston externalseals.Any breakdownin tiretolerances the and thereforereductionin operatingperfgmranceof the driven unit. For example 'sluggish'in it being may be reducedresultingin or tn. r-nanipulatoi ;;i;tp.;"i ntovement. leakageis easilydetectedby visualinspection As with all externalsealsexcessive during pre and postdive checks.

190

12.2.4 Fault diagnostics a faultdilgn-osis procedure for a typicalhydraulicsystem. ligure 110. illustrates Figure(12.0illustrates thefaultfi-ndingprocedure for a sitirationf;;;;y;rJ;irtat is generati ng excessive noise).

Selting too low or loo close to another

REMEDIES A

Any or ail of the followino: . R e p t a c ed i r t y t i l l e r s . Wash slranels in so/yenl compa/ib/e ,///, s/s,le/v //a/iy' . Clean ctogged inlet line . Clean reservoi(b(eathe(vent r Qhange sys\em !\uid . Change to proper pump drive motor speed . Overhaulor replacesuperchargepump . unecx ilutd temoeratute

B Any or a[ of the foilowino. ' T i g h t e n l e a k yi n l e tc o n i e c t i o n s . Fill reservoirto proper level - with few exceptions,arr return rines shourdbe berowfluid reverin the reservoir. . Bleed air from system . Replacepump shaft seal Also replaceshaft if worn at seal journal. C All of the tollowino: . A t i g nu n i t . Check conditionof seals, bearings,and coupling O . lnstalland adjust pressuregauge E

. Overhaulor replacedefectivepart(s)

Figurel2.l(a) l9l

excessive heat. Figure12.l(b)illustrates the procedure for a systemgenerating

R e m e d y :S e e c o l u m n D

R e m e d y :S e e c o l u m n D

Faultyfluid cooling syslem

Worn pump, valve, m o l o r , c y l i n d e ro r other component

REMEOIES Anyor all of the following: . R e p l a c ed i r t y f i l t e r s . C l e a nc l o g g e di n l e t l i n e . C l e a nr e s e r v o ibr r e a t h e rv e n t . C h a n g es y s t e mf l u i d . C h a n g et o p r o p e rp u m p d r i v em o t o rs p e e d . O v e r h a uol r r e p l a c es u p e r c h a r g p eu m p Any or all of the following: . T i g h t e nl e a k yi n l e tc o n n e c t i o n s . Fill reservoirto proper level With tew exceptions,all return lines should be below fluid level in the reservoir. . Bleed air trom system . Replacepump shatl seal Also replaceshaft il worn at seal journal. All of the lollowing: . A l i g nu n i t . Check conditionof seals,bearings,and coupling . Locateand correcl mechanicalbinding . Check for work load in excessot circuit design U

tr F

. Installand adiusl pressuregauge Keep al least 125 PSI differencebetweenvalve settings e Overhaulor replacedefectivepart(s) . C h a n g et i l t e r s . Check systemfluid viscosity.Change if necessary. . Fill reservoirto proper level . Clean cooler and/or cooler strainer . Replacecooler conttol valve . Repairor replacecooler

Figure12.1(b)

t92

Figure12.L(c)illustratestheprocedurefor a systemoperatingwith an incorrectflow.

Relief or unloading valve set loo low

RPM of pump drive molor lncorrecl

Pump drive motor turning in wrong direclion

E n t i r ef l o w p a s s i n g over relief valve I

i Worn pump, valve, molor, cylinder, or

REMEOIES Any or all o, the following: . Replacedirty filters . Clean clogged inlet tine o Clean reservoirbreathervent . Fill reservoirto proper level . Overhaulor replacesuperchargepump . Tightenleaky inlet connections . Bleed air trom system . Check for damaged pump or pump drive . Replaceand align coupling

D . Adiust parl E . Overhaulor replace parl F

Any or all of th€ tollowing: . Check position of manuallyoperatedcontrols . Check electricalcircuit on solenoidoperatedcontrols . Repair or replace pilot pressurepump

G o Reverse rotation H . Replacewith correct unit

Figurel2.l(c) 193

i

Figure12.1(d)illustratesa systemoperatingat an incorrectpressure.

Remedy: See Charl lll, column A

Remedy: See Chart lll. column A and B

Pressure reducing, reliefor unloading valve worn or damaged

A c c u m u l a l o rd e f e c tive or has losl charge

O a m a g e dp u m p , motof or cylinder

REMEDIES

A

. Replacedirty filters and syslem tluid

B . Tightenleaky connections Fill reservoirto proper level and bleed air lrom system C . Check gas valve for leakage . Chargeto correcl ptessure . Overhaulif defective D . Adjust part E . Overhaulor replace part

Figure12.1(d)

194

12.2.5 Summary It can be saidthereforethat the efficientoperationof the hydraulicsis dependent on the cleanlinessof work environment.Shouldany maintenunrLbe requiredthe ROV should be hoseddown with fresh water and the unitin questionremoved'fromth; vehicle and takento a clean,a_v_.worfntace. A high standarilof cleanlinessshouldat*ays Ue maintainedwhenfilling rhesysremwith oil so as to preventingressof dirt. '12.3 Planned maintenance EYtry systemshouldhulg plannedmaintenance procedurethat shouldbe correctly I adheredto at all times. This would normally be kipt in log r".,n "i""-n"ppy oiir. The principle of the PMP is that it recordsthe running timJof all the com6ffi;. Having this informationenablesone to ensurethat th6 relevantunit is serviced afier the appropriatenumberof running hours. The running time is determinedby the manufacturerand may have sfightvariationdepenling on the company.'Figure l2.l illustratesa typical log for the runninghoursof the mfin nyorartic syiiem o?a iypicar ROV.

I\,,IASTER LOG DATE

HOURS

HPU I,4OTOR S/No

HOUBS

HPUPUMP S/No

HOURS

PORTTHRUSTER

STBD.THRUSTER

FWD.THRUSTER

S/No.

S/No-

S/No.

HOURS

Figure12.2

195

HOURS

HOURS

AFTTHRUSTER S/No.

HOURS

VERT.THRUSTEB S/No.

HOUBS

detail of the actual Figure 12.2.illustraresa typical fault docketwhich provide.s.some the *Iintenunce carriedout. Documentationof this natureenables operatorto locate reoccurringfaults more easily. For examplecertainunitsmay breakdoYl more often a nend in the than normil, by consultingthe docketit may be possibleto_detect symptoms. This could indicatea fault som6whereelsein the systemwhich can be and therebyminimisethe overallrepairmaintenancetime. a-ddr^essed indicationasto tha sparescontenton the ROV sy^stem.This The fault docketalsogives -a would normally have separatelog, but in this caseit is possibleto crossreference betweenlogs. of this systemis that it makesmaintenanceeasierfor the One of the main advantages -work with the system.It follows that it is in.everybody's may who crews various procedureas it minimisesrepairmaintenancethat can maintenance follow the to interest ROV cornpanies. the to Drovecostlv

F A U T TD 0 C K E TH o . ) ATE

D I Y EH o . I

lJ08

] ATTGORY : A U T TS Y I 1 P T O T I S

t E t l o v E D F R 0 l " lS Y S T I H 8 q

IEPAtR Y0RKc ^EE!!9_q!IJ

; P A R E SU S E D ; t6nED lAcK ltl sYsTEl'l

IDATE

: A U L TD o C K E T Ho. D I Y Et l o . I

D ATE

|JOB

CATEGORY F A U L TS Y H P T O H S

I

i i x o v e or n o Hs v s r r x e v l ourl R E P A TY R0 R K c A R R t E D

J P A R E SU S E D

; l'ttED

io^t'

I

tAcK tH sYSTEf4

Ho iAULT DOCKET D t v Et l o . I

DATE

lJoB

: ATEGORY :AULT SYF{PTOIIS

I

DUTI T E P A I RV O R KC A R R I E O

S PA R E SU S E D IDATE

S IGIiED

B A C KI H S Y S T E H

Figure12.3 196

CHAPTER13 EMERGENCY PROCEDURES 13.0.0 The natureof ROV operationsis suchthat despitecareful preparationand adherence to proven operationalprocedures,situationsarisethat endangerthe vehicle and require the crew to take emergencyaction. The aims of this chapterare to describe common emergencies,to focus on the crucial considerationsof navigation, communications,and buoyancyin pre-diveplanning and finally to describeactions that should be taken by the crew once an emergencysituationhasarisen. 13.f.0 The following is a descriptionof possibleemergencysituations;13.1.1 Support Ship Entanglementis perhapsthe most commonform of emergency situationand often resultsin the completeloss of the ROV. This can arisewhere the position of the vehicle relative to the ship is uncertainand the ROV surfacesclose to a propeller or thruster,where the ROV entangleswith the taut wire of the DP system, or wherethe relativepositionshavechangeddue to a navigationerror and the umbilical hasmoved 'under'thesupportship. The key factorin theseincidentsis often poor communicationsbetweenthe ROV crew and the suppoft ship'smaster.

13.L.2 StructureEntanglement is alsoverycommon results butusually in ROVor diver

assistance ratherthanthe completelossof the vehicle. This often occursbecausethe pilot becomesdisorientated, the vehiclebecomes'snagged', on debrisor a structural componentsuchas a pile guide,or the vehiclelosespower in precarious circumstances, but may alsooccurif the supportvesselmovespositionwithout the ROV crew being infonned.

13.1.3 Guide Wire Entanglementis commonwithin Drilling Supportactivitiesand can resultin the crushingof the ROV as the Blow Out Preventer(BOP) Stackis landed. This can happen,for example,in remotelocationswherethe Drilling Supervisormay only allow a period of time for the crew to disentanglethe ROV before recommencingdrilling operationsdue to cost pressures,particularly if there are no otherROVs or Divers availableto assist.The mostcommoncausesof this arePilot disorientationdue to lossof visibility possiblyas a resultof disturbedsedimentsor displaceddrilling fluids, and unexpectedchangesin current strengthand direction. 13.I.4 Anchor Chain Entanglementoccurswhen surveyingthe anchorchainsof Bargesor Semi-Submersibles platforms. This is the result of the ROV losing orientationdue to disturbedsedimentsas the chainis lifting, the vehiclethenpassingunderthe chain as it lowers trappingthe vehicleor its umbilical. This situationis alsolikely to occur when laying umbilicalsand pipelinesas the vehiclemonitorsthe touchdown point. It is very important,therefore,that theseoperationsare carriedout in acceptable weatherconditionswhere there is not excessive'heave'of the vesselunder survey, and that the vehicleis positionedfacing into the currentwhereverpossible,so that it benefits-from optimum visibility and the prospectof being canied-safelyaway from the work areaby the currentin the caseof a systemfailure.

197

:

13.1.5 Bottom Debris Entanglementoccurswhen an unseenhazardsuchas mono-filament are not anchored'are nrtting f*" o. nyton-ffi, which tend.to be buoyantwhere..they. 'snagged'around or when the vehicleumbilicalis drawn into the vehicle.ittrruster, htg"; items of debris. The besradviceis to travel slowly.in the vicinity of,these hazardsand in the eventof soft line beingtakeninto the thrusterceaseor slowly winch' reversethe thrusteronAuit.nlpt to pull th"evehicle free using the umbilical

13.2.0 each The abovementionedincidentscan largelybe avoidedby careful planning of conditions, weather and paiO currenta to; ;ittr particutai atrentionbeirig ;Fil;" This navigation,,o.n*uni*tiont, and the bioyalcy of the vehicleand its umbilical' factors' these secti6nexplainsthe importanceof eachof L3.2.L It is crucialto havean accuratepredictionof the weather conditionsand ocean available currents for the nl"*in.rutoexpecteddurationof eachdive. Theseshouldbe f9l,T:I]1YT be,posilio".d io, tt e pre-divemeeringsso that the supportvesselcan rnto safety,ind the dive can be plannedt4ing the currentt3nq weathercondrtrons master ships the crew, ROV ur.olnt. The pre-div. to..ting shouldbJattendedby.the the of result be a u"O-u"Votfrerparticipatingpeisonnel,the plan:rrived at will and the ship'sand RoVs operatingparanreters ;;;i11G;onhitionr, the"srirface experienceof the personnei. 13.2.2 is crucialto the of the supportship and the ROVs navigation s-vstems Consideration vary_considerably. ftunnlng of the dive beiiuse rheaccuraci,of differenisyste.ts (GPS)may.be Sateilite Positioning Global by rf detemrined position The shiis on the locationand satellitepositions, accurateto within -5-10 metres
198

the diving operationunderway. Thesecircumstancesseemall too obvious,but happenall too frequentlydue to poor communications.

13.2.4 The buoyancy of a vehicle and its umbilical can also be a critical factor in avoiding entanglementsand easingsubsequentrescueattempts. The situationof having an ROV positively buoyant(usually about 30lbs for a work size vehicle) may well be suitablefor a pipeline surveyjob where the vehicle can reasonablybe expectedto surfaceclear of the surfaceship in the event of a systemfailure. It may however be more appropriateto have a 'heavy'vehiclefor deepwater work so that in the event of a systemfailure or partedumbilical, it will sink to the bottom where it can be found by the rescueROV or divers. Consideringthe buoyancyrequirementsof the vehicle prior to eachjob can, therefore,significantlyeaseany rescuethat may be attempted subsequentto an entanglementor partedumbilical situationand needsto be given due considerationat the pre-diveplanning stage.

13.3.0 The first time that an ROV operatorexperiences a vehicleentanglementsituationcan be unnerving. It is importantto rememberthat thesesituationsoccur commonlydue to the natureof thejob and the difficultiesencountered in navigatingin poor visibility, avoiding unknown obstacles,and accuratelypredicti-ngwEathir conditions and oceancurrents. Whilst this may be a new and unnervingexperiencefor you it will be familiar to your supervisorwho will haveseennumeroussuchincidents previouslyand will know that they usuallyhavea successfuloutcome. Thereis no substitutefor experiencein thesesituationsbut this sectionwill describeprocedures that may be followed to ensurethe bestchanceof a successful outcome.

13.3.1 The first thing that a Pilot must do in the caseof entanglement is to inform his supervisor. If appropriateactionis takenearly therewill be a much greaterchanceof a successfuloutcome,whereasuninformedattemptsto rectify the situationwill invariably make it worse.

13.3.2 If thevehiclesuffers a lossof poweron thesurface, thefollowingactions should be taken: i) ii) iii)

Deploy suitablefendersor buoysover the sideto minimisecontactbetween the vehicle and the surfaceplatform. Use the umbilicalcablewinch to move the vehicleinto the recoveryposition. Perform the usualrecoveryprocedure.

13.3.3

If poweris lostwhile the vehicleis submergedthefollowingacrionsshouldbe taken: i) ii) iii)

Manoeuvrethe surfaceplatformwherepossibleso that the vehiclewill not come up under the platform. Deploy suitablefendersor buoys. If the vehicleis not rising,usethe umbilicalwinch to haul the vehicletowards the surface.

199

iv) v)

If it is dark the emergencyflasherwill activatewhen the vehicle reachesthe surface. Use the um6iticat winch to move the vehicle into the recovery position. Perform the usualrecoveryprocedure.

13.3.4 If the vehicle is on the surface and the umbilical has been severedthe following actionsshould be taken: i) iil iii) iv) v)

Deploy suitablefendersor buoys. -anoeuure the surfaceplatform closeto the vehicle' Deploy a rescueboat and attachlines to the vehicle. Haul the vehicle into the recoveryposition. Perform the usualrecoveryprocedure.

13.3.5 If the vehicle has becomeentangledthe following actionsshouldbe taken: i)'

ii) iii) iv) v) vi)

'Black-box'videorecorderand with the assistance of the cable Replaythe entangledand to be came vehicle how the to determine twiit indicator attempt the lay of the umbilical. usingthe video camera. Determinethe degreeof entanglement Plan a routeout of the entanglement. Loosenthe umbilical by unwindingthe umbilical winch, and attemptto manoeuvrethe vehicleout of the entanglement. If stepiv) fails atremptto manoeuvretlie surfacevehicle to free the vehicle. If steirv) fails attenrptto pull the vehiclefree using the umbilicalcablewinch. Be careful not to exieed the breakingstrainof the cable and to allow for the bend radius and safeworking load of the sheavewheel and recoverygear.

13.3.6 If the umbilical is severedwhile the vehicleis submergedthe following actions shouldbe taken: i) ii) iii) iv) v)' '

vi)

Estimatewhetherthe vehiclewill surface,float mid-wateror remainon the bottomby calculatingthe resultantbuoyancyof the.vehicleand its umbilical. Infom'rthe ship'smalter andrecordthe ROVs last known positionon the charts. If the vehicle is likely to remain on the bottom arualrgefor an ROV or diver to attemptthe rescue. tf the vehicle surfaces'perform the recoveryprocedurepreviouslydescribed. If the vehicle is likely tb be ftetamid water then the oceanculrents shouldbe predictedand if avaiiablean acoustictransducershouldbe deployedfrom the 'listen'for and locatethe vehicle through.the activationof its iurface ship to 'Pinger'.The vehicleshouldbe 'tracked'and-grappling hooks emergency vehicle. or umb.ilical hook the path to to attempt deplo-yedacrossits Ori hdoking the ROV recoverto ihe surface,immediately attacha line or surfacebuoy and perform the usualrecoveryprocedures.

It is very important in the abovesituationto act quickly. as the ROV can drift away rapidly decreasingthe chancesof locatingald rescuingit. Grapplinghooks,charts und oih"r relevanirescueequipmentshouldbe madeready and the crew briefed beforethe diving operationcomn'lences.

200

13.3.7 In circumstances wherea rescueROV or diversis requiredit is necessary to give the Client'sRepresentative andtheonshoreOperations Managerat leastthefollowing information: i) ii) iii) iv) v) vi)

Last known location. Circumstancesand degreeof entanglement. Depth of ROV. Backgroundinformation and manoeuvresalreadyattempted. Likelihood of the vehicle drifting in the oceancurrenrs. Urgency of the rescuei.e. is the vehicle holding up other platform or drilling operations?

Finally, rememberproper planning can often preventthesesituationsfrom occurring, but they do still occur from time to time due to unforeseencircumstances.Keep calm and follow the relevantemergencyproceduresissuedby your companyand you are likely to have a successfuloutcome. If however,the outcomeis the l,ossof the vehicle,rememberthat it will be coveredby insuranceand that it is acceptedwithin the industry that a numberwill be unavoidablylost due to the natureof the work. Thesesituationsare not usuallycareerlimiting and can be put down to experience.

'l

{

I {

201

CHAPTER 14 COMMUNICATIONS 14.0. Introduction. ROV personnelwill be requiredto usecommunicationsystemsat variousstagesof the work programne offshore. This chaptersetsout to indicatethe proceduresusedfor "hard both radio and wire" communicationssvstems. l4.L

Hard Wire Systems.

This is the terminologyusedto describethe deck to conffol room wire line communicationsystem. The commonconfigurationis a headsetcontaininga speech activatedmicrophoneall connectedto a wanderingleadwhich is connectedto a deck mountedcontrol box. This methodof communicationis useddaily and all ROV personnelmust be familiar with its use. The procedureadoptedfor speakingon a hard wire systemis basedon radio procedurebut is lessformal . For examplethe Proword "Over" is not used.Radio proceduresand Prowordare outlined later in the chapter. 14.2 Radio Communications Radiocommunicationsmay be requiredto communicatebetween: Deck andcontrolroom; a. Vesselto platform; b. c. Vesselto vessel; d. Vesselto shore. There are a variety of differentradio systenrsusedfor theseand other purposes offshore. It is not nec:essary to havean intimateknowledgeof thesesystemsbut a brief resume,highlightingthe pointsaffectingthe userwill be helpfLrl. 14.3 Radi
203

communicationsarepossible24 hoursa day as thereis little interf'erence at all. Commonlyusessimplexfor line of sightandduplexfor satellite conlmunlcattons. 14.4 Radio Procedures. Before using a radio for communicationthe frequencyor channelto use,the callsign.of the transmitiingstation,the callsignof the stationcalled,the personrequiredat.theother must all be known. Oncethis informationis known end and the su6jectto be discussed beginin the sameway. Thereis the call, the text andthe ending all radiotransmissions transmission. PolymarinerTHIS IS StenaMayo The Call: The call consistsof the calisignof the stationrequired,followed by the Pro words This Is and the callsignof the stationcalling. Eachcallsignmay be repeatedup to three times if the initial call is madeon internationalchannel16. Either: Give me a working Channel;or The message. The Text: request for a working channelif the original call was madeon may The text be a 16 international channel or it rnaybe theinformationto be passed. The Ending'fransrnission: OVER or OUT. consistsof the ProwordOver if a reply is requiredor Out if no The endingtransmission reply is expectedor recprired. 14.4.1 VHF Maritime Calling Procedure. on VHF is the mostcornnlonpractiseoffshore.The Callingon Maritin-refiecluencies procedureis: Tune to Chanrrel16 andlistenfor a quietperiod. Make your transnissionasoutlinedaboveeitherrequestingor statinga b. workingchannelin thetext. Wait f'ora lesponsefront the stationcalledfor trp to 10 seconds.If there in thistinremakeyourcall again. is no response is madechangefretluencyto the workingchanneland When a response d. Do not work ott channel16 whichis used re-establishconrntunications. only tor distressandcalling. 14.4.2 How tn Speak the following conlmentswill assistthe Whateversystemis usedfor communication is passed. userin ensuringthat a clearmessage to distressor urgentcalls Always give precedence a. or chat. conversation Do notjam up thechannelwith un-necessary b. Wait to responduntil the transmittingstationmakesan ending c. Only try to interruptif it is most urgentthat you do so. transrnission. not Do swear. d. Do not stammer. e. RememberRSVP f. Rhythmof speech- as normalbut usepausesfor effect. R S Speedof speech- Slightlyslowerthannormal' V Volumeof speech- Slightlyloaderthannomral,but only slightly. Pitchof speech- Slightlyhigherthannormalpitch if possible. P g. Reniemberto pressthe transmitbuttonandallow a shortpause beforespeakingandcontinueto hold the buttondown throughoutthe transntission.

204

14.4.3

Prorvords

Numerousstandardphrases,which haveinternationallyrecognisedmeanings,are used in radio voice communications.Thesephrasesare calledPro,iords. A table'of the more usefulProwordsfollows.

PROWORD MAYDAY

PAN

SECURITE

USEOR MEANING PROWORD USE OR MEAMNG Thedistress signal. HOWDO yOU What is the strength Usedwhenin FIEARME? and clarity of my voice

imminentdangerand lmnteolateasslstance is required. The urgencysignal. READ BACK Used where safetyis threatenedbut danger is notjudged to be imnrinent. The saf'etysignal. Mainly usedfbr navigationor meteorological

ACKNowLEDGE ilil:'i5;.eceivect and understoodthis message? ALL AFTER/ALL BEFORE

OVER

CORRECTION

ROGER

Usedwith a kev " word from the transn]lsslon to identifya parrof the text.

SAY AGAIN

I SPELL

OUT

transmission? Requestto the receivingstationto readbaci the message sent.Used to confirir the messagehasbeen receivedexactlyas sent. A requestfor all, or a part of the messageto be repeated. Usedwhen a word or an abbreviation is spelt out.

Transmission conrpleted andno replyis expected.

Transmissionis I READ BACK The receivingsration corrrpleted. anda reply repeatsback the rs requlred. messageas receivedto confirm it is correct. Cancelsthe word or phrasejust sent. Normallyfollowed inrmediatelyby the correctversion.

WAIT

Message received and I SAy AGAIN understood

205

The stationrequires time to considera reply this allowsup to 5 secondsunless followed by a number which indicatesthe numberof minutes.

Usedwhen a messase or phraseis repeated fbr enrphasis.

l

I j l

14.5 . Deck Communications. As statedabovehard wire communicationsarefrequentlyusedby ROV personnel. They do haveseveraladvantages: a. b. c.

Headsetsleavethe handsfree; Thereis no interference Does not interferewith radio users.

A Typical conversationbetween;Deck Officer (DO), CraneOperator(CO), Pilot, VesselCaptain(VC), and Dive Control (DC) will illustratethe useof voice procedure on thismeans. DO Pilot DO VC m m DC DO

Pilot This is Deck Officer, Pre-divechecksare now completestandbyto launch Pilot, Roger Bridge This is Deck Officer, Pleasereport the statusof the vessel Bridge,Vesselis on station,Heading1100,you areclearto launch. Deck Officer, Roger. Dive Control This is Deck Officer Pleasereport stittusof divers. Dive Control,All diversareout of the water.You areclearto launch. Deck Officer, Roger.

The Deck Officer would thenproceedwith the launchopel'ation.

206

CHAPTER 15 UNDERWATER VIDEO 15.0 Introduction Remotelyoperatedvehiclescould not exist if closedcircuit televisionwas not available. In all typesof vehicleit give a visual imageto the surfaceshowingwhat the vehicleis looking at and allowing topsidestaff to navigatearoundobstacles-or inspect componentsor just generallymonitor the underwatersituation. Thereaie several differenttypesof camerasavailableand in this chapterthe most popularwill be outlined. 15.1 SIT Cameras The Silicon IntensifiedTargetcamerais usedextensivelyfor generalnavigationand observation.The camerawill operatein low light condiiionsequivalentto night time with a quartermoon showingthis as a sensitivityof 1 x 10-aLux. This in turn means that floodlightsarenot requiredand in turbid conditionsbenervisibility is achieved becausethereis no back scatter.It is the prime cameraon most ROVs and is the pilot's first choice.OspreyElectronicsmanufacturea compactSIT camerafor ROV usewhich is 100mm in diameterandapproximately 300 mmlong. It is ratedto 1000m water dqpthand containsan automaticiris. The focus is fixed giving a depthof field from 140mm to infinity. Oneimportantoperatingpoint is to ensurethe lenscoveris put in placeas soonas the Rov is on deck to protecrthe target. The pictureis in monochrome. 15.2 SDA Camera The Silicon Diode Array canrerais specificallydesignedto be tolerantto high intensity light and can,for exantple,be usedto observewelding,the sensitivityof the camerais around1-10Lux. This wouldbe impossible with othertypesof cameras as thelight from the welding arc would destroythe picturetube. Ospieymanufacturean SDA camerawhich is 100ntm in diameterandapproximately 350 ntnrlong. It is ratedto 1000m water depthand containsan autonraticiris. Focusis by remoiecontrol and it is possibleto get closeup viewsof an object.This would be recluiredfor weld inspection for instance.This camerais usedfor specialistpllrposeswherehigh intensitylilht is to be observed. 15.3 CCD Cameras This type of colour camerahasbecomethe industrystandardfor all typesof inspection and observationwhere goodquality colour video picturesarerequired,sensitivities rangefrom +10 to 0. i Lux. Ospreyonceagainmanufacturethii type and they can providetwo models:oneof which hasa pan andtilt mechanismbuili into the 6ead. The overall dimensionsare 104mm diameterand approximately330 mm long. They are ratedto 1000m and haveautomaticirises.The focus is by remotecontrol and is from 10 mm to infinity. 15.4 Video Recording Whatevertype of canrerais calledfor in the contractspecificationsthe video informationwill needto be recorded.Thereare severaldifferent standardsfor doine this and Figure 15.I laysout in tabularform thosecurently available.

207

Paramerer

S-VHS

Hi-g

VHS

U-Matic

Resolution (TV Lines)

>400

>400

260

Colour250 Colour270 Mono330 Mono 370

Signalto NoiseRatio

46 dB

46 dB

43 dB

45 dB

46dB

Max Tape 180 Length(mins)

90

240

Cassette Size 500 (Volume)

90

500

1615

1615

Volumeper Hour Recording

166

60

t25

1615

1615

Signal Input

conrposite or S-Video

composite or S-Video

composite

conrposite composite

U-Matic HB

Figure lS.l Most operatgrsare stipu.latingS-VHS (SuperVideo Home System)becauseit hasgood resolution.To utilisethis systemto its fuli potentialit is necessary to use2 co-axial cablesfrom the cameraas opposedto the usualone . Onecablecarriesthe chrominance signaland theotherthe luminance.The extracableis nor usually,r"J uipi.i"ni. rn orderto recordthevideo signalfrom thecamera.a recordingsuitenrustU" pui iogether. To indicatehow this rrtaybe.donea diagranrmatic layoutrri,tr ,t, .outA b" ;;d;y " S c o r p i oR O V i s s h o w ni n F i g u r e1 5 . 2 -

208

Raw Video Porr

Raw Video Pan and Tilt

RawVideo StM

Nav 1 Monitor Nav 2 Monitor

Switch Matrix

Figure lS.2 15.4.1 Recording Qualit-v As a result of a study sponsoredby severalof the offshoreoil producers;conducted by R.w. Barrett,M. clarke and.B. for the MarineTechnologyDirectoiat.,uno f.ay publishedin Underwatertechnologyvol. lg No. 2 four on siie resrswere recommended: a

Check I Recorderplayback and monitor Using a tapepre-recordedto broadcaststandards

b

Check2 Cameraand transmission Excluding the recorderfrom the system

c

Check3 Recorder and transmission Using a taperecordedon sitein thepreviouscheck

d

Check3 Cameraunderwarcr A simplecheckfor specificunderwaterproblenrs.

Thesecheckscan only provide a measureof the video quality at the time they are implemented. 1l9v can neitherguaranteequality at a aiireie'nttime nor carittey tate acc.ountof.possibledegradationif componentsof the whole systemare changel or additionalitems conne-cted to it. Theyire, however,designedfor technicianswho are competentin the useof relevantunderwaterequipmentbuj who haveno specialiitvideo or electronicknowledse.

209

15.5 Video Signal There are rwo main video systemsin operation, they are PAL (phasealternation by titrc) and NTSC (nationaltelevisionsystemcomminee)which wasdevelopedin the United Statesof America. It is not rhe intention of ttris book to go into greatdetail on these formatsas the subjectis alreadywell documented,but it is sufficeto say that all sysremsarecompatiblewith both types. Video signalis an electricalsignal that is producedby thecaniera,that scansthe object, and it is proportionaito the intensityof light enteringthecamera.Light is made up of the sevencolours red, orange,yellow, green,blue, indigo and violet. However the humaneye is most perceptiveto red, greenand blue,for this reasonthe camerais designedto detect thesethree colours which are recombinedto form an image of the originalobject. The camerais made up of threetubes,eachone designedto receiveeither red, greenor blue light and producean electricalsignal which is proportionalto the colour strength. The colour is then transmittedon the actualvideo sienalanddecodedat the monitor to producethe actualpicture. Figure 15.3illustrateshow video signal appea$ on an oscilloscope.

Sync Pulse

Typical Video Level I Volt Peakto Peak Figure 15.3 It can be seenthat compositevideo signal is madeup of synchronisationpulses,colour burst,chrominanceand luminance. 15.6 Luminance Signal Luminanceis the characteristicusedto provide picturedetailby varying levels of Luminanceis transmittedon the picturesectionof the signal. brightness.

2r0

15.7 Chrominance Signat Chrominance-signal is-usedto conveythe colour informationin the video signal. The r9{, greenand blue colours.produce an electricalsignalthat is proportionalt6 the phase shift betweenthem. It is this electricalsignalthat forms the chrorninancesignal. 15.8 Colour Burst Colour burst is addedto the video signalto provide synchronisationfor the chrominance.This is addedimmediatelyafter the piciure information,beforethe following synchronisation pulse. 15.9 Synchronisation Pulses The synchr^onisation pulsesensurethat thereceiveroperatesin stepwith the vertical scanning^o_f the camera.The TV monitor displayis niadeup of 625 scanlines that are ^Ueing sc^anned per second. This means th-at each line is scannedat a frequency ?!_!ilttl of 15.625KHz. It can be seenthat the time period betweeneac6synchronisationpulse is normally 64ps, the pictureinforn-rationbetweenthe two consecutivesynchronisation pulsesthereforerepresentsthe inforn.rationappliedto one scanline. 15.10 Calibration Of Video Cameras p.u.eto the lengthof umbilical,ROV systemsare subjectto the effectsof line losses. This canmanifestitselfin the ROV video system. The monitorson the systemrequirea certainlevel of video signalto function correctly, if this is not thecasethenit may resultin extremelypoorpictlre quality. A situationmay arisein which the umbilical may be-replaced for a muih longerone. For exampleit may be necessary to incorporate a TMS in to the system,this"would requirethe additionof an amrouredumbiiical. This would obviouslyresultin an increasein the ovet'iillline losses.For this reasonit would be necesstrvto carrvout a calibrationof the vic'leocameras. By calibratingthe camerawe arein fact amplifying the canreraourpurro overcomethe line losses.Normalll, the sjBna_l is monitorbdit th-esurfaceusingan oscilloscope, whilst.thesignal.isldjq$qd at the cameraoutput. This may invoTvethe adjustnientof a potentiometer which will in tum alterthe gainof an outputamplifier. It is importantto adjustthe gain at the canreraend ratherthanthe surfaceas the video signalwill have'noise'.superimposed uponit, by carryingout amplificationat the surfacewe would amplify the nbise sighalas well. Nbis; may be derivedfrom the powerconducrorsthat lie in closeproximitywith the videocoax. 15.11 Colour Loss Due to the difference.intiequencybetweenthe red, greenand blue light it follows that colour absorptionwill takeplaceto a varyingdegreeover a fixed lenlth of umbilical. To overcomethis it tla.y.benecessaryto boolt an individual colour r.iith respectto another. As red is of higherfrequencythan greenand blue it follows that it is subjectto the highestabsorptionfactor and may needto be amplified at the cameraend.

2tl

15.12 Typical Faults With Video Systems The most commonfaults that arisewith video systemsare causedby connector breakdown,this may occur at eitherthe ROV or the surface. Shouldany faults develop it would be wise to checkthat all the connectionsare serviceableprior to carryingout any major dismantling. It may be the casethat the video picture becomesimpaired due to electricalinterference. This can ariseif the video systemdoesnot havean independentearthfrom the rest of the ROV electricalsystem. If this were the case'currentloops'may be inducedinto the video systemfrom the mains supplyand give rise to pictureflicker taking placeat mains frequency. This fault can be provedby monitoringthe video signalon the oscilloscope.It would be found that signalswould be presentat a frequencyof 50 or 60 Hz. Many ROV systemsmake useof fibre optic transmissionto conveyvideo signal,this will illuminateany electricalinterference.Howeverthe physicalsizeof the conductors makesthem susceptibleto breakdown,especiallyat the connectors.This can lead to a total lossof video signal.

