S-000-1353-002_r_0001

JOB No.

Sohar Refinery Company

JGC DOC. No.

0-3100-25

SOHAR Refinery Project

DATE 23 −

PROJECT SPECIFICATION

REV.

S-000-1353-002

JUN

−

2003

R

1

SHEET

OF

PREP’D

T. Miyashita

TM

CHK’D

M. Nakajima

MN

APP’D

A. Ikawa

AI

48

GENERAL SPECIFICATION FOR SHELL & TUBE TYPE HEAT EXCHANGER

FOR CONSTRUCTION

SOHAR REFINERY COMPANY L. L. C.

SOHAR REFINERY PROJECT

SOHAR, SULTANATE OF OMAN

REV.

DATE

PAGE

0

23 Jun 2003

All

R

24 Sep 2003

003 CT-2 06-O

Rev

S-000-1353-002

B

DESCRIPTION

Issued For Approval

10, 15, 21, 25, Issued For Construction, incorporated client’s comment, 26

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Reference ITT Doc. No.

PREP’D

CHK’D

APP’D

TM

MN

AI

DS

MN

AI

OM-JY-E-20124/JY-OM-E-20141.

S-000-1353-002

JOB CODE: 0-3100-25

Sohar Refinery Company SOHAR Refinery Project

DOC NO: S-000-1353-002 rev.R

SHEET : 2 of 48

General Specification for Shell and Tube Heat Exchanger

CONTENTS PAGE

1.

SCOPE

4

2.

CODES, STANDARDS AND DOCUMENTS

4

3.

MATERIALS

6

3.1

General

6

3.2

Pressure Parts

7

3.3

Non-Pressure Parts

9

3.4

Gasket

9

4.

5.

DESIGN CONDITION

10

4.1

Corrosion Allowance

10

4.2

Definition of Weights

10

4.3

External Loads and Climatic Conditions

11

4.4

Allowable Stress

11

4.5

Postweld Heat Treatment (PWHT)

11

4.6

Fireproofing

11

4.7

Hot Insulation

11

DESIGN

12

5.1

General

12

5.2

Support Saddle

13

5.3

Flanges

14

5.4

Nozzles

15

5.5

Bolts and Nuts

16

5.6

Tube to Tubesheet Joint

16

5.7

Baffles and Support Plates

17

5.8

Tube Bundles

18

5.9

Expansion Joints

18

5.10

Jack Bolts

19

5.11

Attachments

19

5.12

Special Application

20

6. FABRICATION

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21

6.1

General

21

6.2

Welding

21

6.3

Heat Treatment

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General Specification for Shell and Tube Heat Exchanger

CONTENTS PAGE

6.4

Tubing

24

6.5

Fabrication Tolerance

24

6.6

Test Rings

24

7. INSPECTION AND TESTING

8.

25

7.1

General

25

7.2

Material Inspection

25

7.3

Welding Inspection

25

7.4

Pressure Test

27

7.5

Inspection of Tube Bundles

29

7.6

Leak Test for Reinforcing Plates

30

7.7

Component Inspections

30

7.8

Other Inspection

30

7.9

Inspection and Testing Records

31

7.10

Scope of Inspection and Testing

31

PREPARRATION FOR SHIPMENT

31

ATTACHMENT

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APPENDIX

I

34

APPENDIX

II

40

APPENDIX

III

47

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General Specification for Shell and Tube Heat Exchanger

1.

SCOPE (1)

This specification covers the general requirements for the design, fabrication, material, inspection and testing of shell and tube type heat exchangers.

(2)

This specification shows supplemental requirements of TEMA Standard Class “R”, ASME Code Sect.VIII, Div.1 and API 660.

(3)

The following Appendix attached herewith shall also be used, where applicable.

Appendix I

“Corrosion Resistant Clad Heat Exchangers”

2.

CODES, STANDARDS AND DOCUMENT

2.1 Design Code The design, fabrication, inspection and testing of heat exchangers shall conform to ASME Code Sect. VIII, Div.1, 2001 including Addenda 2002, “Pressure Vessels”, TEMA Standard Class “R” 8th edition 1999 and API 660 sixth edition 2001.

The following codes and standards, including applicable standards which are referred to in the codes and this specification, shall be used as supplements.

2.2

2.3

ASME Codes (1)

ASME Code Sect. V,

“Non-destructive Examination”

(2)

ASME Code Sect. IX,

“Welding Qualifications”

(3)

ASME Code Sect. II,

“Material Specification”

ASME B-Series Standards (1)

ASME B 1.1 “Unified Inch Screw Threads”

(2)

ASME/ANSI B 16.5 a “Pipe Flanges and Flanged Fittings”

(3)

ASME B 16.20 “Metallic Gaskets for Pipe Flanges Ring-Joint, Spiral-Wound,

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and Jacketed” S-000-1353-002

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General Specification for Shell and Tube Heat Exchanger

(4)

ASME B 16.21 “Nonmetallic Flat Gaskets for Pipe Flanges”

(5)

ASME B 16.47 “Large Diameter Steel Flanges”.

(6)

ASME/ANSI B 18.2.2 “Square and Hex. Nuts”

(7)

ANSI/ASME B 36.10 M “Welded and Seamless Wrought Steel Pipe”

(8)

ANSI/ASME B 46.1 “Surface Texture”

2.4

ASTM Standards “American Society for Testing and Materials”

2.5

ANSI Standards ANSI B 18.2.1 “Square and Hex Bolts and Screws”

2.6

API Standards (1)

API 660 “Shall-and-Tube Heat Exchangers for General Refinery Service”

(2)

API Publication 941 “Steel for Hydrogen Service at Elevated Temperature and Pressure in Petroleum Refineries and Petrochemical Plants”

2.7

AISC “American Institute of Steel Construction” “Manual of Steel Construction”

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General Specification for Shell and Tube Heat Exchanger

2.8

BS 5950 “Structural use of steelwork in buildings”

2.9

EJMA standard “Expansion Joint Manufactures Association” “The Design Standard for Expansion Joints”

2.10

Documents

2.10.1

Language Documents, calculation sheets, drawings, etc., to be submitted to the Purchaser shall be in the English language.

2.10.2

Unit System Unless otherwise specified, the metric units shall be used in documents and drawings.

However,

pipe sizes, flange sizes and bolts/nuts, shall be indicated in inches. 2.10.3

Drawings and Documents The manufacturer shall prepare the calculation sheets, fabrication drawings and fabrication procedure specifications including welding, inspection and testing. The form of fabrication drawings and documents may be as per the manufacturer’s standards.

2.10.4

Purchaser’s Approval on the Manufacturer’s Documents (1)

Drawings and documents such as those mentioned above are subject to the approval of the Purchaser.

However, such approval of the Purchaser shall in no way relieve the

manufacturer of his obligations with respect to such drawings and documents. (2)

Variations from or additions to this specification shall be called to the attention of the Purchaser and approved in writing by the Purchaser prior to starting fabrication.

(3)

3.

The manufacturer shall be provided electronic copy of all drawings and documents.

MATERIALS 3.1

General (1)

Materials shall be conform to ASME material specifications, and ASTM material specification may be used with subject to Purchaser’s approval.

For non-pressure retaining parts, ASTM

material specification or equivalent material specification may be used.

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General Specification for Shell and Tube Heat Exchanger

(2)

Materials shall be identified as to manufacturers and heat numbers.

(3)

Each plate or forging shall be legibly stamped or stenciled with the grade and the plate or forging number.

All materials shall be new.

When metal stamping is required, it shall preferably be done on the long edge of each

component. (4)

In general cast iron shall not be used.

(5) When hydrogen service or wet hydrogen sulfide service construction are specified, all pressure retaining parts in contact with hydrogen or hydrogen sulfide shall be killed carbon steel for carbon steel heat exchanger. For hydrogen service material selection shall be in accordance with API 941 (See paragraph 3.2 (4)).

(6) A material/corrosion engineer shall judge whether additional requirements shall be specified for metallic material for equipment containing process streams with hydrogen sulphide(H2S) in concentrations which might cause sulphide stress cracking(SSC) and hydrogen induced cracking(HIC) , see (Appendix II)

3.2

Pressure Parts (1)

Carbon steel for pressure retaining parts in normal service shall be as given in Table 1. Table 1

Materials for Pressure Parts in Normal Service

Parts

Up to 427ºC

Shell, shell cover Channel, Channel

SA 285 Gr. C

cover, etc.

SA 516 Gr. 60 SA 516 Gr. 70

Tube sheet

SA 266 Gr. 2

Girth flange, Flat cover

SA 266 Gr. 2

Nozzle flange, coupling, Plug, etc.

SA 105

Tube

SA 179

(b)

SA 192 Nozzle neck and Pipe shell

SA 106 Gr. B SA 105

Bolts and Nuts

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Note :

(a)

(a)

Up to 427oC

:

ASTM A 193 Gr. B7/A 194 Gr. 2H S-000-1353-002

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General Specification for Shell and Tube Heat Exchanger

427oC to 480oC

:

ASTM A 193 Gr. B16/A 194 Gr. 4

Wet H2S service

:

ASTM A 193 Gr.B7M/A194 Gr. 2M

(b)

Seamless tube shall be used.

(c)

Material cannot be used over the temperature specified on the table for allowable stress in Code.

(2)

Pressure retaining parts to be welded for carbon steel heat exchangers shall have the following chemical composition :

(3)

≤ 0.23%

Carbon content (C)

:

C

Carbon equivalent (Ceq.)

