Api Piping Plans: ©john Crane Inc. 2006

API Piping Plans

©John Crane Inc. 2006

Sealing Support Plans Supply Cooling & Lubrication To Seal Faces API Piping Plan Numbers. Ø

01 and 02: Internal circulation for single seals.

Ø

11, 12, 13 and 14: Simple recirculation systems for single seals.

Ø

21, 23, 31 and 41: Recirculation systems with auxiliary equipment for single seals.

Ø

32 and 62: External injection systems.

Ø

52, 53 (A, B, & C), 54 and 74: External systems for dual seals.

Ø

72, 75, 76: External systems for containment seals.

©John Crane Inc. 2006

Plan 02 - Dead Headed

Seal Gland Connections Plugged For Pos sible Future Cooling Needs

Typical arrangement stuffing box may be shouldered, tapered flow modified or a through bore (open). ©John Crane Inc. 2006

Plan 11 - Return From Discharge

Arrangement widely used on clean fluids. Higher stuffing box pressure prevents fluid flashing at seal faces & promotes circulation / cooling. ©John Crane Inc. 2006

Plan 13 - Return To Suction

Used on vertical pumps to vent stuffing box or when the box pressure is near discharge pressure. ©John Crane Inc. 2006

Plan 21 - Heat Exchanger Via Pump Discharge Vent

Orifice

T

Goal: flow to seal to be ~ 140°F - 180°F (~ 60°C - 82°C) ©John Crane Inc. 2006

Plan 23 - Heat Exchanger Via Seal Chamber Vent

Orifice T

Typical arrangement on Boiler Feedwater Pump seals. ©John Crane Inc. 2006

Internal Pumping Ring

Pumping Rings

Radial Flow Dri lled Vane Holes

Axial Flow Radial Flow Paddle Wheel

©John Crane Inc. 2006

Heat Exchangers

Water Cooled

High efficiency heat transf er Compact Water required

©John Crane Inc. 2006

Air Cooled

No cooling water needed Remote location use Lower heat transfer

Plan 31 - Cyclone Separator

Clean fluid to seal

Process fluid

Arrangement can be used in place of Plan 11. Cyclone separator is used to remove solids in fluid pumped. ©John Crane Inc. 2006

Abrasives to suction

Plan 32 - Flush, External Source Flow Meter Check Valve

P

When process fluid is too hot or dirty and an external source can be used. Typical packing and single seal support method. ©John Crane Inc. 2006

Valve

Clean external source of flush fluid

Plan 32 - Flush, Single Seal

Flush Fluid

Pressure

Stuffing Box

Box Pressure

©John Crane Inc. 2006

Flush Atmosphere Pressure

Flush pressure 5 psi min. higher than max. box press.

Plan 62 - Quench, External Source

Used to prevent coking or crystallization of process fluid on the atmospheric side of the seal faces in a single seal. ©John Crane Inc. 2006

Plan 62 - Quench, External Source

Quench Fluid

Low pressure restriction dev ice

Pressure

Stuffing Box

Box Pressure

©John Crane Inc. 2006

Quench Pressure Atmosphere

Quench pressure 5 psi max.

API PLAN - Dual Seals § Unpressurized Dual Wet Seals • Plan 52 § Pressurized Dual Wet Seals • Plan 53A • Plan 53B • Plan 53C • Plan 54 • Dual Gas Seals • Plan 74

©John Crane Inc. 2006

Buffer / Barrier Fluid What is the stuff between the two seals? § Buffer fluid (unpressurised dual seal) A fluid which is at a pressure less than the seal chamber pressure (typically at atmospheric pressure) § Barrier fluid (pressurised dual seal) A fluid with is at a pressure greater than the seal chamber pressure

©John Crane Inc. 2006

Plan 52

©John Crane Inc. 2006

Plan 52

©John Crane Inc. 2006

Plan 53A

©John Crane Inc. 2006

Plan 53A

©John Crane Inc. 2006

Plan 53B

©John Crane Inc. 2006

Plan 53B

©John Crane Inc. 2006

Plan 53C

©John Crane Inc. 2006

Plan 53C

©John Crane Inc. 2006

Plan 54 - Pressurized Barrier

Arrangement normally used when process will not allow introduction of external flush. Also used on vacuum services. ©John Crane Inc. 2006

Plan 54

©John Crane Inc. 2006

Plan 54

©John Crane Inc. 2006

Plan 54 - Pressurized Barrier Double Seal Pressurized Barrier Seal Support Barrier Stuffing Box

Pressure

Inboard Seal

Box Pressure

Barrier Atmosphere Pressure

Fluid

Outboard Seal

Barrier pressure 15 psi min. higher than max. box press.