212

CHAPTER 16 UNDERWATER PHOTOGRAPHY 16.0 Introduction. Photographyis usedextensively offshore as a method of providing a permanentrecord of the actual stateof underwatercomponentsand structures. Thesephotographsare in colour and may be stereoscopic.Engineerscan then use them for structural analysis and other purposesand they iorm part of the permanentrecord for any particular structure.Photographyis also one of the prime methodsof recordinginspection information during annualplatform inspectionsand forms part of the final report for this type of survey. Although video taperecordingsare universallyusedfor the purposeof recording information on thesesameunderwaterconstructionsphotographs still have an important role to play and ROV personnelmust be fully competentin the use of underwaterphotography. It is appreciatedthat offshore personnelwill probably neverneedto apply the physicsof underwateroptical systemsdirectly in a system designway but it is still most usefulto havean understandingof the basicprincipals affectinglight in water. 16.L Light in Water Light enteringthe water is affectedby reflection,refraction,lossof intensity,loss of colour and loss of contrastin accordancewith the laws of physics. Thesesamelaws apply when the light entersthe camerahousingfrom the water. As photographyis basicallyrecordinglight imagesonto film a betterunderstanding of theseeffectswill be of benefitfor anyonecontemplatingtaking underwaterphotographs. 16.1.1

Reflection

This is a straightforward effect;whenevera light beammeetsa reflectingsurfaceit is reflected,the angleof reflectionequalsthe angleof incidence.

Angleof incidence

Angleof reflection

Figure L6.l Angleof Incidence EqualstheAngleof Reflection

2t3

l

l

16.1.2

Refraction

As a light beam passesfrom water to air it is refractedin accordancewith Snell'sLaw which can be summarisedby the equation: NwaterSin 0*u1",= Nair Sin 0u;t N*",", = Refractive Index of water Nni, = Refractive Index of air O*ut",= Angle to the Normal subtendedby the light ray in water Oui'= Angle to the Normal subtendedby the light ray in air

Where

In the caseof light passingfrom water througha glassor plasticport into the.airglp in a camerahousirig iiis posiiUte to look at the simple casew-herethe Port consistsof a plane glasswith-parall^elsurfaces. The Refractive Index of glassand perspexis very similar to water and in this casethe equationevolvesto: Sin 0uir = N Sin 0water

Where: A

J

AIR (N air)

WATER(N watefl

LENS

IMAGEoTA[?'

I

L_

3'4d_ PlanePort

Figure 16.2 Refractionfrom Water to Air acrossa PlanePort As can be seenfrom Figure 16.2 the light rays emanatingfrom the image after passing through the port appearto originate from the apparentimage. This has the effect that, witho=utconecting the lens, distortion, focus errors and field of view errors are caused. 16.1.3 Distortion Rays from points forming a rectanglein water will suffer unlessthe lens is correctedfor this underwatereffect .

^ t

A

z l+

"pincushion"distortion,

ROV TECHNOLOGY

Figure 16.3 Pincushion Distortion Jhe d-iagramillustratesthe effectsof pincushiondistortionwhich is more noriceable at the edgeso! qheframe and lessdiscernibletowardsrhecentre. The diagra- i; exaggeratedfor emphasis. 16.I.4

Focus Error.

This effect is illustratedin Figure 16.2. The apparentimageappearsto be larger 3 and 4 nearer. 16.1.5 Field of View Errors. Objectsin water are largerthan thosesameobjectsin air by a factorof approximately

4:3referto Fig 16.?.Thismeansthelens lppearsto have'atongeif*;ii;;til1" water.Theobjectfills moreof theframe.Alio because of ther."ftu.tion-u;tii,ilr beam entering4"pg{ at anangleotherthanthenormalwill leaveat a widerungr6.X lu*.ru hasa fixedfield of view andtherefore in thesecircumstancis its fieldoi ul"* in warer will belessthanin air. 16.1.6 Loss of Intensity. Light passingthroughwateris attenuated in accordance with therelationship: I/Io = s'kx Where

Io is the initial intensity I is the intensityafter icatteringand absorption k is the attenuationcoefficrent x is the distance The attenuationcoefficient,k, is the sum of the absorptioncoefficient cr and the scatteringcoefficientB botl of which dependon rhe wavelengthl. of the light and the type and amountof suspended material.

215

16.1.7

Scattering.

Figure 16.4 shows the effects of scatteringwhere suspendedparticles tl th! water .eflect someof the light at random anglesdependanton the angle the reflecting surface of the particle presen-isto the beam. The more suspensionthe greaterthe amount of scatteringand ihe greaterthe reductionin light penetration.

Figure 16.4 Scattering Scatteringis alsoresponsiblefor back scatterwhich is a problemon the photograph itself analogousto th-eeffect of using headlightsin fog. The light is reflectedback and

reducesthefield of view. 1 6 . 1 . 8 A b so rp ti o n . whichis to reducethe form theeffectof absorption Fig 16.5showsin diagrammatic on theturbidityof is dependant strengthof thelight beam.Thereductionin strength thewaterandon distancetravelled. The greatertheamountof dissolvedmatterin the waterandthegreaterthedistance travelledthegreaterwill betheloss.

2t6

REDUCTION IN LIGHT DUE TO ABSORPTION

Distancefrom LightSource(m)

Figure l6.s Absorption Both absorptionand scatteringcauseproblemswhen the stand-offdistancein sizeable. Scalqryg is more troublesomeas it addsbackgroundillumination as well as removing g1elullight. This backgroundillumination is called "back scater" as shown in Figure" 16.6.

s-O

<

v

no o

o

Figure 16.6 Back Scatter In somecircumstancesit may..bepossibleto compensatefor the lossof light by absorptionby using sffongerlighis,but if back sc^atter is a problem this o[tiorimay not be possibledue to the over?,lldegradationof the light causedby the increasein back scatter,ratherlike usingfull beamheadlightsin G. The effectsof back scattercan be minimisedby plicing the light sourceat an angleto the planeof the lens of the cameraas shownin Fieure-I6.7.

2t7

Strobelightangledto planeof cameralensto reduceback scatter

Figure 16.7 MinimisingBack Scatter Even using this techniqueit is quite possible,especiallyin coastalwaters,that usable photographscan only be takenat a rangeof a meteror two at most. 16.1.9

Loss of colour.

White light is madeup of the coloursof the spectiumand as it penetratesthe water the variousc-olou.sof the-specffum,which havedifferent wavelengths,are absorbedat different rates.The shorterwavelengthsare absorhd at different rates with red light, for example,being absorbedapproximately6 times fasterthanblue light. This effect causesunderwateilong-rangephotographsto havelittle colour other than blue-green. Fig 16.8illustratesthis graphically.

218

COLOUR ABSORPTIONIN WATER

Relativelllumination

Red 70004

15

2U

25

Distance from Source in meters

'A

Anqstroms

Figure l6.tt ColourAbsorprion The methodfor overcomingthi-sproblerrris to usea strobethat is powerful enoughto illuminatethe viewingareasufficiently.The basicadvicetherefoie,with any sr6be, is to get closeto the subject. 16.l.l0

Contrast

When we observeartinrageits fonl andtexturearenracleapparentto theeye by the differentintensitiesof reflectedlight conringfrom its surface.If thedifferencein intensitiesis stronglyrlarked thenthecontrastis goodand the inrageis saidto be 'crisp. Jf l!. differencesare poor thenso is the contrasranclthe iniageis saidto be 'Pu{dy'..Underwaterthere is alw.ays lesslight availablethanin airir-ndwith increasing depthlight intensitydecreases. Thusthe situationin wateris that thereis alwayspoor contrastand withoutintroduc.ing artificiallight this problenrgersworsewith d6pth. The solutionto this problenris to usea powerfulenoughstro-be to compensate ior the lossof naturallight andensureyou areas closeas posiibleto rhe subject. 16.2 Electronic Strobe Lights All the problemsassociated with lossof light can be overcomeor at leastimprovedby an.appropriate underwater strobelight. In air photographythe output frorn stroile llsing lightsis indicatedby theGuideNuntber.This numberis calculitedgenerallyfor use with 100ASA filnr (filnr speedand theASA systemarediscussed llter). W"hena strobe

219

is to be usedto provide the light the camerashutterspeedcontrol is setat the flash synchronisationspeedwhich is often 1/60thsecond.In thesecircumstancesthe appropriateformula is:GuideNumber=f XD f =f stop D = Flashto SubjectDistance henceto determinethe f stop required with 100 ASA film and the shutterspeedset at 1/60thsecondthe formula becomes:GuideNumber

r

16.2.1.

Guide Number.

In order to determinethe Guide Number it is necessaryto considerthe flash rating and the film speed,as indicatedin paragraph16.2.A generalformula is:GN_ v

BCPS = Beam CandlePower Second ASA = Film SpeedRating Most film data sheetsgive the Guide Numberfor the film as a function of BCPS. The BCPSrating of a sffobecan be detemrinedfrom the watt-secondrating by the formula:-

s6p5= ! 4r

0 ' x N r x #)

WS = Watt SecondRating M = Reflector Factor LIW= Lumen Second/lVattsecondRatingof the flash tube. Normally 35 to 50. The guidenumbercan be determinedfrom the watt-second ratingof the strobethus:-t l \t l,= V l o o o r \ w S \ , { S A X Nxl L \\,

For a nominalreflectorgainof 2 and a 50 lumensecondper watt-second flashtube: G N = O . 7 lr / \ v SX A S A andthis meansthat in air thecorrectexposureis:-

16.2.2 Effects
-cD

Wherecr is the atterluatiorlco-efficient per foot of the waterand D is in feet,the returninglight is attenuated a like anrountsuchthatthetotalattenuation of light falling on thefilm is:

220

-2crD e Applying this to the f stop calculation gives for underwaterwork: f

= f u i .X e - 0 D

The attenuationfunction equalsone stopfor eachobjectdistanceincrementd, where:

e-0d={t d=

I

=, O 2.BB For the remainderof this chapgerthis will be called the one sropattenuationdistance' In the clearestoceanwater "d" is 23 feet, however,the conditionsusuallyencountered arelessthan this and can be estimatedas one tenththe limit of horizontal'visibility. Thus, in water with 50 feet visibility, the lens shouldbe openedup one f stop foi each 5 feet of distanceto the objectover ihe "in air" setting. 16.2.2.1

Estimating Horizontal Distance.

It is obviousthatestimatinghorizontaldistanceis a guessbut the analysisabovewill help in understandingthe dlamaticdifferencein the ighting requirementsof underwater photographyversusdry land. As can be seenthe "Un-derw"ater'Guide Number" of a strobelight dependson power, reflectorefficiency,water conditionsand varies dramaticallywith distancecomparedto normal "in air" guide numbercalculations. 16.2.2.2 Estimating Proper Exposure The chartreproduced_a-s figure 16.9showsf stop versusobject distancefor various film speedsusinga.150watt-secstrobe.This is i good rturiingpoint for estimiting exposure. The chartis workedout assumingno ambient'light.In high ambient g.oTec.t light the iris shouldbe stoppedd.9*1 furtherthant"heserringsshoin to rffi.niut.. The amountof iris adjustment will dependon rhelevelsof a'mbientlight in uiy particularapplicationbut a rule of thunrbwould be eitherone half or"on. f sio'p

221

F STOPvs OBJECT DISTANCE BASED ON 150WATT/SEC STROBE

100 22 1 V 1oft)

to

.t6

16

11

l1

B

11

) 2 V 20ft) )

\

N

3 V 40ft ) 4 V 80ft

\\

5.6

F o r ' n r ' m a l ' o inore ! ller usl V=20t

4

0 0

f stop

Fo reep o

\

2.8

5.6

=estimi led vis mit

2

4 0.6

6 1.2

8

1 1.8

0 2.4

1

2 3

1 3.7

4

1 4.3

EAN US

6 4.9

v:80f

1

8 5.5

20 (feeQ 6.1 (metres)

Oblectdistance

Figur e 16.9 F St
A p e r t u r eC o n t r o l .

Thesizeof thgaperture is.controlled by theirisdiaphragm, whichis adjustable, andrhe tocal,length of theparticularlens.Thismgqlsthata largt aperrure anda longfocal lengthcantransmitthe.same brightness of lightasa smailaperture andshorifocal leng^th. Thescaleusedin.photography to relite focallengthandaperture sizeii tUt"O thef numbersystem.This systemisappliedasa standar? methodby manufaclri"rrro thatan aperture of, say,f4 will alwaysLansmitthesamebrightness of tigtiiwtraiever thefocallength.Theseriesof f numbersasa wholeis arranfedsorhateich reduction o.fonef stoph.alves theamountof light admittedinto thecaile.a.nor exampli?4 allowstwicetheamountof lightasf 5.6to enterbutonlyhalftheanlounrdr n.g. fno.

22

16

ll

8

5.6

units of

Figure16.10 F stops

222

2.8

1.4

The size of the apertureaffectsthe image definition of a lens. At maximum aperturethe sharpnessof the image in the centreof the picture is nearly always greaterthan in the corners.Stoppingdown the lens improvescentraldefinition slightly and corner definition much more.At small f stopssuchas f22 thereis usually slight fall-off in sharpness causedby diffraction,the scatteringof light rays collectedin the front of the lens as they passthe edgeof the iris diaphragm,but this is not importantin underwater photography. 16.3.1.1

Depth of Field

Depth of field describesthe extent of the picture in focus at a given f number. The lengthofthe zoneon eithersideofthe subjectdependson the sizeofthe apertureand the focal lengthof the lens.In theory,only the subjectin which you focus is completely sharpbut m areaof acceptablesharpness lies in front of and behindit. As the sizeof the aperturedecreases,the depth of field lengthens,bringing more of the picture on either sideof the subjectinto focus.The subjectfocusedon is not in the centreof this sharpzone which extendstwo-thirdsbeyondand one-thirdin front of the subject.

L6.3.2

S h u tte r S p e e d .

The shutterspeedis set by adjustingthe shutterspeedcontrol, which is calibratedin secondsand partsof seconds.Here, the relationshipbetweenstopsis obvious and follows the samemethodas f stops,the differencebetweenone shutterspeedand the next is a ratio of l:2. A typical seriesis shownas Table 16.1. I

tlz

U4

r/8

lfis

U30

tl6o

Utzs llzsl

1/500 l/1000

Table l6.l Typical Shutter Speeds but twice as much li-qhtas X::. Here Vatpasses/z as much light as T.ro

223

Deothof field at f l.4

I lmage

Depthof fieldat f.l6

F i g u r e 1 6 . lI Depth of Field Using a Typical 50 mm Lens 16.4 Film Films vary from one manufacturerto anotherand thereis a wide variationin choice from one photographerto anotherbecauseeachwill presenta different hue and one may be mbre pleasingthananotherto differentindividuals.Underwaterthe choice of the low light conditions. tendsto be more limited howeverbecause 16.4.1 Film Speed The speedof reactionto light for any film is ratedon one of two internationalscales whicli have beenrationalisedby the InternationalStandardsOrganisation(ISO). The American scaleis referredto as the ASA (AmericanStandardsAssociation)methodand the Europeanscaleis refened to as the DIN (DeutschIndustriesNorm) method.The tablebelbw showstherelationshipbetweenthe two methodsand the ISO rationalisation.

Slstem ASA DIN

rso

25 15

25lts

50 18

Film Speeds 200 100 21 24

ti00 30 200124 400127 800/30

50/18 rwlzl

Table 16.2

114

400 27

As can be seenfrom Table 16.1the ISo hasgroupedthe ASA and DIN merhods together.loth methodsapply the samerules and an examinationof the ASA sysrem will show how both work. As the numberincreasesthe filnr's reactionto liehiis faster. The film speedsillusrratedare groupedinro slow films with ASA of 25 and-50, medium films, ASA 100 and 200 and fast films ASA400 and above.As the value increasesby I step_th9 lighqerytion increasespreciselytwofold; for example 100 ASA is twice as fast as 50-ASA. This equatesto one full stoil on the cameraapertureor shutterlpeed con_trols. The reasonthat a film reactsmore or lessquickly to light is the size of the silver halideson the emulsion. The smaller the grain th^eslower thJreaction to light. By carefulselectionof grain sizethe film manufacturerdeterminesthe ASA r-atin_g 9{ th9 film but as the film speedincreasesthe grain size also increasesand thus the finished_printbecomesmore and more 'grainy'ai the ASA rating increases.Thus in selecting-afilm speedit is necessaryto balancethe reactionto light alainst finished print quality. A sensiblechoicefor most offshorework is EktaChrom--e 200 which is a reasonablyfine grain film with a moderatereactionto light. 16.4.2 Types of Film There are basically two kinds of film; a) Negativefilm which requiresa print to be madebeforeyou can properly interpretthe subject. b) Positiveor Colour Reversalfilm which allows the subjectto be viewed directly on the film. 16.4.2.1 Colour Sensitivity Films.alsovary in their sensitivity_to differentpartsof the light specrrum.For example Ektachromeis more sensitiveto blue light, Kodachrometo ied and Fugicolourto Somefilms are specificallybalancedfor artificial light and are niarked ryen. -used "Tungsten''. It is recommendedthat only daylight film be for underwater photographyas thesefilms are balancedfor-usewith strobeliehts which are exhaustivelyusedin underwaterphotography. 16.4.2.2 Film Format Jltere are basicallytwo filnt forntatsto choosefrom in underwarerphotography,either 35 mm or 70 mm. 35 mm is by far_thenrostpopularfilnr fomrathavingthe fbllowing advantages: a) Camerasaresmallerand lighterandless expensivJthan70 irm. b) 35 nrm film is nroreuniversallyavailableand lessexpensivethan70 mm. c) 35 mm is easierto process. d) 35 nrm film is lessbulky ro srore. 7Op.q film producesa much largernegativethan35 ntnt, ils indicatedin Fig 16.13and for high qualityor photogramnreiy thisls a majoradvantage.

22-5

! 1 ti 1

1

;1

lr

It

1

35mmvs 70mm

Figure 16.12 that 70 mm will give betterquality prints than 35 mm the question It is unquestionable is whether35 mm is acceptableor not. 16.4.3 Film Selection is to experiment Thereis a wide selectionto choosefrom and the basicrecommendation with different films at first and then selectthe one that suitsthe requirementsbestand staywith it. Over time if one film is usedconstantly,betterpictureswill result because of approach. of the consistency 16.5 Framing the Subject Manufacturersof underwatercamerasnornrallylist the angle-of-view(in water)of the at various cameralens system, and fronr this infornrationthe area-of-coverage illustrates this for a 16.13 Figure trigonometry. using sinrple calculated distancescan'be 35 mm camera.

226

VIEWING AREA OF A TYPICAL 35mm CAMERA

35mm camerascover a rectangulararea with the same ratioas the neoative 24mm 1 vertical "' 36mm 1.5horizontal _6r

Figure 16.13 Ar ea of View Thisstraightforwardhead-on situation givesthebasisfor calculation butin a real situation it maybenrorecornplicated. Forexample if rhecanrera is lookingobliquely ' downtheareaof coverage is a trapezoid. Thisi.sillustrated in figure16.1V.

221

Area of view with cameraat an angle is a traoezoid.

Figure 16.14 Area of View When Camera is Tilted This problemof framing a subjectcan be a difficult one to overcomebut applyingthe principal shown hereand with somepractisea satisfactorysolutionshouldbe found. Somecamerasystemsare n'lorehelpful thanothersand thereare two systemswhich usethe samelenssystemfor boththe Video andthe Still carlerathuswhat you seeon video is what you get on the still photograph. 16.6 Camera Systems Thereare severalcarnerasystemsavailablefor useon ROVs but one manufacturer, PhotoseaSystemsInc. arecurrentlythe nrostpopular.They nranufacture several different typesof renrotelyoperatedcanrerasystemsdesignedto takecloseup, standphotographs. off or stereoscopic to complinrenttheirrangeof camerasthey manufacturecompatiblestrobesand can offer total packagessuitablefor all ROV requlrements. 16.6.1 Photosea 1000 Thesec:unerascan be fitted to ROV's and are alsoavailablefor deepseaand diver held modes.Depthcapabilitiesrangefrom 6fi) m to 6000nr. Standardfeaturesinclude: 28 mm water-corrected a) lenssystem. b) Completelyself-contained, weighslessthan 1.1kg. in water. Rechargeable internalpowerpacks. c) Electronicfilnr advance. d) Data chamberwith time, alpha/numericcodeand frame number. e) Daylightloadfilm nragazine acceptsstandard36 exposureor 250 0 exposurecassettes.

228

16.6.2

Photosea 2000

This camerais a single,completelyself-containedstereocamera,incorporatinga dual lens systemanda singlefilm magazine.All problemsassociatedwith t^akingsiereo photographsyitlr_a complex two-camera,/twostrobesystemhave beeneliminated. With the Photosea2ffi0 seriescamerasstereo-scopic viewing can be achievedwith a system as simple-asconventionalsingle frame cameias.Stereopairs are automatically registered.and is a major advantage.over two-camerasstereosystemswheredeveloping and handling.twoseparaterolls of films and trying to matchstereopairscan be a tediousand time consumingtask.

j l

16.6.3 Photosea 70 Series Cameras These70 mm cameraswere designedfor the offshoreprofessionaldesiringthe bestin high resolutiondeepoceanphotography.Thesecamerasutilise largeformit 70 mm film with more than32 times the negativeaieaof 35 mm film. CombinEdwith the high resolutionwater-correctedlensdesignedand built by photosea. 16.6.4 NDT 3000 Macro Stereo Camera This camerahasbeen^specifically designedto provide high resolutionstereo photographs.at closedistances to assisiin the detectioncrTcracks,pitting andcorrosion 9ygg^lgl-destructive testingand structuralinspection.The most uniqJefeatureof the NDT 3000is the ability to takestereophotographs at a subjectdistanceof l5 cm. 16.6.5 Combination Photo/TV Camera Two companiesmanufacture'combinationphotolfV cameras.Theseunits includea televisioncamerainsidethe housing,which is usedas a 'viewfinder'for the photo camera. f6.6.5.1

Sub-Sea Stereo view 2000

This combinationcameraincludesa colourtelevisioncameraanda Photosea 2000 'metric' stereocamerain the samehousing.In additionto the ability to take'rnono'o, stereophotographs,the stereopairsproducedby the cameracan beirsed to take actual photogrammeticmeasurements. The systemalsoincludesa datachamber.This equipmentis availablefrom Sub-SeaSystemsInc. 753 West WashingtonAve. Escondido California 92025 USA 16.6.5.2 Osprey TVP Combination Camera This systemincludeseithera black and white SIT cameraor a colour televisioncamera and a.'mono'single-lensreflexph919camerain the samehousing.The rytt.* ulro includesa datachamberwith capabilityof remotelyannotaringth? titm. ffi" syste. It availablefrom: OspreyElectronics,Ltd. E27 WellheadsIndustrialsCentre Dyce AberdeenAB2 OGD Scotland

)to

l

L6.7 Strobe Lights strobe,lights usinghigh-energy is accomplished still photography Almostall underwater In water. in light of characteristics ligh attenuation the to offsit which arenecessa.ry high for needed illumination balanced proiide the will udaiii*, u po*r*,it strobe in ambientlight at sincered light is virtually non-existent a;;iit iotjur photographs depthsbeyond4-5 m. 16.7.I How They Work madeof glass,or quartz(for high andarc-chamber The srobeflashtubeis essentially outputlamps)with anelectrodesealedinto eachend.The sizeof the arc-chamber, by its.operating.parameters wtrictris normallyfilled with inertXenongas,is determined as straighttubes, available are Flashtubes for whichit is designJd. unAttr" upplications usualattached elecffode, A third or coiledinto a helix for greaterconceniiationof light. An invisible flash. the to trigger is needed to theextemalwall of thiarc-chamber, thewall of around wrapped materialon thetube,or a fine wiie coatingoi Conauctive seefigure circuit, discharge areusedin a capacitor id6;p is usuallyused.Flashtubes 1 6 1. 5 . 'X' syncswitchin camera

High volrage DC powcr supply

Flashtube R (Charging impdancc)

Figure 16.15 Basic Strobe Circuit The main componentsof the circuit are: DC power suPPly. a) - This limits the chargerateof the energystorage Chaigingimp-edance b) capa&toi and allows the flashtubeto de-ioniseand extinguishafter the flash. Capacitors- storethe energyfor the flashtube. c) voltagetriggerpulsecircuit - This is usuallya simple step-up Hilh d) transformei,putied fiom the dischargeof a small capacitorcontrolled The higli vo.ltagepulseactivates by the camerashutter'sync'contact. gas arc-chamber. in the of the ionisation the flash by into light. energy electrical The flashtube changes e) 16.7.2 Strobe Power Ratings As mentionedearlierthe light output of most'topside'strobelights areratedwith a guidenumber,but because-ofttrewide variancein waterclarity and its severelight this guide numberis uselessin water,As a result,most fttenuationcharacteristics, undr.*ut.r strobelights arerate?in rcrmsof wattsper seconds(oules). This rating describesthe input power to the flashtubeitself with:

230

J w-t = 2 CV2 C-= C_apacitance of the main dischargecapacitorbank V = !ol|a8e. to which the capacitorii chaiged (which appliesacrossrhe flashtube). 16.7.3 Maximum Power Input All flashtubesalso havea specificationcalled'maximumpower input'.Although this specificationis normally.onlyof interestto strovedesigners,users'ofstrobetig'trts shouldbe awareof what it means,becauseit can haveind impact on overall rirt"designfor a specificphotographic.requirement wherethe flash frequencyis i#portant. Maximum power input is the relationihip betweenthe energyper fiash, ind maiimum flash frequency.For example,a'218'seriesflashtube(usel"inphotosea1500 strobes),hasa maximumwatt per secondratingof 200.At 150w -sit hasa maximum power input rating of 5 watts. Therefore:

ll0 w s

= 30 secondsmaximumflashrepetitionrate )w If this particulartube operatingon a power level of 150 w -s,were flashedat a rate fasterthan I flash.per30 seconds, it would overheatand prematurelyfail. Thus the w -s raungrs actuallytheinputpowerto the flashtube. 16.7.4

Reflector Efficiency

The amountof actuallight outpugand the parrernof light is affectedsignificantlyby the reflectordesign.The old styleleflectorswbre circulariross sectionsarid theref#e focusedthe lig^htcausing hot s_pots' which were very contmon in many unda.*ut". photographs. SeeFigure 16.16.

Figure 16.16 C i rcu l a r Cr oss- section Reflector s Focus the Light Causing Hotspots New'reflectordesignsthatareparabolicrlup. with coatingsrhatdiffusethelight give goodevenilluminationacrosstherield-of-viewof rhecam"era eliminatingttte.ietrot spots'.SeeFigure16.17

23r

Figure 16.17 Parabolic Shape Provides Even Illumination 16.7.5 Strobe Light Colour Output Becauseof its spectraloutput,no other underwaterlight sourcecan matchthe electronic flash for quality underwatercolour photographs.All flashtubeshavea continuous spectraldistributionthrough-outthe visible energyrange.This visible radiationis 'daylight' approaching which producesexcellentcolour in all partsof the spectrum. 'Daylight'ratedfilm shouldalwaysbe usedwhen usingan electronicflash.SeeFigure 16.19

c< = I r'\

r r'1

z rrl

f r'l

F I fll

6000 ANGSTROMUNITS Figure 16.18 SpectralDistribution of a Typical 1000 v Flashtube

232

16.7.6

Strobe Units

Photoseasupply the 15005and 1500SX(externalpower)whichboth provide energy outprt to 150w -sand the 3000 seriesup to 300 w -s.All theseunits are lightweighi and have housingoptionsto 6000 m deplhsand all haveinternaldiffusingieflectors. 16.8 Operational Control of the Camera System C*9* systemsare commonly actuatedby a contactclosurewhich could be a remote switch initi-ated.bV u.noperator,or a 'bottomcontact'switch which triggersthe system automaticallywhen it reachesthe bottom, or by an intemal electronict'iirer that tiiggets the systemar pre-settimed intervals.In eachcasesomeinterfacingis required.In situationswherelong cablelengthsare used,or wherethereis thJpotent'id foi trign electronic'noise',from manipulatoror thrustermotorsfor example,it is always b-estto 'actuate'.the photo_system wiih a relay locatedcloseto the camera,iuch as in i nearby electronic bottle. The reasonfor this is that most new cameradesignsinclude solid stite timers which are susceptibleto noiseand can be 'false'triggered.if this problem is occurring,it.will be obvious;the camerasystemwill 'actuiie' itself. Thid problem is easilycqed by using a voltagewhich actuatesa relay which in turn actuatlsthe camera designershave also usedopto-isolatorsfor the samepurpose. lVst*' Sory9sy^stem SeeFigure 16.20.

RemoteActuate -l-

]J

Long cableor high noise pickup Actuate

Camera

' X ' s y n cfrom mera fires strobe Relay or opto-isolator

-

Srrobelight

Figur e 16.19 System Actuation 16.8.1 External Power to Strobe Stf:F lightscanbeoperated from internalbatteries or exrernalpower.Whenoperating a highporyeledstrobelight from externalpower,careshouldbetakenwheninierfacin-"g because of thehigtrpeakcurrentsinvolved.Thefollowingcomments applyto photosea 1500strobesbut theprinciplesapplyto all electronicflasf,unitswhich^O'.a* ttigtrpeat currents whenrecharging. a) Srobesdrawshortpeakcurrenlso! up to 10amperes duringrecharge (quiescent currentaftercut-offis 12mA). Thereiorethepoier source should. becapableof supplyingthesepeakcurrents,andit is also advisable to fuseyoursrobepbwerlinewith an 8-10ampslo-blofuse or breaker. b) If possible,a remoteON-OFFswitchshouldbeinstalledin thepower line sothestrobeis notoperating duringprolonged periodsof time whenno in use.

a-'t-',

l

1

Input cableconnectionsarecritical when operatinga high power strob from a remote power source. No. 12 or 14 gaugewire is recommendedto keep line resistanceto a minimum. For examplePhotoseasffobesrequireat least21 volts to fully chargeand shutoff.With just 1 ohm line resistanceand peakcurrentsexceeding8 amp at 24 volts therecould be an 8 volt loss in the cabling to the strobeand it would neverfully chargeand shutoff.The strobewill simply keep turning itself ON and Off and oscillate erratically as the voltage sagsbelow the l8 volt shutoffpoint and then risesafter the currentdrain is removed. Typical curent drain of a Photosea15005 strobeduring its rechargecycle is a short, 250-500ms, peak of up to 10 amp at the beginningof the rechargecycle, average current of approximately4 amp during the 3 secondcharging period, and 12 mA standbycurrent after shutoff. It is recommendedthat the external power sourcebe a batteryor a voltage sourcethat will not 'sag'dueto theseshortpeak currentloads.You should never connecta voltage sourcedirectly to a strobelight that includesinternal batteriesor chancesare the batterieswill be permanentlydamaged. c)

16.8.2 Trickle-charging NICAD Batteries NICAD batteriescan be'trickle-charged'continuously during operationsto keep their capacityup. All NICADs must be chargedfrom a constantcurrentsource.Typically trickle chargecurrentis in the 25-50mA rangefor a l-2 amp per hour batterypack. An importantpoint to rememberis that the voltagecapabilityof the constantcurrent sourcemust be at least4-5 timeshigherthanthe fully chargedvoltageof the battery pack or the batterywill try to chargethe chargingcircuit. For example,a24 V NICAD batterypack,2o cellsat 1.2V per cell, will chargeup to 28 V, I .4 V per cell at full charge.Therefore,if the chargingcircuitry requires2-3 volts drop, the constantcurrent sourceshouldhavea voltagecapabilityof at least30-32volts.Figure 16.20showsa simple and reliableconstantcurrentsource.

30-35V DC (Srobe24Y Btv I to Bty

t0-12v DC (Camera 6 V Bty)

R1Value 48O4w 24Q4w

Note:LM3l7T shouldbe mounted on a heatsink

Tricklechargecurrent I 25 mA 50 mA Figure 16.20 S i mp le Char gingCir cuit

/.-)+

16.8.3

System Installation

Actual installationof a photo systemwill vary dependingon specificapplications,but thereare severalguidelinesthat shouldbe followed whateverthe installation. 16.8.3.1 Camera/Strobe Positioning Back scatterin turbid water can be the biggestenemy in taking quality underwater photographs.Suspended particlesin the water will reflect light back into the ciunera lensresultingin a reductionof contrast.In turbid water this problemcannotbe eliminatedbut separatingthe cameraand strobewith at least-a0.5 m distancewill help significantly. The leastdesirablestrobemounting position is directly adjacentto the camera.The strobe,or strobes,shouldbe mountedso that they intersectwith the cameraaxis at the approximaterangeof the requiredpicture.Figure 16.21illustrates this.

Desiredcamera/subject distance

Secondsrobeif mounted

Camera/strobe separation at least0.5 m Figure 16.21 Mounting Strobes 16.8.3.2 Mounting The normal methodof mountinga cameraand strobeis to usea saddletype mount with a clamping device.If stainlesssteelhoseclampsare used,the units shouldbe secured with at leasttwo clamps,and theclampsshouldbe coveredwith shrinktubingor similar insulatingmaterial.Rememberthat the cameraand strobeshouldbe accessible and easyto install and removefor chargingand film changing.It is also necessaryto haveeasyaccessto the ON-OFF switches.It cannotbe over-emphasised as to the importanceof properrouting and connectionof cables.A very high percentageof problemsoffshoreare causedbecauseof poor cableconnections.

,J)

16.8.4 Pre/post Dive Check List points are pre dive: Some-important Fih installedproperly and cameramechanismtested; a) Lens Focus/irissettingcorrect; b) Data chamberturned ON and properly set; c) Srobe and camerabatteriescharged; d) Power switchesOFF until dive; e) Systemall connectedand Testmade 0 g) O rings properly greasedand installed; Postdive: a) b) c) d) e)

All units flusheddown with fresh water; Film unloadedin the dark and then labelled; All power switchesswitchedOFF; Batteriescharged; HousingsProPerlYstowed.

236

C H A P T E R 1 7 S E A MA N S H IP

-...-'

17.0 Introduction In a handbookof this n.alurg it is not possibleto coverii vasttopic suchas seamanship in any detail. Seamanship itself includestopicsasdiverseas th^euseof lifting equipmenton one handto the art of navigationon the other. It includessafeworking practices,rigging, boat handling,weatherpredictionand all the many and various tectrniquesand skills which go to make up the art and skills of seamanship.The objectiveof this chapteris to cover in enoughdetail for operationaluse,t6osesubjects which will haverelevancefor ROV Pilot/technicians offshore. 17.l

Lifting Equipment

One operationthat the piloVtechnicianwill certainlyundertakeregularlyis the depJoyment andrecoveryof theROV. This entaili the useof lifting devicesand as it is sucha regulartaskthis aspectof seamanship will be coveredfirst. the subjectwill be brokendown into threecategories. Safety,which will be dealtwith first, rigging and adiaitales of fillttY blocksandtackleswhich will give an insightinto rhenrechanical lifting equipntent. 17.l.l

Safety Aspects

As statedin Chapter2 safetyin the work placeis the subjecrof numerousActs of Parliamentand StatutoryInstruments.The basicrequirementis thateveryonemust shouldertheir own .partof the responsibilityfor ensirringa safework place. On any work siteyou are likely to go to it is no unlikelythatyori will find locil safety requirements whichhaveto be followed.In thenraiorityof casesthesewill be alons " the lineslaid out here.Oneshouldbe aware,however,thatthereis a possibilitvof somelocalvariations. l7 .l.l.l

P e r s o n a lS a f e t _ v .