:

Ceq. ≤ 0.4% , where Ceq.=C+Mn/6

Material specification of pressure parts made of low alloy are given on Table 2. Table 2

Alloy

Forging

Plate

Pipe

Tube

5Cr-½Mo

SA 182 Gr.F5

SA 387 Gr.5

SA 335 Gr. P5

SA 213 Gr. T5

2¼Cr-1Mo

SA 182 Gr.F22

SA 387 Gr.22

SA 335 Gr.P22

SA 213 Gr.T22

1¼Cr-½Mo

SA 182 Gr.F11

SA387 Gr.11

SA 335 Gr.P11

SA 213 Gr. T11

(4)

Materials of pressure retaining parts for hydrogen service, to be operated at hydrogen partial pressures 7 Bar(a) and over, shall be selected in accordance with Fig. 1 “Operating limitations for steels in Hydrogen Service” of API standard 941.

(5)

All tubes shall be in the fully heat treated condition as received from the mill.

Heat treatment

may be annealed, normalized, or normalized and tempered per the material Specification. (6)

Welded austenitic stainless steel tubes shall be cold drawn to a minimum reduction of 15% in wall thickness rior to a final full solution anneal.

Selective cold reduction of the weld bead is an

acceptable alternative. (7)

Welded tubing shall pass the nondestructive eddy current test set forth in SA 450.

(8)

Integral low fin tubes shall conform to SA 498 (ferrous) or SB 359 (nonferrous).

(9)

Ferrous and nonferrous tubing shall be annealed after finning as defined in the appropriate material Specification, when the application involves contact with “HF” acid.

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JOB CODE: 0-3100-25

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DOC NO: S-000-1353-002 rev.R

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General Specification for Shell and Tube Heat Exchanger

3.3

Non-Pressure Parts (1)

Non-pressure retaining parts directly welded to pressure retaining parts of a heat exchanger, having a design temperature of 344oC and over, or being made of low or high alloy steel, shall be of the same material as the heat exchanger shell or head.

Welded attachments on carbon steel

o

pressure parts below 344 C should be A283, A36 or better. (2)

Reinforcing pads of nozzles and manholes, and wear-plates of saddles for heat exchangers shall be of the same materials as the heat exchanger shells or heads, regardless of design temperatures.

(3)

External bolting shall be carbon steel ASTM A307 Gr.B or equivalent.

(4)

Material of anchor bolts shall be carbon steel ASTM A 307 Gr. B.

3.4 Gasket (1)

Gaskets for blanked-off nozzles : Blanked-off nozzle gaskets, including manholes and handholes, if required, shall conform to the piping specification for lines connected to nozzles in the same zone of heat exchangers.

(2)

Gaskets for girth flange joints : Use of gaskets for girth flange joints shall conform to the following conditions and also to the requirements of TEMA Standard, unless otherwise specified. (a)

(b)

(c)

(d)

Flat metal jacketed non-asbestos filled gaskets : Design temperature

:

Up to 400 oC

Design pressure

:

Up to ANSI class 300 rating

Spiral wound non-asbestos filled gaskets : Design temperature

:

Up to 450 oC

Design pressure

:

Up to ANSI class 2500 rating

Spiral wound graphite filled gaskets : Design temperature

:

450 to 600 oC

Design pressure

:

Up to ANSI class 2500 rating

Solid flat metal gaskets may be used under any design conditions, and those shall be made in one piece construction except for the gaskets for pass partitions.

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JOB CODE: 0-3100-25

Sohar Refinery Company SOHAR Refinery Project

DOC NO: S-000-1353-002 rev.R

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General Specification for Shell and Tube Heat Exchanger

(e)

Where the channel side fluid is sea water, non-asbestos sheet may be used at : Design temperature

:

200 oC

Design pressure

:

10 Barg

and under and under

Graphite gaskets shall not be used in seawater service. (f)

4.

Copper gaskets are not permitted when fluids contain wet H2S or amine.

DESIGN CONDITION 4.1

Corrosion Allowance (1)

A corrosion allowance of 1.6 mm shall be taken for carbon steel or low alloy steel heat exchangers as a minimum except for tubes. No corrosion allowance shall be considered for high alloy or non-ferrous materials, unless otherwise specified.

(2)

The thicknesses of baffles and pass partition plates specified in TEMA, shall include standard corrosion allowance. Where a corrosion allowance exceeding standard of TEMA is specified, this corrosion allowance shall be provided to the parts in lieu of standard corrosion allowance.

4.2

Definition of Weights Weight of heat exchangers used for calculations shall be defined as follows : (1)

Unit weight (empty weight) : The weight of a heat exchanger at a fabrication shop including saddles and internal parts such as a tube bundle. This weight is used as the lift-up weight at site for installation.

(2)

Bundle weight : This weight is the complete weight of a tube bundle consist of such as tubes, tube sheets, baffles, spacers and tie rods, excluding fluid in tubes.

(3)

Operating weight : Total weight of item (1) above and full of fluid in operation including external attachments such as insulation, piping and platform.

(4)

Test weight : Unit weight defined in item (1) above added with the weight of test water, etc.

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General Specification for Shell and Tube Heat Exchanger

4.3

External Loads and Climatic Conditions

4.3.1 Wind Load Wind load shall be calculated as following basis. Applicable standard

:

ANSI / ASCE 7-98

Basic wind speed

:

22.9 m/sec

Important factor

:

Category II (I=1.0)

Exposure

:

Category D

4.3.2 Earthquake Load Not applicable.

4.4

Allowable Stress Allowable stress shall be in accordance with the applicable codes.

4.5

Postweld Heat Treatment (PWHT) PWHT shall be required for the following parts : (1)

Necessity of PWHT shall be judged based on the kind of fluid to be handled, such as caustic service, wet H2S service, and the requirements of the applicable codes shall also be taken into consideration.

(2)

For caustic service, PWHT shall be carried out in accordance with “Caustic Soda Service Graph” in the CORROSION DATA SURVERY OF NACE.

(3)

Carbon steel channels and bonnets with six or more tube passes

(4)

Carbon steel floating head covers that are fabricated by welding a dished-only head into a ring flange.

4.6

Fireproofing Fireproofing is not required.

4.7

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Hot Insulation

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General Specification for Shell and Tube Heat Exchanger

Where hot insulation is specified in the data sheets, the requirement shall be in accordance with the project specification “General Specification for Hot Insulation” : S-000-1390-001.

5.

DESIGN 5.1

General (1)

Heat exchangers shall be designed to allow maximum interchangeability.

(2)

Generally, heat exchangers shall be designed in accordance with design temperatures and pressures of the shell side and tube side, specified in individual data sheet, and no part of heat exchangers shall be designed based on “differential pressure” of shell and tube sides, except in special cases on which approval has been given.

(3)

Heat exchangers, 18 in. or smaller in diameter, may use pipe materials for the shells; however, those over 18 in. diameter shall be made from plates.

(4)

Heat exchangers including their supports shall be capable of supporting a full load of water at atmospheric pressure in the installed position.

(5)

Sharp discontinuities located in regions subjected to operational cyclic mechanical and/or thermal stresses shall be avoided to prevent cracking due to thermal fatigue.

(6)

For design temperatures of 427 oC and higher, nozzles, supports and other attachments of heat exchanger shells shall be free from high local stress concentrations. Fillet welds

shall be free

from stress concentration unless ground to a smooth radius. (7)

Floating head covers shall be formed spherically and floating head flanges shall be through-bolted type, unless otherwise specified.

(8)

Load bearing welds attaching non-pressure retaining parts to pressure retaining parts shall be designed according to the same allowable stress basis for primary membrane tensile (compressive) and shear stresses as required for pressure retaining components of like material.

(9)

For single pass tube bundle exchangers with a bellows type expansion joint between floating head and shell covers, expansion bellows shall be hydraulically or mandrel formed type that permit replacement in the field.

It shall be constructed of Inconel 600, Inconel 625, Incoloy 800 or

Incoloy 825.

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General Specification for Shell and Tube Heat Exchanger

(10)

Following standard dimensions shall be applied, unless otherwise specified. (a)

Preferred tube length shall be 6100 mm ; however, shorter or longer tubes may be used under the following conditions : -

Small heat exchanger

-

Process requirement

-

To avoid increasing the number of shells unnecessarily

-

Vertical heat exchangers

For U-tube units, the maximum nominal length (from tube ends to bend tangent) shall be limited to the straight tube length. (b)

O.D of carbon steel tube shall be 1”. 1” of tube O.D shall be also applied to low alloy and including 5Cr-1/2Mo, SS321, Titanium, Copper alloy.

(c)

Tube thickness/material (except for special services) : Carbon Steel

BWG# 12 for 1” tube (seamless)

Low alloy steel

BWG# 12 for 1” tube (seamless)

Stainless steel

BWG# 14 for 1” tube (seamless)

Copper alloy

BWG# 14 for 1” tube (seamless)

Titanium

BWG# 20 for 1” tube (seamless)

Basically, the seamless tube shall be used in spite of the tube material ,unless otherwise approved by purchaser with technical justification. (d) 5.2

The minimum mean radius of U-tubes shall be 1½ times the OD of the tubes.

Support Saddle (1)

Heat exchangers shall be supported by a minimum of two saddles with reinforcing plates.

(2)

Saddle interval shall be in the range of 50 to 80 % of the tube length.

(3)

The wall thickness of a heat exchanger shell shall have sufficient strength to withstand circumferential buckling, local bending moment and shear stresses.

(4)

The channel side of a heat exchanger shall be fixed as a rule.

(5)

A sliding plate shall be provided at the sliding side of a heat exchanger installed on concrete foundations.

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General Specification for Shell and Tube Heat Exchanger

5.3 Flanges (1)

Girth Flanges (a)

Girth flanges shall conform to ASME Code Sect. VIII, Div. 1, Appendix 2 according to the design conditions of a heat exchanger.

(b)

In general girth flanges shall be of welding neck type and lap-joint construction may be applied to titanium shells.

(c)

Where spiral wound gaskets are employed, the girth flanges shall be flat and groove type or confined type according to TEMA standard FIG. R-6.5.

(2)

Nozzle Flanges (a)

Flanges, other than those indicated below in (b) and (c), shall conform to ASME/ANSI B 16.5 a.