Higher pressure barrier fluid acts as the lubricating film across inboard seal faces ©John Crane Inc. 2006

Sealing Water Regulator Systems Complete Systems To Control Sealing Water Flow & Pressure Monitor Water Supply & Indicate Trouble Alarm If Low / No Flow Use With: Ø Packing Ø Single seals Ø Quench seals Ø Double seals Clean In Place Features During Operation

©John Crane Inc. 2006

Plan 74 API PLAN 74 Systems that provide pressurized gas (N2 or steam) at a pressure higher then stuffing box pressure to avoid pumped fluid leakage to atmosphere

©John Crane Inc. 2006

Plan 74

©John Crane Inc. 2006

Secondary Containment Plans Purpose: § Direct the flow of Volatile Organic Compound (VOC) and other hazardous substances leaking past the primary seal faces for safe disposal. • Plan 72 • Plan 75 • Plan 76

©John Crane Inc. 2006

Plan 72 •

API PLAN 72 Systems that provide gas at low pressure pressure to reduce fugitive emission and prevent icing on cold applications

©John Crane Inc. 2006

Plan 72

©John Crane Inc. 2006

Plan 75 API PLAN 75 Systems that collect both liquid and gas leakages

©John Crane Inc. 2006

Plan 75

©John Crane Inc. 2006

Plan 76 API PLAN 76 Systems that collect gas leakages

©John Crane Inc. 2006

Plan 76

©John Crane Inc. 2006

Comparisson Plan 72 v 74 • API PLAN 72 Systems that provide gas at low pressure pressure to reduce fugitive emission and prevent icing on cold applications • API PLAN 74 Systems that provide pressurized gas (N2 or steam) at a pressure higher then stuffing box pressure to avoid pumped fluid leakage to atmosphere

©John Crane Inc. 2006

Plan 75 and Plan 76 Main Components

Components

Plan 75

Plan 76

Reservoir

No

Yes

Yes

Pressure Sw itch (*)

Yes (high)

Yes (high)

Level Gauge

Yes

No

Level Sw itch (*)

Option (high)

No

Orifice

Yes

Yes

Tank for liquid collector Pressure Gauge

NOTE:

(*) Pressure and Level Transmitter can be adopted instead of Pressure and Level Sw itch

©John Crane Inc. 2006

Coffee Break

©John Crane Inc. 2006

Seal Failure Analysis A brief overview

©John Crane Inc. 2006

What is a failed seal? Leakage of the pumping fluid thru the sealing components, which causes § Dilution of the process stream § Poisoning of the environment § An Immediate safety Hazard.

.

©John Crane Inc. 2006

Seal Leakage § All mechanical seals will leak to some extent during operation.

§ If the seal is operating correctly then the leakage should be extremely low, to the point where it may not be noticed or visible.

©John Crane Inc. 2006

Leakage Rates

Fluid film thickness is very important too thin - wear, causing early seal failure too thick - visible leakage

©John Crane Inc. 2006

Acceptable Leakage Rates § Varies depending on application • Environmental considerations/legislation

• Process contamination • Minimum levels of cleanliness • Economic considerations Note : Leakage rate vary depending on the size, seal type, application Depending upon the properties of the sealed fluid the leakage may be liquid or a gas.

©John Crane Inc. 2006

Increasing leakage.

• High hazard or pollution risk

Leakage rate for Fluids Diameter (mm) 100

Speed (rpm)

15

00

80

00

18 30 0 0 00

60

36

40 30

20

. Pressure (bar g) 0

2

4

6

8

10 12 1 4 1 6 1 8 20 0.01 Balanced Seal

©John Crane Inc. 2006

L e a k a g e ( m l/h ) 0.1

1 Unbalanced Seal

10

100

Normal Operational Life of the Seal Normal Operational Life of the Seal First Few

Incidence of Failures

Hours

Time

©John Crane Inc. 2006

.

What is an Acceptable Seal Life?

§ API 682 States the design is to have “High probability of meeting the objective of at least 3 years of uninterrupted service while complying with Emissions Regulations.”

©John Crane Inc. 2006

Sources of Seal Unreliability I.Mech.E

Chemical Co. PP & JC

Seal selection & design

Design

Pump selection, design & suction circuitry. Installation, alignment, bearing & pump condi tion

Maintenance

28%

15%

4%*

24%

20%

47%

48%

65%

49%

Seal & system fitting & installation functions

Operation

Process upsets,off-duty operating, primi ng, mal-operation. Seal flushing, cooling, quenching.