On a personallevelone shouldalways: a) Observeandcomply-withall safetynoticesand instructions. b) Always wearthecorrecrsafetyequipnrent. c g. Safety.boots, gloves,helmets,goggles,ear protectors, safety hantesses, lrtepreservers etc. c) Be sttreof thecorrectoperationof any,and all, toolsand,or equipment likely to be requiredduringany lifting operations. Readoperating instructiottsbeforeusingany devicefor the first time or if in any-doubt. d) Always usethe right tool fbr thejob. Nevernrakedo with the wrong one. e) Always standwell clearof overheadloads. Understand fully what is requiredfcrrany particulartaskundertakenas 0 part of the overall operation. g) Avoid leaningover the sideof the shipand be awareof the locationof life savingequipment. h) Tie all ecluipntent down and stow it crorrectl)/ duringperiodsof heavy weather. 1 7 . 1 . 1 . 2 L i f t i n g E c l u i p m e n tS a f e t y . All appliances and gearusedfor lifting, loweringand handlingloadsmustbe inspected and testedat regularintervals.In theNorth Seaatt suchecluiphentis testedevery6 monthsby a competentperson.The actlraltestingis normallycaried out by speiialist companiesand certificates are issuedoncetheequipntentunclertesthasbeenapproved.

:_1 I

It is necessarv to testto 1.5timestheSWL for loadtestingcurrentlyasoutlinedin Chapter2 paragraph 2.1.i.

17.1.1.3Safe Working Loads musrbemarked withthesafgwgrkingload(swl-). If anyitemof

frflltj,:q.ruipment Ilftlng equlpmentls not markedit must not be used. If the ltem is in apparentlygood conditionit should F Pu.,to one side andse.ntto a speciilist cornpany'fbrteiiiirg ano cerrificationafter which ir may be put back into use.' L7.1.1.4 Out Of Date Equipment.

It is commol p{a.ctlsqfor lifting srops, shacklesand other such lifting equipmentto be colour codedwith oaint in the coloui of the month. riris iimptifi;s-;fe j;t"oitlir.ting that it is in date as ill that ls .equi.eaii to.nr^ur. that only the correctly colouredstrops etc',areused. Any jQuipment which is out of datemustnot be used bit can be Uact loadedand re-certifiedby an appropriareaurhority. 17.1.1.5 Safe Practises If equipmentbecomesdamagedduringuserheoperarionnrusrbe suspended and the offendingitem replaced. Inexperienced personneland anyoneunderl8 yearsofage shouldnor bg in charge of poweredlifting equipmentunleis underinstruition,in wiich .ur" .r,rt. r"p.*ijion uy a competentpersonis requir-ed at all times. Controlsof lifting anclhandlingequipmentshouldbe pernmnently and legibly marked with functionand opera.ting diiectionshownby arrowsor other(i*pi. ri.u,ir. Make-shiftextensiorlsshouldnot be fitteclto conrrolsnor any unauthorised alterations madeto them. Foot-operated controlsshouldhaveslip-resistant surfaces. No lifting.applianceshouldbe usedwith any lockingpawl,saf'ety attachmentor device renderedin-operative. If, exceptionally, limit switchesneedto be isolatedin orderto lower a craneto its stowageposition,the utmostcareshouldbe takento ensurethe operation iico.preteA safely. Any powerapplianceshouldalwayshavea man ar rhecontrolswhile it is in operafion, it shouldneverbe left ro mn with l controlsecuredin the oN pos,t,on. power.lifringequipmentis to be left unattended with - the - poweron, loadsmust be ff,any takenoff and controlsput in 'neutral'or'off positions. wh91epractical,controls shouldbe lockedor otherwiseinactivated to prevent accidentalrestarting. When work is compietedpower must be shutoff. l;:i:"tt

safetypointsmay be summarised in a chartform which can be seenas Figure

238

Figure 17.l Personal Safety START i

I

T H I N KA B O U TT H ED A N G E R S

W e i g hu p e n v i r o n m e nht a z a r d s

W e i g hu p j o b h a z a r d s

D e c i d eo n p r e c a u t i o n s to betaken P RE P A RE Puton appropriate s a f e t yc l o t h i n g

A s s e m b l ec o r r e c t t o o l sa n d e q u i p m e n t i n s p e c tf o r s e r vi c e ab i l i t y

P o s i t i oD n ANGER W A R N I N Gn o t i c e s , s a f e t yb a r r i e r sa s r e q ui r e d

R e m o v ea n y l o o s e e q u i p m e nftr o m a r e a r v h i c hm i g h t c a u s ea h a z a r d .E r e c ts a f e t y e q u i p m e n at sr e q u i r e d fio'nhin

P o s i t i o ne q ui p m e n t a n d r o u t ea n y e l e c t r i c ,p n e u m a t i c or hydraulicables i n s a f e sp t osible way

n'r:rrl

p r o t e c t i v es c r e e n )

C A R R YO U TT A S K

Alwaysusecorrecttool N E V E RI M P R O V I S E O NT O O L S

W e a ra p p r o p r i a t e s a f e t yc l o t h i n g

C L E A RU PO N C O M P L E T I O N

C o l l e c tt o o l s

R e t u r ne q u i p m e n t t o s t o r eo r b a y

R e m o v en o t i c e s s a f e t yb a r r i e r s s a f e t ye q u i p m e n t

F I NI S H

239

Replaca eny l o o s ee q u i p m e n t moved

Crane Signals

17.l.L6

It is most colilnon thesedaysto usesomeform of voice communicationdirectly to the cranedriver but theremay itill be occasionswhen it is necessaryto usehand signalsto indicateyour requiremenis.The currentstandardCodeof Hand Signalsis reproduced as Figure 17.2. Code of Hand Sigrals

{? n_ s, H l

l

C L E N C HA N D UNCLENCH F I N G E R ST O 'TAKE SIGNAL T H ES T R A I N ' OR'INCH THE LOAO'

l

t

EMERGENCY STOP

?-

HOIST

SL I N D I R E C T I ON I N D I C A T E D

LOWER

S I G N A LW T H O N E H A N D . O T H E RH . N OO N H E A D

S I G N A L\ \ I T H O N E H A N D O T H E RHA N O O N H E A O

\

'l ] I

D E F R I K I N GJ I B

J I B- . EXTEND

JIB DOWN

.

JIB I E L t r 5 U Lr P I N G

R E T R A CJTI

/,? ii \ ;=-

T R A V E LT O M E

T R A V E LF R O MM E

T R A V E LI N D I R T C T I O NI N D I C A T E D

S I G N A LW I T F B O T H H A N O S

ROTATEWRIST OF L E F TH A N O

O P E R A T I O NCSE A S E

K SO N / O F F TWTSTLOC

Figure17.2 240

17.2 Fibre and Wire Ropes. Tferg are a variety of both man-madeand naturalfibre ropesand severaldifferent types of wire rope in useoffshoreon vesselsand platforms. The intention hereis to introduce the commontypesof both wire and fibre ropes,indicatingthe way they are constructed, their breakingstrainsand someuses. 17.2.1 Fibre Rope Construction. All twistedor laid up ropesare manufacturedin the sameway. The selectedfibres are combed.intolong ribbons which are then twistedinto yarns. Theseyarnsare then twistedinto strandswhich in turn are laid up into the finished threeor four strandrope. In order to achievea good quality rope it is necessaryto selectand blend the fibres carefullyto ensureunifomtity. The spinninginto yarnsmustbe cerefullycontrolledto achievea uniformcross-sectional size,andwith all thefibrestwistedin at the correct tensionand at thecorrectangle. Finally the layingup of the finishedropemust alsobe at thecorrecttensionandanglewhich is detemrinedaccordingro the intended applicationof the finishedrope. Threestrandropesarereferiedto as plain lay and four strandas shroudlay. with the four strandsconrnionlylaid round a centralheart.Both thesetypesof rope are nomtallylaid up right handed. 17.2.1.1 Variations Both plaited and braidedropesareavailablebut they iire nor so commonas laid up ropesoffshore.Their constructionis the santeas outlinedaboveexceotthat the final stageof layingtlP the ropeis achieveddiff-erently.Theseropesnorrnallyareput to specialusessuchas for ruooringwarpsor anchorropesancltherefbrethe ROV pilot is lesslikely to conleintocontactwith thenr. 17.2.2 Types and Properties
' c. . d.

Manila - This is madefrom "abaca"fibre and n-rayvary in colour from dark brown to ivory white The rope is smooth,glossy,strong,flexibre,very easl'to handleand hasa very high resistance to seawaterrotting. ly.able, Sisal - This is madefrom "aloe"leavesand is a creanry-white colour. ihe rope is very brittle,glossy,swellsup when wet anclit hasa hairy surface.Top gradesisalis e.cpral to rnediumgrademanila but it is an unpleasantrope to handledue to its rough in marinb work if - finish and is not usedfor pref-erenCe manilais available. Coir - This is madefrom coconutfibre and is a reddishcolour. The rope is very elastic,floats,is roughto handleandis extremelyresistantto seawater rotting. It rf aboutone sixth the strengthand half the weightof manila. H9*p - This is n-radefrom the fibre of the Hemp plant and is a dark brown in colour. It is ntainlyfoundin sntallsizesor as seiziirgtwin in marine applications.It can be strongerthanmanilabr.rtits u.ieis restricted.

?.41

17.2 Fibre and Wire Ropes. Tferg are a variety of both man-madeand natural fibre ropes and severaldifferent types of wire rope in useoffshoreon vesselsand platforms. The intentionhereis to introduce the commontypesof both wire and fibre ropes,indicatingthe way they are constructed, their breakingstrainsand someuses. 17.2.1 Fibre Rope Construction. All twistedor laid up ropesare manufacturedin the sameway. The selectedfibres are combedinto long ribbons which are then twistedinto yarns. Theseyarnsare then twisted into strandswhich in turn are laid up into the finishedthreeor four strandrope. In order to achievea good quality rope it is necessaryto selectand blend the fibres carefullyto ensureunifom'rity.The spinninginto yarnsmustbe carefullycontrolledto achievea uniformcross-sectional size,andwith all the fibrestwistedin at the correct tensionand at thecorrectangle. Finally the layingup of rhefinishedropemust alsobe at thecorrecttensionandanglewhich is detemrinedaccordingro the intended applicationof the finishedrope. Threestrandropesarereferredto as plain lay and four strandas shroudlay. with the fbur strandscommonlylaid rounda centralheart.Both thesetypesof ropeare nomrallylaid up right handed. 17.2.1.1 Variations Both plaitedand braidedropesare availablebut they are nor so commonas laid up ropesoffshore.Their constructionis the sameasoutiinedaboveexceptthat the final stageof layingup the ropeis achieveddifferently.Theseropesnorrnallyareput to specialusessuchas for tnooringwarpsor anchorropesanclthereforethe ROV pilot is lesslikeli,to comeirrtocorltactwith the'. 17.2.2 Types and Properties
' c. _ d.

Manila - This is rnadefrom "Abaca"fibre and nray vary in colour from dark brown to ivory white. The ropeis smooth,glossy,strong,tlexible,very easl'to handleand hasa very high resistance to seawaterrotting. 9ytable, Sisal - This is rnadefrom "aloe"leavesand is a creanry-white colour. the rope is very brittle,glossy,sweilsup when wet and it hasa hairy surface.Top gradesisalis eclualto mediumgrademanilabut it is an unpleasant ropeto handledue to its rough finish and is not pref-erence used for in marine work if manilais available. Coir - This is madefrom coconutfibre and is a redclishcolour. The rope is very elastic,floats,is roughto handleand is exrremelyresistantto seawater rotting. It is aboutone sixth the strengthand half the weightof manila. Hemp - This is madefiom the fibre of the Hempplant and is a dark brown in colour. It is nrainlyfoundin snrallsizesor as seizingtwin in marine applications.It can be strongerthanmanilabLrtits useis restricted.

241

r

L7.2.2.2 Synthetic Fibre Ropes a.

b.

c.

d.

Polyamide (Nylon) - This is the strongestsyntheticfibre after Kevlar which is only availablefor specialuses. The rope is very elastic,soft, pliable, easyto handle,will not rot in seawater and is pestresistant.It will absorb water howeverand will swell up if left for periodsin the water. The rope dries quickly but shouldnot be exposedto sunlightfor long periods. Nylon is the du Pont tradenarnefor polyamide. Polyester (Terylene) - This rope is only a little less strongthan nylon, for example6 mm Nylon would havea breakingstrainof 750 kg. while 6 mm Polyesterwould be 550 kg., and it haslow stretch,with somegradesbeing as Nylon except availablepre-stretched.This rope hasthe samecharacteristics polyester. for water. ICI name Teryleneis the trade that it will not absorb In polyester. as Polypropylene This rope has almostthe samestrength parting, it will and common with Nylon it will stretch,in fact 407obefore absorbwaterbut only 0.IVoof its weight. This ropefloatsand it will melt at 1650C. It is very commonoffshore. Polythene(Courlene) - This ropeis much lessstrongthanpolyester,for exampleits breakingstrainfor 6 nrm would be 375 kg. This rope haslow stretch,it floats,it will not absorbwater,it is resistantto sunlight,it is usually orangein colourand hasa waxy, slipperyfeel to it. It is cheapand is widely available.Courleneis the manufacturer's tradename.

17.2.3 Use and Care of Ropes The Commoncausesof failureare:excessivestress;this danrages the fibres,abrasion; or cutting;on a sharpobject:exposlrreto chemicalsandbad storagewith inadequate ventilation,particularlyof wet ropes. Rottingoftencomn.lences on the insideof a rope andis difficult to detectunlessthe lay is opened.Loosefibresor duston the inside indicatesdry rot. If the interioris darkerthantheoutside,this is a signof dampness while a greypowderl,substance indicates niildew andpoorventilation.Ropesshould hooks. The be storedawavwherrdry, on gratingsor hungon woodenor galvanised storeroomshouldbe well ventilatedanddry, awayf}om r.noistair. Artificially dried ropeswill becornebrittle,as nrostfibre ropesarespunwith a srnallamountof lubricant introducedat the tinreof manufacture ropelife. to reduceinternalfric:tionand increase If left on deck,ropesshouldbe protectedfrom sunlight,rain and frost (asthe ice particlescut.throughthe frozenrope). Ropesshouldalsobe kept awayfrom all paint thinners,etc. After usein saltwater,ropes chemicals,suchas cleaningnraterials, shouldideally be hoseddown with freshwater. Knots and kinks shouldbe avoidedas much as possible.When coiling rope,as mostropesarelaid up right-handed, they shouldbe coiledright handedi.e. clockwise.When heavingon a rope,ensurethat it doesnot chafewherrpassingthroughfair leadsor over the roughedgeof a dock wall ashore.Sharpedgesmust alsobe avoided.Mooring lines(warps)may haveshort lengthsof plastichosetiedonto thenlto reducechafe. When a ropepassesarounda sheave,the sheavediametershouldbe nineto twelvetinresthe ropediameter. When usingwincheswith ropes,ensurethata laid ropeis put onto the winch in the samedirectionthat it shouldbe coileddown. The leadonto the winch must be such that the furnson the drunrdo not ride over the followir]gturns.SeeFigure 17.3

242

Figure I7.3 Lrading a Rope OntoaWinch

17.2,4 Wire Ropes wire ropesgreysedextensively,for all typeof standingandrunningrigging,crane wires,winch wiresandstrops.In any o{shorgapp[cltion whereF.oVs #e ueing deployedwire ropesin oneform or anottrerwill G used. 17.2.4.1 Selection when selectinga wire ropefour mainfactorsshouldbeconsidered: a. Whatjob is it to beusedfor? i) If th. wire is requiredfor standingriggingit witl be lessflexible f9r example,than if it is to be usedfoi runningrigging. , b. What safeworkingloadis required? i) This will effecteitherthediameteror thematerialpropertiesof thepp9. If.it is ryquiredttratthediameterof theropebe a particulalsize,for example,it maybenecessary toselecta high tensiletypeof wire rope. c. Will thejob requirespecialist propertiesform thewire? i) A Tirfor wire needsto be wire coreinsteadof hempcore for example. d. Will it haveadequate resistance to thecorrosivefactorspresentin the environment? i) Standingriggingis oftengalvanisedto providesomecorrosion protectionbecause of theaggressive environmentit hasto withstand. 17.2.4.2 Construction All specialisthandlingqualitiesa Iopqpossesses areintroducedinto theropein the manufacturingstage.Therefore,it is importantthatwe know how a ropeis formedas the materialpropertiesareselectedto matchthemethodof lay. Therearethreebasic forms: OrdinaryLay; Lang'sLay; Preformed. a. Ordinary \uy - { roqeof.ordinarylay hasits strandslaid up togettrerright handed,in thegppositedirectionof theirconstituentwires,whiih aie Uia up left handedto form a srrand.SeeFigure17.4

-+-l

ORDINARY LAY

Figure17.4 b..

Lang's Lay - A ropeof Lang'slay hasits strandslaid up togetherin the samedirectionastheirconstituentwiresaretwisted.This meansthatca.reis requiredwhen handlingLang'sLay asit tendsto unlayitself. SeeFigure 17.5

LANGS LAY

Figure17.5

c.

Preformed rope - This is a moderndevelopmentin the manufactureof wire rope.The manufacturers form individualstrandsinto spiralsbeforethe strandsarelaid into therope.This is knownaspreformingandresultsin each sfand layingin its correctpositionin a completedropewithouta tendencyto springout shouldthe ropebreakof becut.Preformedropesaresaferto handle.

L7.2.4.3 Specialist Qualities Threefactorswhichdeterminea rope'sspecialistqualitiesare: a. The typeof corethatis usedin thewire rope; The sizeandnumberof individualwiresusedto form a sffand; b. The numberof strandsusedto form thewire rope. c. a.

Cores - The type of coreusedin a wire ropeplaysa part in the whe's flexibility, rigidity andresistance to crushing. 1) FlexibleSteelWire Rope(FSWR)andExtra SpecialFlexible SteelWire Rope@SFSWR)generallyhavea coreof manmadefibre, occasionallynatural, which is impregnated with a lubricantto reducecorrosion.ESFSWRis generallystrongerthanFSWR,asit is madeof betterquality steel. ii) SteelWire Rope(SWR)frequentlyhasa steelcoreandcontainsfewer wiresin eachstrandthanflexibleropes.trtis generallyusedwhenstrengthis a greaterneedthanflexibility.

.,AA

b.

Wires.Steelwiresareoften describedas beingof , for exanrple,"6x37" construction.This descriptionmeansthat the wire consistsof 6 strands,each comprising37 wires. Thereis a wide varietyto choosefrom, as an illustration: i) 6 x 24 Galvanised.Figure 17.6illustratesa RoundStrandRope,right handlay, which is 6 x 24\aid over a fibre core. This typeof rope would commonly be usedfor toppingrope and cargorunners. The maJorityof wire ropeshave six strandswhich form the rope. There are,howevei, multistrandedropes,usedfor theirnon-rotational propertiesand as many as l6 strandsrnay be usedto form a rope. 6 x 24 Galvanized

Figure 17.6 ii) 12 x 6 over 3 x 24. Figure 17.7 showsdiagrunntaticlya Multi-strand, right handLang'slay ropewhichis 12 x 6laid over A 3 x24 core. This typeof rope would comnronlybe usedfbr, cargopurchases on derrickcranes,and deckcraneswherenon-rotatingpropertiesaredesirable. 12x6over3x24

17.2.2.4 Handling

Figure17.7

Wire.ropesshouldalwaysbe treatedwith the utmostrespecr.The following points shouldbe noted: a.

Never handlewire ropeswhen wearingringson the fingers.

b.

Neverkeep l wire ropg turnedup arounda bollard for a long period,especially if you havea pull of 50o/o or moreof the breakingstrainofthe rope. fhis wiil deform the rope.

c.

A wire.ropewhich is undera load nearto the linrit of its breakingstrainwill 91xt a high pitchedwhining note,it may vibrateandit r"nayshow signsof oil beingsqueezed out berweenthe wires. A ropein this statein under6xtreme

stressand the loadingshouldbe easedat oncebut in a controlledway, not suddenly. Always inspectbeforeuse.Look for distortionof strands,as this is a result of kinking, crushingor seriouscrippling. Broken wires are a result of fatigue and but with a dry powdery heart wear. A rope with a good externalappearance shouldbe discarded. d.

The diameterof any sheaveover which the rope will passmust be correct. The smallerthe sheave,the greaterthe friction and the smallerthe bendradius. The smallerthe bendradiusthe greaterthe stressconcentrationfactor. SeeChapter 4 paragraph4.3. The greaterfiiction is causedbecausethe strandsand wires furthestfronr the centreof curvaturemove apartwhilst thosenearestmove closertogether.This resultsin friction betweenthe wiresand strandsand the smallerthe sheavethe greaterthis friction will be. Generallythe diameterof the sheaveshouldbe at least6 times the circumferenceof the rope. Coiling. Long lengthsof wire rope shouldbe stowedon reels. Wire ropeis lessableto absorbturnsthanfibre rope,so whencoiling down it is sometimes "Frenchmen".Frenchmenserveto necessary to useleft handedloopscalled counteractany twistscausedby coiling down right handed.SeeFigure 17.8

Figure17.8 f.

Openinga coil. A coil of wire nlustnot be openedup in the samemanneras a "kinks" it shouldbe will be theresult.Instead, coil of ropeor a multitudeof unrolledin tlreoppositeway to which it wasnradeup. Smallcoils can be rolled alongthe deck in the santenrAnneras a hoseis unrolled,but largeronesrequire a turntable.No specialturntableis keptfor the purpose,so one hasalwaysto piecesof wood lashed be improvisecl.This is bestdonewith two substantial togetherto fomr a cross. Two bridlesare attachedby nrakingan end fast on eachleg of thecross,aboutmidway betweenthecentreandthe ends,and the bightsmustbe long enoughto reachthroughthe centreof the coil when it is laid from a suitableposition,or on the woodencross. The bridleis then suspended a small craneif one can be dedicatedfor this purpose. The wire can then be unis coiledand it will revolvefreelyif thecranehook or nrethodof suspension fitted with a swivel. Otherwisethecoil mustbe landedoccasionallyto takeout device. any turnsput into the suspension

tt D'

Cutting. Befbrecuttingwhippingor strongtapemust be put onto the wire eithersideof the cut, otherwise,oncecut, the strandsnrayfly apartand spoil theropefor someconsiderable distance.A few sharpblows with the edgeof the hammerin the spacebetweenthewhippings(about25 nrm) will flattJnthe surface,so that the sharpcold chiselwill cut moreevenly. Cuttingmust be doneon a good,solid foundation,so that a cleancut is achieved.

246

17.3 Safe Rigging Practise Ropemanufacturers will provideinfbmrationon the safeworking loadsfor their productsand tablesare availablewhich can be consulted.For generaluse,however, laid out below asFigure |J.9, arethe recommendedsafeloadswhich can be used with fibre rope, FSWR, stud and open link chain. Theseformulascan be usedin normalworking conditions. METRICFORt',4ULAE FOF BREAKING STRESSES OF NATURALANDSYNTHETIC FIBREROPE, STEELWIREROP€AND CHAIN

MATERIAL

FACTOR Strajn) {Breaklng

G r a d e1 m a n i l l a H i g hg r a d em a n i l l a

( 7 m mt o 1 4 4 m m ) ( 7 m mt o 1 4 4 m m )

zDz/3oo

Polylhene Polypropylene

(4mmto 72mm) (7mmto 80mm)

3D'l3oo

Polyester Oerylene)

4mmto 96mm)

4D'/300

(Nylon) Polyamide

(4mmto 96mm)

5D' l3oo

6 x12

( 4 m mt o 4 8 m m )

15d'1500

6 x24

( 8 m mt o 5 6 m m )

zoD' l5oo ., EreakingStrain

6x37

(8mmto 56mm)

21D' /5oo

G R A D E1

(12.5mm to120mm)

2oD2/600

GRADE2

(12.5mm to 120mm)

3oD2/6oo

GRADE 3

( 1 2 . 5 m m t1o2 0 m m )

43D' /6oo

G R A D E1

(12.5mm to50mm)

2oD2/600

GRADE 2

(12.5mm to50mm)

3oD2/6oo

FIBREROPE3 strandhawserlaid

F L E X I B LSET E E L W I R ER O P E SWt

S T U DL I N KC H A I N

OPENLINK CHAIN

The drameter D is expressed in millimetres, the breaking stress in tonnes.

Figure17.9

I7.3.1

Shackles

Shacklesizesand typesvary rangingfrorn about25 mm in lengthto over 1 m. They do haveone thing in commonfor offshoreuse;all are testedand stampedwith their safeworking load (SWL). It is alsocommonpractisein the North Sea, as hasbeen statedpreviously,for all lifting equipment,includingshackles,to be colourcoded to indicatethat it is in datefor test.. 17.3.1.1 Safe Use of Shackles In any situationwherea shackleis employedaspart of the riggingonly testedshackles shouldbe used. This will elinrinateany risk of failureof the riggingand thusensure safetyof personnel.Whenevershacklesarebeingusedthey rnustbe mousedto preventthem beconringaccidentallyun-fastened. Figure 17.10Showsdiagrammaticly how this is done.

1,1'7

Mousing

Figure 17. l0 MousedShackle L7.3.2 Lifting Strops Similarly wheneverlifting stropsare employedthey must neverbe doubledover and the recommendednrethodrecluiresthe lifting hook to be placedcentrallywith the strop this. formingan angleof 1200whereit hangsover the hook. Figure17.11illustrates

Figure l7.ll SafeUse of a Lifting Strop 17 .4 Knots, Bends and Hitches and Their Uses In the normal courseof work aroundan ROV spreadit is probablethat you will frequentlyneedto secureobjectsin placeandthe mostlikely way of doing this is by "knot" is then acceptedas the general usingrope or someform of cordage.If the term work for a fasteningmadewith cordage,somemore precisedefinitionsfollow: a. b. c. d. e.

f g.

The standingpart.Is the main part of the ropeabovea loop or bight.It is the part opposedto the end. part ofthe rope. The end.Is the end or unsecured A bight.Is a half or opencirclein a rope and alsorefersto the middle part of a lengthof rope. A loop. Is a closedcircle in a rope. A knot. In theprecisemeaningof the temr , is any knot otherthana "stopping"knots, bendor a hitch.The bestknown knotsare suchas the Figureof Eight knot, which is usedto preventthe roperunningout througha cleator fairlead. A bend.ls the knot usedfor tying one rope to another. A hitch. Is usedfor fasteninga rope to anotherobject,suchas a spar,or tent peg.Seethe followingdiagrams. Figure17.12to 1l.25.

248

Figure 17.12

249

FIGURE OF EIGHT KNOT

Stoppingtail end of rope running througha sheaveof a block

Used on tail ends of sheets,to stop ends runningthroughclews or sheavesof blocks.

Figure17.13

Figure17.14

KNOT Generalpurposeknot for joiningtwo of equalsizedroPestogether.

Figure17.15

FigureL7.16

250

: SHERMAN'S : =ND

Sheet bend or swab hitch

Doublesheet bend

Figuref7.18

To secureboats painterto buoy ring

Figure17.17

(ii) Blackwallhitch To secureliftingpennantto liftinghook

Figure17.19

251

Used in life-savingsituations,i.e. securinga lifelineto a diver,or man workingfrom heights

Figure 17.20

To join two unevensized ropes together

Figure17.21 252

-----ar

I

II

II I l

: CLOVEHITCH

ROUNDTURNAND TWO HALFHITCHES

tl i l l l

Generalpurposehitch for securinq lifelinesto anchorpointson barge' or harbourwall. Boatspaintersto bollardor mooringpointson jetties,

Generalpurposehitch.Can be used for securingboats painterto mooring ringfor short durations.

Figure17.23

Figure17.22

TIMBER HITCH

c liftpilings,timberor any round cylindricalobjects.

Liftingslippery,shinycylinders, scaffoldpoles.etc.

Figure17.24

Figure 17.25 2_53

17.5 Blocks such This itemof riggingis in comnronusein manydifferentlYPesof lifting equipment use.the widespread in'such it is sy;i";;, winches"t.. bJ"uute launching ascranes, go to makingup a "on1-onblockareshownin Figure17'26 parts which various

Swollow

SheavePin

Figure 17.26 Partsof a Block 17.5.1 Types of Block obviously for ty.pe.s.available, Blocks areput to nany usesand thereare specialised. systems deployment ROV in which may well be included ip.riri puipor.t. Tw'o type^s aie snatchblocksand leadblocks. They can Snatchblocksf,aueone itreet
254

Oncein placethey can then be employedto changethe directionof pull on the load and thusbecomeLead blocks. Commonblocksarefrequentlyusedfoi this purposewhen the riggingis first beingsetup and theycan be threadedonrorhefalls oi working line. 17.6 Tackles A brief introductionto tackleswill illustratethemethodemployedby all cranesand similarlifting devices.A tackleis a sin-rple devicewhich givei incr6ased powerby a conrbinationof blocksandropes. The numberof sheavesin the block,the mannerin which^theropeof fall is rove throughthem,and whetheror not the standingpart is made.fasttg.the.top or bottorr.r block areall distinguishingfeaturesof the uiious types of tackle. The theoreticalpower gainedis proportionatewith the numberof sheav'es in the tackleand typically variesfrom two to nine timesaccordingto the type of tackle useo. 17.6.1 Gun Tackle The namefor this sirnpletackleis derivedfiom thefact thatthesetackleswereusedto run out the gunson sailingtren o' war. It simplyillustrates the principleinvolvedin usingp.urchases to ittcrease lifting powerwhiihis why it is illusirated^here. The theoreticalpow^er gainis two or threedependingon whetherit is riggedto advantage or disadvantage. SeeFigures17.21and 17.29.

DIRECTION OF PULL

DIRECTION OF TRAVEL

Gun tackleriggedto disadvantage Powergain ratio2:1

Figure 17.27

DIRECTION OF TRAVEL

Gun tackleriggedto advantage. Powergainratio3:1.

Figure 17.28 255

DIRECTION OF PULL

Figure17,29

":

Figure17.31 257

17.7 ROV DeploynrentSystems ROV'scan be operatedfronr thefollowing: a b. c.

Monohullvessels; vessels; Semi-submersible Fixed pliitfornts.

ROVs arelaunchedeitherover the sideor througha moonpoolandmay be deployed with or without a cageor garage.Thereare severalhandlingstrategiesbn_tfour andtheseareoutlinedbelow. ilhtstratethepossibilities exampleswill adequately Whateverthe method,however,it will requirethe useof eithera craneor a winch to conrrolthevehicle.SeeFigure17.29 unOtZ.lO. If a winchis usedit will commonly employ an A frame to suspendthe ROV clearof the deck and move it inboardand out'boatO.The cranehasthe advantageof beingable to cover a largerareaon the deck and is more flexible. The A frame is-morerigid and therearefewer controlswhich makesoperatingeasier.Both cranesand winchesmustbe designedwithin the ^ society,suchas:AntericanBureauof ofan approvedclassification requirements Shipping;Lloyds Registerof Shippingor Det NorskeVeritas. Winchesarevery wideiy JsedanOare 'ilost often controlleddirectly by the ROV teanrasopposedto cranei which mostoften havea dedicatedoperator.Somespecificpointson winches thereforewill not go amiss. 17.7.1 Winches whendesigningor choosinga winch the most Of the numerousfactorsconsidered is determinedby the weightto berecoveredand This pull required. line is the obvious of the cable,taking accountof the fPPropriate strain 6reaking more than the not be will diameterwhich will be determinedby the is drum factor the Another factor. safety The numberof wrapsto be storedon the drum wire. the radius of minimum bending by thelengthof the umbilicalto be will detennined This be will alsobe considered. theclruntflangediameter.It is will detemrine in turn this usedandthe cablecliameter, is evenlyspooled.If this unrbilical the to ensure with Ievel wind a bestto usea winch possiblewhendeck is not always required which is fleet angle is not possiblea goocl Two methods method. braking is the factor important spaceis at o p.etiirm. Anothdr brake automatic an and normaloperations is used during -e co--on. Manualbraking pressure. in oil rapid drop as a such will be appliedin an emergencysituation, 17.7.2 Pick-up Hook Recover-v In this casethe umbilicaluseclis mediumandlightweightandnraybe winch or hand o-nan. tended.When this approachis usedsimplecranesareenlployecl,often when generally employed opportunitybasis.Thjs methodof launchandrecoveryis l i v e b o a t i n sS . e eF i s u r e1 7 . 3 1

258

1 7 . 7. 3

Speciatist Latching

A specialist"grabit"or "go-getter'isrun down the umbilicarl andlatchesa pick-up device to the top of trrevehidle. The vehicleis ttten.i.or.r.o usinga dedicatedcrane. This methodis generallyused*iihort a cageand in a live boatsituation. 17.7.4 Umbilical Launch and Recovery This methodis occasionallyusedwith largevehicleswhich havesufficientpowerto manoeuwewith the amrouredcablethat iJnecessary to tu[. tne weigtrioiiti. u.r,i.t. during the launchandrecovery.once more this -etnoa is mainly usedwhen live boatingand without a cage. 17.7.5 Cage and Winch Deployment - - - - - - - - - . the r. . . i ^ vehicre :.._::" is r J rlowered v v y w r u u from rrvrrr d a udedicated s u l u i . l r . s owinch wlncn u usin.q srng a an n A A tframe. rame.

fr:.^t:.::,"l1rl]"g

yl'.f thevehicle ispa.[eoinio-it'or. it :T,ttji"l:1s: yflligi,'3s.. arrangemenl uer,icie

ii r,*r,.j",i;,fi;:#:'"rfi;i.';.,

T:l:::;,:*1{^f::,,r:ryll thgre"th.e type of cageis employedir will contain thefbllo*in*r g ntaJor ili elenrents: The framework Spoolingdrunr Slip rings Powersource.