(b)

The ratings of non-standard flanges shall be calculated per Appendix 2 of ASME Code Sect. VIII, Div. 1 based on the design conditions of the exchangers.

(c)

For large flanges over 24 in. nominal pipe size, large-diameter flanges in accordance with ASME B 16.47, series “B” shall be used.

(d)

For titanium heat exchangers, lap-joint nozzle flanges may be used.

(e)

All nozzles shall be of welding neck or long welding neck flanged, and the minimum size is 1”, and 1½” for lined nozzle, unless otherwise specified.

(f)

Flange facing finish for raised face type shall be as follows. -

Machining The finish of contact faces of pipe flanges and connecting end flanges shall be smooth finish and be machined as follows. A continuous spiral groove generated by a 0.8 mm radius round nosed tool at a feed of 0.30 mm to 0.37 mm per revolution shall be applied and tolerance of roughness shall be from 3.2 Ra to 6.3 Ra (3.2 micrometers to 6.3 micrometers).

-

Inspection The finish of contact faces of pipe flanges and connecting end flanges shall be judged by visual comparison with Ra standards (See ANSI/ASME B46.1) and not by instrument having stylus tracers and electronic amplification.

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General Specification for Shell and Tube Heat Exchanger

5.4

Nozzles (1)

Nozzles : (a) Flanges with rating of ANSI Class 600 and higher shall be used for forged integrally reinforced long-welding-neck nozzles (LWN). (b) Threaded connections shall not be permitted, unless otherwise specified. (c) Nozzles shall normally be designed as set-through types. Where this is not possible a set-on type nozzle weld may be used. (d) Nozzles shall be of flanged or butt welded type per the data sheets. (e) Nozzles shall be provided with reinforcement per table 4.

Reinforcing pad should normally

be no thicker than the shell plate to which they are attached and limited to a maximum thickness of 50 mm. (f) The nozzle loading requirements shall be accordance with the specification for nozzle loadings S-000-1351-004. (2)

Necks of nozzles shall be made of seamless pipe except for necks of 14 in. or more which can be made of plate materials and shall be full penetration with butt joint. Where plate materials are used for nozzle and manhole necks, these materials shall be the same as those used for heat exchanger shells and heads.

(3)

Bolt holes in nozzle and manhole flanges located in heads of vertical heat exchangers shall straddle the principal centerline of the heat exchangers or lines parallel thereto. Bolt holes in nozzle and manhole flanges located in shells shall straddle the centerline of heat exchangers.

(4)

Minimum projection of nozzles and manholes from exchanger external surface shall normally be 150 mm for nozzles up to 6 in. and 200 mm for 8 in. and over. Insulation thickness shall be considered when nozzle projections are decided.

(5)

The minimum nozzle thickness and the dimension of reinforcing pad shall be in accordance with Table 4.

(6)

Pipe flanged connections such as vent, drain, shall be provided in accordance with TEMA standard, except for following nozzles.

(7)

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(a)

Clad or lining type.

(b)

Flange rating is class 600 or over.

Vents, Drains, and Other Connections

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General Specification for Shell and Tube Heat Exchanger

(a)

When tube side fluid is steam or condensing hydrocarbon, a 1 inch flanged minimum vent connection shall be provided in the channel cover or bonnet head at the high point of second pass as per data sheet.

(b)

When the shell side fluid is steam or condensing hydrocarbon, provide a flanged 1 inch minimum vent nozzle on the top of shell at the end opposite to shell inlet as per data sheet. For stacked units, provide a vent nozzle in each shell, if required.

(c)

Provide 2 inch minimum flanged neutralizing connections in all main shell and tube side nozzles of exchangers constructed of, or lined with, austenitic stainless steel material.

(d)

Thermowells and pressure gage connection are not required as per S-000-1225-001 Para.5.2..

5.5

Bolts and Nuts (1)

Bolting for pressure parts : (a)

Stud-bolts shall be threaded full length and be semi-finished and conform to class 2A dimensions, and shall have semi-finished nuts conforming to heavy nuts having class 2B dimensions with double chamfered.(ASME/ANSI B 18.2.2, Table 9)

(b)

Bolting shall normally be threaded in accordance with ASME B 1.1, unified screw thread. The threads for bolts of nominal size 1 in. and smaller shall be the coarse thread series, while the threads for bolts of nominal size 1-1/8 in. and larger shall be the 8-thread series.

(2)

Bolting for non-pressure parts : (a)

Threads of bolts and nuts shall be of the coarse thread series in accordance with ASME B 1.1, Class 1A and 1B, respectively.

(b)

Bolts (machine bolts) shall be in accordance with Table 2 “Dimension of Hex Bolts” of ANSI B 18.2.1 and nuts shall be in accordance with Table 2 “Dimension of Hex Flat Nuts and Hex Flat Jam Nuts” of ASME/ANSI B 18.2.2.

(3)

Pipe threads : Pipe threads shall be in accordance with ANSI B 2.1 NPT.

(4)

When diameter of bolting exceeds 1½ inches, the bolting design shall provide clearance dimensions that permit use of a stud and bolt tensioned device.

It may be the hydraulic type, the

spring tension-resilient washer type or the electric stud heater type. 5.6

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Tube to Tubesheet Joint

S-000-1353-002

JOB CODE: 0-3100-25

Sohar Refinery Company SOHAR Refinery Project

DOC NO: S-000-1353-002 rev.R

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General Specification for Shell and Tube Heat Exchanger

(1)

Tube to tubesheet joints shall normally be made by “expanding”.

(2)

Tubes shall be expanded into the tube sheet per TEMA “R”requirements.

In addition, for tube

sheets with thickness in excess of 50 mm, expand one tube O.D. beginning at 3 mm from the shell side face.

The expanding procedure shall provide substantially uniform expansion

throughout the expanded portion of the tube without a sharp transition to the unexpanded portion. (3)

All tube sheet holes and the grooving in them shall conform to TEMA “R”. square edged and concentric.

Grooves shall be

When heat treatment of tube sheet is required, final tube hole

sizing shall be attained by reaming after heat treatment. (4)

“Strength weld” of tube to tubesheet joints shall be employed under any of the following conditions : (a)

Nozzle flanges having ANSI Class 600 rating and over on shell or channel side of a heat exchanger.

(b)

Shell or channel side design temperatures exceeding 400 oC .

(c)

Tube materials to which expanding is ineffectively applied.

(d)

When dictated by code requirements for the mechanical design of the exchanger (eg. Fixed Tubesheets).

(e) (5)

H2 and Wet H2S services.

Strength weld of tube to tubesheet joints shall be designed, inspected, tested and qualified in accordance with EEMUA No. 143.

Configuration and test method for strength weld shall be as

follows.

(6)

5.7

(a)

Joints shall be grooved and fillet type with at least two GTAW passes.

(b)

Joints shall comply with ASME VⅢ,Div,1,appendix A.

(c)

Joints shall be lightly expanded after welding.

Refer to para. 5.7-(1)-(b).

Baffles and Support Plates (1)

For exchangers subject to vibration, the tube bundles design shall include the following: (a)

For baffles spaced less than 300 mm apart, tube hole diameter shall not exceed the OD of the tube plus 0.53 mm.

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For baffles spaced 300 mm or more apart or for the tube support

plates the tube hole diameter shall not exceed the OD of the tube plus S-000-1353-002

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General Specification for Shell and Tube Heat Exchanger

0.38 mm. (b)

Tube holes in tube sheet shall be finished to the diameters and tolerances given by TEMA for special close fit.

(c)

Use a full periphery distribution belt at the shell inlet, or provide adequate internal distribution space and impingement protection.

(2)

The last baffle used as a support plate in a floating head type heat exchanger shall have a concentric hole with a diameter of 60 % of the inside diameter of the shell.

(3)

Drain notches of a 120 degree angle and a height of 10 mm shall be provided at baffle plates except for dam baffles.

(4)

Impact baffles shall be no closer to the inlet nozzle than is required for escape height and flow area. (a)

Impingement plates shall be a solid plate that extend at least 25 mm beyond the projection of the nozzle bore.

(b)

Rod impingement devices shall include a minimum of 2 rows of rods on a triangular pitch.

(c)

Perforated baffles are not permitted.

5.8 Tube Bundles

(1) A tube bundle shall have two bundle runners (guide shoes) in accordance with Table 2.

Table 2

5.9

Bundle Runners Requirement

Bundle Weight (kg)

Thickness of Bundle Runners

Up to 5000

12

5001 - 10000

19

(2)

The sealing strips may be specified in the data sheets.

(3)

Nuts for tie rods should be double nuts.

Expansion Joints The design and fabrication of expansion joints installed on heat exchanger shall be in accordance with

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EJMA (Expansion Joint Manufacturers Association) standard and specific requirements or TEMA S-000-1353-002

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General Specification for Shell and Tube Heat Exchanger

standards for thick wall type expansion joints.

5.10

Jack Bolts Shell cover flanges and channel covers having a diameter of 800 mm or smaller shall be provided with two jack bolts, and those having a diameter of 801 mm or larger shall be provided with four. The size of the jack bolts shall be selected according to the shell flange bolt sizes as shown in Table 3. Table 3

5.11

Sizes of Jack Bolt

Size of Shell Flange Bolt

Size of Jack Bolt

(inch)

(inch)

3/4

to

7/8

5/8

1

to

1-1/4

7/8

1-3/8

to

3

1

Attachments (1)

Guide rails of kettle type exchangers shall be provided inside the shell with full seal welds, as supports and guides for the tube bundles.

(2)

Each heat exchanger shall be provided with a stainless steel nameplate, permanently fastened at the middle of channel cover or the center of the shell.

(3)

Lifting devices shall be provided as follows : (a)

Shell covers, channels, channel covers and floating head covers shall be equipped with lifting lugs. Shell covers and channels shall be provided with 2 sets of lugs respectively, which shall be disposed 120o apart straddling the vertical line on the upper part.