* No Data included for Pump Design unreliability data ©John Crane Inc. 2006

Leak Path

©John Crane Inc. 2006

Preparation for Improving Seal Reliability

Where do I start? - The Statistician Data Segregation Seal or Bearing Reliability?

Macro Survey

Operational Life? Process Criticality? Hazard or Pollution Risk?

©John Crane Inc. 2006

Preparation for Improving Seal Reliability

What’s The Problem? - The Detective The Duty & Equipment Specification Seal Design Arrangement & Materials

Information

Failure Description History Seal Component condition

©John Crane Inc. 2006

Preparation for Improving Seal Reliability Seal Component condition • • • • • •

Record Condition as Removed from Equipment. Record ALL Visible Effects (Compared to As New). Examine ALL Parts & Their Relative Positions. Check Functional Flexibility. Rubbing Surfaces Require Detailed & x5 Mag. Store Failed Parts for Statistical Examination.

THIS IS YOUR ONLY RELIABLE INFORMATION EVERYTHING ELSE MUST EXPLAIN IT.

©John Crane Inc. 2006

Common Sources of Seal Unreliability

§

Failure Analysis How Can This Happen? How Can This Happen? How Can This Happen?

©John Crane Inc. 2006

Visible Evidence on Seal Components § Rubbing Face Condition • • • • • • • •

Wear level Contact Level and breakdown of material structure Chipping on track or edges Cracking of section (dynamic or static?) Rubbing, abrasion or corrosion Heavy ID damage, OD or both. Uneven damage circumferentially Eccentric or overlapped tracking

©John Crane Inc. 2006

Rubbing Face Condition Carbon Graphite Face operating under high contact stress

©John Crane Inc. 2006

Rubbing Face Condition Carbon Graphite Face operating under excessive contact stress

©John Crane Inc. 2006

Rubbing Face Condition Carbon Graphite Face with ‘edge chipping’

ID

OD ©John Crane Inc. 2006

Rubbing Face Condition Antimony impregnated carbon graphite with melted film of Antimony

ID

OD ©John Crane Inc. 2006

Rubbing Face Condition Carbon Graphite Face with abrasive damage and erosion

©John Crane Inc. 2006

Rubbing Face Condition Carbon Graphite primary ring (metal bellows) abrasive damage and erosion

Corresponding Mating Ring

May be caused by Catalyst Fines ©John Crane Inc. 2006

Rubbing Face Condition Carbon Graphite Face with damage caused by polymerisation

OD

ID ©John Crane Inc. 2006

Rubbing Face Condition

‘Blistering’

©John Crane Inc. 2006

Rubbing Face Condition Detail of blister on Carbon Graphite Face

©John Crane Inc. 2006

Rubbing Face Condition

Thermal Crazing of track ©John Crane Inc. 2006

Rubbing Face Condition Tungsten Carbide Face with hydropads Thermal Crazing

ID

OD Hydropad ©John Crane Inc. 2006

Rubbing Face Condition Mating Ring damage in SiC - Blistering

©John Crane Inc. 2006

Rubbing Face Condition Mating Ring damage in SiC – Thermal Cracking

©John Crane Inc. 2006

Rubbing Face Condition Primary Ring in Sic/Graphite Composite - Blister damage

©John Crane Inc. 2006

Rubbing Face Condition Primary Ring in Sic/Graphite Composite - Blister damage

©John Crane Inc. 2006

Rubbing Face Condition

Uneven Contact Circumferentially - 2 point ©John Crane Inc. 2006

Rubbing Face Condition

Uneven Contact Circumferentially - 3 point ©John Crane Inc. 2006

Rubbing Face Condition

Vaporisation Damage ©John Crane Inc. 2006

Visible Evidence on Seal Components Primary / Mating Ring Condition • • • • • • • •

Drive wear or damage Edge chipping Erosion or polishing on rear surface Localised rubbing/polishing Radial Sectional crack Circumferential crack Process surface erosion Spinning of inserted designs