Additio-nallysomecagesaretlttedwith a depthgaugeand a T'v canrera.This enables the Rov's positionrelativeto.thecageto beass"essJo. ir'. ,,nrhrilical_f'rom_the surface winch to the cageis annouredand hJavyduty to takethe *,1.rr., and strainsof the launch,,anp recoie+ ancithe vehicleun.,uiti.riiirigrrLi. rrlls vehicle umbilicalmay be neutrally.buoyant in seawater.This neutraluroya'ncyir iur'tit.ty to rotl[o*.u., u, any smallcut itl thecableouterwill allow seawaterto enterancltheneurralbuoyancyis dependant on the specificgravityof the wareranyway. The cage merhodof launchand recoveryprovidesseveraladvantages cornparedio oti.r metirois. Thesein.ruo., Vehicleprotectionduringlaunchandrecovery: Isolationof unrbilicaldrig from the vehicle; ' A merhodof carryingtools down ro rhe *oikrit.: A nreansof kcepin-e ihe mainunrbiricar .te'oiourrrircrions.

byfendering toabsorb rhestrains imposed by 111.":X;,::11,-o^Y.:'::19_.|:.iJ,?,::,.d whi,9l is ine,vitabt. t,, no"'1ri;p;;;;,,; ti;. ffiJi';.Ji't: 1:-:glly:k minimised bycaref,r handring - paying i" ,rrii"irr til*rr;;;;;iil rslngswlnglng m o t i o n sS . e eF i g u r e lj.3Z.

I

I

Figure17.32 2-59

17.8 Navigation of^some The natureof the work undertakenby ROVs is suchthat an understanding for compass.c.ourse, a. Being able-to.follow an asset. are aspectsof navigation be able to to ability the p1lqt. Similarly of any-ROV is required that e*lmpte ,is a sf,ll a planning when have to technique helilful chartiis a on interpiet intormationavailabie dive in a new location. 17.8.1

Compasses

o; but now they Tradirionally compasscardswere markedin points (onepoint is i i4 are marked in degrees. It is often adequatewhen steeringan ROV . to gi by theroseis ieproducedas Figure 17.33. lf "o-pitr points ind for this reasonthe compass. it is necessaryto steera more accuratecourseit is conventionalpractiseto use3 digis to indicatethe bearing,as in l80o or 0300'

$'l{1y; V V t (),,1-l

\: ll

Figure17.33

260

1 7 . 7 . 3 S p e c i a t i s rL a t c h i n g A specialist"grabit"or "go-getter'is run down the umbilical andlatchesa pick-up deviceto.the top of the vehidte. The vehicleis thenrecovered using. oraiJui"a crane. This methodis generallyusedwithouta cageandin a tive uoatsituation. 17.7.4 Umbilical Launch and Recnvery This methodis occasionallyusedwith largevehicleswhich havesufficientpowerto manoeuvrewith the armouredcablethat iinecessaryto tu[. the weighioiirie uenicte duringthe launchand recovery.Oncemore this *"thoO is mainly usedwhen live boatingand withouta cage. 17.7,5 Cage and Winch Deptoyment

i

: I

A cagecontainingthevehicleis loweredfrom a dedicatedwrnch usingan A frame. The actual, cagernaybe a garage*r*g"nl.nt wherethe vehicleis parked into it or it "top may be a hat" arrangenrerit wherc"thevehicleis larched,no.rirr'. tog"."wt ur.u", typeof cageis enrpr.yedit will corrainthefbllowing"r;.i"i elenrents: The tiamework Spoolingdrunr Slip rings Power source. Additio,nallysomecagesarefitted with a depthgaugeand a'fv camera.This enables the ROV'spositionreiativeto,the.cageto t',eas#ssJo. i6e unrt,ilical-from_the surface winch to the cageis anrlourecl and hJavyduty lo iot. trr. yressesand strainsof the launchandreco-veuanclthevehicleun.,bili.niiirigrrLi. iiris vehicleumbilicalmay be neutrally.buoyant in seawater.This neutraruroyiniy is iiirritelyto lasrhowever as any snrallcut in thecableouterwill allow seawarerro enreranclihe r;;;;i bJoyuncyi, dependant on the specificgravityof the wareranyway. The cagemethod of launchand recoveryprovidesseveraladvantages comparedio otirermetho"ds.Thesein.l-uO-", Vehicleprotectionduringlaunchandrecovery; Isolationof unrbilicaldragfronrthe vehicle;' A methodof carrying toolsdown ro the *oikrit.: A nreansof keepingihe mainunrbiricar ctea.oiourrrucrions. The cageand RoV 'shouldbe protectecl by fenderingto absorb.the strainsimposedby the odd knock which is inevitiiblein nomialop..atl3,ii. ih.r. knockscan be minimisedby carefirlhandlingpayirrgparticulirattentiorr " ' to nrininrisingswinging m o t i o n sS . e eF i g u r c 1 1 . 3 2 .

261

I

17.7.6 Motion Compensation Occasionallymotion compensationis requiredfor the system. One techniqueusedin live boatingis to attachfloats to the umbilical;this essentiallydecouplesthe vehicle from the surfaceforces. Active and passivewinch compensationis also availablebut thesemethodsare complex and involve the useof: high responsedrive systems; counterweightsor accumulators.A different approachhasbeenusedwhich involves the aerationof the moonpool. This permitsthe safelaunchand recoveryof the vehicle up to force 5/6. 17.7.7 Launch Hazards If motioncompensation is not usedthe hominganddockingof the ROV with the launchercan be both difficult and hazardous.Small ROVs, up to 500 kg, normally respondadequatelyto a little applicationof appropriateshockabsorptionand brute force. Where ROVs arebeing deployedwithout cagesthey are normallyconnectedto the handlingarrangenrent at the surfaceand hazardouslycloseto the vessel. Abrupt, dynamicloadingto the hoistingsystemoftenoccurswhen lifting the vehicleclearof the waterin thesecases.If motioncompensation is not usedthis callsfor carefultiming and a gooddealofexperienceon the partof the winch or craneoperator. 17.7.ll Porver Requirenrents Normallythis is 440 volts 3 phaseandmostoften,thepowertrainon the winch is which allowsfor goodspeedcontrol. The sizeof thepower supplyis electro-hydraulic by distanceper unit time dictatedby the line speedandpull. This is established rnultipliedby force (theunitsof power). The numberof wrapsof cablearoundthe drum mustbe takeninto consideration as this affectsthe torcluerequiredand starting currents,which are higherthanworking current,must alsobe considered. 17.7.9 Locating the Launch Site A centrallylocatedsiteon thevesselplacestheROV nearto the pitchandroll centreand maximisessafetyanclefficiencyduringlaunchandrecovery.A centrallocationwill periodswhich is of benefitduringnlaintenance alsoprovideshelterfrorn theelemerrts If a falsedeckcan bc providedit will allow accessunderthedeploymentsystemandit will help to isolatethe systemfronr seawater. It will alsogive accessfor cablesand hydrauliclines. Finally if a winch is beingusedin conjunc:tiolr with a craneof opportunityit nraytrenecessary to useleadblocksto ensurea c:orectleadis maintained. 17.7.10 Operating in Tide or Weather ROV weighsseveralhundredkilos with powerto matchit is not expectedto Unless_an operateon the surfaceor in the splashzonein any adverseweatherconditions.The first point aboutoperatingin theseconditionsthen,is to get below the surfaceas 'fhe quickly as possible. secondpoint is thatthe effectsof currentwill be more noticeableon the unrbilicalthanon thevehicleitself. As a guide"eyeball"ROV's will generallyoperatein 1.5 knotsof tide or currentbut, because of the currenteffects,it is prudentto pay particulerattentionto the reductionof drag on the umbilical. This is wherethe garagemethodof launchandrecoveryis suchan assetand why it has becomeso favoured.

262

E

17.8 Navigational The natureof the work undertakenby ROVs is suchthat an understandingof some aspectsof navig.ationare an asset.Being able to follow a compasscou.Ie, for example,is a skill that is.req-uired of any ROV pilot. Similarly ihe ability to be ableto interpretinformationavailableon chartsis a helpful techniqueiohavewhen planninga dive in a new location. 17.8.1

Compasses

Traditionallycompasscardsweremarkedin points(onepoint is 114o) but now rhey are markedin degree.s.It is often adequatewhen steeringan ROV to go by the pointsand for this reasonthe compassroseis ieproducedasFigure 17.33. If co.mpass it is necessaryto steera more accuratecourseit is conventionalpractisetJ use3 digits to indicatethe bearing,as in l80o or 0300.

+

lui, ,\ (;\. l Lr )

\: l/

ffi Figure 17.33

263

Itr

r(?\

+

Na\. i"*c

Yle

\,,'

/ LJti

f.c ; *

f p EI -

tl

s//c ,.E

rf Ar)i

:l/

r ) - : ) //,

5.;

\:,\Y/ nq" v/,6

7

V

% ' (

17.8.2 Magnetic Compass The magneticcompassrespondsto the earth'smagneticfield by way of a magnetic needle,which is freely suspected, aligningitself North South. On the bowl of the "Lubber Line" and connectedto the magneticneedleis a compasscard. compassis a The compassis suspended in gimbalsso that movementsof the ROV do not interfere with the swingingof the needle. As the ROV then changesdirection,the compass bowl moveswith the vehicle,while the card is held in a North/Southdirectionby the needle. The relativemovementbetweenthe lubberline and the card can then be read off directly in degreeswhich indicatesthe headingof the vehicle. 17.8.3 Gyro Compass Most ROVs are fitted with gyro compasseswhich usethe propertiesof gyroscopic inertiaand precession.A child'sconicaltop, when not spinning,will toppleover. If it is madeto rotaterapidlyit will not deviatefrom the uprightposition.This is an exampleof gyroscopicinertia,i.e. the axleof a rotatingbody tendsto remainpointing in a fixed direction. If a forcecould be appliedto therotatingpartsof a spinningbody in sucha way that it werenot sloweddown, it would be seenthatthe objectwould move in a directioncontraryto that expected.This is the propertyof precession exhibitedonly by rotatingobjects.Thesetwo propeniesof rotatingbodiesare harnessed in the gyro compassto producea mechanismwhich continuouslypointsto North, providedits sensitiverotatingpartsare kept energisedfrom a suitableelectrical power supply. The gyro compassideallyseeksto align itself in the true north-south direction,but, in commonwith mostmechanicalapparatusit is subjectto smallerrors. Thesemustbe allowedfor whentheconrpass is in use. 1 7. 9 C h a r t s The chartis an importantandreliablesourceof infonrration,which is availableto the ROV pilot asrequiredvia the ship'sbridge. The mostconlnlonchartsavailablein the North SeaareAdmiraltycharts,but word wide therearea greatnranyvariations.All chartsusesimilarmethodsto indicatevariousfeaturesandobjectson whatis a conventionalisedpictureon a flat surfaceof a portion of the curved surfaceof the earth.

17.9.I

Scale

The naturalscaleof a chartis theratio of the areaof the pictureto the actualarea represented therein.The largertheratio,thesmallerthe scaleandthe lessthe extentof t h e d e t a itl h a t c a nb e s h o w n .T h u sa c h a r t h a v i n g a n a t u r aslc a l e o f1 : 7 2 , 0 0 0( 1 " t o 1 nauticalmile) shows moredetailthanone with a naturalscaleof 1: 393,000(5 " to 1 nauticalmile). 17.9.2 General lnformation The generalinformationin chartsis given by meansof standardised synrbolsand abbreviations,which are listedin a key chart.In the caseof Admiralty chartsthis is known as chan 5011 and is availableis book form. This kei,chartwill be availablein the ship'sbridge.

264

17.9.3 Chart Title The title is much more than a merelabeland shouldbe readcarefully,sinceit contains much key information. The contains,in additionto a statementof the areacharted, suchkey informationas the naturalscale,the way in which bearings,soundings,and heightsof land,drying banks,or rocksaregivenand the datumlevelsfrom which soundingsand heightsaremeasured.The surveyson which the chartis basedare also included,and oftenfurtherinformation,suchas theexactpositionsof prominent land features. 17,9.4 Corrections Always seethat a chart is up to date and so far as possiblekeepit so. Chartsas sold by the agentare correctedup to dateat the time of saleand the correctionsincorporatedare shown by a stringof numbersoutsidethe frame of the chart at the bottom. They representthe yearand numbersof the Admiraltyor similarorganisation's noticesto Marinerswhich are issuedregularly.Thesenotices,which arenunrberedin sequence, arecareful,plain languagestatements of changesin harbourlights,positionsor removalof wrecksetc. 17.9.5 True Cornpass Roses Circularnotation. Severalcompassrosesareusuallyprovided. Eachrosealways includesan olrtercircleor truecompassrose,which is dividedin degreesfrom 0o at True North,clockwisethroughEast,Southand West to 3600. The evennumbered degreesbeingindicatedby radiallines,with theodd nunrbered degreesindicatedby dotsbetweenthem. Everytenthdegreeis indicatedby a longerradialline markedwith the numberof degrees.Thesetrlle rosesareso orientedthat a line between0o and l 8 0 o i s t h et r u eN o r t ha n d S o u t h . 17.9.6 Magnetic Compass Rose within the tnrecompassrosesandare QuadrantalNotation. Theseareconcentrically orientedso thatthe North point corresponds to magneticinsteadof trueNorth,Degree markingsaregiven in the sameway ason the truerose. 1 7 . 9 . 7 M a g n e t i c V a r i a fi o n A magneticroseis twistedin relationto a truerose,for the North point of the former is magneticNor1h,whereas,thatof the latteris true North,the anglebetweenNorth and trueNorth is calledthe variatit'rn.It is not consmnt,but variesall over the surfaceof the earth.It alsochangesslowly with tinre. This canbe ascertained from the information printed acrossthe E-W line of the rose. 17.9.9 Tidal Diamonds The directionand rate of the tidal streamsis given at selectedpointson the chart,in the form of a magentadiamondif it is an Admiraltychan. The chartshowsa numberof letters,tidal diamonds,with printeddetailsreferringto the dianrond'spositiongiven in a box on the chart. 17.10 Tidal Infornration Thereare manyoccasiorts when ROV'soperatein areassubjectedto tides.the following informationshouldbe of usein thesecircuntstance.

26-5

-

l

ii J

17.10.1 Causes of Tides The tidesare causedby the gravitationalpull of the Moon and the Sun,the moon has the greatereffect. The-rationof the effecisof eachbody is roughly l:,3 \.e. the Moon's "units" and the Sun'sfor 3 "units". The planetsalsoexefi much pulftccounts for 7 smallergravitationalattractions.Both the earth'satmosphereand the water the earthare free to move in responseto the motion of the sun and moon surround.ing a small aroundtheiarth. The atmosphericmotion is not significant,causingonly ubulg^es" changein pressurethroughthe day, but the water;being more dense, signiEcantiytowardsthe attractingbody. The bulgeoccurson both sidesof the earth, as shownin Fisure 17.34

Hw

Sun--)

Figure 17.34 Tidal Bulges Generallythereare two high watel and two Iow water times in each24hour period onceevery 24 exceptin the Pacific. The earthrotatesaboutits axis anticloc:kwise hours. The moon orbitsaroundthe earth,in the samedirectiortas theearth'srotation, onceevery 292 days(approxiniately).This meansthe lunarday is longerthanan earth day by about50 minutesdue to the nroonnrovingin the saniedirectionas the earth's roiation. This in tllnt nteansthe intervalbetweentwo high watersor two low watersis "semi-diurnal" tidei.e.twiceaday. In on average12 hours?-5minutes,givinga in character.In the pacific invariably semi-diurnal Europeanwatersthe tidesare alnrost Local anomaliesdo occur, low day. each the tide is diurnalwith only one high andone low waters eachday causedby the thereare four high and at Southamptonfor exan-rple tidal streaniflowing aroundthe Isle of Wight. The rangeof the tide is much affectedby the shapeof the seaor ocean,the gradientof the seabed etc. If a seaor oceanhasa naturalperiod -The of oscillationnearto the periodof the tidal forces,then a greaterrange North Atlantic hassomeof the greatestrangesin the world, particularlyin results. the Bay of Fundy wherea 17 rnetrerangeoccursat springtides. In the Mediterranean thereis very little tidal moventent;generallylessthan0.7 nletres. 17.10.2 Springs and Neaps The Sun and Moon ntay act togetheror at 900to eachother.They act togetherat New At New and Full moon and Full Moon and at 900 to eachother at flrst and last quar"ters. the tidesare higher at High Water and lower at Low Water than the average,giving springtides.At first and last cluartersthe High Water is lower and the Low Water is lrigherthan the averilge,giving a smallerrangethanaverageltermedneaptides.See Fieure 17.35

266

LastQuaner

C

Neaps Full Moon

New Moon

o

Springs

{ Earth } \-/

o

Springs

Ncaps

c

First Qua,rter

Figure 17.35 Springand Neap Tides The Sun and Moon move North and Southaboveand below the Equator.The Sun takesa year to make a full cycle front 2320N to 2320S and back again,while the Moon takesabout26 daysto move from 2820N to 2820S and backagain. When the Sunis at the Equatorit givesthemostdirectpull to the senti-diurnal tidesand thusthe greatesttidal range. The sameappliesto the Moon. The Sun is at the Ecluatoron March 21 st. and Sept.21 st. andthe New or Full Moon nearestto this dategivesrise to themostextremetidal range;pru-ticularly with the Moon alsoat theEquatoi. The springtidesnearMarch21 st..presunrablv giveriseto the narlefbr thetideshavingthe greatestrange.

: :

I

17.10.3 Tidal Definitions A numberof termshaveto be understood beforecalculations arecaried out on heights and tintesof tides. Thesearebestexplainedby the useof a diagrantshowinga tide pole in a coastalarea.seeFigure 17.36.

I

I I I

HWS High Watcr Springs HWN High WatcrNcaps

Height of tide

[TJ,;"*'

MSL Mean SeaLevcl LWN bw Water Ncaps LWS Low Water Sprints CD Chart Datum This is a lcvcl choscnsuchthat the sea level rarcly falls bclow it. This is approximatcl1,thc low'csIpredictab'lctide level undcravcraScnrclc\)rologicral conditions.

Figur e 17.36 TideTemrinology

267

Spring Range

I

17.10.4 Times ancl Heights at StirndardPorts Ports' At these' theword areknownasStandard A numberof portsthroughout of thepositionsof effects the and havebeenmadeovera nu*l"ioiye-ans observations thatpredictions so Port' each for rheSun,Moon anOG PlanetsnaueUeenditermineO at theseports will occur canbemadefor manyyearsaheadfor thetidalheights.which various form in tabular andthetimesof HW'.fi;W:'Tht;l;i;rmation iiavailable Thewayin Almanac' Af-unut or theMacmillan suchastnenimiralry, R'eed's sources of rise curves allow to which the tiderisesandfalls hasatsoU.en-iattfullyrcxamined of number u ap Rlodugq{9y andfall to beproducedfor SpringanaNiai tides.'These can be curves tidal thebestt.nownof ifricfris ttre'nimiiuft' Thesebobtsof asencies whenthetidalheightis required' c6nsulted 17.11 Weather Weather In anyoperationundertakenat seathe weathermustbe considered' consulted be forecastsare availableworld wide and the local forecastshould beforeconductingoPerations.

268

CHAPTER 18 DRAG, BUOYANCY AND NAVIGATION f8.0 Introduction Thereare two purposesfor this chapter. The first is to introducethe effectsof two forcesthat effect ROVs in the working environment;namelydrag and buoyancy. The secondis to discussnavigationon the ROV in practicalterrns. 18.1 The Drag Force One importan-tfactor that shouldbe appreciatedwhen consideringthe effectsof drag - is that.thedragforce itself is still imperfectlyunderstoodand a greatdeal of empirical work is undertaken, in wind tunnelsand testtanks,at the designstagefor new developments because of this. This doesnot meanthat ROVs arethustestednor does it imply that nothingis known theoretically aboutthedragforce. It is simply stated hereto underlinethe complexnatureof drag. l8.l.l

Fluid Florv

In consideringdragthe first consideration hasto be the typeof flow of the liquid causingthe drag. This can be eitherLAMINAR or TURBULENT and manydetailed experimentshavebeenundertakento studythe effectsof flow notablyby O.sboune Reynoldswho publishedhis resultsin 1883. His nanreis usedto denotethe nondimensionalREYNOLDSNUMBER that is decisivein deternriningthe type of flow. The Reynoldsnumberis deterntined thus: Re=

pul

u

Re - Reynoldsnurnber p - Density I - Selected Dimension tt - Viscosity

The densityof freshwateris takento be 10tX)kg m-3and seawarerabout1025kg m 3. The viscosityof freshwareris 10 3 Nsnr2 (1.0mPa)(Pa- Pascaland 1.0pa = 1.0 Nsm-2) An exanrpleshouldillustratethe useof this formula Example :What is the Reynoldsnurnberfbr seawaterflowing at 2 knotsover a I m length of pipe? (i Kt approximatelyequals2 nrl) Thus2Kt=2X2=Int-I

Re=

pul l.r

1025X1Xl ?

1010 2 5 0 0

269

l

At low Re the flow is saidto be laminarbut at high Re it is turbulent. The actual flol.and Reynoldsnumberseparatingthesetwo statesdepends9n l 1ndthe ge_neral plate aligned flat Figure 18.1showst6,etransitionfrom laminarto turbulentfor a ttrin = with the flow to be at aboutRe 500000. 18.1.2 Boundary Layers hasled The conceptof boundarylayerswhichwasfirst inroducedby Ludrvig.Prandtl of FiuidMechanicsasa science.This concepthasbeenthe subject to ttredevelopment in of muchexperimentespeciallyin the aircraftindustryandmany-advances andwork haveociuned. Thereis still muchthatis not understood understandi:ng continuesin tiris field. To illusfiatecrurentknowledgeconsidera thin flat plate aligned with this flow w-ouldngrmally !e with the flow. The dragcoefficientassociated for a single thedrag-coefficient on have concenrated but experinients C6 denoted is often surface for a single The drag coefficient the study. siniplifies surfaceasihis general = The simplest friction coefficient. (Ca the is callid 2 and C) denotedCr in Figure18.1 caseis summarised boundary-layer

c"^

0.010

0.008

\ \

t \

0.006

\

0.005 \

0.004 0.003

l e

f

\

0.002

\

I

\ \

I

Cll'

uvr

0.001

t d z s t d z s 1 0 z6 s d z 5 to8z 5 toe Re

Figure 18.1 Cg As indicatedon thediagramtheCpat low Re (lessthan500000)is laminarand_ AboveRe = 500000the boundarylayeris likely to be asRe increas-es. decreases nrrbulent. The more turbulentthe flow thebetterit resistsseparationfrom the plate. Separationgenerallycauseshigh dragandto minimisethis andgive an attachedflow a streamlinedshapeasillustratedin Figure18.2is employed.

Figure 18.2 vehicle from theshapeof a typicalunderwater This shapeis obviouslyfar removed "bluff" shape. which mustbe consideredasa

210

-

!

18.1.3 Bluff Shape Bluff shapeshavedetachedflow at therearandsucha shapeis shownin Figure 18.3

) : :

Figure 18.3 This sectionhasa waketypically.about thesamewidth asthe sectioncontainingflow thatmay be;very turbulent,varyingin a regularmanner,or somecombination"ofthese cylindersthewakeis oftenin the 1wo. F^ora varietyof sections,particularlycircular torm of vorticesin a regularpatterncalledthe"KarmanVortexSffeet"asshownin figure 18.4 d

Flow

-+

+

ot

l--=4.5d-J

O

H

Y=1.26d

Vortex streetat Red 2000 Figure 18.4 von Karmanwasableto demonsffate thearrangement in Figure18.4wasa stableone t$t is-by no means the usual case as most such aoangeirents areunstable. -Ug Whetherthevortexsffeetis stableor not,however,it cauiesviolentlateralmotionsof thefluid behindtheobjectandis associated with a highdragcoefficient,which ior bluff shapesis oftendenotedcap (thisbeingc6 basedon fr6ntalarea). a. A standardequationusedthroughoutstudiesinto fluid flow is Bernoullie's equation:P=p*2puzx+pgz P = Total Pressure p = Staticpressure p - Density g = Gravity z = Heightabovedatum term P Ez= Potentialpressure u = Velocity 2 = Constantof integration

271

This equationandpracticalexperimentsshowthatfluid dynamicfgr-cesale proportional to the rqu*" of th6 speed.It is a commonpractiseto expressfluid force by a nondimensionalforcecoefficientC and:F=2pu2CA "drag WhereA is a referencearea. A commonexampleof the forcecoefficientC is the coefficient"denotedC-6. " A usefuldeviceto redice dragis a splitterplate"behindthe object.The effectsof this form in Figure18.5. areillustratedin diagrammatic

o Shape

Car 1.03

0.59

Flow

4

0.62 Effectsof SplitterPlate Figure 18.5 18.5 Effects of Drag in Practise of theeffectsof dragconsidera neutallY byo131tt To illustratethepracticalaspecLs m of wateron a pipeli3einspection.Lh. ROV is 150 in ROV operating ;;tk;6rJ ontothepipeline.th" diugt*.nq Fig. 18.7.shows locates aid the dect deployedfrom when ttrevesielis stationaryvertically.abqy"St moment a in time at a;fsnapsfrot" vertically..Thisis not a realisticsituationbut rising also rtution'*y ROV with thetether o.fth9t?S forcgl at this point in time. analysis it doesginea startpoint for a simple in Figure L8.6 table from ihe found The drig coefficieirtcanbe 3D SHAPES SHAPE

co, 0.4

0.8

1.1

272

SupportVessel Umbilical Diameter= 40 mm Tidalcurrent=2kts ( ApproxI m-l) 150m

<|--Fr Frontal area

1 . 5 m x2 m = 3 m 2

-/ {___

Figure 18.7 Considerfirst theforceon the umbilical. F r=2 p u 2C a sA = 2 x 1 0 2 5x 1 2 x 0 . 4 x1 5 0 x 0 . 0 4 = 1230N Now considertheforceon the vehicle. Fz=2 p u2C61A =2x1025x12x1.1x3 = 1691.25N (1690I{) thattheforceon theumbilicalis considerable andfor long F"tg figuresdemonstrate lgngtltsthedragontheumbilicalis greaterthanthedragon thevehicle.The umbilicil dragis effectivelyreacted50Voatthevesselendand56Voatthevehicle. This means that the total forcereactedby ttrevehicleis: 615+ 1690= 2305N This in turn meansthatwhatevelpolveris availableto thevehiclea percentage of that powelis requiredto overcomethisdragforcethusreducingthepoweravailible for otherfunctionssuchasmanoeuvring.In the situationbein! coniideredheretheROV mustachievea rateof advancealongthepipelineof approximatnlylD ms-I. This will impose^greater forcesonto both theumbifi&l andthevitricte andiequire evenmore power.fromthevehiclejust to go forward, T!" situationposedin this simpleexample is obvio-usly far frgm therealcasewheretheforceson theumbilicalin particularwiti Ue imposedin a muchmorecomplicatedmannerasindicatedin Figure1g.g.

:t-1

SupportVessel Umbilical =40mm

FFr

Tidalcunent=2kts ( Approx I m-l )

150m Ftn 0r

a,n G-Fz Figure 18.8 In this situationtheforceon the umbilicalreactedbv theROV mustberesolvedinto its two components thus: Fln = F1 Sin 300 and Fth = F1 Cos300 In this casewhich is slightlymorerealisticsomevehiclepoweris requiredfor both horizontalandverticalreactions.Therealsituationis evenmorecomplexof coursebut thefwo pointsto bearin mind are;ttredragforceon theumbilicalis considerable and will alwaysaffectthevehiclehandling,andthetotalavailablevehiclepoweris neverall availablefor forwardmotionbecause a proportionhasto beusedto counterthe drag forces. In any situationthisputsanonuson thepilot to navigateaccuratelyandthus minimisethe needfor manoeuvring andconservepower. Thedragforceon the umbilical is alsoan importantreasonfor employinga cageor tethermanagementsystem wheneverpossibie whendeployingtheROV. 18.8 The Buoyancy Force i

This forceis encapsulated in Archimedes'principal, whichstates,"An objectimmersed in a fluid is subjectedto anupthrustequalto the weightof thevolume of fluid displaced".Quantitativelyit is easilyevolvedby consideringa verticalcylinder filled with air immersedin a liquid asshownin Figure18.9

274

Znro gaagepressure

j\ z

I

t

Cylindercross-sectional areais S andlengthis I

l Figure f8.9

Fromthediagram:BuoyancyforceB=Fz-Fr

Fz=PBhzS

Fr=PghrS

and

. . l. = p E h z S - p g h r =pgS(hz-hr) but

h2-h1-l

hence 3=pgSl howeverSl=V Thus B= pgV It canalsobe seenfrom thediagramthatthebuoyancyforceactsverticallyupwards throughthe centreof gravityi.e. it opposesgravity. 18.2.1 Practical Applications In practisethe applicationof thebuoyancyforce to ROVs is in eitherfreshor saltwater andit revolvesaroundbalancingtheweightof objects.This allowsa simplificationto be madesubstitutingweightfor mass.It is thenpossibleto assumethat 1l of fresh wateris equalto 1 kg weight.andif 11of freshwateris displacedthe buoyancyforce will producean upthrustequivalentto 1 kg of lift. In orderto applythese simplificationsthebasicequationis: of Object= Lift Required Weightof Object- Displacement

275

18.2,1.L Examples Supposethat a blockof concrete2m x 1.5mx 3m is to belifted from the seabedin lSffaipttr of water.An inflatablelifting bagis to be used.How muchfree air will be required? of Object= Lift Required Weight of Object- Displacement a.

(D) =2x1.5 x 3 = 9m3 DisPlacement now 1m3= 10001infreshwaterand 10251insaltwater h e n ce D =9 x 1 0 25=9225k8

b.

=2200kg m-r Weightof concrete block=9x2200 = 19800kg henceweightof

.'. 19800- 9225= 10575kg of wareris displacedthe upthrustwill equalthis. Thusan airbaqfull of Now if 10,5751 of uir will displacethii amountof seawater. If ahisconcreteblock is to be 10,5751 mted trom the seabedhoweverthelift bagwill haveto be full of this amountof air at of tftut a"ptft. Boyles -be Law mustthereforebe ap4ied-to determinethereqqrgd amount thus:be stated may Law Boyles surface. from the air thafhasto supplied Pt Vr = PzYz The pressureat the surfaceis p1an4thepressureat the seabe{ is-p.z1ndtl.thge I4.7 p.s.i.). Thusthe it is easierto woihin Bars( I Bar is approximately calculations amountof freeair requiredwill be:-

p"v V' = p 't andPt = 1 Bar is 4.5 bar (approximately) At 35mwaterdepththeAbsolutepressure .'. Vr = 4.5 x 10575= 47587'51 It would be anusualROV taskto placesuchan air bagbut it couldbedone. on the-seabedfor a sitesurvey. a moreusualexamplemaybe to piaceEansponders a:! aii and tg_1n gflindrical in t!ry".yog u (;O Soppot"the transpbnders-weigtr buoysof 5l displacement many Grimqby How lm. of lengtfi diineter of 0.2 mand a buoyant? neutrally arerequiredto makethe tansponders of Object= Lift Required Weightof Object- Displacement a.

= lt t2l=TI x 0.12x 1 =.0314m3= 31'41 Displacement 60 - 31.4=28.61

In this casethedisplacementmakesvery little differenceto the amountof lift required but thecalculationis includedfor completness.

iI t

L_

2'76

b.

The numberof Grimsbybuoysrequiredwill be: 28.6 = 6 5

18.3 Navigation Navigating a1 Rov can be very straightforward operationas, for example, when

following a nrnglile o1a surveywhen'thenltiguti6l *iii u" ir the handi oi a ipeciatist team. It may alsobedifficult asit canbewhei workingoff a plaforminath; sonilr andcompass go unserviceable. 18.3.1 Open Water Navigation The.taskin.openwateri,qmadestraightforwardby theprovisionof the vessel,s navigationinformationdisplayedon-aVOU is ttrehOV'connolroom. fne n-OV witt be providedwith a sonartranspondelwhShis interrogar"aUvtrtestript iiyoioa"ourti" PositioningReferenceSystemiHPRS).The."tponrl"r.o- tttr RoV is the'n displayed on theelectronicchartandthepilot canseeat a glancehis relativeto thevessel. fosition Navigationaltargetsare_displayed on thecharta"nattr. piioi can,,read,, his course directlyfrom this. The ROV will normallyhaveitsow'nsonarand -rrt.will beprovided with a magneticcompass and probablya gyrocompassur *Jr. .t-pt r"rl, to maintaincourseyhich is checkedby th6'trackon theVou andasttteta'ne" "r.a to tlre targetclosestheRov sonaris.used to-pinpoint therarget.Th" pil"t;;;"d;; informationto negotiatethevehiclein itremostenicieii way to the."quir.a porition. 18.3.2 Navigation Without Electronic Aids On occasiol^it^TayFnecessary to navigateontoa targetwithouttheaidsoutlinedin pagagraph18.1.1.In this caseit will be teggssaryto resorrto under*ai". pilo[g" usingvisualinformation_gained from theROV cl6seactcoit television.The basic coursecanbemaintained_using thecompass but to establishthecourse-aO" eooath" "setand drift" of theRoV mus=t beestimated.Thiscanu" u.rri"uJ;r;.u*f,;%vel by facingthe ROV intothe current,centralisingttreca-era anJtunng thebearinewhen the sediment isobservedio gl9ryq sggpgn$ed becomine aiiedtrv it;h;;;#. Th" rectprocalof this bearingis thecurrentdirection.Havin'gestablished ttresii the drift adjustingtheRoVs positionsotttatitte,suspended particieiare :T,T::l_llP9_!r dnrnngclrectlyacrossthefront of thecamera.The timetakenfor a sel6ctedparticle to passa knowndistancecanberecorded.Theknowndistancecanbethelendh of a manipulatoror some.other visiblepartof theROV. Usingtrt. ii-fr" .quu-ii|,itrr'ut 'uppro*i-ut"ty distancedividedby.gmeequalss.peed apppxrmlion thatz -t ?nd^the equalsI knot thedrift canbeestimated.As exlirience is gainedtttecurienirpe"o *a direction canbeesuy,led"intuitively bul.ini tialiy dd;p;;;;";;, u"i"i g"i *a ryhit" theforegoingshouldbeof some.heip.The setind drifroith" .uo.nt togetheiioitt tt " vehiclespeedcanthenbe appliedto a VetocityVectorrriangre andtheri*ii *a ti-" to thetargetcanthenbeestimated.Thesemeihods.-.nri" thattheRov is navigatedontoa targetusingonly its compass. f83.3 Navigating Around a Structure It is mostimportantthatthepilot makeshimselffamilarwith thestructureby consulting theplatrormdrawingp.Someplatformshaveunderwater identification--t"wrricrr 9d ngvigalionandwherethesearein usethepilot -uit *uti himselfawareof where theyhave\en placed.A hazardto navigation*ound u ,t utt*" is debrisand sometimesfishineline, wherethisis likeiy to be^a-probtem iimust U" antiiipat"Abefore thedive. once th"eROV is on tt" ituiiurc itselfthe_compass maynor be of any assistance asit may uy ft9 magneticfield of trr!-it uctureitselfandthepilot f {rgcte$ mustrely on navigating visuallymuchmdrethanis thecase-in openwater.