Channel

covers and floating head covers shall be provided with one lug each at the topmost part. (b)

Eye bolts or lifting lugs for stationary tube sheet shall be designed based on 100% of the tube bundle weight.

(4)

Heat exchangers shall have earth lugs attached to their supports, except for those installed on the steel structures. Earth lugs shall be provided on lower exchangers only in case of stacked items.

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General Specification for Shell and Tube Heat Exchanger

5.12

Special Application

5.12.1 Hydrogen Service Construction When the data sheet or drawing indicates that hydrogen service construction is required, the following additional requirements shall be included: (1)

Parts in contact with hydrogen shall be killed carbon steel.

(2)

Vent and drain connections shall be provided with a blind flange of the same rating and facing as main inlet nozzles.

(3)

Girth joint gaskets shall be solid metal type, spiral wound, or double jacketed graphite filled. (a)

Material shall provide hydrogen protection and/or corrosion protection properties, equal to or better than minimum requirement of materials involved at joint.

(b) Use spiral wound with stainless steel winding and flexible graphite filler. For design temperatures above 430ºC use type 347 or 321 stainless steel.

For design pressure

over 34 Barg use flexible graphite filler with inner ring. (4) All welds in contact with hydrogen shall be full penetration. (5) Weld neck flanges shall be used for terminal connection. 5.12.2 Wet Hydrogen sulfide Service Construction When the data sheet or drawing indicates that wet hydrogen sulfide service construction is required, the following additional requirements shall be included. (1)

Corrosion allowance shall be in accordance with equipment data sheet or material selection diagram.

Postweld heat treat shell and floating head cover.

After postweld heat treatment,

killed carbon steel welds must have a maximum Briell hardness of 200. (2)

Bolts for floating heads and girth flanges shall be continuously threaded.

Use ASTM A193

grade B7M bots and ASTM A194 grade 2M nuts. (3) Parts in contact with wet hydrogen sulphide shall be killed carbon steel. 5.12.3 Seawater or Brackish Water Service (Tubeside) (1)

Tubes shall be aluminum brass, 90-10 Cu-Ni, 70-30 Cu-Ni or titanium. When ammonia, amines, or hot sulfides are present on the shell side, use 70-30 Cu-Ni or titanium tubes only.

(2)

Tubes sheets and floating heads shall be clad steel or solid naval brass, aluminum bronze, 90-10 Cu-Ni, 70-30 Cu-Ni or titanium, or Monel.

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General Specification for Shell and Tube Heat Exchanger

(3)

Channels shall be solid naval brass, aluminum bronze, 90-10 Cu-Ni, 70-30 Cu-Ni, titanium, Monel, or steel clad with the same materials. Alternatively they may be solid steel that is faced and coated as follows: (a)

A weld deposited machined facing of either aluminum bronze, Monel, or 90-10 Cu-Ni, 70-30 Cu-Ni, shall be applied to the contact edges of the partition plates at the tube sheet sides, and the face of the channel flange which is adjacent to the tube sheet. These weld deposits shall extend a minimum of 1 inch (25mm) from the tube sheet contact surface.

(b)

Install sacrificial zinc anodes in the channel and the floating head. Anode shall be of sufficient size for four years of continuous operation.

(c)

All steel surface including nozzles and supports, excluding the zinc anodes, shall be coated.

(d)

Steel channels shall not be applied when tubes and tube sheets are made of titanium or monel.

(e)

Copper Alloy channels shall have sacrificial iron anodes when coupled to titanium tubes and tube sheet.

6.

FABRICATION 6.1

General (1)

The thickness of a head plate shall not be less than the required design thickness.

Reduction in

thickness due to forming shall be taken into account. (2)

The inner edge of manholes and nozzles shall be formed flush with the heat exchanger inside radius.

(3)

Reinforcing pads shall be provided with a 1/4 in. NPT

telltale hole which shall be filled with

grease. Where a reinforcing pads is divided into two pieces, a telltale hole shall be provided at each piece and seams shall be located on the circumferential direction of heat exchangers. Telltale hole shall be located on the circumferential direction of heat exchangers as much as possible.

6.2

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(4)

Single weld butt joint with backing strips shall not be used without approval.

(5)

All machined surfaces shall be protected against oxidation during heat treatment.

Welding S-000-1353-002

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DOC NO: S-000-1353-002 rev.R

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General Specification for Shell and Tube Heat Exchanger

(1)

Before any welding commences on the vessel, all welding procedures shall be approved by the Purchaser and shall be qualified by the appropriate tests specified herein. All welding procedure including non-pressure welds shall be identified by a number and shall be referenced on weld maps.

(2)

Qualification for welding procedures and welders shall be conducted in accordance with the ASME Code Section Ⅸ requirements.

(3)

The actual test may be waived, where the welding procedure qualification test has already been qualified, and the welding procedure specifications and welding procedure qualification records have been approved.

(4)

All welding shall be done by a metal arc process. welded butt joints with full penetration.

All shell and head joints shall be double

Double welded groove joints shall have their root

passes back gouged to sound metal on the reverse side before welding on that side. In cases where double welding is impractical, the root pass shall be made by the Gas Tungsten Arc Welding (GTAW) process. (5)

All pressure shell weld joints of categories A or B shall be Type No. 1 full penetration butt welds in accordance with UW-3 and table UW-12 of the ASME Code.

(6)

Full penetration weld with full fusion shall be required for pressure retaining part welds. Nozzles and manholes shall be attached to heat exchangers by full penetration welds. Fillet weld is acceptable for the outside circle of reinforcing pads.

(7)

Longitudinal seams shall clear nozzles and their reinforcement with a minimum distance of 25 mm. Longitudinal seams for vertical heat exchangers shall preferably be located 180o apart.

(8)

In horizontal heat exchangers, the longitudinal weld seams shall not be located at the under parts of heat exchanger shells, and saddles shall be located so as not to coincide with the circumferential and longitudinal seams of heat exchanger shells.

(9)

Joints of heat exchanger shell plates with different thicknesses shall be aligned inside surface flush.

(10)

Longitudinal and circumferential welds of shells except for kettle-type exchangers shall be finished flush with the inner contour for ease of tube-bundle insertion and withdrawal.

(11)

Welding shall be performed in “Flat” position as far as possible, and the welding sequence shall be established in order to minimize residual stresses.

(12)

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Alloy elements containing flux powder for submerged arc automatic and semiautomatic welding S-000-1353-002

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General Specification for Shell and Tube Heat Exchanger

techniques shall not be employed. (13)

Welding shall be completed prior to final heat treatment.

(14)

The use of the Flux Cored Arc Welding (FCAW) and Gas Metal Arc Welding (GMAW) processes shall be approved by the purchaser.

(15)

The flux Cored Arc Welding Process shall utilize an external shielding gas and is not permitted for single sided tee or corner joints.

(16)

The Gas Metal Arc Welding process in the short circuiting mode (GMAW-S) may be used for following applications only. (a)

The root pass for any material thickness.

(b) Complete groove or fillet welds providing that the wall thhickness does not excced ¼ inch (6 mm). (c)

Tack welds, temporary attachments and other applications where the weld made by this process is completely removed.

(17)

The Gas Metal Arc Welding process in the spray transfer mode shall not be used for the root pass.

(18)

Covered welding electrodes for non-alloy welding shall be in accordance with Specification AWS A5.1, ASME SFA-5.1.

(19)

(20)

Bare electrodes shall be in accordance with the following: Welding Process

Electrode

Submerged Arc Welding

AWS A5.17, ASME SFA-5.17

Inert Gas Welding

AWS A5.18, ASME SFA-5.18

Flux-Cored Arc Welding

AWS A5.20, ASME SFA-5.20

Each category A or B pressure retaining weld in accordance with Figure UW-3 of the ASME Code shall be spot radiographed, as a minimum requirement.

Each spot radiograph shall be a

minimum of 150 mm in length and in accordance with the ASME Code.

All welds to be

covered by nozzle reinforcing pads and at least one weld intersection shall be included.

Nozzle

welds shall be spot examined by magnetic particle or dye penetrant as a minimum requirement. (21)

Welds in vessel shells 50 mm and greater in thickness shall be 100% examined by ultrasonic in accordance with the ASME Code, after final post weld heat treatment.

(22)

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Deposited weld metal mechanical properties shall conform to the ASME requirements for the S-000-1353-002

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General Specification for Shell and Tube Heat Exchanger

base metal.

6.3

Low-alloy, high strength weld material for carbon steel vessel shall not be used.

Heat Treatment (1)

Postweld heat treatment (PWHT) shall comply with the governing Code requirements, or as specified.

(2)

Flange facings must be protected against oxidation during heat treatment.

(3)

When postweld heat treatment is required, one Brinell hardness reading shall be taken on the inside (except in alloy lined portions of vessels) of each shell section, head, longitudinal weld, and nozzle, and each longitudinal, girth and nozzle weld after final postweld heat treatment; and no reading shall exceed a value of 200.

(4)

The holding temperature and time, heating and cooling rate shall be verified with time-temperature record charts.

6.4

Tubing (1)

U-tubes made of chromium-molybdenum and ferritic stainless steel having bend radii smaller than five times their outside diameters, shall be stress relieved.

6.5

(2)

Nonferrous U-tubes shall be stress relief annealed after bending.

(3)

Carbon steel U-tubes for amine or caustic service shall be stress relieved.

(4)

For U-tubes, the wall thickness specified applied to the bending.

(5)

U-tubes shall be formed from a continuous length of tubing, free of girth welds.

Fabrication Tolerance Fabrication tolerances of heat exchangers shall conform to TEMA standard.

6.6

Test Rings Test rings shall be provided as follows : (1)

Removable bundle type heat exchangers : One test ring shall be provided per two identical units. However, for stacked heat exchangers, a sufficient number of test rings shall be provided to enable their testing in a stacked position.