©John Crane Inc. 2006

Primary Ring Condition

©John Crane Inc. 2006

Primary Ring Condition

©John Crane Inc. 2006

Primary Ring Condition

©John Crane Inc. 2006

Primary Ring Condition

Radial Sectional Fracture

©John Crane Inc. 2006

Primary Ring Condition

Circumferential Sectional Fracture ©John Crane Inc. 2006

Bellows Condition

Over pressurised from OD

Normal Over pressurised from ID ©John Crane Inc. 2006

Bellows Condition

Failed Seal ©John Crane Inc. 2006

New Seal

Visible Evidence on Seal Components Secondary Seal Condition • • • • • • •

Cuts or slicing damage Wear or abrasion on the rubbing surface Twisting of the section Hardness of the elastomer Extrusion Blistering of surface on process side Change in section or diameter

©John Crane Inc. 2006

Secondary Seal Condition Extrusion • A thin lip has formed on the entire ID or OD of the O-ring. Some materials may exhibit a shredded appearance. • Often caused by an application where pressure is beyond the design limitations for the material in use. Also, will result from thermal expansion of the material if groove width is too narrow, or from swell caused by chemical interaction with material.

Normal Ring

©John Crane Inc. 2006

Lip Shredding

Secondary Seal Condition

O-ring sliding damage

Damaged Surface

©John Crane Inc. 2006

Edge View

Secondary Seal Condition Hard or cracked Elastomer • The part is hard and has several cracks, it is easily broken when bent by hand. Damage may be on process side, atmospheric side, or only in areas in contact with a specific part. • Temperature too high for material in use. Possible chemical attack if the damage is evident only on the process side of the part.

Normal Ring

©John Crane Inc. 2006

Flat Surfaces

Cracks

Secondary Seal Condition Compression Set • The part is permanently deformed with flat sides on the sealing surfaces. • Caused by improper design of parts which houses the O-ring resulting in over compression of the material or by chemical attack (swelling) of the material while in service. • Compression set is a common cause of O-ring failure. If it occurs on a dynamic O-ring the ability of a primary ring to track will be impaired.

Normal Ring

©John Crane Inc. 2006

Flat Surfaces

Secondary Seal Condition Blistered and ruptured elastomer • Many small blisters and ruptures throughout the part caused by explosive decompression. • A fluid which is a gas at atmospheric pressure, is being sealed under high pressure and over time is absorbed into the elastomeric material. When the pressure is released too quickly the fluid which is trapped in the elastomer expands rapidly resulting in damage to the part.

Blister ©John Crane Inc. 2006

Rupture

Case Study - Recent Example (Abu Dhabi) § Pressurised dual metal bellows seal found contaminated with process fluid

©John Crane Inc. 2006

Recent Example (Abu Dhabi) § Inspection of the IB bellows shows:

©John Crane Inc. 2006

Recent Example (Abu Dhabi)

§ That explains the contamination

§ But, how did that happen?

©John Crane Inc. 2006

Recent Example (Abu Dhabi) LBI

©John Crane Inc. 2006

Recent Example (Abu Dhabi) The evidence:

©John Crane Inc. 2006

Recent Example (Abu Dhabi) The evidence:

§ Light grooving on inboard primary ring § Possible comet trails may indicate vaporisation

©John Crane Inc. 2006

Recent Example (Abu Dhabi) The evidence:

§ Mating Ring in good condition § No sign of high heat generation

©John Crane Inc. 2006

Recent Example (Abu Dhabi) The evidence:

§ Heavy coke formation on OB primary ring § This is coked barrier fluid!

©John Crane Inc. 2006

§ This requires face temperatures above 150°C

Recent Example (Abu Dhabi) The evidence:

§ Once cleaned, the OB faces are in excellent condition § No sign of high heat generation at the faces

©John Crane Inc. 2006

Recent Example (Abu Dhabi) § From the evidence, it is likely that the following sequences of events occurred: § At some time, possibly for a prolonged period, the barrier fluid has been allowed to become very hot (in excess of 130 ° C) This is clear from the coking observed on the atmospheric side of the OB seal. Note that the good condition of the OB faces indicates normal level of heat generation.

©John Crane Inc. 2006

Recent Example (Abu Dhabi)

§ Barrier fluid degrades, and high stuffing box temperature, high barrier fluid temperature plus degraded oil lead to vaporization of fluid on IB seal faces

©John Crane Inc. 2006

Recent Example (Abu Dhabi)

§ Vaporisation leads to micro-movement causing fatigue failure of the IB bellows assembly at the weld.

©John Crane Inc. 2006

Recent Example (Abu Dhabi) § Bellows failure allows contamination of the seal and seal system with process fluid

©John Crane Inc. 2006

Thank you Any Questions??

©John Crane Inc. 2006