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providedthepilot is preparedto sit thevehicle The sonarcanstill be of greatassistance in onepositionandallow the sonarpictue to build. It is vitally importantthattheroute takenaroundthe structureby theROV is memorised by thepilot. This will ensurethe in is not umbilicalfouledup. Thepilot needsto cultivatetheskill of spatialawareness because of this hazard this typeof operationmuchmorethanfor otherROV operations to theumbilical.

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CHAPTER 19 PRINCIPLES OF ROV PILOTING & SONAR 19.1.0 Piloting Competencies 19.l.l This chapteris concernedwith the principlesof piloting ROVs which is often consideredas somethingof a 'Black art'. The aimsof this chapterare to explainas simply as possiblethe competencies (a competencyis a combinationof both knowledgeand skills) that an ROV pilot shouldhaveif he is to succeedin what is a very difficult operar ionalenvironment. 19.1.2 Piloting an ROV is often consideredtoo difficult to teach,but ratheras a setof competencies that only 'talented'peoplecan learn,and only thenby yearsof operating experience.It is clearlytrue that work experienceis requiredfor the Pilot to be fullycapable,but we havefound that the learningprocesscan be considerablyaccelerated by initial Pilot trainingin thesefundamental -ompetencies.

r9.1.3 Althougheachprincipleis easilyunderstood in isolation,thefully capableROV Pilot must incorporatethenrall at onceand this can only be acconrplished by practising them. It is also true,that the progressof the traineePilot is boundto b-eimpeded-if theseprincipiesare not properlyunderstood during his initial trainingperiod as they form a valuable'frarnework'to build uponthrouglipractice. 19.2.0Teamrvork t9.2.1 The ROV Pilot is ottenrenrber of a snrallteamof usuallythreepeople.For the Pilot to be able to operatesuccessfullyhe nrustbe ableto uncierstancltheroles of, and communicatewith the otherteammenrbers.The pilot dependson and must communicatewith the supervisorto takecareof overallsafetyand the operational planning,the observerto keep trackof the vehiclespositionand keeprecords,and the winch man to adjustthe umbilicallengthaccordingto the vehiclescircumstances. Thefirst fundamentulp,rincipLeis thereforethat the Pilot c:anonly be successfulwith the assistanceof the other teammembersand that clear uno,mbiiuouscommunication must exist betweenettchof theseteammembers.. 19.3.0 Navigation 19.3.1 Navigatingan ROV can be anythingfrom very straightforward to extremelydifficult. In open waterthetaskis_madestraightforward by the provisionof a shipsnavigation displayshowingthe ROVs positionrelativeto obstaclbsand targetsusinginfoimation from the shipssurface. navigationsysternand the Hydroacoustic-Position"Referencing System. This systemts howeveroften unavailableand the Pilot may be requiredto navigatein openwater. This is againstraightforward if the targetis"largeenoughto be displayedclearlvon sonar,it is nruchmoredifficLrlt,howevEr,if thelilot is' searching for a smalltargetsuchas a well-heador a transponcler, particularlyif it is

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necessary to estimatethe ROVs'Set and Drift' to the target,allowing for the current directionand speedas outlinedin Chapter18. i) Once the currerltis known,providedthe throughwaterspeedof the vehicleis kno*n allowing for umbilical lengih, then the Set,Drift and time to targetcan be estimatedusingnonrralmethodsof Trianglesof Velocities'

19.3.2 When navigatingaround structuresthe Pilot needsto be familiar with the structure marksan Chapterl8 givesmore informationon this subject. and any ide"ntifiJation 19.3.3 Navigationis assistedby planningthe dive to ensurethat work is carriedout with the optirium visibility. Wheieverpoisible the task shouldbe undertakenwith the vehicle ficing into the currentto preventsedimentdisturbedby the vehiclesown thrusters fromibscuring the work .site.In additionsedimentmust not be unnecessarily. disturbedfrom-thestructureitself or the seabed.Although irt many casesthis is 'easier saidthandgne'carefulplanningand careduring divescan appreciablyimprove the situation. principle is that the pilot must be u.bleto navigate.effecttvelyThe seconclfunclamt:ntal takinguccounto.fcurrent,visibil,ityand umbilical in open *aie, or arountl'structures resirictionsmaking useofnu,t;igationalaids effectively,incLutlingwhere necessary 'Dead Reckoning'. 19,4.0 Spatial Arvareness

19.4.r In additionto beingcapableof Navigation,the ROV Pilot r.nustdevelop_a fig! degree fhat is, he muit not only be ableto go from A to B, but he must of spatialawat'etres=s. to A and with reference be ableto visualisehis relativepositionin threedimensions B. It is very comntonfor ROV Pilotsto be awareonly of the video monitorsand to determinethe vehiclespositionon thisaloneduringtasks. that Pilot will howeverdevelopa senseof spatialawareness The accomplished lhis and enableshim to visualisethe whole situationin threedimensions, transcends ratherlike he was ableto look at a modelof the situationwithout the waterbeing there. In this way he is ableto referenceeverythingto North and know the lie of the umbilicalthroughor aroundstructuresand obstacles. This essentiala6ility comesntorenaturallyto somethanto others,but in all casesit can be improvedby clrawingthe supportvessel,ROV and Umbilical onto working drawingsat regularintervalsduring dives. developedsenseof spatial The rhird principle is rhat the Pilot must havea hi44hl,v awareness.

andSystems 19.5.0VehicleGeometry 19.5.r The positionand powerof vehiclethrusters,and the positionof the umbilical of the vehicles attachmentpointsare particularlyrelevantto the understanding performanci. fhe geonretryof the thrustersaffectsthe pedornlanceof the vehiclein

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the most fundamentalway. It is clearthat a vehiclein the standardconfigurationof two sternthrusters,one verticalthruster,and one lateralthrusterwill behavequite differently to a vehicle having threevertical thrusters,and one horizontalthruiter in eachcorner of the frame at 45 . The latter configurationis more effective in c.ountering the upwardpull of the umbilicaland enablinguniform manoeuvrabilityin the horizontalplane. The attachmentpositionof the umbilical to the frameis also important because,as will be seenlater, the umbilical pull is often very substantial and the point of applicationof this pull can severelyeffectmanoeuvrabitity. L9.5.2 A.knowledgeof the vehiclestechnicalsystemsis againessential.As an exampleof this;.takea hydraulic vehiclethat hasa pump capableof providingan outputo? IOOO PS.I.hydraulic pre^ssure at a maximumflbw rateof 15 Gallonsperfuinute. tf tnis vehiclehasfour thrusterseachrequiring5 Gallonsper Minute at full speed,thenit is clearthat the Pilot will not be ableto demandfull speedfrom eachthrusterat the sametime. In this situationit may be inappropriateto attentptto manoeuvrethe vehiclein turbulentconditionsaroundsrructuieswith the AutomaticDepth and HeadingCircuitsengaged,as the total oil demandedfrom the thrustersmay be more than the 15 Gallonsper Mirtuteavailableresultingin a severedrop in oil piessure hencethrusterpower. The informedPilot may well decideto disengagethe Automaticcircuitswhilst ntarroeuvring in theseconditionto ensurehaximumpower at the thrusterswherc it is nrostrecluired.

r9.5.3 Clearly a knowledgeof all the vehiclessystemsis essentialfor efficientand effective ROV operations anclthe Pilotmustbe well awareof the vehiclescapabilities. Thefourth principle is tlut tha Pilot mustknow the vehtr:les geometry', systemsand performanc'ccapu hi I i ri cs. 19.6.0 Effects of Controls 19.6.1 The effectsand secondaryeffectsof thecontrolsmust be appreciated by the ROV Pilot and theseare not.alwavsas straightforwardas it first seenrs.For'exampleif lateralthrust.is lpplied to a vehicleit nray be expectedto sintplytraverselaterally maintainingits heacling.Howeverit is unlikelylhatthelateralihrusteris positiohed in the exactmetacentreof the vehicle,and thereis thereforelikely to be the secondary of a headingc:hange, or roll which will be requiredto be counteracted. 9{fu-cJ S.imilarly,if a pilot is endeavouringto changethe h^eading of a vehiclehe may well find that the vehiclecreepsforwardas the siernthrusters-nlay well be more eifective when operatingin the forwarddirectionthan when operatingin the reversedirection, this may needto be counteructed by the applicationof rever^-se thrustin association with headingcontrols. Thefifth principle is; thereJore,that the Pilot must know the effectsand secondary effectsof the control inputs. This is often bestestablishediniiialty in a test tank or on the surface,where the Pilot can seethe vehicleand cun monitor ihe eXectsdirectly, but can be quickly ttppreciatedby the experiencedPilot in the work siiuation.

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19.7.0 Vehicle Momentum 19.7.1 The significanceof the vehiclesmomentumis very often not appreciatedsufficiently by PilSts as ROVs behavevery differently to cqq il this respect. Whenturning a co.ner in a car the steeringis simply applieduntil the desirednew direction is achieved,then removed. iire coritrotinput and resultanteffect on the car is shown in Figure 1. The Samecontrol input to an ROV would not, however,have the same efiect. Becausethe car is in contactwith the road, the momentumeffects are minimal. The ROV will, however,continueto turn after the control input has been removed,due to the high momentum and low drag forces (particularlyin the caseof heavycompactvehicles). 19.7.2 A similarcontrolinput to an ROV will thereforeresultin overshootas shownin Figure2. The requiredcontrol input to affecta headingchangeof an ROV would be as"shownin Figuie 3. The ROV Pilot is thereforerequiredto put in an opposite control actionio every initiatingactionto achievethe desiredvehiclemovements. This is a very important skill for the ROV Pilot to attain and becomesapparentas the vehicle descendito seabed,when thePilot is requiredto cotlnleraclIhe rrehrc\e momentumby applyingup-thfuston seeingthe seabed,if he is to avoid touching rp,iifing t'f'eiisiUifity. If the Pil6t.simplyremovesthe down thrust,the ;;;;;"d momentum'ofthJvehicle will ensureit continueidownwardsuntil eitherdr.ag,the umbilicalor the seabedpreventsit, often obscuringthe visibility by dislodging sediments. that the ROV Pitot must be dwore ofthe vehicles The sixth principle is thereJore, with an momentumond be prepured to countcructeach inititttirtgt:rtntrolntovement oppositerno\)enrcnl.

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O 1&3 STEERING WHEEL POSITIONS

Figure19.1 I i

19.7.0 Vehicle Momentum 19.7.1 The significanceof the vehiclesmomentumis very often not appreciatedsufficiently by Pilots as ROVs behavevery differently to carsin this respect. When turning a corner in a car the steeringis simply applieduntil the desirednew direction is achieved,then removed. The control input and resultanteffect on the car is shown in Figure 1. The samecontrol input to an ROV would not, however,have the same effect. Becausethe car is in contactwith the road, the momentumeffectsare minimal. The ROV will, however,continueto turn after the control input has been removed,due to the high momentum and low drag forces (particularlyin the caseof heavycompactvehicles). 19.7.2 A similarcontrol input to an ROV will thereforeresultin overshootas shownin Figure2. The requiredcontrol input to affecta headingchangeof an ROV would be as shownin Figure.1. The ROV Pilot is thereforerequiredto put in an opposite control actionto every initiatingactionto achievethe desiredvehiclemovements. This is a very importantskill for the ROV Pilot to attainand becomesapparentas the vehicledescendsto seabed,when the Pilot is requiredto counteractthe vehicle momentumby applyingup-thruston seeingthe seabed,if he is to avoid touching down and spoilingthe visibility. If the Pilot simply removesthe down thrust,the momentumof the vehiclewill ensureit continuesdownwardsuntil eitherdrag,the umbilicalor the seabedpreventsit, often obscuringthe visibility by dislodging sediments. The sixth principle is theref'orethat the ROV Pilot must be uwore oJ'thevehicles each initittting control movementwith an momentumund be preparetl to courLtcrut:t )\'(tttc ttl. opprtsitetn(

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19.8.0Drag Effects 19.8.1 is the effect of drag on Perhapsthe most crucial factor effecting vehicle p-erformance umbilical can be much on the fact the dragforces particular thai the the vehicle and in in Figure 19.4shows shown The example itself. vehicle the greaterthan the drag on medium sizedwork vehicle forces a typi-al on drag Elearlythe relative iize of these the effect of the also shows The example traveliing at ll2 a knot at a depthof300m. forces. these of direction vehicle, the on umbilicallength,henceangleat the 19.8.2 In this examplethe drag on the vehicleitself is shownto be 20 kg whereasthe horizontalcomponentof tne umbilical drag is 120 kg. This correspoqqsto^atension in the umbilicai of 140 kg at 30 to the horizontal and 240 kg at 60 . SiglLftllntly the upwardcomponentof this forceis 70 kg in the first case(Figure4.) and207kg i1 the secondcase(Figure 5). This neans that in many casesthe primaryforce at a vehicle may well be the upwardpull of the umbilicaland not a backwardsforce as may be expected.For furtherinforrlation on the rnethodof calculatingdragforcessee Chapter18. the The seventhprincipte is that theforcesJ'rotnthe umbilical can be at least ten times 'tight drag force on the vehicleitself, and the length of the umbilical is significant as a stri"ng'tendsto pull the vehicleup off the.iob, rather than exert a purell' horizontal force astern as tnay otherwisebe expected.

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l f9.9.0 Hand/Eye Co-ordination 19.1.0 Hand/eyeco-ordinationis a skill that is partly hereditaryand partly developed through practice. Co-ordinationis generallyover rated as a Piloting skill, as it is just one of the many requiredand not an end in itself . The differencein co-ordination as very few ROV abilitiesbetweenone Pilot and anotheris often inconsequential tasksdemanda very high degreeof co-ordination.It is generallypreferablethat a Pilot hasa good graspof all the principlesmentionedhere,ratherthan simply having highly developedHand - eye co-ordination. The eighthprinciple is that the ROV Pilot must developa high degreeof Hand - eye co-ordination. 19.10.0BE IN IT! 19.10.0 ROVs are difficult to fly becausethey are RemotelyOperated,that is , thereis no 'feel' with them. The capablePilot will, however,imaginethathe is associated actuallyonboardthe vehicle,to the extentthat he nray actLrallylean when turning and 'duck' as the vehicleapproaches obstacles.This is a good trait as being able to imagine.onesself to be ac:tuallyin the vehicleassistsgreatlywith navigationand onentatl0n.

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The ninth principle is that the ROV Pilot should be able to imagine that he is actually 'in' the vehicle,particulurll,wlrcnnavigatingand attemptingto orientatehimself.

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1 9 . 1 1 . 0F a m i l i a r i t l ,a n d E x p e r i e n c e 19.1l.l To be fully competentthe ROV Pilotmusthave'internalised' the principlesand skills mentionedin the previousnine sections.This can onlv be achievedby thorough initial training,as providedat Wray Castle,followed by fanriliarityof the ROV systemoperatedand experienceof thejob in hanC.The pragnraticROV Pilot will alwaystakethe time to familiarisehimselfwith a new vehicleor taskin a sheltered environmentprior to undertakingtheiob for real. The tenthprinciple is that the ROV Pilot will befamiliar wirh the ROV he is operating and will have experienceof tlrc task in hand whereverpossibleprior to the offshore operatbn. 19.12.0 Diffi cult"vComparison

19.t2.r The following comparisonis usedat Wray Castleas a methodof explainingthe degreeof difficultl, experiencedby ROV Pilotsas comparedwith airline Pilots:Imagineyou are to f1y an airlinefrom London to New York. Firstly replacethe aircraft'shigh resolutionradarsystemswith its sonarequivalent, a systemthatis many thousandtinresiessaccurate.Then limit thePilotsvisibilityto aroundthree metres. Arrangefor the wind to blow at around300 Knots with directionalchanges

'6-\

every 6 hours. Finally arrangefor a massivesteelstructurein the middle of the Atlantic oceanand attachthe aircraft to a tetheranchoredto the ground at the other end. Effectively you will be reducingthe information availableto the Pilot and increasingthe externalforces acting on the aircraft. This comparisonservesto enablethe traineeto understandthe natureof thejob and to 'internalising' comprehendthe reasonsfor fully the l0 Piloting principles explained above. 19.f3.0 Sonar Interpretation 19.13.1 In order for the ROV Pilotftechnician to be able to understandand interpretthe sonarsthat are typically usedduring ROV operationsit is necessaryto review the theory. The depth of this review is sufficient to allow the scientifically educated readerto gain an appreciationof the complexity of sonartheory and the factors that affect the ability of a Sonarand its Operatorto detecta target. This review is not intendedto be exhaustiveand the interestedreaderis recommendedto read the appropriatescientific literature. 19.13.2 SONAR is an acronymfor SoundNavigationand Ranging. The term is usedfor systemsthat utiliseunderwateracousticenergyfor obseruationand obstacle avoidance.Sonaris preferredto Radarbecauseof the extremelyhigh attenuationand scatteringthat Electro-Magnetic(EM) radiatedenergysuffersin a highly conductive medium suchas seawater. The AcousticTrianglehasthe sanrepurposeas the ElectricalTriangleusedfor Ohms law andis to showthe relationships quantities responsible betweenthe fundantental for soundtransfer:-

Figure 19.6 Where:- P = AcousticPressure(Equivalentto VoltageV) in micro Pascals. U = ParticleVelocity (Equivalentto CurrentI) in m/s. Z = AcousticImpedance(Equivalentto Resistance R) in AcousticOhms.

286

Then the acousticecluivalent of V = IR is P =UZ and the acousticequivalentof ElectricalPoweris:- Instantaneous AcousticIntensity= PU. The soundvelocity (C) at or nearthe surfacein a watertemperature of 15.5C and a salinityof 34 partsper thousandis 1500m/s.This valuecan be takento be reasonably constantthroughoutnormaloperatingconditions,but allowancesshouldbe madefor its varianceswhen undertakingdetailedsurveywork or similar.

l

1 9 . 1 4 . 0T h e S o n a r E q u a t i o n : The generallyacceptedequationfor the signalto noiseratio (Ns/N) at the transducer of a sonaris:Ns/N = (SL - 2PL + TS) - (BN - DI) Where: SI- rs the SourceLevel in dBs. This variesfrom l0dBs to over 100dllsdependenton the powercapabilityof the sonartransmitter, type, sizeand the directionalityof the transducerarray.

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PL is the propagationlossesfor which thereare the following types:i) i;) iii) iv) vi) v)

Spreading loss. AttenuationLoss. Scattering and Absolution. Heatingby absorbtion. Seabedand surfacereflectionand absorption. Reverberatiorrs.

'IS

is theTargetStrengthand is the echolevel fronr an actualtargetin dBs uhovethe echolevel of a referencesphere.The value ofTarset Strengthis dependent on:i) ii) iii) iv) v) vi)

Sizeof targer. Shapeof target. Orientation of tarset. Internalconstructlonof target. Extentof Anechoiccoatingl. Frequerrcy of transntission.

BN is the Background Noiseandconsistsof thefollowingtypes:i) ii) iii)

Self noiseis that noiseproducedby the receiverand its platform,it can be decreased by good designand maintenance. Ambient Noise is from; Thermal,SeaSurface,Biological, Traffic, Rain, Surf. and Turbulencesources. Reverberations are the portionof the scatteredsound from any reflectingsurfacein the oceanwhich returnsto the l i s t e n i n gt r a n s d u c e r .

DI is ihe Directivity Index of the receivingarraywhich is dependent on the frecluencyand the lengthof the array. Directivity is for exanrplebetterwhen the lengthof the arrayis twice the wavelengthof the ri:c:eived signalthan a quarterof the wavelength.Put anotherway, the transducerarrayneedsto be longerat lower frequenciesto obtain t h c s r r n rdei r e c t i v i t v .

287

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The operatorsability to detecttargetsis also a factor which shouldbe taken account of by the Recognition Differential RD where the RD = NsA.{when thereis a 50Vo chanceof detectionby the operator. The aboveservesto show the complexity of the Physicsinvolved in Sonaroperations. In practice,althoughit is important to be awareof all thesefactors,the experienced operatorwill becomefamiliar with his equipment,the optimum settingsand the displayedinformation in order to identify targets. 19.15.0The Transducer The Transduceris the name given to deviceswhich convert energyfrom one form to another,in the active(ratherthanthe'Passive'i.e.hydrophone)casethis is the conversionof electricalenergyinto soundandvice versa. Thereare two main typesof transducers:Electric Field Types Piezo-electric- CrystalMicrophones,Transnritters etc. Electrostrictive- The alterationof physicaldinrensionswhen under the actionof an electricfield. MagneticField Types - movingcoil. Electrodynamic - nrovirrgiron. Elec:tnlnragrrelic the Of thesethe Electric:Field typesare most conlmon. With all Transducers amplitudeof the signaloutputdependsuponthe signalstrengthover the frequency bandwidth.

Output Signal dBs

Frequency Figure19.7

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Q is the Quality Factor Q = fRBandwidth (W). Q is important in the designof transducersand in an active Rx hydrophonethe bandwidth W should be wide enoughto accommodatethe transmissionfrequencyand the full rangeof Doppler shift while maintaininga high quality factor to attain satisfactoryoutput signal levels. Transducersof the Electrostrictivetype have capacitanceand the only way to measuretransducerdeteriorationis to measurethe capacitanceplus insulationand noise. Transducersare generallyconstructedfrom severalsmallerelenrentsratherthan one larger one for severalreasonsbut primarily to enabledirectionalcoverageto be shiftedfrom MechanicalSteeringto Electrical Scanning,and to improvedependabilityalthoughit alsoimprovesdiiectivity and easesmanufacture.

f9.16.0 Trade-off: 19.16.1 In all casesthe lossesare higherthe greaterthe frequency,this meansthat the Sonars with the highestfrerluencies havethe shortests range. Howeverthe higherfrequency sonarshavegreaterDirectivity enablinggreaterresolutionto be obtained.This means that thereis inevitablya 'trade-offto be madebetweenResolutionand Rangewhen decidinga Sonarsoperatingfrequency. 19.17.0 Transmissionpulses: Thereare two basictypesof transmission usedin modernday Sonar: 19.17.1 The first transntitsa f)'ecluency ranrpand conrparesthe frecprency of the returning signalwith that beingtransrlitted(thedifferencefrecluency)ro obtaintherange. 19.t7.2 The rampedfrequenciesarecontainedwithin a pulseand thereis a blankingperiod betweenpulses. 19.t7.3 The pulserepetitionfrequency(PRF)is increasedas the rangeis decreased enabling the^display(usuallyPPI) to usethe sarnegraticuleson the CRT and simply to usea differentscale. t9.17.4 A major advantageof this type is the fact that the differencesignal can be amplified and listenedto by the operatorwho can thenjudge the rangeof targetsby theflequency; the lower the frequencythe lessis the differencefrequencyairOtherefore the closerthe target. The disadvantageis that theseare often more efpensive than the simplepulsealternative. t9.17.5 The simp_le pulset1,pesimply sendsshortpulsesof soundat one fiecluency.The rangeis determined fronrthe time takenforthe pulsetoreturn. It is-usuaiforthe

289

receiverto be blankedas the transmissionpulse is transmittedto protect the receiver circuits. The headcan eitherbe mechanicallyor electricallyscannedand the returns are usually displayedon a computermonitor where they can be logged on computer disks. 19.17.6 The advantagesof theseare that they are cheap,small andbecausethe data communicationsprotocol allow muliiple deviCessuch as altimetersand profilers to be connectedto a singletwistedpair, simpleto install and versatile. 19.17.7 The disadvantagesare that they transmitonly one frequencymaking them a compromisebeiweenrangeand resolution,and also ir is not possibleto judge the rangeby an audibleoutput. 19.18.0 Example of Ramped Frequency Sonar frequencySonaris the Ametek SeaProbemodel 19.18.1 An exampleof a ran.rped 2504 as fitted ro many Scorpircvehicles.The transmittedpulseis a frequencyrampfrom 107to l22KHz. The iransmittingand receivingheadsare fitted to the front of the vehicleand scanningtakesplaceas the headis turnedeitherin sectorscanmode sonarreturnsthat or continuouslyby an electricaimotor. The audiooutputrepresents havebeenconveriedinto audiodifferencefrequenciesby the receiverand fed into the and{itpluy in the.analyser speaker.The samereceiveroutputis furtherprocessed circuitsand is presentedin PPI forrnaton the CRT. Figure 19.8showsthe display unit for this sonar.

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19.18.2 The operatingcontrolsof the Ametek 250,4havethe following functions:1. CRT: 7 inch CRT thatrepresents targetdatain PPI format. Equippedwith an illuminatedgraticuleand filter. Graticuleis graduatedin 5 degreeinciementsand m^arkedevery 45 degreesfrom 0 degreesrelative with rangerings for determination of targetrange. 2. Threshold cnntrol: Adjuststhe level of intensityat which targetsare displayedand setsthe level for rejectionof low amplitudevideo signalsthat arein the output^ofthe.analyzer.This controlis effectivelyusedto improvethe signalto noise ratio of the displayedinfomrationby rejectingthe low level iignals and noiseleaving only the strongersignalsdisplayed. 3. Illumination control: Controlsthe brightnessof the controlpaneland graticules on the displayunit. 4.

ScanSrvitch: Selectsthetransducer scanmode: ON position:Transducers scancontinuously in a clockwisedirection. OFF position: TransdLlcer scanis halted. SEC_p^ositiort: Transducerscanningis a preset90 degreesscananglecenffed on (X)0degreesautomaticallyreversingat the scanliritits

5.

REV button: Whendepressed, causesthe scanto rotatein the counterclockwise direction. When released,scanis in the clockwisedirection.

6.

RCVR GAIN: Controlsthe gainof the Sonarand markerreceivercircuit, therebycontrollingthe level of its outputto the analyzerand audiocircuits. Increasin_g the gain increasesthe level of the signalsand the noisetogether therebydoesnot improvethe signalto noiseraiio.

7.

POWER Srvitch: Controlsthe powerro the DisplayUnit.

8.

VOLUME control: Controlsthe loudness of the soundheardvia the speaker or headset.

9.

RANGE FT: Selectsrheoperatingrangeof the sysremor rheMarker m o d e . S e l e c t a b l e r a n gaerse ;0 - 2 0 f t , 0 - 7 5 f t , 0 - 2 ( [ f t , 0 - 7 5 0 f t a n d0 2000ft.

10.

MKR Channel:May be tunedto any frequency.Displaysthedirectionbut not the rangeto markerbeacons.

The basicfunctionsof thesecontrolssuchas gain and thresholdare similarfor all Sonarsand a full understanding of thesefunctionsarereqLrired by the operator.

291

ScannedSimplePulseSonar 19.19.0Mechanicall-v

l9.19.r theTritechST325,525 Sonars.are Examplesof MechanicallyScannedSimple_Pulse display A typical Sonars. Avoidance ina iS Imagingand Obsiacle _f91tle1eis areincludedas Figure19.10 It is inoludedur Fig.ir. 19.9and the specifications 'trade-offb-etween.range andresolutionwith theseso that the importantto n6t. the job. For examplethe ST325KHz hasa rangecorrectSonarsan be selectedfor each"degtees, ST725KHz hasa shorterrange.of the 4.5 of 200 metresand a beamwidthof 100 metresbut a grearerresolutionwith ibeamwidth of 2 degrees.In.bothcasesthe which narrows resolutioncan belmprovedby increasingthe sizeof the transducers the beamwidth.

{ R E €

{ o

e s

€ E V)

Figure 19.9 Sonar DisPlaY

Frequency Beamwidth,normal Beamwidth,Big ToP Maximumrange Pulsewidth Scan rate

ST325 325kHz 4 . 5 "x 2 4 " 2.5"x24" 200 metres 60 - 1000psec. 8 - 40" sec.

sT525 525 kHz 2 . 5 "x 2 4 " 1.2"x24" 150metres 60 - 1000psec. 8 - 40" sec.

sT725 725 kHz 2" x24" N/A 100metres 60 - 1000psec. 8 - 40" sec.

Overalllength Overalllength,Big ToP Diameter Maximumdiameter,Big ToP Weightin air Weight in water

1 9 5m m 1 9 9m m 70 mm 1 2 3m m 1kg 0.5kg

1 9 5m m 1 9 9m m 70 mm 1 2 3m m 1kg 0.5kg

1 9 5m m N/A 70 mm N/A 1kg 0.5kg

Depthrating Communications Long line drive Protection

3000metres RS485,RS232 2,200metres Optoisolation Zenerclamping 18- 30 VDC @ 900mAmax Tritech6 pin

3000metres RS485,RS232 2,200metres Optoisolation Zenerclamping 't8 - 30 vDC @ 900mAmax Tritech6 pin

3000metres RS485,RS232 2,200metres Optoisolation Zenerclamping 18- 30 VDC @ 900mAmax Tritech6 pin

Powerrequirements Gonnector/ penetrator

Figure 19.10 Tritech Sonar Specification

292

19.20.0ElectronicallyScanningSonar 19.20.1 An exanrpleof an ElectronicallyScanningSonaris the Tritech SE500. An example of a displayfbr this is shownin Figure19.11. This hasrapidSonarimageupdate of only allowing a 60 degreescanangleratherthanthe ratesbJt hasthe disadvantage 19.12 Figure showsthe Sonarheaditselfand the system full 360 degrees. specifications.

Sonor inrage of platform

risers

Figure 19.11Tritech SE500ElectronicallyScannedHigh ResolutionSonar Displa-v

- rpact, high speedimagingsonarfor

. ROTV, MCM andothersubsea .:tionsthat requireveryfastsonarimage .J\.

Sonarhead

4 persecond Sonarupdaterate,maximum 500 kHz Frequency 60' SectorWidth 64 Numberof sonarbeams 13.4" angle Verticalscan 3' - 13.4" Optionalverticalscanangles 2.7" Horizontal beamwidth 75 metres Maximumrange on range) 100mm (depending Rangeresolution FastFourierTransform Beamformingmethod SDLC@375kBaud Dataprotocol twistedpair Screened, Datatransmission 265mm Length 1 0 0m m Diameter 24 VDC @ 2A Powersupply 300 metres Depthrating 2.5 kg Weightin air 1.25kg Weightin water polyurethane aluminium, Anodised Materials

Figure19.12SE500Headand Specifications

193

! !

19.21.0MultibeamBathvmetricSonar

t9.2r.r An exampleof a MultibeanrBathymetricSonarsystemis the SeaBat9001,shownin Figure19.13. This Sonarsystenldisplaysandupdatesthe sonarimageand afull digitisedprofile of the seabedin real time. The high datadensityallow total area 'footprint' of 90 by 1.-5degreesmakingit suitablefor such coveragewithin a floor mapping. as sea applications

Figure19.13Reson,SeaBat9001MultibeamBathymetricSonarSystem

294

19.22.0ScanningpnrfilingSonars 19.22.1 (usuallydual)Scanning Profilerdisplayis shownin An exampleof a nrultihead theprofileof the to determine 19.14.TheSonaris usedto scanverticallydownwards seabedandanyfeaturesuchasa pipelinethatmaybe acrossit. i

n .i. ar a

{.4 \

Figure19.14TritechSTl000Multi-HeadScanningprofilerDisplay 19.23.0Altimeters Altimetersareused altinreter. 19.23.1Figure19.1-5 showsanexampleof an acoustic theheiehtof thevehiclefronrtheseabed. on ROVsto detemrirre

Altimeters Figure19.15TritechsT200and ST500Precision

195

19.24.0Doppler Sonar L9.24.1The Doppler Sonarworks on the principlethat their transmittedfrequency or decreaseif thereis relative movementof the Sonarwith respect appearsto increas-e toine watercolumnor seabedto preciselydeterminespeedand distancemoved. Figure19.16showstheTritechDS30DopplerSonarandFigure19.17showsthe of this sonar. technicalspecifications

Figure9.16 TritechDS30DopplerSonarUnit

Operatingfrequency Transducer Operatingmooe ............. Operatingrange(forseabedtracking) Trackingmodes ....'..-.... Operatingvoltage Velocitv VelocitYaccuracy Velocityresolution Uodaterate ......."....... Length(inc.connector) Minimumdiameter Depthrating W e i g h itn a i r . . . . . . . . . . . . . . . . . . W e i g n itn w a t e r. . . . . . . . . . . . . ...'...........'.. Communications Analogueoutput.......'....

1 MHz """"""""""" "" 4transducerJANUSanay .. PulseDoppler 2 metresto 30 metres Seabedand Seawater .""" 12 VDC to 48 VDC +o to 3'75 m/sec +2'5 cm/sec +0'5 cm/sec """' 5 updates/sec 365mm ' 95mm """"' 3,000m .."""""-"""" skg """"""""""' 2kg RS-232/RS-485 """' 0-3'75VDC

Figure19.17TritechDS30DopplerSonarSpecifications

296

:

19.25.0 Use of the Sonar 19.25.1 It is important to ensurethat the Sonaris correctly installedand maintained or prior to testing. In particularthe transducerheadsshouldbe_wipedclean as-grease and clean kept be filled this should head is if oil performance and the bit witt impair water free. 19.25.2 Sonarscan be testedin air by turningthem on and observingthat the head scanscorrectly,placing targetsin the beampath in closeproximity to the_headshould indicate Sonai tiansnrii and receivecircuitry is operatingcorrectly. The Sonar manual should be referredto, prior to thesetests,as somemodelswill overheatif operatedfor too long in air. 19.25.3After a successfulsurfacetestthe vehiclecan be deployed.Sonarswill only show echoesthat reflect soundback, suchthat hard shiny surfacesare sometimesonly seenwhen they are at right angleto the Sonarhead,and rough seabedtexturescan blot out smallertargetscompletely. 19.25.4The plan view alsodoesnot showhow high an objectis unlessa shadowis cast,in which casethe lengthof the shadowis relatedto the heightof theobject,its of Sonardatadevellps with range,and the heightof the Sonarhead. Interpretatiorl expirience. Sonarreflectionsof isolatedsmallobjectsgive no indicationof shapeor suchas Platformsor Pipelinestend to haveregular attitude. Man madestructures, patternswhich are easierto identify. 19.25.5Using a Sonaris ratherlike looking at a world madeof shiny black plastic,in the dark, witlionly a narrowtorch beamfor illumination,targetsonly show when the beamshineson thentdirectlyat right angles. 19,25.6 Renremberthat when closeto largeobjects,or in a depressionin the seabed, may give that the viewing rangentay be severelylinrited. Very strongref-lectors in.range. equispaced by being identifled line and are a bearing along nrultipleechoes air their due to produce echoes excellent Fish persist, also reduc:C the Gain. If they obliterate targets. sacsand can often 19.25.7When searchingfbr objects,keepthe vehicleheadingas steadyas possibleto stopthe imageblurring.-Sit on the seabed if necessary.If usinga sidescanmodefor sealching,keepthe vehiclesteady,at longerrangesf1y the vehiclea few metresabove the seabEdto improvethe detectionrangeand quality. Dependingon waterdepth and vehicledepth,therenray be ring like echoes.Thesecan be causedby surfaceor seabed directreflectiortsand may be difficult to avoid. 19,25.8Experiencewith Sonarwill enablethe operatorto be able to quickly setthe Gain, ThresholdanclRangecontrolsto give as evena backgroundas possible,without <;apabilities. theSonarsperfornrance swampingthedisplay,thu.snraxinrising

297

1

I

CHAPTER 20 QUALITY ASSURANCE (QA) SCHEMES 20.1.0 Background to QA Schemes

20.r.r The revolution in the quality of Japaneseproducts,and their consequentincreasein that Global market share,has brbught aboutthe generalbelief throughoutbusiness. 'Quality Marters'. This belief fias permeatedinto the Offshore industry and.it is now ndr-ui for Operatorsto require thbir suppliersto be registered_fo1 1 recognised is ROV Contractors to euality Assuiancescheme. The standaidthat is relevant Council Accreditation National Institute,a British uir.rt6d by the British Standards C"rtifi"A dody and is known as B55750 Part 1 which is the sameas international standardISOEQQ1and the EuropeanstandardEN 29001. This standardfirsr appeared in 1979as BS5750 which was basedon the ministry of defence05 seriesof standards which was updatedwith a lessprescriptive,more flexible framework in 1987. It is this standardthat is now acceptedas the internationalstandardISO9000 which without provides a practicalaction plan for managersto implementquality.standards 'management ionfused by the intangiblesandvagariesof .theso called becoming "The remainderof this chapterwill refer to this standardas IS09000. experts'.