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(2)

Test rings are not necessary: S-000-1353-002

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General Specification for Shell and Tube Heat Exchanger

7.

(a)

Fixed bundle type heat exchangers

(b)

C or N type channels

INSPECTION AND TESTING 7.1

General (1)

The inspection and testing of heat exchangers at the manufacturer’s shop shall be performed in accordance with the inspection and testing requirements of TEMA class “R”, ASME Code Section VIII Division 1 and API 660.

(2)

Covers, gaskets, bolting, apparatus and tools for inspections and testings shall be prepared by the manufacturer.

(3)

The manufacturer to produce a testing and inspection plan for purchaser*s approval.

7.2 Material Inspection (1)

The material inspection shall be conducted by confirming the material certificates of mill test reports of pressure retaining parts including non-pressure parts of low and high alloy, and non-ferrous materials.

(2) 7.3 7.3.1

Positive Material Identification (PMI) shall be conducted for alloy materials.

Welding Inspection Radiographic Examination (RT) Spot radiographic examination shall be a minimum requirement for the welding of heat exchangers. The radiographic examination shall be carried out before postweld heat treatment. Welds to be covered by attachments and at least T-cross weld shall be radiographed.

7.3.2

Ultrasonic Examination (UT) Where ultrasonic examination is specified, it shall be carried out before PWHT.

7.3.3

Magnetic Particle Examination (MT) and Liquid Penetrant Examination (PT) Magnetic particle examination shall be applied to the portions required by the code and to the following portions. If the magnetic particle examination is not practicable because of non-magnetic materials or it is not practicable with regard to the welded portion to be examined, a liquid penetrant examination may be alternatively applied. (1)

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Welded joints for pressure retaining parts, greater than 1.5” in thickness, shall be examined by PT or MT after PWHT. S-000-1353-002

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General Specification for Shell and Tube Heat Exchanger

(2)

For materials having a specified minimum tensile strength of 50 kgf/mm2 and over, the welds of attachments and the removed surfaces of temporary jigs, welded to heat exchanger shells or heads, shall be examined by yoke method after PWHT, where it is required.

(3)

The back gouged portion where the material having a specified minimum tensile strength of 50 kgf/mm2 and over shall be examined by magnetic particle method.

(4)

Strength weld and seal weld for tube-to-tubesheet joint shall be inspected by PT.

7.3.4

RT, UT, MT and PT shall conform to ASME Sect. Ⅴ article 2, 5, 7 and 6 respectively.

7.3.5

Hardness Test (1)

(2)

Hardness test shall be applied to the following heat exchangers: (a)

Heat exchangers under wet H2S, caustic or amine service.

(b)

Heat exchangers which are PWHT.

(c)

Heat exchangers which are made of low alloy

(d)

Heat exchangers for which hardness is specified on data sheet.

For heat exchangers as mentioned in para. 7.3.5 (1), hardness reading shall be taken on inside (except in alloy lined portions of vessels) and on the outside of each shell section, head, and nozzle, and each longitudinal, girth and nozzle weld after, if required, final postweld heat treatment.

(3)

For carbon steel vessels in wet H2S/sour service, hardness test requirement is according to Appendix-Ⅱ para.1.7.

(4)

One hardness test shall be made against the weldments of each welding procedure per heat exchanger.

(5)

The hardness test shall be carried out using a portable Brinell hardness tester with a 10 mm diameter ball after postweld heat treatment.

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(6)

The hardness test locations shall be designated by the witness inspectors.

(7)

The location to be hardness tested shall be flush and smooth.

(8)

The maximum hardness of weld metal and heat affected zone shall be as follows : Carbon steel ( Material Group : P-1 )

:HB 200

Low alloy steel ( Material Group : P-3, 4, 5 )

:HB 235

Ferritic stainless steel ( Material Group : P-6 & 7 )

:HB 235

Austenitic stainless steel ( Material Group : P-8 )

:HB 235

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General Specification for Shell and Tube Heat Exchanger

7.3.6

Weldment checking Weld joint of pressure retaining parts and non-pressure retaining parts shall be visually inspected to confirm that there is no defect in the weldment.

7.4

Pressure Test (1)

The minimum metal temperature during pressure testing shall be in accordance with either (a), (b) or (c) below. (a)

16ºC

(b)

17ºC above the minimum design metal temperature (MDMT)

(c)

17ºC above the ductile to brittle transition temperature for all of the materials of construction.

The transition temperature shall be established from impact test data.

(2)

TEMA RCB-1.3 “TESTING” shall be satisfied at pressure testing.

(3)

Gasket compound for flange joint contact surface may be used with prior approval.

(4)

Service gaskets shall be used for girth flange, nozzles and manholes, except for nozzles connected to piping, at pressure test.

(5)

For heat exchangers made of austenitic stainless steel or austenitic stainless clad steel and for heat exchangers having austenitic stainless steel internals, clean fresh water shall be used as the primary test medium, and the use of other test mediums shall be subject to prior approval. The test water shall have a chloride content of less then 50 ppm.

(6)

Hydrostatic tests for vertical type heat exchangers may be performed in the horizontal position.

(7)

Two pressure gauges per heat exchanger shall be used for the pressure test. One

test gauge shall

be set at the highest position and the other at the lowest position of the heat exchanger. (8)

The test pressure shall be held for not less than one hour and time- pressure record charts shall be required.

(9)

Abnormal deformation or leak of test medium shall not

(10)

The pressure test of stacked heat exchangers shall be performed in the stacked condition.

(11)

The pressure test of heat exchangers shall be as follows : (a)

be permitted.

Floating head type heat exchangers

<Step 1> :

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General Specification for Shell and Tube Heat Exchanger

A channel shall be connected to a tube bundle with a test ring, and a floating head shall be assembled. Then the test pressure shall be applied to the tube side and held for the specified time. The tubes, tube-to-tubesheet joints of stationary and floating tubesheet, channel and floating head assembly shall be inspected. (In the case where the shell side test pressure is higher than the tube side, this step of the test may be waived.) <Step 2> : After removing the floating head cover and channel, the tube bundle shall be inserted into and fixed to the shell using test rings. Then the test pressure shall be applied to the shell side and held for the specified time. The tube-to-tubesheet joints of stationary and floating tubesheets and the shell shall be inspected. In this step, a service gasket shall be used between the stationary tubesheet and the shell flange. <Step 3> : After the test rings are removed, the floating head and the channel with cover shall be assembled with service gaskets. Then the test pressure shall be applied to the tube side and held for the specified time. The girth flange joints shall be inspected. (In the case where the test step 1 is waived, the channel and floating head assembly shall also be inspected in this step.) <Step 4> : The shell cover shall be installed with the service gasket. Then the test pressure shall be applied to the shell side and held for the specified time. The

shell cover and the girth

flange joint shall be inspected. (b)

U-Tube type heat exchangers

<Step 1> : A channel shall be connected to a tube bundle using a test ring. Then the test pressure shall be applied to the tube side and held for the specified time. Next, the tubes, tube-to-tubesheet joints and channel assembly shall be inspected. (In the case where the shell side test pressure is higher than the tube side, this step of the test may be waived.) <Step 2> : After removing the channel, the tube bundle shall be inserted and assembled into the shell using a test ring with a service gasket between the tubesheet and shell flange. Then the test pressure shall be applied to the shell side and held for the specified time. The shell and tube-to-tubesheet joints shall be inspected. <Step 3> :

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General Specification for Shell and Tube Heat Exchanger

After the channel has been installed with service gaskets, the test pressure shall be applied to the tube side, and held for the specified time. The girth flange joint shall be inspected. (In the case where the test step 1 is waived, the channel shall also be inspected in this step.) (c)

Fixed tubesheet type heat exchangers

<Step 1> : The test pressure shall be applied to the shell side without channel or channel cover (or bonnet), and held for the specified time. The shell and tube-to-tubesheet joints of the stationary tubesheet shall be inspected. <Step 2> : After the channel and channel covers (or bonnets) have been installed with service gaskets, the channel assembly and girth flange joints shall be inspected.

7.5

Inspection of Tube Bundles Dimensions of tube outside diameters and tube holes in tubesheets shall be measured and the expanding ratio of tube to tubesheet joints shall be checked. The checking points shall be 20 where the number of tube-to-tubesheet joints is 200 and over, and 10 points shall be checked where the number of joints is under 200. The expanding ratio shall be the manufacturer’s guaranteed value.

Expanding Ratio (only for reference) Material of Tube Carbon steel, Low alloy steel

6-8

Stainless steel

7-8

Nickel alloy

5-6

Copper alloy

5

X =

X :

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Expanding Ratio (%)

d '− d − ( H − D ) × 100 2t

Expanding Ratio (Tube Thickness Reduction

Ratio)(%)

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General Specification for Shell and Tube Heat Exchanger

7.6

H :

Tube Hole Diameter of Tubesheet (mm)

D :

Tube Outside Diameter Before Expanding (mm)

d :

Tube Inside Diameter Before Expanding (mm)

d’ :

Tube Inside Diameter After Expanding (mm)

t

Tube Thickness (mm)

:

Leak Test for Reinforcing Plates (1)

Weld joints of reinforcing plates for opening shall be leak tested by pneumatic pressure. The test shall be performed at least 1.0 Barg using compressed air.

(2)

The test shall be carried out before PWHT, even if it is required.

(3)

Where the postweld heat treatment is not neccessory, the leak test shall be performed before hydrostatic test.

(4)

No leak or no abnormality shall be accepted.

7.7 Component Inspection (1)

Formed heads and cones shall be (a)

inspected as follows :

The portions, such as heads and cones with knuckles, where plate thickness reduction may be caused by forming, the thicknesses shall be measured

using an ultrasonic thickness

meter. (b)

When the heads and cones are heat treated after forming, the temperature shall be checked with time-temperature record charts.