20.1.2 are a meansof ensuringan agreedlevel of.quality TheseQuality Assurancestandards and throughbutthe servicecontractfrom bidding through to job completion/rep.orting r"*eio reassurethe client that the performanceof the contractwill be carriedout to There is a generalconception.offshore, agreedperformanceand reporting slandards. 'paperworkexercise'and 'somethingthat tliat theseQuality Assuranieschemesarea only affectsthe office'. It is the intentionof this c!ap19rto explainthe quality. sysrenland its relevanceto offshoreROV work as a meansto raising managemenr andreducingequiprrlent'downtime'. standards operaiional

20.1.3 procedures nlanagement ISO9000is fundamentallya setof quality policy statements, Assurance but is of standard is the accepted this Quality and work placereferences, ideal e.ncompassing (TQM). is all TQM an only part of totat Quality Management an quality throughout total to and a commitment thai includesattitudeassessmenf quality improve further can organisation.Companiesthat haveachievedIS09000 thiough the implementationof TQM and many ROV contractorsare strivingto achievethis. 20.2.0 The Quality ManagementSystem

20.2.1 The quality managementsystemcan be thoughtof as a threelevel structureas shown in Figure 20.f. fne threelevelsare linked togetherby quality recordsand the auditingprocess.

20.2.2 level wherepolicy, plansand strategicdecisions Level 1 is the Seniorlnanagement poticy manual coversihe quality policiesand planscoming are made. The Quality from the Seniorlevel of managentent..

299

20.2.3 Level 2 is the middle or operationalmanagementlevel which will include the Offshore Superintendentor Team Leaderand the OnshoreProject Manager. This key quaryy group will bi responsiblefor the interpretationand implementationof -th-e The follow. for procedures workable gyeryonelo of the development and ioliiies and are developed which procedures all the Manual covers Procedures Quality implementedat this middle level of the organisation.

20.2.4 The Quatity Policy Manual and the Quality Procedures Manual togetherwith a guide-toworkplacereferencesare often referredto by the genericterm:- The Quality Management Manual

20.2.5 teamitself. The The third level is the workforce which includestheoperational workforce will follow the proceduresandconsulttheWorkplaceReference Documents. lcvel Organisational

Level I

Planning and Polic.v

Documentatiott

Quality Policy Manual

Quality Management

Level2

Management and Procedures

Level 3

Task

Quality procedures or Operations manual

Workplace References

FIGURE20.1 20.3.0The QualityPolicyManual 20.3.1Thisis usuallydividedinto six sections: i)

Introduction

ii)

PolicyStatements

300

Manual

-----l

iii)

OrganisationalStructure

iv)

ManagementResponsibilityand Authority

v)

ManagementReview

vi)

The Quality Managemenrsystemand it relationshipto ISo9000.

20.3.2 The organisations quality.programmeis put into contextin the introduction by introducingthe organisationand its quality managementsysrem. 20.3.3 Thgjt are usuallytwo Policy Statements,the Mission Statementand the Quality Policy Statement An exampleof a Mission Statementmight be:- Company'x' undertakesto deliver the highg_s1 technologyservicepossibleto the custo-ers iatisfaction uny *fr"ir in the world. 'World-wideserviceattemptedwith perfection'. An exampl.e_of a Quality Policy Statementmight be:- It is the Policy of Company 'x'to: Provideproductsand serviceswhich nreeiourclientsrecluirements, by the implementationand maintenance of a costeffectiveQuality Mbnagemeniryri"'and basedon the conceptof 'TotalQuality'in which euerynrenibe.of itaff has accepts.a personalresponsibilityfor q.uality.Thesepolicy statements are usually signedby the seniormanagement of the organisationto indicatetheir commitment and supportfor them. 20.3.4 The organisationalstructure sectionof the Policy Manualwill describehow the organisation works. This will includean organisaiional chartwhichwill show:i) How the linesof authoritythroughoutthe organisationareorganisedaround projectsor functionssuchas; salesor oplrations. How many linesof authoritythereare,and the titlesof the rolesin the ii) hierarchy. iii) What formaliseddirectand cross-reporting relationshipsexist betweenlines of management responsibility. In additionto showingmanagentent rolesthe chartwill show the roleswhich are rpPortantfor the Quality Managementsystemsuchas the Quality vfunug"i anO Quality Inspectors.

20.3.5 The.Management Responsibility andAuthoritysecrion will describe in further

detail.the.responsibilities and reportingrelationships of the rolesidentifiedin the organisational chart.

20.3.6 The Management Review sectionwill describethe systenrby which senior management will evaluatethe Qualitl,Management systent.

3f)l

: i

20.3.7 The Quality Managementsystemand its conformancewith ISO9000 requirements sectionwill describethe scopeof the Quality ManagementSystemand its ielationship with ISO9000requirements.The scopemay be limited by the fact that only somedivisions of the companyareregisteredand by the fact that product Part 1 whilst supplyand designcompaniesarecoveredby ISO9001/BS5750 Productionand Installalioncompaniesare coveredby ISO90028S5750 Part2. In the caseof ROV contractingcompanies;the whole companyis usuallycoveredby Part 1. ISO9001/8S5750 20.4.0 The Quality ProceduresManual 20.4.1 The Quality ProceduresManual is oftenreferredto as the Operations Manual It 'nriddlemanagement' and will is primarily intendedfor the useof the organisations processes in the organisationand the procedures defineand describethe management that must be followed to make theseprocesseswork smoothly. This manual is the systemand setsup a detailedmodelof operationalheartof the quality management how the organisationshouldoperate. 20.4.2 The Management processessectionwill describethe main groupsof management and the role of activitiessuchas:-Salesand marketing,conffacts,projectmanagement member of the as a the offshore supervisoror Team Leaderwho may be considered ROV providers processes suchas for service managementteam. The management 'customer driven'. This meansthat the managementteams Contractorsare usually will behavein a way that providesthe maximum satisfactionfor the client. Some 'technology driven'sucha researchand areasof the organisationmay alsobe development. 20.4.3 manualare The Quality Management Proceduressectionof the Quality Procedures 'the Procedures'.The procedures are thereto inform oftenreferredto sinrplyas: peoplehow to implementall the n'lanagenrent activitiesthat areto be donein the organisation.The proceduresarethereto ensurethat all the peopleacrossthe organisationdo thingsin the sameway which fits with how otherpeopleare working. The procedureswill include:i)

How all the managernent activitiesarecarriedout.

ii)

Who will carry out all theseactivities.

iii)

How the activitiesare to be docunrented.

iv)

A list of the workplaceinstructionsthat will be neededfor referenceand their location.

Procedureswill be focusedon management activities,suchas;ensuringthat contracts are carriedout to the requirementsof the client, and personnelselection,training and reward structures. Training standardsare consideredto be extremelyimportant,if quality proceduresare to be followed,personnelmust know how to follow them. It is preferredif training

302

to recognisedstandards standardsare verified by someform of externalassessment (NVQs). NVQs can be extremely useful as suchas National Vocational Qualification instructions follow workplace partly to on the ability of employees they are assessed as requiredby Quality Assuranceschemes. An important part of the operationsmanualwill however be a descriptionof the duties and responsibilitiesof personnelat every level. An exampleof a typical descriptionof the dutiesof an ROV OperatorMaintainer(This is the sameas Pilotfiechnician and is the term preferredby Cablelaying companiessuch as BT (Marine)Ltd from whoseOperation Manual this was taken)is given below :JOB TITLE: OPERATOR/MAINTAINER To undertakethe safeoperationof Equipment as PURPOSE OF JOB: directedby the Team Leaderor SeniorOperator/lMaintainer. ACCOUNTABLETO:

SeniorOperatorMaintainer

DUTIES AND RESPONSIBILITIES has a responsibilityto:An Operatorfit4aintainer i) Protectpersonalhealthand safety,and to take all stepsto safeguardothers,in line with the BT (Marine)Healthand SafetyPolicy. and to ii) Understandthe companyconceptof Total Quality Managentent, contributeto the continningprocessof improvement. iii) Have an awareness of the potentialdamagethat can be causedby the various forms of environmentalpollution,and to ensurethat all work is carriedout in protection. with the companypolicieson environnrental accordance iv)

Undertakethe safeoperationof subseaEquipment as directed.

v) work, as directedby the Undertakebreakdownand routinemaintenance Senior Operator. vi)

Assistin maintainingrecordsas rerluired.

vii) Undertakenraintenance and modificationwork on Equipment, as directedby the Senior Operator. viii)

Assistin mobilisation,as required

ix)

Assistin the productionof operatinginstructions.

xi)

Assistin applyingcompanyquality assurance procedures.

x)

recordsas necessary. Updatestoresand maintenance

NOTE: Equipment in the abovecaserefersto the Trencher, Plough, Scarab and other specialisedtools and associated equipmentoperatedby BT (Marine)Ltd. This will vary from contractto contractand companyto companydependingon the equipmentoperated.

30-3

20.5.0WorkplaceReferences 20.5.1 The Quality Policy and Quality Proceduresmanualsare providedprimarily for the middle and seniormanagementlevel of an organisation, and as suth are unlikely to be referredto regularly by the ROV Pilot/Technician,exceptto gain an understanding of the policies and managementproceduresas they affect his job. Whilst it is important for the Pilotffechnician to be awareof iheseit is the workplacereferences that will be most essentialto ensuringthat he carriesout his responsibilitiesto the prescribedquality standards.

20.5.2 The ISO9000 standardrequiresthat personnelknow exactly what referencematerials they are_likelyto needand where to find them. It is also extremelyimportant that thesereferencedocumentsare kept up-to-dateand complete.

20.s.3 Workplacereferencescan be eitherinternally or externally generated.Examplesof internally generatedworkplacereferences are:i)

Forms

ii)

TechnicalManuals

iii)

TechnicalInstructions

iv)

TechnicalDrawings

v)

Instructionsand Checklists

VI)

InternalSpecifications and Standards

vi)

Methodologiesfor Testing

vii)

Referenceand ResearchMaterials

20.5.4 Examplesof Forms would include:Daily reports,Dive Logs and Equipment maintenance logs.

20.5.5 Examplesof Technical Manuals would include:the Manualsprovidedby manufacturersfor specificequipment.

20.5.6 Examples of Jgghnical Drawingswouldinclude: workingdrawings for the

equipme^nt.NOTE: It is particularly importantto modify thesedrawings and manuals as modificationsare undertakenon the iystems,for the benefit of otheicrews.

304

20.5.7 Examplesof Instructions and Checklists would include:Pre/PostDive Checklists.

20.5.8 Examples of InternalSpecifications andstandardswouldinclude: video acceptancestandardsand calibrationstandards. 20.5.9 Examplesof Methodologies for Testing would include: calibrationand equipment testprocedures, and proceduresfor handlingnon-conformance's.

20.5.10 Examplesof Referenceand ResearchMaterials would include:Detailsof equipmentand methodsunderdevelopment,and areasof specialistknowledge availablewithin the organisation.Thesewould alsoincluderelevantperiodicalsand researchreports.

20.6.0 Externally Generatedworkplace Referencesarethe laws, standardsand guidelinessetby bodieswhich are outsideyour organisation, but which influence aspectsof what you do. Exarnplesof externallygeneratedworkplacereferencesare:i)

Legislation.

ii)

Industrystandards, codesof practiceand tradeassociationguidelines.

iii)

CustomerSpecifications

iv)

NationalVocationalQualificationswork instructionsor bookssuchas this.

20.6.r Fxamplesof legislation would includeHealthand Safetylegislationsuchas (SI)1019,the healthand safetyat worliact SI 840andthe StatutoryInstruments Controlof Substances Hazardousro Healthregulations(COSHH).

20.6.2 Examples of IndustryCodesof Practiceinclude thoseissued by theAODCsuchas 'The Safeuseof Electricityunderwater'and 'ROV HandlingSystems'.

20.6.3 Examplesof Cu.stomerSpecificationsinclude'Scopesof Work' on Inspection contractsor similar specifications for Ploughing/Cable laying or drill support activities.

20.6.4 Examples of Nationalvocational mightinclude theEnTra Qualifications

engineering. maintenance work instructionsor similarif developedfor this specific industry.They may alsoincludetrainingnotesor handbooks suchas this.

305

20.7.0 It is importantthata guideto workplacereferences existsandis easilyavailableat Manual refersto the everywork site. It is alsoimportantthatthe QualityProcedures workplacereferenceswherevertheyform part of theproceduresandfurther specific procedures for modifyingandupdatingtheseworkplacereferences. 20.8.0 In conclusionit is essential for theROV Pilot/Technician to understand the importance and of followingprocedures, consultingworkplacereferences internalisingtheconceptof 'TotalQualityManagement'for the successful completion of contractsto thesatisfaction of theclient,to ensurethe safetyandproperoperation of theequipmentandto safeguard theirown welfare.

306

Appendices

.

-307

; l l =

t :

it

AppendixA ResistorColour Codes

COLOUR

FIRST

SECOND

Drcrr(A)

DrGrT(B) 2

RED

2

ORANGE YELLOW

a

-) 4

GREEN BLUE

5

VIOLET

6 7

GRAY WHITE

8 9

a J A a

5 6 7 8

MULTIPLIER TOLERANC (D) (c0

100 1,000 10,000 100,000 1,000,000 10,000,000 100,000,000

9

GOLD

+l- 5Vo

SILVER NO COLOUR

+l- l07o +l- 20Va

308

Appendix B Electrical Formula R, C, and L Circuit (Series)Impedance

RL Circuit (Series)Impedence

Z = . , 1 R 2 +( X t -- x O 2

z = " , 1 n 26*1 p 1) Sine-WaveVoltage Relationships

Maximum Value

Effectiveor r.m.sValue Eeff =Ema^ = E*a*=0.707Emax

AC Circuit Current

AC Circuit Voltage E=lZ-

Emax = {Z Geff) = l.4I4Beff

P l=E = Z ExP.F

P 1xP.F

2) AC Circuit Porver True Power

ApparentPower

P=EIcos0=EIxP.F.

P=EI Power Factor P.F.= P

= cos 0

EI

cos 0 = -------!MSSI power apparent 3) Transformers VoltageRelationship E p = N po r E . = E p x \ Es

Ns

Np

CurrentRelationships s = Secondary p = Primary

Ip=Nt Is Np

N = Numberof turns

Z=ZZ

ParallelCircuit Impedance

Zt +Zz

309

AppendixC Formulasand Data (Hydraulic) 1.

power.lt maybe usedto multiplyforceor modifymotions' is a meansof transmitting Hydraulics

z.

in all directions undiminished fluidis transmitted on a confined exerted LAW:Pressure PASCAL'S them. to right angles at and areas and actswith equalforceon all equal and multiplyby .7854. A = D2 x '7854' squareihe diameter To findthe areaof a piston(circle),

A

exertedby a pistoncan be determined The force(pounds) bythepressure inches) thepistonarea(square by multiplying = x P A F applied(PSl).

, ultiply 5 . T o d e t e r m i n et h e v o l u m eo f l i q u i d( c u b i ci n c h e s )r e q u i r e dt o m o v ea p i s t o na g i v e nd i s t a n c e m t h e p i s t o n a r e a ( s q . i n c h e s )b y t h e s l r o k e r e q u i r e d( i n c h e s ) . V o l . = A x L . 2 3 1 c u b i ci n c h e s = O n eU . S .G a l l o n W o r k i s f o r c e a c t i n g t h r o u g h a d i s t a n c e .W O R K = F O R C E x D I S T A N C E E x a m p l e :W o r k ( i n . l b s . ) =F o r c e( l b s . )x D i s t a n c e( i n . ) Work 7 . P o r v e ri s t h e r a t e o f d o i n g r v o r k . P o w e r = - - = Time o.

Force x Distance Time

y o n - c o m p r e s s i b llet .w i l l c o m p r e s sa p p r o x H y d r a u l i co i l s e r v e sa s a l u b r i c a n at n d i s p r a c t i c a l l n P S I at 120oF. a t 3 0 0 0 1 . 1 9 2 0 l m a t e l y0 . 4 o f 1 o / oa t 1 0 O OP S I a n d

9 . T h e w e i g h to f h y d r a u l i co i l m a y v a r y r v i t ha c h a n g e i n v i s c o s i t y .H o w e v e r ,5 5 t o 5 8 l b s . p e r c u b l c f o o t c o v e r st h e v t s c o s i t yr a n g e f r o m 1 5 0 S S U t o 9 0 0 S S U a t 1 0 0 o F .

1 0 . p r e s s u r ea t t h e b o t t o mo f a o n e f o o t c o l u m no f o i l r v i l lb e a p p r o x i m a l e l 0y . 4 P S l . T o l i n d t h e a p p r o x i m a t ep r e s s u r ea t t h e b o t t o mo f a n y c o l u m no f o i l , m u l t i p l yt h e h e i g h ti n f e e t b y 0 . 4 .

c r e s s u r ee q u a l s1 4 7 P S I A a t s e a l e v e l . 1 1 . A t m o s p i t e r ip

1 2 . G a u g e r e a d i n g sd o n o t i n c l u c ea t m o s p l - e r ipcr e s s u r eu n l e s sm a r k e dP S I A . a n o r i f i c eo r o t h e rr e s t r i c l i o tno c a u s e e i i f e r e n c ea) c r o S S T h e r em u s tb e a p r e s s u r ed r o p( p r e s s u r d ' fl o r vt h r o u g hi t . C o n v e r s e l yi,f t h e r ei s n o i l o w , t h e r e w ' i l lb e n o p r e s s u r ed r o p . 1 A

A f l u i d i s p u s h e d ,n o t d r a w n ,i n t o a p u m p . A p u m p d o e sn o t p u m p p r e s s u r ei;1 sp u r p o s ei s t o c r e a l efl o r v .P u m p s u s e dl o t r a n s m i tp o w e ra r e u s u a i l yp o s i t i v ed i s p l a c e m e ntty p e .

to.

a a

p r e s s u r ei s c a u s e db y r e s i s t a n c teo { l c r v A . p r e s s u r eg a u g ei n d i c a t e st h e l v o r k l c a da t a n y g i v e n moment. F l u i d st a k e t h e c o u r s eo f l e a s tr e s i s t a n c e .

1 8 . S p e e d o f a c y l i n d e rp i s t o n i s d e p e n d e n tu p o n i t s s i z e ( p i s t o na r e a ) a n d t h e r a t e o f f l o v r i n t o i t . F l o r v( c u j n c h e s / m i n ' ) o R V e i o c i t y( i n c h e s / m r n . -) A r e a ( s q .i n . ) Flow=VelocitvxArea

310

as the squareof the insidediameter.Doublingthe Flowvelocitythrougha pipevariesinversely i n s i d ed i a m e t eirn c r e a s etsh e a r e af o u rt i m e s . drop)of a liquidin a pipe vary with velocity. 20. Frictionlosses(pressure 2 1 . To find the actualareaol a pipe neededto handlea givenflow,use the formula: A r e a( s q .i n . ; =

GPM x '3208 Velocity(Ft./Sec.)

Velocity(Ft./Sec.)

\JN

GPM 3 . 1 1 7x A r e a( s q .i n . )

2 2 . Theactualinsidediameterof standardpipeis usuallylargerthanthe nominalsizequoted.A conv e r s i o nc h a r ts h o u l db e c o n s u l t e w d h e ns e l e c t i n p gi p e . 2 3 . S t e e la n d c o p p e rt u b i n gs i z ei n d i c a t etsh e o u t s i d ed i a m e t e rT. o f i n dt h e a c t u a il n s i d ed i a m e t e r , subtracttwo timesthe vrallthicknessfromthe tube sizequoted. z+.

Hydraulichosesizesare usuallydesignated by theirnominalinsidediameter.Withsomeexcept i o n s t, h i si s i n d i c a t e bd y a d a s hn u m b e r e p r e s e n t i nt hge n u m b e ro f s i x t e e n t ihn c hi n c r e m e n t s i n t h e i ri n s i d ed i a m e t e r . O n e H . P . = 3 3 , 0 0 0f t . l b s .p e r m i n u t eo r 3 3 , 0 0 0l b s .r a i s e do n e f o o ti n o n e m i n u t eO . n eH . P . = 7 4 6 w a t t s .O n e H . P . = 4 2 . 4B T U p e r m i n u t e .

zo

T o f i n dt h e H . P .r e q u i r e df o r a g i v e nf l o l r a t ea t a k n o w np r e s s u r eu, s e t h e f o r m u l a : PumpOutputH P. = GPlv'lx PSI x .000583= GPlilalqL 1 7 14 T o f i n dt h e H . P .r e q u i r e tdo d r i v ea h y d r a u l ipcu m po f a g i v e nv o l u m ea t a k n o w np r e s s u r eu, s e t h ef o r m u l a : Prrmn

lnnrrt

l__p l

_-

v r Pr v M r Ax P I uS r l ,x \ C . u u0u J0 Q J5 8 3 G Pump Efficiency

vr PM x PSI G 1714 x Pump Efficicncy

l f a c t u a l p u m p e f f i c i e n c yi s n o t k n o v r n ,u s e l h e f o l l o w i n gr u l e o f t h u m b f o r m u l af o r I n p u t H . P . I n p u tH , P . = G F l . l x P S I x . 0 0 0 7

2 7 . T h e r e l a t i o n s h ibpe t y / e e nT o r q u ea n d H P . i s : 43025

T o r q u (el b .i n ) = t : A r i , ' x1 -H' . P-. O B u . or . = T o r q u e( l b . i n . ) x F P \ 1 n 63025

2 8 . T o d e l e r m i n et h e p u m p c a p a c i l y ( G P l ' , 1n)e u . C e dt o e x t e n d a c y l i n d e rp i s t o n o f a g i v e n a r e a ( s q . i n . ) t h r u a g i v e n C i s l ; , n c el , r l c h c s )i r r a s p u ' c r f i tci n r c ( s t - ' c o n d s ) : . 1 - o ^ t P j s t o nA r e a - ( s o . _ i n ,4) L q n g i n ( l p c f e s ) x Q 0 s g . q , = uTtvt _ T i r n e ( s c c o r : d s )x l - r 1 c u , r r .

-1 I I

Appendix D Meteric Unit For Fluid PorverAPPlication QUANTITY NAME Acceleration

METRIC SYMBOLS UNITS metre per secondsquared m/s" o degree minute second mm2 squaremillimetre kelvin per metre watt w/m .K A ampere kg/L kilogram per litre (Note 1) kg/m: kilogramper cubic m g/cm: gram per cubic cm crn3 cubiccn-t L Iitre

U.S.CUSTOMARY SYMBOLS ft/sec2 :

I

Angle,Plane Area Conductivity,Therr.nal Current,Electric hydraulicfluids & other liquids gases Density solids pneumatlc Di spiacement (unit discharge; hydraulic Efficiency Energy,Heat Flow Rate,Heat

mL

llllll

Flow Rate,Mass Ptteutrtittic

Flow Rate, volume hydrarrlic Force Forceper Length

percellt kilojoule watt granrper second kilogranrper second per sec cubicdecinretre per sec cubiccentinletre Litre per ntirtLlte nrillinretreper nrinute ne\.\'toll newton l)er ll"llll hrrrtz_

(Cyclel Freciuency ) Frequency(Rotattonal Heat Specific HeatCapac:ity, HeatTransfer, Cocffic:icrrt

inertiu.Montetttot

o/-

KJ

w

g/s kg/s dnvr/s cm/r/s L/min nrL/rlirt N N/nrnr HZ 1/rtrin

leciprocal tttittute reciprocltltttittttte kilo.joule kilo.jouleper kilograttt kclvin

k . l / k' g ' K

\\'ittt l)er s(ll.lilrellletre kelvin

W/nrt'k

I/min k.l

Btu/hrft oF A lb/gal lb/ft: lb/ft: in: gal ln3

Va Btu Btu/min lb/min lb/s ftr/min (cfm) in:/min (cim) gallmin inr/min tb lb/in Hz (cps) cpm rpm Btu Btu/lb.'F

Btu/hr.ftz'uF

kilognrrtrnlctrc sclultrctl Kg'l1tl

312

mm2

lb. ft2

AppendixE Hydraulic Symbols 1)

: :

Lines

L t N E ,W O R K T N (GM A t N ) L I N E SC R O S S I N G L t N E ,P T L O(TF O RC O N T R O L ) L I N E SJ O I N I N G LINEL . I Q U I DD R A I N

C O M P O N E NETN C L O S U R E

HYDRAULIF CL O W

P N E U M A T IFCL O W

L I N EW I T HF I X E D RESTRICTION

r-_l

t- - ----r

FLEXIBLE

\,,

\J

_)_ STATION, TESTING, M E A S U R E M E NP TO . WER TAKE.OFF O,R P L U G G E D PORT

----+-

FLUIDSTORAGE RESERVOV I RE. N T E D

l

I

L I N E ,T O R E S E R V O I R . A B O V EF L U I DL E V E L . B E L O WF L U I DLE V E L

l

R E S E R V O IP RR . ESSURIZED

V E N T E DM A N I F O L D

3l.i

J {

{

2)

\ / a r i a b l e d i s p l a c e r n e n ltl u m p s

CLO N T R O L M A N U A LH,A N D W H E E

PRESSURECOMPENSATOR CONTROL

COMPENSATOR PRESSURE A N DT O R Q U EL I M I T E R

L O A DS E N S I N G CONTROL

L O A DS E N S I N GA N D P R E S S U R LEI M I T E R CONTROL

ELECTRO-HYDRAULIC CONTROL

314

3)

l i i x e d d i s p l a c e n t c r rpt u n r p s

S I N G L EV. A N E & G E A RT Y P E

SINGLE. W I T HI N T E G R A L PRIORITYVALVE

S I N G L EP , OWER STEERING PUMP W I T HI N T E G R A L FLOWCONTROL A N DH E L I E F VALVES

SINGLE, W I T HI N T E G R A L FLOW CONTROL VALVE

SINGLE, PISTON TYPE W I T HD R A I N

I

\ A -r-\-,/ t

I

DOUBLE. VANEANT) G E A RT Y P E

I

w

-jl5

1 ) D i r e c t i o t r a lc o n t r o l v a l v c s TWO P O S I T I O N TWO C O N N E C T I O N

SPRING CENTERED, A I RO P E R A T E D

TWO POSITION T H R E EC O N N E C T I O N

TWOPOSITION F O U RC O N N E C T I O N

S P R I N GO R PRESSURE CENTERED, PILOTOPERATED

TWO POSITION INTRANSITION

| ,r*r, PostrtoN roun coNNEcrloN I

SPRING CENTERED, SOLENOID OPERATED

I vnlves cAPABLE i or t r u r l r u l r E I pos t r t o r u t r u c 1(HontzotlrAlBARS i t t 'ro t c n rlrN F l N lrE

] rostrtorutruo

SOLENOID CONTROLLED, P I L O TO P E R A T E D

I ABlLlrY) r

_

NOSPFING DETENTED, MANUALLY OPERATED

S P R I N GO F F S E T , MECHANICALLY OPERATED

SPFING CENTERED, SOLENOID CONTFOLLED, P I L O TO P E R A T E D

I

r_L_ t

S P R I N GO F F S E T , LEVER OPERATEDTWO WAY

NOSPRING W I T HD E T E N T S , LEVER OPERATED

o . . _ | 1 . .. .q .

, 1|Y/\ ltlHill ltt;:J lu l

I

l

PFESSURE CENTERED, SOLENOID CONTROLLED, P I L O TO P E R A T E D ( s n 4 P L l F l ESDY M B O L )

r

316

l

|

5)

Proportionalr iilves

PROPORTIONAL VALVE

SERVOVALVES TWO.STAGE SERVOVALVE

CHECKVALVES PILOTOPERATED CHECKVALVE

CHECKVALVE

VALVES DECELERATION ADJUSTABLE DECELERATION W I T HC H E C K VALVE

NON-ADJUSTABLE DECELERATION VALVE

H Y D R A U L IM COTORS VARIABLE DISPLACEMENT, D U A LD I R E C T I O N A L

F I X E DD I S P L A C E M E N T D U A LD I R E C T I O N A L

CYLINDERS S I N G L EE N D , N OC U S H I O N S

S I N G L EE N D ,A D J U S T A B L E C U S H I O NR, O DE N D

S I N G L EE N D ,A D J U S T A B L E C U S H I O N SC, A P A N DR O DE N D S

SINGLE ND, HEAVYDUTYROD

S I N G L EE N D ,A D J U S T A B L E C U S H I O NC, A PE N D

DOUBLEND I

-1 I /

6)

P r e s s u r ec o n t r o l v a l v e s

PRESSURE RELIEF

COUNTERBALANCE VALVEWITH I N T E G R AC LHECK

PRESSURE RELIEFVALVE, SOLENOID CONTROLLED

I

UNLOADING R E L I E FV A L V E WITH I N T E G R AC LHECK Hl-1t))u11tr

R E L I E FV A L V E , REMOTE ELECTRICALLY MODULATED PRESSURE REDUCING

PRESSURE REDUCING \ALVE WITH I N T E G R ACLH E C K

rhtr))unE

R E L I E FV A L V E , CARTFIDGE VALVETYPE

I I I

I

r--.l PRESSURE FEDUCING VT\LVE, CARTRIDGE VALVETYPE

VALVE SEOUENCE

I

VALVE, SEQUENCE A U X I L I A R fY] E M O T E CONTROL OPERATION

r-T-_l

I lf l--e

i |l_l-l--

I IFTI * [ - t -

318

itr5

I

I I I

ffir-?

ryi

-j i

7)

Florv Control valvcs

FLOWCONTROL, ADJUSTABLENON-COMPENSATED

-*-

FLOWREGULATOR WITHREVERSE F R E EF L O W

FLOWCONTROLVALVE

= I - O WC O N T R O LV A L V EW I T H C H E C K SI|'4PLIFIE SD YMBOL)

i E i U O T EC O N T R O L L E DE,L E C T R I C A L L Y ..IODULATED W I T HC H E C KV A L V E

F L O WC O N T R O LA N DO V E R L O A D B E L I E FV A L V E

: R E S S U R EC O M P E N S A T EC DA R T R I D G L .:ALVE TYPE

3r9

A p p e n d i xF

E n g l i s h \ l e t r i c C o t t v e r s i o nF a c t o r s

Into ....----_--->

To convert lnto

MultiPlYbY D i v i d eb y

To convert

Factor

Unit

Symbol

Unit

Symbol

Atmospheres

Atm

bat

bat

1.013250

BTU/hour

Blu/h

kilowatts

kw

0.293071x 10-3

C u b i cc e n t i m e t r e s

cm3

litres

0.001

cm3

millilitres

ml

C u b i cf e e l

tt3

cubic metres

m3

C u b i cf e e t

tt3

Ii t r e s

C u b i ci n c h e s

in3

c u b i cc e n t i m e t r e s

C u b i cc e n t i m e t r e s

C u b i ci n c h e s

in3

1.0 0.0283168 28.3161 16.3871

cm3

0.0163866

litres

D e g r e e s( a n g l e )

r a dr a n s

Fahrenheit

C e l s i u s( c e n t i g r a c e )

rad

0.0174533

Feet

tt

m

0.3048

Feet of water

tl HzO

bar

0.0298907

USfl oz

cm3

29.s735

melres

F l u i do u n c e s ,U S Footpoundsf.

tr lbl

c u b i cc e n l r m e t r e s joules

F o o tp o u n d s / m i n u t o

t1Ibf/min

wails

G a l l o n sU , S

llQ c:l

latres

3.78531

Horsepower

hp

kilowails

0.7457

I n c h e so f m e r c u r y

in Hg

millibar

moar

33.8639

I n c h e so f w a t e r

in HaO

millibar

mDar

2.49089

In c h e s

tn

cenlimeires

cm

2.54

lnches

ln

millrmetres

mm

?5.4

Krlogramforce

Kgl

ne\l1ons

N

9.60665

kEt m

newlcn meires

Nm

Kilogram f. nrelre

1.35582

J

81.3492

9.80665

bar

K i l o g r a mf . / s qc e n t i r e t r s

U JdUCOJ

Kilopascals

kPa

L . r

bar

0.01

Kiloponds

kp

n e,rlo n s

N

9.80665 9.8066s

K i l o p c n dm e t r e s

kpm

n e ! \ 4 0 nm e i r e s

Nm

K i l o p o n d s / s q u a r ec e n l i m e t fe

kpicmz

bar

bar

0 980665

l,'licrcinches

]lln

mtcrons

pm

0.0254

l , 4 i i l i m e l r eosf m e r c u r y

mm ng

mrllrbar

mbar

1.33322

l , 4 i l l i m e l r e so f w a l e r

mm HaO

mrlrrbar

mbar

0 . 0 9t 0 6

N e M o n s / s q u a rce€ n t r m e l r e

N/crn2

oar

0.1

N e w l o n s / s q u a r em e l r 9

l'J/n2

bar

q elre) P a s c a l s( n e w t o n s / sm

Pa

Dar

P i n i sU , S

U S i i qp t

lrires

P o u n d s( m a s s )

to

kitograns

xg

P o u n C J c u b ilco o t

tb/lil

kiiogr;ns/cubic rneire

kg/mr

16.0185

P o u n d J c u b i ci n c h

lb/i'il

k i l o g r a m s , 'ucb r c c e n 1i m e i r s

k9.1cmJ

0.0276799

Poundsforce

lbl

ne$ions

N

4.44822

P o u n d sf . f e e t

t b fh

nesion muir€s

Nm

|.35582

newion nrelreS

Nm

0.112985

raCians'second

raols

o.104770

s q u a r en e l r e s

1p2

0 092903

ine

s Q U a rm eelres

m2

6.4516 x 10-a

ine

s q u a r ec e n l i m e l i e s

cm2

6.4516

P o u n d sf . i n c h c s

lbl in

P o u n d sl . / s q u a r et n c h

l b l ii n z

R e v o l u t i o n g r ni n u l o

r/mrn

S q u a r ef e e l S q u a r oi n c h e s S q u a r ei n c h e s

10 10-5

Dar

0.473163 0.4536

0.06894

"C = 5("F-32)/s F o rm u l t i p i e s P r e l i x e sd e n o t i n gd e c i m a l F l u i dp o w e re q u i v a l e n t s m u l t i p l e so r s u b - m u l t i P l e s 1 b a r = 1 0 5N / m z 1 b a r = 1 0N / c n r 2= 1 d N i m m z l p a s c a l= 1 f J / m 2 1 l i t r e = 1 0 0 0 . 0 2c8m 3 1 centistoke(cSt) = 1 66:75 1 joule = 1 wattsecond(Ws) Hertz(Hz) = cycles/seccnd

320

F o rs u b - m u l l i p l e s

E

A p p e n d i x G H 1 ' d r a u l i cF l u i d s Contamlnant

Character

Source and Remarks

Acidic by-products

Corrosive

Breakdownof oil. May also arise from water-contamination of phosphate-ester fluids.