(2)

7.8 7.8.1

For expansion joints, the inspection shall be conducted in accordance with the standard of EJMA.

Other Inspection Dimensional Inspection Dimensional inspection of completed heat exchangers shall be performed per TEMA.

7.8.2

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Inspection of Prefabricated Section

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In the fabrication of fixed tubesheet type heat exchangers, the tube bundle and shell shall be visually and dimensionally inspected before inserting the tube bundle into the shell. 7.8.3

Flange Surface Check Just before nozzle flanges are set in position, gasket contact surfaces of flanges shall be visually inspected with respect to the existence of harmful defects.

7.8.4

Heat Treatment Check (1)

Where a heat exchanger requires a heat treatment, the holding temperature, holding time, heating and cooling rate shall be checked with time-temperature record charts.

(2)

Item number, part number or part name, date of heat treatment, and shop name in the chart shall be also assured.

7.9

Inspection and Testing Records The manufacturer’s inspection and test records shall be prepared.

7.10

Scope of Inspection and Testing The scope of inspection shall be as called for in each requisition.

8.

PREPARATION FOR SHIPMENT (1)

Prior to shipment, heat exchangers shall be thoroughly cleaned, and all water, dirt, sand, weld metal spatter, welding electrode studs and foreign matter shall be removed.

(2)

Heat exchangers shall be painted in accordance with specification for paint.

(3)

Finished surfaces shall be coated with heavy grease, and flanged openings shall be properly protected with suitable covers. The preferred method of protecting flange finishes is as follows: Machined surfaces shall be coated with an easily removable rust preventative grease or strippable protective coating, and the entire gasket surface of the flanges shall then be covered with heavy duty plastic flange protectors, bolted or steel - strapped wood, wood fiber or metal covers.

Where wood,

wood fiber or metal covers are used, a plastic sheet shall be placed between the coated flange and cover for additional protection.

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For ocean shipment, flanged openings should also be covered with

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Table 4

Minimum Thickness for Nozzle and Manway Neck Nozzle Neck

Nominal

Reinf.

Nozzle

Pad.

Size

Dia.

(in)

(mm)

1

Corr. Allow.

Corr. Allow.

Corr. Allow.

Corr. Allow.

Corr. Allow.

0.0 mm

1.5 mm

3.0 mm

5.0 mm

6.0 mm

Min.

Sch.

Min.

Sch.

Min.

Sch.

Min.

Sch.

Min.

Sch.

Th’k

No.

Th’k

No.

Th’k

No.

Th’k

No.

Th’k

No.

6.0

XXS(5

8.0

L.W.N

9.0

3.0

4.5

3.3

4.8

1-1/2

160

6.3

2

160

3.5

5.0

6.5

3

190

4.8

6.3

6.9

4

220

5.3

6.8

6

300

6.3

7.8

8

400

7.2

8.7

10

500

8.2

)

L.W.N 8.3 8.5

160

9.3 XXS(5 )

9.5

9.9

10.9

8.3

10.3

11.3

9.3

11.3

10.2

12.2

13.2

13.2

14.2

160

XXS(5 )

12.3 160

80

40 9.7

11.2 80

12

600

14

680

16

780

80 80 8.4 18

870

20

970

24

1,160

9.9

11.4

13.4

14.4

40

Remarks

(1)

40 40

40

The minimum thickness shown in above table is the standard wall thickness minus 12.5%, plus corrosion allowance.

(2)

These sch. nos. shall be applied only for 150# and 300# ratings.

(3)

Above reinforcing pads are standard dimensions having the same thickness as shell or heads, and, those thicknesses for various diameters different from above may be obtained through the

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(4)

Dimensions of outside diameter and thickness for nozzle neck shall be in accordance with ANSI B36.10.

(5) LWN may be used.

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APPENDIX Ⅰ CORROSION RESISTANT CLAD HEAT EXCHANGERS

1.

SCOPE (1)

This appendix covers the additional requirements for design, fabrication, inspection and testing of heat exchangers constructed of material with corrosion resistant integral cladding or weld metal overlay cladding.

(2)

2.

This appendix supplements the basic requirements given in general specification for heat exchangers.

MATERIALS 2.1

Clad Plate (1)

The clad plate bonded by rolling or explosion method shall be homogeneously made to have a material quality and a thickness as specified.

The clad plates used for heat exchangers shall meet

one of the following standard specifications or equivalent . (a)

ASTM A 263

“Corrosion-Resisting Chromium Steel-Clad Plate, Sheet, and Strip”

(b)

ASTM A 264

“Stainless Chromium-Nickel Steel Clad Plate, Sheet, and Strip”

(c)

ASTM A 265

“Nickel and Nickel-Base Alloy Clad Steel Plate”

(d)

ASTM B 432

“Copper and Copper Alloy Clad Steel Plate”

(2)

Strip lining is not permitted unless specified in the data sheet.

(3)

Alloy lining for shells and heads shall be integrally cladding or weld deposit overlay.

(4)

Tube sheets may be alloy lined by cladding or weld deposit overlay with the following restrictions: (a)

Cladding shall be integrally and continuously bonded to the base metal

(b)

When other parts in contact with the same fluid are specified as “killed steel”, the base metal of the clad or faced tube sheet shall also be killed steel.

(c)

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Silver soldered or brazed bonded liners shall not be used.

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3.

DESIGN 3.1

Thickness (1)

No corrosion allowance shall be added to the base metal.

(2)

The thickness of the clad metal an/or weld deposit overlay shall be considered as corrosion allowance.

(3)

When clad plate is used, the clad metal shall be cut back at all seams to permit backwelding of the base metal.

Weld metal shall be ground flush and fully covered with the applicable weld deposit

overlay. The weld deposit overlay shall be at least as thick as the lining but no greater than twice its thickness. 3.2

Nozzles and Manholes (1)

Nozzles with alloy lining shall be flanged and be sized to a minimum of 1½ in. nominal pipe size.

(2)

Nozzles and manholes shall be fabricated with integral cladding or weld metal overlay cladding, where possible. However, the nozzles sized 4 in. and smaller may be fabricated with sleeve lining which behind space shall be vented to the atmosphere with a ¼ in. NPT telltale hole and the hole is filled with grease.

Sleeves shall be welded to the alloy facing at the flange end.

Attachment

of the sleeves at the inside surface of the exchanger may be by welding, flush with the exchanger inside surface, or an expansion (contraction) collar.

Sleeves with a different expansion

coefficient (e.g. Austenitic SS/CS) to the nozzle shall not be used for design temperatures above 400ºC.

4.

Sleeves shall be welded before PWHT for low alloy steel exchangers.

(3)

The flange facings and nozzle attachment weld shall be lined with weld metal overlay cladding.

(4)

Solid stainless steel nozzles are not permitted.

FABRICATION 4.1

Welding Electrodes Welding electrodes for clad metal shall be used as shown in Table 5.

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Table 5

Welding Electrodes for Clad Metal AWS-Welding Electrode Specification

ASME

Clad Metal

SPEC.

Weld to Base Metal

SA 263

SA 264

SA 265

Weld with Clad Metal

Type 405 or 410S

E309L-xx

E309L-xx

Type 304

E309L-xx

E308-xx

Type 304L

E309L-xx

E308L-xx

Type 316

E309-Mo-xx

E316-xx

Type 316L

E309-MoL-xx

E316L-xx

Type 321 or 347

E309L-xx

E347-xx

ENi Cu-7

ENi Cu-7

ENi Cu-7 or ENi-1

ENi Cu-7 or E Cu Ni

UNS 04400 (Ni-Cu Alloy) UNS C 70600

B 432

UNS C 72200 UNS C 71500 (Cu-Ni Alloy)

Note *

AWS electrode designation xx are 15 or 16. The equivalent grade of AWS specifications may be used. When inert gas shielded or submerged metal-arc processes are used, stainless-filler metals made in accordance with Specification AWS A5.9, ASME SFA-5.9, with composition similar to those listed above, or Monel (nickel copper alloy) in accordance with AWS A5.14, ASME SFA-5.14 shall be used.

4.2

Welding Unless otherwise specified, lugs and rings for internal supports in lined portions of the exchanger may be welded directly to the lining only if the exchanger is lined with integrally bonded lining or weld deposit overlay meeting the requirements of Paragraph UCL-11(a) and (c) Section VIII Division 1 of the ASME Code.

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4.3

Alloy Lining (1)

In this specification the term “Alloy Lining” is a general term that does not imply a specific fabrication or manufacturing process.

(2)

When integrally bonded clad exchangers are used, a minimum of 10% of the clad surface, including no less than 0.1 square m in each 1.0 square m or fraction thereof, shall be ultrasonic examined for lack of bond after forming.

The cladding shall be 100% ultrasonically examined

in areas where attachments are to be welded directly to the cladding.

Unbonded areas that

cannot be encompassed by a 75 mm diameter circle shall be repaired by weld deposit overlay in accordance with paragraph 4.1 of this Appendix.

When repairs in excess of 5 percent of the total

examined area are required, the exchanger shall be 100 percent ultrasonic examined.

Repaired

areas and weld deposit overlay at weld seams shall be 100% liquid dye penetrant examined in accordance with ASTM E165.

Ultrasonic examination shall be in accordance with SA578 SD6

for spot examination or S7 for 100% examination. (3)

The weld overlay shall be applied circumferentially to the exchanger and shall be relatively smooth with no notches and undercuts that would act as stress intensifiers.

Flaws on the surface

of the base metal that would interfere with bonding of the overlay shall be removed by grinding. (4)

All weld deposit overlay, whether by manual or automatic procedures, shall be 100% liquid dye penetrant (PT) examined in accordance with the methods described in ASTM E 165.

When the

overlay involves two passes )layers) and the procedure uses an intermediate heat treatment with cooling to room temperature prior to applying the second layer, each layer shall 100% PT examined.