Sludge

Blocking

Breakdownof oil.

Water

Emulsion

Alreadyin fluid or introducedby system faultor breakdown ol oxidation-inhibitors.

Air

Solublo

Etfectcan be controlled L., ^^r;,^^^f,ri.i, oy anil-roamaooruves. E x c e s sa i r d u e l o i m p r o p e b r leeding, poor systemdesignor air leaks.

lnsoluble O t h e ro i l s

M i s c i b l eb u t I rrdy

Use of wrong fluid for toppingup, etc.

I vdu(

Grease

fu1ayor may not 0e miscible

From lubricationpoints

Scale

lnsolu ble

F r o mp i p e sn o t p r o p e r l y c l e a n e db e f o r ea s s e m b l y .

M e t a l l i cp a r t i c l e s

lnsoluble with cataiy,lic action

May be causedby water c o n l a m i n a i i o cno, n t r o l l a b l e w i t h a n t i - r u sat d d i t i v e s .

Paintflakes

Insoluble, blccking

P a i n to n i n s i d eo f t a n k o l d o r n o t c o m p a t i b lw eithfluid

Abrasiveparticles

Abrasiveand blocking

A i r b o i ' n ep a r t i c l e (sr e m o v ew i t h a i r { i l l e r ) .

Elastomeric parlicles

Blocking

S e a l b r e a k d o w nC. h e c kf l u i d ,c o m p a t i b i l i toyf s e a l d e s i g n ,

Sealingcompound particles

Blocking

S e a l i n gc o m p o u n d s h o u l dn o t b e u s e do n p i p ej o i n t s .

Sand

Abrasiveand blocking

S a n d s h o u l dn o t b e u s e da s a f i l l e rf o r m a n i o u l a t i nooi p e b e n d s .

Adhesiveparticles Lint or labric threads

Blocking Blocking

Adhesivesor jointingcompoundsshould not be used on gaskets. Only lint-freeclothsof rags shouldbe used for cleaningor plugging d i s m a n t l e cdo m o o n e n t s .

: i

i

-r_ I

2 ) I S O V i s c o s i t - vg r l r l e s f o r H 1 ' 4 l ' a u l i cO i l s I ISO I Viscosity I Grade I

Midpoint K i n e m a t iV c i s c o s i t Ly i m i t s K i n e m a t iVci s c o s i t y c S ta t 4 0 o C c S ta t 4 0 o C Minimum '

Maximum

l__l!eYG2 I tsovcg

z.z s.z

t.sa z.Bs

2.42

I' l s o v c s

4.6

4.14

5.06

6,8

6.12

7.48

llsovcT

r |

, i

3.s2

i

' j I

j

llsovcls

1s

13.5

16.s

I |SOVG22

22

19.8

24.2

I tsovcsz

sz

ze.s

ss.z

j

46 58

41.4 61,2

s0.6 74.8

i j

100

90.0

I r s o vc4 6 I l s o vc6 s

I |SOVG100

I

i

11 0

;

I 1 9 9 v G2 2 0 2 2 0 320 I tsovcszo 460 I l s o v c4 6 0 r s o v c6 8 0 _680 I I lsovc1000 1000

1s8 2Bs 414 612 900 _ __ 3 ) C o n r p a t i b i l i t l ' oIf{ 1 ' d r a u l ifcl u i d sa n d s e a l i n gt n a t c r i a l s

ACCEPTABLE S E A LA N O PACKING MATEBIALS

N E O P F E NE , EUNA N

O I LA N D WATER EMULSION

N E C P R EEN, B U N AN , ( N OC O F n

8 U T Y L ,V I T O N ' , VYRAM, srLtcoNE, TEFI.ON FBA

NEOPBENE, B U N AN ,

( N oc o F n

, ' A I RC U B E " E P O X YA S FECOMNIENDED

CONVENTIONAL

CONVENTIONAL

A C C E P T A BEL P I P ED O P E S

CONVENTIONAL

C O N V E N T I O N A L P I P ED O P E SA S F E C O I , , ! M E N D ETD E,F L O NT A P E

ACCEPTABLE SUCIION STRAINERS

1 0 0r " l E s Hw t R E 1 . 1 / 2T [ , 1 E S P U M PC A P A C I T Y

ACCEPTABLE r tLt Eh5

CELLULOSE F t 8 E F ,2 0 0 3 C OM E S HW I R E , K N I F EE D G E OB PLATETYPE

ACCEPTAELE M E T A L SO F CONVENTIONAL CONSTRUCTION

9U55

tittH

?00-300 \ V I F EK , NIFE EUbtr

UH

PLATE

i

PHOSPHATE ESTERS

WATER.GLYCOL MIXTURE

ACCEPTABLE PAINTS

1 O h , l E S H! V I R E 4 T I I , I E SP U h , l P CAPACIry

_i

N O N . W A T E R . B A SFE LUIDS

W A T E R - B A SFEL U I D S MATEBIALS UNDER P E T R O L E U MO I L S CONSIOERATION

242 gs2 506 748 11 0 0

AS FECO[4TlENDED 8YSUPPLIER

50 '\.1ESH W I F E . 4 T I | t , l E SP U M P C A P A C I T Y

CELLULOSE F I B E R 2, O O 300 |"IESHWIRE, K N I F EE D G EO R PLATE

AVOJD GALVAI.lIZED C O N V E N T I O N A L M E T A LA N D CADMIUM PLATING

JZL

CELLULOSF E I 8 E R ,? O O - 3 OM OE S HW I R E ,K N I F E E D G EO R P L A T ET Y P E( F U L L E R ' S E A R T HO R M I C R O N I C T } ' P E M A YB E U S E DO N N O N A D D I T I VFEL U I D S . )

CONVENTIONAL

Appendix H

Hydraulic Pipcs

1 ) P i p e s i z e s b y s c h e d u l en u m b e r (STANDARD) (EXTRAHEAVY) SCHEDULE 40

COMPARISON

SCHEDULE BO

S C H E D U L EDOUBLE

EXTRAHEAVY

tou

IAMETER SCHED. 160

1tB 114 3/8 1t2 314 '| t- v+

1-1t2 z- vz

3 3-112 A

5 6 B 10 1C

.405 .540 .675 .840 1.050 1.3.15 LCOU

1.900 2.375 2 875 3.500 4.000 4.500 5.563 6625 8625 10.750 12.750

.215 .302 .423 .546 .742 .957

,z o J ,c o4

.493 .622 .824 1.049 1.380 1.610

t.zto

1.500

/,uol

LY-ly

2.169 .r.uo6

3.518 4.026 5.047 o.uo3

7.981 10.020 1 1. 9 3 4

2.323 2.900 3.364 3.826 4.813 5.761 7.625 9.564 I l.J/o

.466 .614 . B1 5 1.160 1.338 1.689 2.125 2 624 3.438 4.313 5.189 6.813 8.500 10 . 1 26

DOUBLE EXTRA HEAVY

.252 ,Z+J '+

.599 .896 '1.100 1.503 1.771

4.063

2 ) P r e s s u r er a t i l r go f p i p e s Nominal Pipe Size in.

Oulside Diameter ot Pipe .in.

Number ot Threads P e rI n c h

Length of Eflective Threads -in.

1/8

0.405

27

0.26

1t4 3/8 1t2 3t4

0.540 0.675 0.840 1.050

1B 18

0.40 0-41 0.53 0.55

1

t.J tc

1-1t2

1.660 1.900 z,Jt3

1- tIZ

2.875 3.500

14 11-1t2 11-1t2 I t-tt1

0.68 0.71 0.72

| 1-1t2

0.76

A tt

1.20

S c h e d u l e4 0 (Standard) Pipe lD-in.

Schedule 80 ( E x t r aH e a v y )

Burst Press- P i p e lD-in. PSI

.364 .493

16,000 .302 '13.500 .423 13,200 .546 .824 1 1 , 0 0 0 .742 1.049 '10,000 .957 1.380 8,400 1.278 1 . 6 1 0 7,600 1.500 2.Q67 2.469 3.068

1.939 7,000 2.323 6,'100 2,900

Burst PressPSI

Schedule 160

Burst Press.

Pipe lD-in.

PSI

22,000 19,000 17,500 .q6s 15,000 .614 '13,600 '1 1,500 1 . 1 6 0 10,500 I.JJd

21,000

9 , 10 0 1 . 6 8 9 9,600 z . t z 3 8,500 2.624

14,500 13,000 12,500

Pipe lD-in.

: 21,000 ;^ .434

Burst PressPSI

35,000 30,000

1 9 , 0 0 0 . 5 9 9 27,O00 1 5 , 0 0 0 .896 23,000 14,800 r. 1 0 0 21,000

Workingpressuresfor variousschedulepipesare obtainedby dividingburstpressureby the safetyfactor.

-11-1

Double (ExtraHeavy)

I (ne

,.!,

19,000 18,000

3)

Oil florv velocit]' in tubilrg

Figuresin chartale GPN4florv capacityof tubing,and werecalculatedfrorn fornrula CPI\4=VxA 0.3208 V = Velocity(feet/ second) A = Insidesquareinch areaof tube

F i q u r e si n B o d y o f C h a r ta r eG P MF l o w s

Tube Wall o.D. Thick. n?q

112

.042 .049 .058 .065 .o72 .083 .UJf,

518

.049 .058 .065 .072 .083 .095 .049 .058 .UOJ

3t4

7t8

I

1-1t4

.072 .083 .095 ,1C9 .049 .058 .065 .072 .083 .095 . 10 9

2 Ft/Sec . 9 0 5G P M .847 .791 .670 .620

J.O I

6 . 7 9G P M O.JJ

5.41

7.54 7 . 16 6.60 6.34 6.00 5.66 5 . 16

11 . 3 10.7 10.2 9.51 9.00 8.49 7.73

1.85

o. Yf

1 5 .1 14.3 13.6 12.7 12.0 11 . 3 10.3 9.26

2.08 1.97 1.88 1.75 1.67 1.53 1.39

4.17 3.93 3.76 3.51 3,34 3.07 2.77

10.4 9.8.+ 9.41 8.77 8.35

15.6 14.8

2.95 2.82 2.72

).v

.51 ,43 ,36 .27 .20

3.01 2.85 2.72 2.54 2.10

.03 . 92 6

z.vo

z.c<

2.46 2.30 2.11

.049 .058 .065 .072 .033

650 6.29

J.Oa

370 3.59 J.Z

I

3.00 z.6J

l

5.43 5.23 4.-42 4.60 4.22 7.96 7.65 7. 1 1 7.17 6.81 o.\ z

6.00 5.65

13.2 12.5 1 1 q

6.93 14.8

22.2 2 1, 1

13.6 13.1 12.3 11.5 10.6

19.6 18.5 17.2 15.8

19.9 19.1 18.5 17.9 17.0 16 . 1 15.0

29.9

32.5 31.5 30.7 30.0 28.8

48.7

27.8 lo.t 25.) 24.1

5.00

.065 .o7? .083 .095 .109 .120

9.19 9.00 8.71 8.40 8.4 7.77

18.4 18.0 17.4 16.8 16 . 1 15.5

45.9 45.0 43.5 42.0 40.2 38.8

68.9

12.8 12.6 12.3 11.9 11.5 11.2 10.7

25.7

64.2 63.1

YO. J

1 7. 1 16.9 16.5

6.00 5 . 75 5.50

.065 .072 .063 .095 .109 .12Q - t J {

I

io,u

15.5 15.2 14.7

1J.Z

24.6 23.8 23.0

zt.3

26.1 25.0

o l . $

s9.6 57.4

11,O

3f .d

21.5

53,7

34.2 33.7 32.9

bf,. o

JZ,

I

J t - l

30.3 29.4

84.3 82.3 80.2 77.7 75 . 8 73.4

324

20.8 19.7 18.8 17.5 16.7 15.3

28.2 27.2 26.2 21.6 23.0 21.1

46.0 14.9 43.1 4 1. 2 39.1 37.4 o/.f

65.3 oJ.v

60.3 co.J

94.7 92.1 89.3 86.1 83.7 80.6 128 126 lzJ

120 117 110

30 Ft/Sec 13.6 12.7 11.9 10.8 ' 10 . 1 9.30 8 . 16 22.6 20.4 ron 18.0 17.0 15,5 13.9 na t

29.6 2e.2 26.4 13.v

23.0 20.8 44.3 42.3 10.7 39.2 34.4 J t . ,

39.8 38.2 37.0

3V. /

34.0

51.1 18.2 44.9 42.4

a ) 1

29.9 28.3

.120

o. tq

5.46

10.4

13.0 12.6 12.3 12.0 11 . 5 11.0 10.4 10.0

065 072 083 095 109 120

9 . 0 5G P M 6.47 7.91 7.22 o./u o.4v

1.09

3.98

| -1+

2

4 . 5 2G P M 4.23 3.95

4.65 4.09

.54b

J.Z

1-3t4

1 . 8 1G P M 1.63 1.58 1.14 1.34

zv

Ft/Sec

3 . 10

.049 .058 .065 .072 .083 .095 .109 .120

.UYJ

1-1l2

l c l l o l l s I rvs"" I rvsec I rvsec

64.9 oz.t 61.4

57.4

97.4 94.4 92.1 89.8 do.J

55.U \ ) 1

82.5 IO.a

74.9 9 1. 9 90.0 87.1 84.0 80.4 77.7 '128 126 123 11 9 . 115 112 107

138

171 169 165 160 155 152

ZJT z3J

t ?(

131 126 '193 189 184 179 172 167 '161

247 ZJJ

220

Appendix I

Cl,lindersizeselecfiorr

will e.xertwhen supplied with various working pressures,plus This chart lists the theoreticalpush and puil forcesthat cylinders ji pi"ton vetocitieswhen suppliedwith 15 Ft.lsec. lluid velocitythrough scH 80 size pipe' iriii"*irc

cvl. Pislon

Bore Rod Dia. Dia.

1-112 5/8 1

2

r-

1-3/8

Work Area Sq.In. 1.767 1.460 .982 3.1 41 2.356 1 656

500 883 730 491 tJ/ |

1178 828

1000 1500 2000 750 3534 1767 2651 1325 2 1 9 0 2520 1460 1095 1473 1964 982 736 6283 47 11 31 41 2356 3534 4712 2356 li67 3312 2484 1656 3682 4909 7363 9 8 18 8218 3093 4124 6186 5 1 3 6 6848 2568 3424 3756 s00B 2504 1878

4.909 4.124 3.424 2.504

.^FA

2-112 i-3l8

-S,t 3-114 t1-3t4

B 2-46 6.811 5.891 5.154

4 14 8 3405 2945 2577

6222 5108 4418 3865

12 566 '10.161 9.424 7 657

6283 5080 4712 3B2B

"q425 12566 r-621 1 0 1 6 1 7068 9424

1 96 3 5 16 . 4 S 2 14.726 12.566 1 0 . 04i

961B 8246 7363 6283 5007

1 1-314

4

o

1 25 6 6 1 01. 6 1 3t4 I 424 7 657 '19 635 16492 14.726 3 t 4 12.566 '10.014

28.274 14137 23.365 11682 10602 T.245 1 5 . 7 0 8 7854

21245 1/-524 15904 11i81

4 2827 23365 21205 15708

la.41 1 56548 35047 46730 3 1 8 0 7 A2410 31416 23562

38.485 31.416 2 59 1 9 18850

23861

38,185

15708 23562 3 1 1 i 6 12960 19139 2 5 9 i 9 9425 11137 18850

57i28 47124 38878 28275

50.265 40 644 37.699 26.507

25133 20322 18850 13253

376"09 30483 4 2827 19880

50265 $61,4 37699 26507

78.510 62.636 54.782 40.055

39270 31318 27391 20027

58905 46977 41086 30041

78510 1 1 7 8 1 0157080 235620 62636 93954 125272 187908 82173 109564 164346 54i82 10055 60082 8 0 1 1 0 120165

5-112 7 I

11 3 . 1 0 89.34 74.62 62.84

56550 44670 3i310 31420

84825 6700s 55,o65 47130

7 8 10

153.S4 115.46 103.68 75 . 4 0

153940 769i0 r l q / ( ( 57730 86595 115160 51840 77760 1036t0 37700 56550 75400

2-1t2

3-1t2 ^ 5-1t2

,n 10 o 5-1t2 7

IJL9

'

ll)

12369

3927C 32984 29542 25132 20c28

53905 49476 441t'B 37698 30c42

0850 074 1 0637 0544 0133,

8,1822 70095 63615 47124

1224 1 01 098 1 0680

1 1 3 1 0 0169650 226240 89340 134010 1786E0 74620 1 1 1 9 3 0 119240 62840 94260 1256E0

11.0

11.0

24.0 29.0 43.1 13.5 18.0 25.6 8.6 10.3 ta.q

to.Y

203

9.4 11,5 IJ.J

15.2

1(,{

6.2 1 1

203

20.3

8,3 10.2 4.0 4.7 5.3 62 7.8 4.6 5.6

338

38.465 3 1 . 4 1 6 I 1/4 25.919 1 88 5 0

602

6.0 7.4 8.9 12.3

150795 2176 121932 1759 113097 1632 79521

50.265 40.644 37.699 26.507

83.0

6.4 7.9 8.5 12.0

3400 2711 2371 1734

78.540 62.636 51.782 40.055

339300 4896 268020 3867 223860 3230 188s20 2720

307880 161820 .6664 230920 346380.4998 207360 311040 .4488 150800 226200 .3264

per o f p i s t o nt r a v e l ' O i l . " ^ r , ^ p t i o " i n g a l l o n sp e r m i n u t e= G a l l o n sp e ri n c h x i n c h e s m i n u l e p i s t o n a d i a m e l e r s r ei n i n c h e s . r o d a n d d i a r n e t e r s b o r e C y l i n d e r i n c h e s . c u O i c Z S t i;;il;:

32-s

(

1t0

4 28.?7 23.365 21.205 1 57 0 8

7 6 9 7 0 115455 1666 62832 94248 1360 7 7 7 5 7 1122 51836 1 37700 56550 0 8 6

75398 100530 60966 8 1 2 8 8 56548 75398 4 39760 5301

0 23091 173i90 155520 113100

4.909 4 . 1 2 4 1t2 3.424 2.504

25132 37698 .0544 20322 30483 .0440 18B1B 28272 .0408 r(211 1 22971 .033

9421 7 5 10

2-112 3 3-112

t\l

1.767 1 . 4 6 0 1t2 .s82 3.141 2.356 1t2 1.656

8 296 6.811 3t4 5.891

24888 20433 17673 15162

29.153 2'!738 22089 188.19 15021

I

14

10216 BB36 7731

Piston Size F l o w Vel. GPM ln./Sec. Cu.In.

.0359 .0295 ,0255 .0223

65,Q2 3622 17E2 0308

1'/AA

Gal. 00765 00632 00425 01360 01020 00717

14727 .02125 12372 0 17 8 5 10272 .01482 7512 . 0 1 0 8 4

9635 61-o2 4726 2566 0014

2

12

8296 6 8 11 5891 5154

5301 4380 2946 9423 7068 4968

7657

1-314 2 2-1t2

^

I

2062 1712 1252

3000

BB49 5241 4136 1465

c

5

F l u i dR e q u i r e d P e rl n . 0 f S t r o k e Port

P.S.I. PRESSURE WORKING HYDRAULIC

FluidVelocity 6 15Fl./Sec.

11 3 . 1 0 89.34 74 . 6 2 62.84

t-Uz

o.o

139

a-UL

153.94 I 1 5 . 4 6 2-1t2 103.68 1e

/i

o. I

83

199

8.5 9.8 13.4 6.8 8.6 10.3 It.t

J.U

199

6.6 7.4 10.2

Appendix J Heavy, Medium and Lightweight ROVs (As vesse-lspecifications are tiaUteto change,pleaserefer to manufacturer for current specifications.) a) AN/SLQ-48(V) Mine Neutralisation System Inc. Manufacturer.Alliant Techsystems Work capabilities. Intendedto neutralisebottom and moored lines. Also survey operatiolls. Dimensions. Length 3.70m Breadth 1.20m Height 1.20m Weight tn air l,247kgs Construction GRP frame Operatingdepth. 1000nr. Propulsion.Twin 15hp. 4 x thrusters,2horizontal,1 lateral,I vertical. and tools. Manipulatorand cablecutter,2 low light level cameras Instrumentation and lights. High resolutionsonarand trackingsystem. b) Boxer Compact Manufacturer.SeaeyeMarineLtd. Work capabilities.Inspectionand survey. Dimensions.Length 0.725rr Breadth 0.65m Height 0.50rn Weightin air 70kgs Construction.POlypropylenewith stainlesssteelf-asterlers. Operatingdepth.300nr Propulsion.4 x dc brushlessthrusters.2 horizontaland2 vertical. Instrumentation and tools. 1 functionmanipulatoroptional. CP probe,FMD optional. Cblour CCD camera,2x 150w halogenlampsof varyingintensity. AdditionalTV camerasoptional. Fluxgategyro with compass,depth sensor,auto pilot for depth and heading,sonaroptional. c) Diablo Manufacturer.HydrovisionLtd. Work capabilities.Generalsubseasupport,drilling andconstructionsupport,survey and inspection. Dimensions.Length 2.10m Breadth 1.50m Height 1.70m Weightin air 1980kgs

326

designedto

Construction.HE30 aluminiumchannelspacefrilnre,specially give throughframelift capabilityof 3 tonnes. !

Operatingdepth. l000nr Propulsion.75hp. 6 x HT300 Curvtechhydraulicthrusters,2 axial,2lateral,2 vertical. Instrumentationand tools. 1 x 7 function manipulator,1 x 5 function grabber,low pressurewaterjet. Depth sensor,water alarms. I x Osprey 1323dSIT camera,2 x Osprey1360colour cameras,1 x OspreyCCD BSW low light camera,8 x 250w lights,2 x 400w wide flood lights. Sonarand gyrocompass. d) Examiner Manufacturer.SubSeaOffshoreLtd. Work capabilities.Subseaengineering,subseacompletionsupport,pipelinesupport, platforminspectionand drill rig support. Dimensions.Length 2.00m Breadth 1.95m H e i g h tl . 8 0 n r W e i g h ti n a i r I , 7 0 0 k g s Construction.Aluntiniunrfrante Operatingdepth. 500nrsw. Propulsion.HPU 75 hp, 8 x hydraulicinner spacethrusters.4 x vertical,2 x lateral, 2 x horizontal. Instrumentation and tools. 7 firnctionmanipulator,5 functionnranipulator,provision for specifictooling packages. Sensors.2 x hydraulicpressure,2 x hydraulictemperature, hyclraulicflow, variable buoyancypressure, wateringress. conrpensator vacuum,powersupplyvoltages, cableIRs. Provisionfor 6 canterasrvith separate locus and on/off controls. Expandableto 12 with video switching,provisionfor fibre opticvideomtrltiplexing. Obstacleavoidancesonar',depthsensor,headingsensor,pitch and roll sensors. Auxiliarypowersupplies.Auxiliaryhydraulicsystem.HPU 1tt.75Kw(25hp). Additional datalspecialfeatures.An eyeballROV can be incorporatedinto the systemand mountedwithin the main ROV frame. e ) H y d r a 2 0 14 0

:

Manufacturer.Oceaneering productionsystents. Work capabilities.Drilling andconsrruction sltpporttasks. Dimensions.Length 1.80m Breadth 1.20nr Height l.30rn Weightin air 862kgs Construction6061T6 aluminiumframe.stainlesssteelfittinss. Operatingdepth. 1000nr- 2,50011

-1: I

Fropulsion. 7 x thrusters(2 fore / aft,2lateral' 3 vertical) Instrumentationand tools. 1 x 7 function manipulator,1 x 5 function. ! -Osarey 1323SIT camera,1 x OspreyOE 1335colourcamera,1x Osprey1352 CCD' Photosea1000,2000 or NDT 4000. Auto depth and headingcontrol, fluxgate magneticcompass,digital depth meter,highresolutionsonarand acoustictracking.

0 Hysub5000 Manufacturer.InternationalSubmarineEngineeringLtd. Work Capabilities. Researchand salvageoperations. Dimensions.Length 2.54m Breadth 1.52m Height 1.6[lnt Weightin air 2,091kgs Construction.Anodisedalunliniumframe. Operatingdepth. 5,000rn Propulsion.40hp hydraglicpowerpack,6 x hydraulicthrusters. and tools. 1 x -5functionrateam1,1 x 7 functiottmanipulator, Instrumentation sampleskid for geophysicaltools and sanrplecollection. depthgauge.1x OspreySIT 1323video camera,I x CpSpAC compitet^sy.ttenl, Ospreycolour^CCDf:Ot uiOeocamera,4 x 250-wlights,gyro corltpassand Mesotechsonar. NB Also availableareHysub2-5,HysubATP 10,HysubATP 40, HystrbATP 50 and HysubATP 150. g) MiniROVER MKI I Manufacturer.BenthosInc. and light work capabilities. observation Work capabilities.Inspection, Dimensions.Length 86cnt Breadth 50cm Height 4}ctt't Weight in air 34kgs Conitruction. Altiminium hull, PVC motor housing,rectangularkeel skids. Operatingdepth. 305nr Propulsion.ElectricthruSters,I x lateral,I x vertical,2 horizontal. and tools. Low light high resolutionvideo camera,2 x 150wquartz Instrumentation lamps. halogen NB Also availableMax ROV MK 1, MKII, MKIII andMicroVER.

328

h) MRV (Multi Roll Vehicle) Manufacturer.SlingsbyEngineering Ltd. Work Capabilities.Survey,drill support,intervention, construction,cableburial recovery,salvage(work packageavailableto suit customerrequirements. Dimensions.Length 1.92m Breadth 1.50m Height 1.56m Weight in air 1,590- 2,250kgs(basicvehicle) Construction.High strengthaluminiumspaceframe,stainlesssteel fasteners. Operatingdepth 600m / l,000nr/ 2,000nrdeeperon recluesr. hopulsion Up to 200hp, 4 x horizontal,2x vertical,additionalthrLlsters can be fitted on request. Instrumentation and tools SEL offer a rangeof toolingpackages.Maximum of 5 cameras, mono,colour,stillsor SIT, 3.5kwmax lighting,spotor flood with dimming facility. Auto altitude,autodepth.pitchandroll, heading,trim. Digicluanzdepthgauge,gyro / fluxgatecompass.sonrrrto suitcr.rstonrer rerluirements, pingeland enrergency flasher. i) OffshoreHyball ManufacturerHydrovision Work capabilities Inspectionand observarion. Dimensions Length 0.575nt Breadth0.77nr Height 0.575nr Weightin air 60kgs ConstrucrionFibreglass, stainless steelfittings. Operatingdepth 300m Propulsion 4 electric thrusters,2 fore / aft and rotationalmoventent,2 lateral and vertical movernent. Instrumentation and tools Manipulatorinterfacekit fitted as optionalextra. Digital depthindicator,leak detectionsystem,microphoneto provideaudiofeedbackto the operator,groundfault interrupterartdcircuit breakersto protectsrrrf-ace equipment and vehicle,CP interfacestandard. Remotefocus low light CCD canreranrountedon 360ororaringchassis.2 x 100w quartzhalogenlights,2 x 75w lightson chassis.AC6000 supershortbaseline trackingsystemoptional,AC9000 sonaroptional,magnetic-onrpassand rate gyro compass. NB OffshoreHyball is a more powertulversionof Hyball having 1007amore power.

,j29

j) Phantom Ultimate Manufacturer. Deep OceanEngineering Work capabilities.lnspection Dimensions.Length 1.81m Breadth 1.17m Height 0.97m Weightin air 363kgs Construction.Full perimeterpolypropylenewith stainlesssteelcrash recessedand frameprotectingall components, cameraDons. hardened Operatingdepth 610m, testdepthl62nt xverticalthrusters,2xlateral Propulsion.Electric.4x horizontalthrusters,3 thrusters. and tools. Compatiblewith almostall ntanipulatorsystems. Instrumentation Optionsincludecablecutter,toolsand santplingdevices. includesaudiofeedbackreflectingvehiclecondition,CP optional. Instrumentation PALNTSC, colour high resolution,low light CCD canrera,built in video switch for optionalsecondcamera. Camera/ instrumentplatfomr with 360otilt. 2 x 250w dimmerabletungstenhalogenlights. depthtransducer.Optionsincludesonar,tracking Fluid gimballedfluxgatec'ompa.ss, systemand altinteter. NB Also availableare Phantont300, 500, PhantomDHD2, PhantonlDS4, Phantom HVS4 attdPhantompipeline. HD2, Phantonr k) Pioneer Manufacturer.SubSeaOffshoreLtd. Work capabilities.Drill rig support,generalsurveyand inspectionwork, guiding drill string,leakchecking,bullseyecheckinganddebrisremoval. Dimensions.Length 1.65rn Breadth l.65nr W e i g h ti n a i r l , 3 1 5 k g s aluminiumframe. Construction.Polyrtrerbr.royancy, Operatingdepth 1,525nr Propulsion.50hp power hydraulicpowerpack (pioneerplus has75hp), 5 x proportionallycontrolledthrusters. lnstrumentationand tools. I x 7 functionrnanipulatorwith positionfeedbackcontrol and 1 x 5 functionmanipulator.Vehiclestatussensors,hydraulicpressureand water ingressalarnrsat 12 points,telemetrystatuspanel,low oil alarms. temperature,

330

I

I

:

I x low light camerawith facility for up to 3 additionalcameras.6 x 250w lights. Depth sensor,headingsensor( slaveablegyro),autodepth,headingand altitude, acousticpinger,emergencyflasher,obstacleavoidancesonarwith hydraulic tilt,vehicleturnsindicator,pitch and roll sensors, optionaltransponder.

l) Recon MIA Manufacturer. Perry Tritech Inc. Work capabilities.Drill support,constructionsupport,pipelinesurvey. Dimensions.Length 2.06m Breadth0.90nr Height 0.85nr Weightin air 467kgs Operatingdepth.300nrsw Propulsion.Electric. 2 x axial, 1 x lateraland 1 x vertical. Instrumentation and tools. 2 functionmanipulator,cablecutter,marinegrowth cleaningpackage,5 or 7 functionHerculesmanipulator,5 or 6 firnctionSchilling manipulator.CP probe. High resolutionblackand whitecanler{rwith optionfor colourand SIT camera,panancltilt. 2 x 250w variableintensitylights,sonar,auto headingand trackings),stenr. m) Rigworker MK 4 R3000 Manufacturer.HydrovisionLtd. Work capabilities.Drill suppofiplus firll rangeof work tasks. Dimensions.Length 2.lOnt Breadth l..40nr Height 1.50rrr W e i g h ti n a i r 1 , ( r 5 O k g s Operatingdepth 1,000nr Propulsion.Hydraulicpower pack. 2 x forward/ reverse,3 lateralthrusters,2 vertical thrusters. Instrumentation and tools. lnterfacefor all proprietyof ntanipularors, typically I x7 and 1 x 5 function. Cotrprehensiverangeof tooling alsoavailable. Interfacefor 4 camerasincludingpanand tilt. Auto depth,altitudeanclheading.Provisionto fit proprietary obstacleavoidance sonars.Optionalinterfacefor a full rangeof surveysensorsinc:ludingbathymetric system,dual scanningprofileandpipe/ cablerrackerandgyro. NB Also available,Rigrvorker30001/ R3000S. n) ScarabIV Manufacturer.Oceaneering ProductioltSystenrs.

331

cableburial and repatr. Work capabilities.Telecommunication Dimensions.Length 4.00m Breadth 2.00m Height 2.00m Weight rn air 2,722kgs Operatingdepth 1,850nr Propulsion.Hydraulic, l50hp Instrumentationand tools. 2 x 7 function manipulators,cable gripper and cable cutter. 4 x SIT cameras,I colour CCD cameraand variableintensitylighting. system,acousticpositioningsystem,high resolution Cabletrackingmagnetometer pitch androll sensors,depthtransducers. fluxgate compass, sonar,altimeter, o) Super Scorpio Manufacturer.PerryTritech Work capabilities.Surveyand inspection,includingplatfomr and pipeline,Pre installationsurveysand as laid surveys,diver supportand sub sealemote intervention. Dimensions.Length 2.-50nt Breadth 2.50nr Height 1.90m W e i g h ti n r t i r 2 , 1 0 0 k g s Operatingdepth 1,000ntsw(otherdepthsoptional) P r o p u l s i o n6. 2 h p . - 5x h r , d r a L r ltihcr u s t e r s ,a2x i a l s , 2 l a t e r aaln c l1 v e r t i c a l . Instrumentation and tools. Manipulators,grabbers,suctionarnrs. Standardsurvey junctionbox, optionsincludeCP probe,bathynretric sertsor. Camerasincludepanand tilt andcolourwith suitablelighting. Auto heading,depth, pitchandroll. OptionsSortar,Digiquartz,responder.

AppendixK PropertiesOf CableConductors 1) Copperconductors Attenuetin Loop AWG number Diameter i Km) dB i Km resistance(Q (mm)

0.25s

30

0.30 0.32

30 28

0.40 0.405

28 26

0.50 0 . 5 11

26

0.60

a 1 L+

r a 1

0.644

/_'

107

0.70

z?

0.80 0.90

22

90 69

22 19 19

5-5 -53 44

')

0.91 1.00

2:4 2..23 2..03 r.62 1.61 1.30 r.27 l.0tJ 1.01 0.92 0.81 0.12 0.71 0.65

680 492 433 277 270 177 170

,l

Resistances are basedon purecopperanddo not takeinto accourrtcablemakeup impedanceirregLrlarities assunleabscenceof Attenuationand impedances 2) Coaxial cable Characteristics

M43

Max RF Attenuation impedance capacitanceMax dc overafl pF / m dB/l0m voltage(kVpeak diameter. (O) (mm) voltagekV @100MHz 1.3 2.6 I00 21 5 50

M67

10.3

.50

l(x)

M70

5.ti

75

67

-50

100

50

100

3.5

75

6ti

6

50 -50

100

6

1.5

96

4

1

-A

|

-1./.

-50 -50

r00 r00

r

5

1.25

0.62

96

5

1.25

0.76

50

96

r.9

0.450

1.58

50

r02

t.7

0.400

36.0

Type

}/{16 5 RGsSCAJ5 RG59BAJ6.is RG174AnJ 2.8 1.tl RG178B^J RGI79Bru 2.5 RG213/U10.3 RG214|U10.8 RG223N 5.s RG316 J 2.6

15

40

0.68

l+

6.s l.ti

21

2.6

1.6 3 . 1*

1

* = AttenuationdB / 10m@200MHz

333

A

1.5

1.3 4 . 2* 4.4 a

^

r&5 1400 13r3 1050 1036 839 822 700 652 597 524 468 460 418

Appendix L Umbilical specifications l) MRV Tether

YellowTPRiocket,I 49 mm jocketthickhess: 3.4 mm opprox dTex Aromidbroid,24x10x3360 oPProx mm 40.5 Diometer: YellowTPRoverPURjocket,I 38 mm 2 mm 3.9 mm; PURthickness: TPRthickness: ( t 2 ) l n s u l o t ecdo n d u c t o r..Jl 4 - m m 2

mm,I 1.5 ploincopper19x0.J0 lon'OrCiott I 4.7 mm XLPE, insulotion: ( 1 ) D r o i n w i1r .eJ 4m m Z. ^ ^ 2. mm, 1.5 mrn iohductor:ploincopper19x0.J toPe Loppedcopper/polYester Filler,64.7 mm

/

(O) Ooticolfibresin qel-filledloosetube Stionfeaoroundstedlwirecentre,/ 2.2 mm Tubesize;lD : 0.85 mm; 0D = 2 mm P Ej o c k e t I, 7 . 1 m m fl 4.7 mm Fillers, (5) Droinwires 1 mm2 '1.5 mm,I i o h d u c t o r sp:l o i nc o p p e r1 9 x 0 . 2 6 (4) lnsuloted 0.75 mm2 conductor r x 0 . 3 7m m ,6 1 . 1 1m m i o n d u c t o rp: l o i nc o p p e 7 XLPE,I 4.7 mm insulotion:

diometer:

OpticolFibre Properties: *)

uomPonent M o d e N u m e n c 0 l B o n d Attenuotton Aporturewidthof 850nm MHz*kmdBAm 50/125

Multi

0.2

400

4

for the *)' Note: Thevoluesore corrected of the elements. ouerlength

: *) Properties Electricol C o m p o n e n tRsc o n d R i n s u l Volt. H i g h )00 V D( R o t i n gVolt.test lnll I 1' of 5 min. hm/kmlvlohm*kn

KV

'2/J.J

KV

Currentroting

12 500 2E.J Enn 12 ?/3.5 1 . 3 4m m Z 16 . 1 2 2 . 0 droinwire rnm2 1.34mmZ 1 1. O droinwire -TtToIe: Uo is voltoqeto eorth ' U is line-t5-line-voltoqe 0 ./ 5 m m Z

MechonicolProperties:

Breoking strenoth colcr.tloted

KN 76

Bending rodius recornmended, min-

"lnterstices filled" "Theweiqhtin seowoter oppliesto on ossumed densityof 1026kglm3." seowote-r

Weight

Core

current

1.34 mmZPower 0.75 mm2 Power 1 . 3 4m m 2 d r o i n

5.8 Amp 4.0 Amp 5.8 Amp

I mm2 droin

4.8 Amp

conditions: 25 deg C woter;ombienttemPeroture operotion continuous (5) loversof cobleon winch 85 deg C temperoture m6x 6onductor

calailaled

stotic d v n o m i c o i r seowoter kolkm kolkm mm mm -9 19 2 5

-)-12+

2) MRV Umbilical

(2) Controhelicol loyersof greosed,preformed, ioivonisedsteelwir-es2260 N/mm? iirst lover: 45 wires6 2.3 mm secondlover:60 wiresI 1'9 mm to minimise Theloyeriore bolonced torque& rototion,I 4J.6 mm BlockPURiocket,F 35.2 mm jocketthicliness: 2.2 mm (26) lnsuloted conductor2 mm? i o n d u c t o rp: l o i nc o p p e r1 9 x 0 . J 7m m , / 1 . 8 5m m XLPE,I 4.7 mm insulotion: ( t 2 ) O o t i c of li b r e si n q e l - f i l l e dl o o s et u b e centre'I 0'9 mm oroundsteel-wire Str
C o b l ed i o m e t e r: 4 3 . 6 m m .

( 5 ) D r o i n w i r e1sm m 2 i o ' n d u c t opr :l o i nc o p p e r1 9 x 0 . 2 6m m , 6 1 . 3m m

OPticolFibre ProPerties: *)

u o m p o n e n (M O 0 e NumencoltsondAttenuotton Aporture width ot 650nm MHz*kmdBlkm 50/125

o.2

Mult

400

4

ElectricolProperties: *) C o m p o n e n t sR c o n d

Volt. H i g h r00 V DCRotingVolt.test l ^ / 1 11 1 of 5 min. KINSUI

10.?

1 mmZ

708

1) ' Note:

500

for the +) Note: Thevoluesore corrected of the elements. overlenoth "Theweiohtin ,.onot.r oppliesto on ossumed densityof 1026 kglmJ." seowotdr

KV

/ohm*kn

2 mm?

"lnterstices filled"

t.2/J.t

roting Current

orornwrre

Core

Uo is voltogeto eorth U is line-to-line-voltoqe

MechonicolProperties:

Breoking strenqth calculated.

KN

594

Weight

Bending rodius recommended *-itt-

stotic d v n o m i c mm rnm

kolkm

4170

2 mm?Power

6.1Amp

1 m m 2dr oin

3.9Amp

conditions: 45 deg C still oir; ombienttemperoture operotion continuous (5) loversof cobleon winch 85 deg C m6x ionductortemPeroture

calcttlated

olr

current

seowoter

kolkm

J2J5

33,5

3) Lightu'eightROV Urnbilical

YellowPURjocket,/ 37 mm jocketthickness: 2.5 mm (2) Controhelicol loversof oromid. topeoi eochloyer,I 3'1.9mm Non-woven BlockPURiocket,F 26 mm jocketthicliness: 1.2 mm (12) lnsutoted conductor2.4 mm? ionductors:ploincopper19x0.4mm, 6 2.0 mrn PP,I 4.6 rnm insulotion: Aluminium topescreen,/ ?3.5 (6) Opticolfibresin gel-filledloosetube Stronded oroundsteelwirecentre.Q 2.2 mm Tubesize;lD = 0.8 mm; 0D = 2 mm P Ej o c k e t /, 7 . 1 m m (12) Intersticiol 0.88 mm2 droinwires ionductors:ploincopper7x0.4mm, Q 1.2 mm topescreen,/ 14.3 Aluminium droinwire 2.4 mmZ lntersticiol c o n d u c t opr :l o i nc o p p e r1 9 x 0 . 4m m , I 2 . 0 m m (2) lnsuloted conductors 2.4 mm? ploincopper19x0.4mm, f, 2.0 mm dohductor: insulotioP n :P , 6 4 . 7 m m

C o b l ed i o m e t e r: 3 7 m m .

"lnterstices filled"

quod[4x0.5mm2] Twisted shielded ploincopper7x0.3mm, / 0.9 mm conductors: tope. PE,I 1.6 mm. Twist& polyester insulotion: (5x0.2flot) tope & droinwires Aluminium 2-poss PEjocket,fr 7.1 mm

Properties Electricol : *) R i n s u l Volt. High C o m p o n e n tRcond s t00 v D( RotingVolt.test of 5 min. ).4 mm2

2.4 mm?

8.6

500

7.+ mm.1

9.5

O . E Em m 2 l Q U . bm m z

24

drornwrre drornwrre

+1

500

*) Note: Thevoluesore corrected for the of ihe elements. overlength "Theweightin seowoter oppliesto on ossumed seowoter densityof 1026kg/m3."

KV

)hm/kmlMohm*kn 8.9 500

I LJ

JJOO

to

60 Component:

OoticolFibre Prooerties: *)

5.5 Currentroting: conditions: operotion. still oir. continuous ombientoir temperoture: 45 mox.conductor temperoture: 75 5 loyersof cobleon winch.

ComponentM o d e NumericolB o n d Attenuotion Aporture width ot 850nm MHzrkm dB/km 50/125

tJ.'l

Multi

400

4

M e c h o n i cP o rl o p e r t i e: s Breoking strenoth calailated,

KN 195

Bending rodius recqnmended min^ slotic dvnomic

mm

mm 608

power cores 2.4 mm2

Weight

Amp

deg C deg C

83.8 48.+ Voltogedrop (V/km): 2292 (l-ph) sJsJ (J-phj Supplyvoltoge(V): (Hz): 60 60 frequency 70 ienip.(deqC): 57 con'ductor (A): 5 currentper cohducto? J.5

calculoted,

orr seowoter ko/km kolkm 1425 320

336

.f) IvIRV Conductor idenri[ication

B

K

c

I

Coblediomeler:44.2mm

"lnterstices filled" "Theweightin seowoter oppliesto on ossumed seowoter densityof 1026kg,/m3."

Ooticol Fibre Properties: Component M o d e N u m e n c o l u o n d Attenuotion Aporturewidthof 850 nm MHzlkm dB,/km

50/125

Multi

o.2

+

MechonicolProperties:

Breoking strenoth colcdated,

ElectricolProoerties:

Bending rodius recorntnended

*) Note: Thevoluesore corrected for the overlength of the elements.

tnill^

Weight

C o m p o n e n tRsc o n d R i n s u l Volt. High i00 v DcRotingVolt.test of 5 min-

calculated

stotic d v n o m i c o t r

KN EE7

mm

mm 551

seowoter ko/km ko/km

6800 5 2 0 0

KV

hm/kn / o h m * k n

4 mm? 4 mm2

5.2 5.2

500 500

2000 -(1En

I U

15

:

:

: l I : : l l

ITEM NUMBERDESCRIPTION A

2 4

Fiber-opticunits,eochcomprising: Opticolfibresin qel-filledloosetube. Tubesize:lD = 0'.Emm, OD= 2.0 mm Stronded oroundo centrolsteelwire/ 0.9 mm PEjocket,I 5.8 mm Powercores4 mm2 - 2kV Conductors: ploincopper19x0.52mm, / 2.6 mm Insulotion: PP,I J.8 mm

c

PEjocket,I 12.7mm jocketthickness: 0.5 mm Ploincopperwire/ polyester yornbroid.6 13.4mm Ploincopper12x8x0.2mm / Polyester12x2x1100 dTex Coveroge of copperportl.64 % Loyerof non-woven tope0.2 mm, lopped.

12

Powercores4mm2-JkV Conductors: ploincopper19x0.52mm, / 2.6 mm I n s u l o t i oP n :P ,I 4 . 4 m m Loyerof non-woven tope0.2 mm, lopped. Ploincopperwire/ polyester yornbroid,/ 24.3mm Ploincopper24x8x0.25mm I Polyester24x2x1100dTex Coveroge of copperport:65 Z PURjocket,/ 28.4 mm jocketthickness: 2 mm opprox Controhelicol loyers. of preformed, greosed, golvonised steelwires1960N/mm2 Firstloyer: 42 wiresf, 2.0 mm S e c o n dl o y e r5: 8 w i r e s/ 1 . 0 m m Thirdloyei: 46 wiresQ 2.5 mm Fourthioyer: 58 wires6 2.0 mm The loyersore bolonced to minimisetorque& rototion,6 44.2mm

338

5 ) S u p e rS c o r p i oU m b i l i c a l

J x Twisted Conductor 0.5mm2PloinCopper[7/.3] to 01.65 lnsulotion Polyethylene Tope& DW Ali-Polyester Shield to 14.8/5.'lmm Polyethylene Jocket

r) Note : The voluesore correctedfor the overlengthof the elements. "lntersticesfilled."

CooxiolQ4.8mm 4x75Ohm 0.22mm2PloinCopperlltO.Zl Centre to /3.5mm Dielectric SolidPolyethylene PC Broid [Cover95%] Screen to /4.8mm Polyethylene Jocket 6 x LowPow e r C o r e s9 1 . 7 m m Conductor 0.5mm2PloinCopper lttO.Sl to d1.7mm Insulotion Polyethylene & DroinWire TopeShield Ali-Polyester InnerJocket Polyethylene to l16.4mm Moteriol Thickn ess 0 . 8 m mR o d i o l 15 x PowerCoresl4.0mm C o n d u c t o r: 4 . O m m 2P l o i nC o p p e rl l S t O . S Z l to 64.1mm Insulotion : Polypropylene Jocket Bedding lo l26.2mm Moteriol : Polyethylene T h i c k n e s s: 0 . 8 m mR o d i o l SpirolScreenPloinCopperWiresoverCu Tope Sheoth Bedding to l30.6mm Moteriol : Polyurethone T h i c k n e s s: 1 . 9 m mR o d i o l

N o mC o b l ed i o m e t e:r 3 8 . 0 m m . "The weightin seowoteroppliesto on ossumed seowoterdensityof 1026 kglm3."

StrengthMember : Stondord Modulus Aromid Broid

ElectricolProperties: *)

OuterJocket to l38mm Moteriol : Polyurethone T h i c k n e s s: 1 . 9 m mR o d i o l

ComponenisRcond R i n s u l Volt.

High Volt. test 500v D( Roting of 5 min. )hmlkn ilch m * k n KV q )C 4.0 mm2 5 500 3000 'C U.5 mm 4J 60 500 CooxCentre 9 4 500 600 3.6

CooxiolProperties: *)

MechonicolProoerties; Breoking strenoth calaiated"

KN 9E

Bending rodius recorntnended nbt

Weight

ComponentsC o p o c l m p e d . ot r t l k H 10 MHz

colctlaled

stotic d v n o m i c seowoter mm mm kolkm kolkm

1966

EOJ

339

oF/m

7 5 O h mC o o x 7 1

Attenuotion

dBl100m 0 h m 1 M H z l SM H z10 MHz

75

1 . 4 5| 2 . 4 5 4 . J

Appendix M Video Commonly accepableTV camera F
Country

B&W Standard

Antilles Netherlands RS-1170

ColourStandard NTSC

Argentina

CCIR

PAL

Australia

PAL

Bahamas

CCIR RS-170

Belgium

CCIR

PAL

Brazil

CCIR

PAL

Brunei

PAL

Canada

CCIR CCIR RS-170

NTSC

Chilie

RS-170

NTSC

China

CCIR

PAL

Columbia

SECAM

Czechoslovakia

CCIR CCIR

SECAM

Denmark

C C IR

PAL

Finland

C C IR CCIR

PAL

Bulgaria

France

NTSC

SECAM

PAL

CCIR C C IR

PAL PAL

Hungary

C C IR CCIR

India

C C IR

PAL

Indonesia

CCIR

PAL

Italy

PAL

Japan

C C IR R S -1 7 0

South Korea

RS-170

NTSC

Malaysia

PAL

Mexico

C C IR RS1 - 70

Netherlands

CCIR

PAL

New Zealand

CCIR

PAL

Norway

PAL

Peru

C C IR RS1 - 70

NTSC

Philippines

RS-170

NTSC

Poland

CCIR

SECAM

Portugal

C C IR

PAL

Romania

C C IR

SECAM

Germany Greece Hong Kong

SECAM SECAM

NTSC

NTSC

340

Countr-v

B & W S ta n d ar d

ColourStandard

SaudiArabia

C C IR

SECAM

Singapore South Africa

CCIR CCIR

SECAM PAL

Spain

CCIR

Sweden

CCIR

PAL PAL

Switzerland

CCIR

PAL

Taiwan

R S -17 0

NTSC

Thailand

CCIR CCIR RS-170

PAL PAL NTSC

Venezuela

CCIR RS-170

SECAM NTSC

Yugoslavia

C C IR

PAL

United Kingdom United States U.S.S.R.

For TypicalUnderwaterVideoCameras Specifications Osprey 1382 CCD camera i) Electrical Resolution

320 lines

Sensitivity

0.9 Lux (faceplate)

Pick up Device

CCD (q inch format) Interlinetransf-er

Signalto noiseratio

> , 4 Ud B

Scan

625 line I 50Hz PAL fbrnrat

HorizontalFrequency

15.625KH2

satiolr Auto light con'lpen

15,000: 1

Power

ConstantVoltage16 - 24Y dc (0.6A)

Video Output

I . O VP K - P K

ii) Environmental Waterdepth Temperature

I (XX)rnetres(deeperratingsavailable) Operating-5('C to +400C

Optical StandardLens

li.5nrm f:1.6

Iris

Automatic

Focus

Remotevia telemetr),l0nrm to infinity

Angle of view

600 Oiagonal(in water)

3ll

iii) Mechanical Size

Length:327nm Diameter:104mnr

Weight

Air 3.9Kg.Water0.8Kg (Branter) Sea-Con XSL-5-BCR

Connector Connections

Port Guard

Pin 1.Ground Pin2. PositiveSupply Pin 3. Telemetry(+) Pin4. Telemetry(-) Pin5. Video Removable stainless steelmesh

Osprey 1323S.I.T Canrera i) Electrical Resolution

>600televisionlines

Sensitivity

-5x 10-aLux

Tube type

1 i n s .S . I . T .

Signalto noiseratio

40dB

Scan

625I 50H2,525I 60Hz available

Horizontalfrequency

1 5 . 6 2 5 K H 21,5 . 7 5 K H 2

Auto light compensation

7 5 , 0 0 0 :1

Power

Constantvoltage16 - 24 v dc (650mA)

Video output

1 . 4v o l t sP K - P Ki n t o 7 5 W

Bandwidth

l2MHz (- 3dB)

ii) Environmental Water depth Temperature

1(XX)m _-50C to +400C

iii) Optical Standardlens

5 . 5 m mf : 1 . 5

Iris

Autonraticmotorized

Angleof view

l 1 0 od i a g o n ailn w a t e r

342

iii) Mechanical Size

298mmlong, lOOmnrdianreter

Weight

A i r 3 . 7 K g ,W a t e rl . I K g

Connector

5 pin Sea-Con(Branter)type XSL - 5 -BCR

Connections

Pin 1. Ground Pin2. Positivesupply Pin 3. Focus(N/A) Pin 4. Focus(N/A) Pin 5. Video

NB Dimensionsareexcludincconnector.

)

-r+-)

Appendix N

Dive Exercises

Dive Exercise l. Surface Navigation And Control Familiarity Referto the diagranrshowingthe Wray CastleROV OperationalTraining Area. The objectivesof this exerciseis to practicecommunicationsbetweenthe Deck Officer and the Pilot, and to gain familiarity with ROV controlsand their effects,particular attenrionshouldbe given to directionalorientationand field of view/scaleof video cameras. i)

Pilot the ROV on the instructionsof the Deck Officer to the most Easterlyleg of the wooden.letty(TargetArea A). The ROV shouldbe on a Westerly Heading.

ii)

Pilot the ROV to rhe most Northerly leg and back againto surveythe South Easterlysideof the Jetty.Care shouldbe takento allow for the reductionin the targetsizedue to the effectof the cameralens,it is inrportantto manoe^uvre 'snagging'. video recording of each A vehicleaway from the targetto avoid Jettyleg shouldbe nradewith descriptiveconlnlentary.

ii)

Followingrheinstructions of theDeck Officermanoeuvrethe ROV into the middleof the areabetweentheJettyand the wet dock, thenfollow his instructionsto takethe ROV on the surfaceout on a headingof 0100for at least 50 metresthertturrtitttdreturnto the launchpoint.

to usethe NOTE: At the discretiolrof the instructorthe studentcan be ertcouraged by following legsor on retumingfronr the lastnranoeuvre verticalcontrolon the.jetty, wherethe student the Lake bed backro rhelaunchpoint.This canonly be encouraged with theexercises on the suditce. contpetence hasdemonstrated 'stab-in' D i v e E x e r c i s e2 T r o n i c R O V M i n i C e C o n n e c t o t ' is Target receptacle TrainingArea,theconnec:tor Ref'erto thediagrantof theOperational Area C. on A typical The obiectiveof this cxerciseis to practiccc:ontrolco-orclinittion problern. intervention i)

Referringto thediagranrsof theTronic ROV rrini CE Plugiind receptacle, ensuringthatthelocatinglug is attachtheplugto theViking ROVsmanipulator Positionthe manipulator rec:eptacles orientation. sideto nratchthe on thecorrecrt video camerawhen plug in view of the will be horizontal and suchthatthe submerged.

ii)

Launchthe vehicleanclnavigateunderthe instructionof the Deck Officer to the rargetuea. Align thevehiclewith theplateandbeconrefanriliarwith distance/ (Cameraperspective) whilst underthe instructionof video imagerelationship the Deckofficer and thevehicleis on the sudhce.

iii)

Usingthe verticalthrustercontrol,dive the vehicleto thecorrectdepthand, Gain full controlof align the plug with the receptacle. allowingfbr perspective, to locatetheplug at this stageand setthe trims to thevehiclebeforeatten.lpting maintainpositionas accuratelyas possible.

iv)

GENTLY nrovethevehicleforwardmaintainingalignmentandplacethe and apply connector.It is importantto allow for the vehiclesntorlentul"n

344

reverseihru:ter BEFORE actuatcon&rt to avtid hiuiry th urFt wift ary signitlcanttorce anddanraginethe .-onnerncr v)

thenapplyinga thevehiclerrim andalignnrent Remoretheplugb1 ntainrainine sharpfull re\erserhrusrcraction.Returnthe vehicleto it standoff positionat of the DeckOtficer. thediscretiorr

D i v e E x e r c i s e3 . S t r u c t u r a l S u r v e y Referto rhe Diagrantsshowingthe OperationalTraining Area and the structural drawings.The structureis locatedat targetareaB. The objectiveof this exerciseis to plan,carryout, andrecorda full structuralsurvey. i)

nreetand plantheoperationin detail. The teantshoLrld

ii)

The Safetyboatshoulclproceedto the targetareartnddrop a nrarkerbuoy in the vicinityof the stnrctrrre.

iii)

of theDeck Officerbe andunderthedirections The vehicleslioulclbe launched navigated to thenrarkerbuoy.The vehicieshouldbe divedfbllowingthe markerbuoy line to within sightof thelakebed.Usingthenrarkerbuoy asa referenceanclthe vehiclesonarandcompassthe structureis to be locatedand to therrtarkerbuoy rec:orcled. the positionwith ref-erenc:e

is to renrainin thevicinityof theTargetto rhesafetl,bout NOTE: DuringalloPerations LakeLtsers. warnoff appnltchingrecrelttional iv)

asntuchdetailas lecttrclittg is to be unclertltkett A logiculsurvcvot'thcstnlctLlrc The instructor inclucling CPPu'hereuppropriitte. possiblein rhetintelrliou'ecl principlesltttclrccordingnlethods inspection will givc guicltnccon csttblislrecl as theexerclsel)ro_grcssL's.

v)

data,logsand itnclall clrawittgs, thevehicleshoulcilrerec:overed On conrpletion for assesslllent. vicleotapesgivento the instructor

3.r5

WRAY CASTLE ROV OPERATIONALTRAINING AREA

---+

Target AreaC 'Stab-in' Connector

Target AreaA (Jetty)

-

70mal Target AreaB (Structure 30'Depth)

Launch Point

N

tI I

I

LakeWindermere - _ -'-.-.'-\\

/

346

TargetB - SteelStructure

tI I

Platform North

./

,4

500mm

'15mm Holes

frP

\,

Whiteplateweldedto MA43and MA31 horizontal members

PlanView (asseenfromabove)

347

PlatformNorthEastFace

Tubularo Estimated

". .

Anode (Active) 0% Wastage

Leg 2 SteelPlate with2 Holes

NorthWestFace VerticalDiagonal SleeveWelded 4.'t\ \os ontoMC44

BottomNodeObscurred by MudSuspectStructure SettledintoSeaBedon Leg3

FineSiltyBottom No Evidence of Scouror SeabedErrosion

348

TwoWhite Band

PlatformNorthWestFace

Anode (Active) 0% Wasted

SingleWhite Band

BothLeg1 andLeg2 BottomNodesBuriedin SiltSuspect SouthEastFaceSettledintoSeaBed

FineSiltyBottom No Evidence of Scouror SeabedErrosion

3-19

PlatformSouthFace

E E

o o

O N

FineSiltyBottom No Evidence of Scouror SeabedErrosion

350

l

351

I Appendix O

Examples of Exercises

Question I With the aid of the servicemanualcarry out a full inspectionof the Fl1 fixed displacmentpump/motor.On completioncompile a reportindicatingthe following:a

What componentswereinspected?

b

What conditionthey werein?

c

The effect of faulty componentson the operationof the unit

Question 2 Using the technicalmanualbriefly explainthe testthat can be carriedout in situ on the F1 1-5pump/motorto determineits generalconditionof operation.Includetypical resultsin your explanation. Question 3 Briefly explain the purposeof the inlet and outlet portsand the two casedrain ports with referenceto the operationof the ROV Task I Purpose. This particularassessment is designedto assess threemain abilities:In order Firstly the studentstheoreticalknowedgeof the unit is beingassessed. to explain the effectsof the variouscomponentson the operationof the unit the underpinningtheoreticalknowledgemustbe present. Secondlythe studentsability to apply informationobtainedfrom a technical manualto a practicalsituationis beingassessed. Lastlythe studentsabilityto inspectmechanical and appreciate the conlponents effectsmechanicalwearcanhaveon theoperationof the unit. Validity. During the coursethe studentshavecarriedout inspections on varioushydraulic units.Thesehavebeencarriedout by referingto technicalmanualsas well as discussingthe effect of wear on generalperformance. This assignnrent is designedto assess all thesepointsandis thereforevalid to the course. The taskscarriedout in the assignnrentare typical of tasksundertakenin the ROV indusn'1,. This assignment is thereforevalid in that someof its contents can be appliedin the workplace.

tt . 1,.-

3s2

Appendix P Task 2 Fit Co-ax Connector Detailed noteson Co-ax connectorsare given under the video sectionof the course notes.Read thesecarefully before attemptingthis exercise. Equipmentrequired:1 BNC Kit Solder Iron and Holder Snips Wire Strippers Multimeter Identify the type of connectorand co-ax cable you have beenprovided with. Follow the instructionsgiven in the notesand carefullyfit the connectorto the co-ax NOTIFY THE INSTRUCTOR

-1)-J

I Appendix R

Teeside Valve and Fitting Company Ltd

TeesideValve and Fitting CompanyLtd is a privately owned company,founded in October lgll as an exclusiveauthoriseddistributor,for fluid systemcomponents manfacturedby the Swagelok $oup of comapnies.The serviceterritory for the companyis the countiesof Northumberland,Durham,Tyne and Wear, Cleavland,Cumbria,North Yorkshire and North and outh Humberside. TeesideValve and Fitting Company also provide training to customersfor various products in the range. As part of tnis ffain1ng,we provide installation seminarsfor the correct installation of Swageloktube fittings. For the last 5 yearswe have been associatedwith Subserveal Wray Castlein this role On the ROV Pilot/Technician's Course.

354

Appendir Q Task 3 Repair of Underwater Cable You are reguired ro make a warerproof repair/join to the cable provided to you by the instructor.You are ro employ the following procedure:a Cut and staggerthe conductorsto preventa large bulge at the splice b

Cut 1/4" of insulationback from eachconductor

c

Placethe correct size heat shrink over the conductors

d

Solder the conductorstogetherensuringeachis of the samelength to ensurestrainis equally applied

When you have completedall the necessarytasksto this stageTELLTHE INSTRUCTOR e

Apply heatto rheheatshrinktubing

f

Cleanand roughenthe cableinsulation

g

Apply self-amalgan-rating tapeto eachjoin of the conductor

h

Either:i

Apply self-amalganrating tapeover the whole connection

or ii

preparewithin a potting box for porring

Note:in eithercasei or ii ensurea rlininrumof air is trappedin thecavities. NOTIFY THE INSTRUCTOR

!

355

AppendixS Rigging WEIGHT AND BREAKING LOAD TABLES CargoHandlingGear

RoundStrandRope Right-handOrdinaryLay

6x19

Minimum Breaking Load at 145 kg/100m tonnef

Weight Size Nominal Diameter mm

Applications: ToppingRopes,Guy pendants

109 134

aA L+

193

25.7

100 t24 r36 150 i78

13.2 16.2 r7.9 19.7 23.4

kg/l00m

Grade tonnef

18 20 21 22 'lA

r63

2r.6

ar1tt0

6 x 36 &6 x 4l Galvanised

: : : !

I I

f t t I

356 E"\

T4.4 17.8

18 20 22

L+

I ,

SteelCore

Fibre Core

6 x 19 Galvanised

at 1tl0 Grade kg/l00m tonnef

RoundStrandRopes Right-handOrdinaryLay

16 18

r9

20 Applications: 22 ToppingRopes,Cargo 24 Purchases for Derrick 26 CranesandDeckCranes. 28 Preventer Guys,Standing 32 Rigging 35 36 38 40

94.5

r20 l

a a

- IJ J

148

r79 2r3 250 289 378 452 478 533 591

15.2 t9.2 21.4 23.8 28.7 34.2 40.1 46.6 60.8 72.7 77.0 85.7 95.0

AA AT

48 52 56 1 7x 7 Multi-strandRope Right-hand Lang'sLay Applications: CargoPurchases for Derrick Cranes,DeckCraneswhere non-rotating properties al'e desirable

l6 18 19 20 22 24 26

9s.2 r20 134 149 180 1 1 4 L t+

251

104

r32

146

r63 r97 234 275 318 4t6 497 526 586 650 787 935 l 100 1280

t+. I

18.6 20.7 22.9 27.8 33.0 38.8

CargoHandlingGear 12x6over3x24 Size

Weight

357

Mininrunr

t6.4 20.7

23.r 25.7 31.0 36.9 43.3 s0.3 65.7 78.5 83.2 92.6 10.3 124 148 174

201

Multi-StrandRope Lang'sLay Right-hand

Nominal Diarneter mm

Applications: Cargo Purchasesfor Derrick Cranes.Deck Craneswhere non-rotatingproperties are desirable

16 18 19

20 22 1A LA

26 28 32

Breaking Load ar 180 Grade kg/100m tonnef 92.6 ttl i31 t45 t75 208 245 284 310

StandingRigging- Shrouds,Stays,HangerRopes 6 x 19 (lalvanised

SteelCore

3sB

13.8 17.5 19.5

2r.6 26.2 31.1

36.s 42.4 55.3

\

RoundStrandRope Right-handOrdinaryLay (180gradesteel)

Size Weight Nominal Diameter mn]

Minimum Breaking Load ar 180 Grade kg/100m tonnef

22 24 26 28

193 229 270 312

7 x 19 Galvanized

RoundStrandRope Right-handOrdinaryLay (145gradesteel)

Minimum Breaking Load at 145 Grade tonnef JZ

36 40 44

PreventerGu-vs

RoundStrandRope Right-hand OrdinaryLay

31.1 37.0 43.5 50.4

380 481 594 719

53.9 68.2 84.2 102

Fibre Core Size Weight Nominal Dianreter

nrll

20 22 1 4 :+

26

M ininr unr Breaking Load a r1 4 5 Grade kg/l00nr tonnef I -1.1 163 193 227

17.t4 21.6 25.7 30.1

SlewingGuy Falls

Size Weight Dianreter lllnt

Polypropylene Ropes ('Fibrefilm'or Staplespu n

l6 lti

20 22 24 28

Minimum Breaking Load Kg/100m kg/220nr tonnef 19

A"l +L

22 27

49 6l

a a

- 1

-f -)

40 53

3-59

t-)

uti l lti

-1.-)

4.5 5.4 6.5 7.6 10.1

Manila Ropes- Grade I

SisalRopes

t6 18 20 22 24 28

19 22 27 33 40 53

42 49 6T 73 88 118

16 18 20 22 24 28

19 22 27

42 49 6T

aa -fJ

-a

t)

40 53

88 118

2.0s 2.45 3.25 3.85 4.55 6.10 1.80 2.t5 2.85 3.40 4.05 5.35

METRIC FORMULAEFOR BREAKINGSTRESSES OF NATURAL AND SYNTHETIC F IB R ER OP E ,S TEELW IRE ROPEAND CHAIN l). FibreRope3 StrandHarvserLaid Material

Diameter

BreakingStrainFactor

Grade 1 manila High grademanilir

77rrnr- 144mnr 7nr - 144nrrl

2D2l3(X)

Polythene Polypropylene

4rn Tntrtt -

72nrnr tl0rurn

lD2/j(x)

Polyester(Terylenet

4nrrn - 96nrnr

4Dtl3tx)

Polyamide(Nylon)

;lnrrn -

5Dt/3txl

96nrnr

2). FlexibleSteelWirc Rope Material

Dianreter

BreakingStrainFactor

6x 12

(4nrnr to 4t{nrnr)

15p:/.500

6x24

(tlnrnr to 56nrm)

211p2/-500

6x37

(8nrnr to -56nrnr)

21D2l5(X)

I

360

3). Stud Link Chain Material

Diameter

BreakingStrainFactor

Grade I Grade 2 Grade 3

(12.5n-rnr to l20mm) ( 1 2 . - 5 m mt o 120mm) (12.-5mm t o 120mm)

20D21600 20D21500 43D21600

Material.

Diameter

Breaking Strain Factor

Grade I

( l 2 . 5 n t n rt o 5 0 n r m ) ( 1 2 . 5 n r n tro - 5 0 n r m )

20d2t600

4). Open Link Chain

Grade 2

30D2/6fi)

= =

361

VFDQ[ [ EM SHJ