Weld deposit overlay machined surfaces shall be 100% PT examined after final heat

treatment.

Weld deposit overlay shall be spot PT examined (a minimum of 10% of the surface,

including no less than 0.1 square m in each 1.0 square m of fraction thereof) after final heat treatment and shop hydrostatic testing.

Flange facings need not be included in the spot

examination after hydrotest. (5)

All cracks and fissures and circular defects greater than 1.6 mm diameter in weld deposit overlay shall be removed.

(6)

Repaired areas shall be 100% re-inspected by liquid dye penetrant.

The weld deposit overlay procedure shall be qualified on base metl of the same composition as the exchanger and thickness of one-half of the exchanger thickness, or 50 mm, whichever is less.

(7)

A minimum of two samples of the weld deposit overlay shall be taken from each overlayed shell section and head to confirm required analysis. seams and nozzles, shall also be sampled.

Each manual weld overlay, such as those on girth

Analysis to a depth of 3/4 of the required overlay

thickness shall conform to the chemistry requirements for the alloy specified on the data sheet or

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drawing.

Where automatic weld deposit overlay is applied by more than one welding operator,

samples shall include deposits made by each operator. (8)

Nozzles and manways in alloy lined portions of exchangers shall be alloy lined and faced. facing shall be made with weld deposit which is at least as thick as the lining machined and of the same alloy as the lining.

The

when properly

When nozzles are lined with ferritic type 405 or

410S stainless steel linings, the facing weld deposit shall be made with type 309L welding electrode.

The facing weld deposit for austenitic stainless steel linings shall be made with type

309L welding electrode for the first pass, and the welding electrode for the second pass shall be of the same or similar analysis as the lining. (9)

The method of lining large nozzles and manways shall be by integrally bonded cladding or weld deposit overlay.

(10)

Tubular liners are not acceptable in nozzles greater than 4 inch NPS. and smaller tubular liners may be used. end.

For nozzles 4 inch NPS

They shall be welded to the alloy facing at the flange

Attachment of the liner at the inside surface of the exchanger may be by welding, flush

with the exchanger inside surface, or an expansion (contraction) collar.

The final design details,

accounting for the sustained and cyclic stresses due to the intended operation of the exchanger, are the responsibility of the manufacturer. (11)

For hydrogen service, nozzles with tubular liners welded on both ends shall be vented with an ¼ inch NPT hole, drilled from the outside to the OD of the liner.

(12)

Solid alloy nozzles, are not recommended, and shall not be used at design temperature above 450ºF (232ºC).

(13)

Paragraphs NF-7 and NF-14 of Appendix NF in Part UNF of Section VIII of the ASME Code are mandatory for nonferrous types of cladding or applied lining.

5.

INSPECTION AND TESTING 5.1

Material Inspection The materials of clad plate to be used for heat exchangers shall be inspected by ultrasonic examination so as to check the quality of the bonding in accordance with SA 578 “Straight-Beam Ultrasonic Examination of Plain and Clad Steel Plates for Special Applications”, and acceptance level shall be S6 as specified in the standards.

However the band having a width not less than 75 mm along with cut edge

shall have no defects.

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5.2

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Air Test (1)

Air test for the weld of sleeve shall be performed before PWHT, even if it is required.

(2)

No leak shall be permitted.

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APPENDIX II CARBON STEEL PRESSURE VESSELS IN WET H2S / SOUR SERVICE INCLUDING THE HIC RESISTANT MATERIAL REQUIREMENTS

1.

GENERAL MATERIALS, WELDING AND HARDNESS REQUIREMENTS FOR VESSELS IN WET H2S/SOUR SERVICE

1.1

GENERAL All materials shall be in accordance with the materials property and heat treatment requirements of NACE MR0175 as supplemented or modified by this Appendix.

1.2

HEAT TREATMENT CONDITION All materials shall be supplied in the normalised condition. Normalising shall be carried out as a separate heat treatment. The acceptability of hot-finished material shall be subject to the approval of the Principal.

1.3

PLATE Plate shall comply with ASTM A 516, as modified below. 1.3.1

Chemical composition

In order to ensure effective resistance to SSC(Sulphide Stress Corrosion) in the as-welded condition, the chemical composition (product analysis) shall be restricted as follows, except where the standard material specification is more restrictive: Single Elements

Maximum wt.%

Carbon (C)

0.20

Sulphur (S)

0.01

Multiple Elements Vanadium (V) + Niobium (Nb)

0.02

Carbon Equivalent (Note 1)

0.43

Notes 1

Carbon Equivalent (CE) shall be calculated using the following formula: CE= C + Mn/6 + (Ni+Cu)/15 + (Cr+Mo+V)/5

1.3.2

Through-thickness testing

All plates shall meet the through-thickness testing requirements of ASTM A 770 S3 (with a minimum area reduction of 35%). HIC-tested plate in accordance with Sections 2 and 3 of this appendix is an acceptable alternative.

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1.4

FORGINGS (Flanges, etc.) Forgings shall be in accordance with ASTM A 105N or ASTM A 350-LF2, with the following restrictions:

1.5

Carbon :

0.25 wt.% max.

CE

0.43 max.

:

SEAMLESS PIPE (e.g. for nozzles) Seamless pipe shall be in accordance with ASTM A 106 Grade B or ASTM A 333 Grade 6, with the following restrictions:

1.6

Carbon :

0.23 wt.% max.

CE

0.43 max.

:

WELDED PIPE AND FITTINGS Fittings shall be in accordance with ASTM A 234 WPB or WPC. Generally, only seamless pipe and fittings should be used for vessel nozzles. Base materials shall be in accordance with the above specifications for forging or pipe, as applicable. Where this is impractical, welded pipe and fittings may be used and shall be manufactured from plate complying with Section 1.3 of this Appendix. Welding of such fittings shall be done using welding procedures qualified in accordance with Section 1.7 of this Appendix.

1.7

WELDING AND HARDNESS REQUIREMENTS 1.7.1

Welding Procedure Qualification

Material purchased for the contract, or equivalent material (i.e., specification, grade, CE and chemistry controls), shall be used for all welding procedure qualification tests (WPQTs). In addition to the standard mechanical tests, each WPQT shall include a macro section and hardness traverses in accordance with EN 1043-1. The series of readings shall extend from unaffected base material on one side, across the weld to unaffected base metal on the other side. Three traverses shall be made: one 2 mm below the outer surface, one 2 mm below the inner surface and one across the centre. The distance between measurements across the weld shall not exceed 2 mm. No part of the weld, HAZ or base metal shall exceed 248 HV 10. WPQT hardness testing shall be performed by the Vickers method. NOTE:

1.7.2

The weld metal deposit shall not contain more than 1.00% nickel.

Production Welds

Transverse weld hardness testing of production welds shall be carried out using a portable Vickers or Rockwell tester in accordance with ASTM

E 110 or by another method capable of detecting a hard HAZ

in a reliable and repeatable manner (e.g., Equotip, Microdur or other equivalent if approved by the Principal). Whenever possible, hardness tests shall be made on the inside (process-contacted side) of the vessel.

_ _ _ __ R_A_| D N I _ _ | _

Hardness tests shall be made on properly ground surfaces.

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On heat-treated vessels, hardness testing shall be carried out after PWHT. One set of hardness measurements shall be carried out for each welding procedure qualification applied and for each 10 metres of finished weld (with a minimum of one test). For each set of hardness measurements required, the average of three measurements on the weld and on each HAZ shall be reported. No part of the weld, HAZ or base metal shall exceed 248 HV 10.

2.

HIC RESISTANT MATERIALS REQUIREMENTS The requirements of this Section are additional to the general requirements of Section 1 of this Appendix.

2.1

HEAT TREATMENT CONDITION Vessels shall be given PWHT unless otherwise specified by the Principal. The minimum PWHT time and temperature shall be 1 hour at 610 deg C. The maximum PWHT time and temperature shall be governed by the design code requirements and the material properties as guaranteed by the material supplier.

2.2

PLATE 2.2.1

General

Plate complying with ASTM A 516, as modified below, shall be used for all pressure boundary plate components in contact with the process environment. All other plate materials (e.g. reinforcing pads, clips, skirts) shall be made from material complying with Section 1.3 of this Appendix. Plate material shall be HIC-tested in accordance with Section 3 of this Appendix. Plate shall be tested in a simulated PWHT condition (see Section 2.1 of this Appendix). 2.2.2

Manufacturing process

The steel shall be vacuum-treated, fully deoxidised, desulphurised and dephosphorised. The manufacturing/rolling process shall be such that a homogeneous microstructure is obtained, i.e. the structure shall be free of any significant ferrite/pearlite banding (see Section 3.6 of this Appendix). Calcium treatment shall be applied for inclusion shape control, except that it need not be applied to plate with very low sulphur levels (below 0.001%). The calcium content should not exceed 3 times the sulphur content. Alternative methods of inclusion shape control shall be subject to the approval of the Principal. 2.2.3

Chemical composition

In order to ensure effective resistance to both HIC and SSC, the chemical composition (product analysis) shall be restricted as follows, except where the standard material specification is more restrictive: Single Elements

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Maximum wt.%

Carbon (C)

0.20

Manganese (Mn)

1.30

Phosphorous (P)

0.01

Sulphur

0.002

Silicon (Si)

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Copper (Cu)

0.4

Nickel (Ni)

0.4

Chromium (Cr)

0.3

Molybdenum (Mo)

0.12

Vanadium (V)

0.015

Niobium (Nb)

0.015

Titanium (Ti)

0.02

Boron (B)

0.0005

Multiple Elements Cr + Mo

0.3

Ni + Cu + Cr + Mo

0.7

V + Nb

0.02

Carbon Equivalent (Note 1)

0.43

Notes :1.

Carbon Equivalent (CE) shall be calculated using the following formula: CE= C + Mn/6 + (Ni+Cu)/15 + (Cr+Mo+V)/5

2.2.4

Lamination check Plate shall be subjected to an ultrasonic lamination check in accordance with ASTM A578 with a supplementary acceptance standard S2.

2.3

WELDED PIPE AND FITTINGS

Generally, only seamless pipe and fittings should be used for vessel nozzles. Where this is impractical, welded pipe and fittings manufactured from plate complying with Section 2.2 of this Appendix shall be used. Welding of such fittings shall be done using welding procedures complying with Section 1.7 of this Appendix.

3.

HIC TESTING 3.1.1

Responsibility HIC testing is the responsibility of the vessel manufacturer but the testing may be performed by the steel manufacturer. Material inspection certificates shall be in accordance with ISO 10474, type 3.1.C (for which the vessel manufacturer or steel manufacturer shall appoint the witnessing party, which shall be subject to the approval of the Principal).

3.1.2

Frequency of Testing The vessel Manufacturer shall perform HIC sensitivity tests in the solution prescribed in Section

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Plate materials shall be subjected to HIC testing at a frequency of one test per heat. For pressure vessel plate where more than one thickness may be rolled from the same heat, tests shall be performed on both the thickest and the thinnest plates produced from each heat. 3.2

QUALIFICATION OF TEST METHOD Before commencement of the work, the vessel Manufacturer shall provide the Purchaser with a detailed procedure for the testing, metallographic preparation and evaluation of HIC specimens. The Manufacturer shall qualify the test method using samples from a steel of known crack sensitivity. The Principal shall indicate if any of these tests are to be witnessed.

3.3

SAMPLING 3.3.1

Removal of Test Specimens Three adjacent specimens shall be removed cold, by machining from the test plate. The dimensions shall be 100 mm x 20 mm x t, where t is the plate thickness. The long dimension of the specimen shall be parallel to the plate rolling direction. For plates or pipe greater than 20 mm in thickness but less than 50 mm, specimens shall be extracted from the middle of the plate such that the specimen thickness is not greater than 20 mm. For plate thickness equal to or greater than 50 mm, an additional set of specimens shall be removed from the surface.

3.3.2

Specimen Preparation The specimens shall first be rough ground on a belt grinder or by surface grinding. This shall be followed by final grinding to a 320 grit finish using silicon carbide papers. They shall then be degreased in acetone. The effectiveness of degreasing shall be demonstrated by using the atomiser test of ASTM F 21. Thereafter, extreme care shall be taken not to contaminate the coupons, which should only be handled with tongs or clean gloves.

3.4

TEST SOLUTION The test shall be performed in the NACE TM0177 (low pH) test solution, i.e. 0.5% acetic acid + 5% NaCl + H2S in water, with a pH of 2.9 to 3.3. The test shall be performed in glass vessels only. The solution shall be de-aerated by bubbling nitrogen through it at a rate of 100 cm3/l/min for 1 hour. The specimens shall be immersed in the solution with the face of 100 mm x 20 mm in the vertical position and the lower face raised from the cell bottom on Teflon or glass rods. When stacked, the specimens shall also be separated by similar rods. Nitrogen bubbling shall be continued for a further 1 hour, after which the solution shall be saturated by bubbling H2S at the rate of 2 to 5 l/min for one hour through an open-ended tube with a 5 mm internal diameter. Upon reaching saturation, the H2S flow rate may be reduced to 100 cm3/min. for a 10 litre solution, or pro rata, and maintained at this rate for the test period. The H S purity shall be 99.5 vol.% or higher, and oxygen-free.

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A small positive pressure of H2S should be maintained in the test cell by the use of an outlet trap to prevent oxygen contamination from the air. If at any time during the test a white haze clouds the solution, the test shall be stopped and repeated with new specimens and fresh solution. Conditions for the test shall be as follows: Temperature

25 +/-

H2S concentration

2300 to 3500 ppm, saturated condition

pH value

initial

2.9 to 3.3

final

3.5 to 4.0

Test period

3 deg C

96 hours

The pH value of the solution shall be measured at the beginning and the end of the the H2S concentration in the solution shall be determined at the end by 3.5

test and

iodometric titration.

EVALUATION OF BLISTERING AND HYDROGEN INDUCED CRACKING 3.5.1

Blistering

The tendency to blistering shall be reported after visual examination, and photographs shall be taken of the two wide faces of each coupon to show any blistering. 3.5.2

Hydrogen Induced Cracking

Specimens, taken with their long axis (100 mm) parallel to the rolling direction, shall be sectioned transversely at three points. The intention of this sectioning procedure is to examine for cracks, in each case on a plane transverse to the rolling direction. Cracking shall be estimated by micrographic examination at magnifications of X30 and X100. 3.5.3

Evaluation

For each crack observed, the length and extent of stepwise propagation shall be measured. For each section containing cracks, one photograph shall be taken showing the complete transverse sections. HIC is defined in terms of crack length ratio (CLR), crack thickness ratio (CTR) and crack sensitivity ratio (CSR). These values shall be reported for each section examined, and as the average of three (3) sections per specimen. In this evaluation, cracks which have no part more than 1 mm from the surface associated with surface blistering shall be disregarded. 3.5.4

Acceptance Criteria

The following acceptance criteria shall be met: TABLE 5 % (maximum)

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CLR

CTR

CSR

Average

5

1.5

0.5

Single

7

2

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Sohar Refinery Company SOHAR Refinery Project

JOB CODE: 0-3100-25 DOC NO: S-000-1353-002 rev.R

SHEET : 46 of 48

General Specification for Shell and Tube Heat Exchanger

The maximum individual crack length on any section shall not exceed 5 mm. If any specimen fails to meet the above acceptance criteria, the heat of steel represented by the test shall be rejected. 3.6

EVALUATION OF PLATE MICROSTRUCTURE FOR BANDING One specimen from each plate shall be polished and etched (in thicker plates, multiple specimens representing the full thickness shall be prepared) and the microstructure evaluated for the degree of banding according to ASTM E 1268. Microindentation hardness tests are not required. Results shall be reported, for information only, using ASTM E 1268 reporting nomenclature.

3.7

REPORTING a)

Results of cracking evaluation indicating individual CLR, CTR and CSR for each section and also averaged over 3 sections, and pass/fail.

b)

Photomicrographs of the specimens showing cracking, together with photomicrographs of adjacent material structures and photomicrographs of the bulk material structure (samples) used to assess microstructure banding:

c)

i)

Unetched, showing the type of inclusions in the steel

ii)

Etched, showing the parent material microstructure.

iii)

Assessment of microstructure banding per ASTM E 1268.

pH of the H2S saturated solution at the beginning and at the end of the test, the H2S

content

and confirmation of the type of solution. d)

Photographs of specimens, showing any blisters.

e)

Location and dimensions of specimens.

f)

Full chemical analysis of material tested including analysis for micro-alloying elements.

g)

Mechanical properties of materials tested after a simulated PWHT cycle.

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JOB CODE: 0-3100-25

Sohar Refinery Company SOHAR Refinery Project

DOC NO: S-000-1353-002 rev.R

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General Specification for Shell and Tube Heat Exchanger

APPENDIX III GENERAL SPECIFICATION FOR ZINC SACRIFICIAL ANODE FOR USE IN SEA WATER HEAT EXCHANGERS

1.

General This specification covers the requirements for supply, identification, inspection, and testing of sacrificial anodes made of zinc, intended for use in shell-and-tube heat exchangers using sea water as a cooling medium, where carbon steel parts is used in conjunction with copper-alloy tubes. Carbon steel parts which is electrically coupled with copper-alloys and is in contact with sea water, should be protected from galvanic attack by fitting sacrificial anodes. The ordering/purchasing documents shall specify required dimensions of anode, steel insert, and brackets and net weight of anodes, or alternatively reference shall be made to a supplier's standard type and size of anode.

2.

Anode Materials Zinc anodes shall be used provided that maximum operating temperature of sea water is less than 50 degree C. Zinc anodes shall meet the requirements of ASTM B418 Type II. The specification is:

3.

Al

: 0.005 % max.

Cd

: 0.003 % max.

Fe

: 0.0014 % max.

Pb

: 0.003 % max.

Cu

: 0.002 % max.

Zn

: remainder

Identification of Anodes Each anode shall be clearly marked with the type of material or trade name, the cast number, and a piece serial number. The numbers of any rejected anodes shall not used again for replacement anodes.

4.

Documentation The supplier shall provide full documentation on number, size, weight, type of anodes, type of steel inserts, dimensions, results of analysis on casting samples, results of checks on anode potentials, and results of any other test(s) required to be done by the supplier.

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Any certificates issued by an inspection agency shall be included in the documentation.

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Sohar Refinery Company SOHAR Refinery Project

JOB CODE: 0-3100-25 DOC NO: S-000-1353-002 rev.R

SHEET : 48 of 48

General Specification for Shell and Tube Heat Exchanger

5.

Testing of Anodes The supplier shall carry out the following tests: a)

A full chemical analysis of each cast. The results shall meet the requirements of ASTM B418 Type II.

b)

A short-term potential test in synthetic sea water of ambient temperature shall be carried out for each cast. The open circuit potential shall be minus 1050 mV or more negative with reference to an Ag/AgCl electrode.

6.

Quality of Anode Casting The as-cast anode surface shall be free from surface slag or other embedded material. Cracks are not acceptable, except in the form of micro (hairline) cooling cracks of maximum width of 1 mm. Shrinkage cavities shall not exceed 10 mm in depth, as taken from anode surface. Slag inclusions are not acceptable. Tolerance on the dimensions of anodes, position of anode inserts and gross weight of anodes, to be plus 5% and minus 2%.

7.

Quality of Steel Inserts Any type of steel insert shall be fabricated from low-carbon steel, and plate/strip to be ASTM A185 Gr. C or equivalent which is to be substantiated by mill certificates. The steel incerts shall be blast-cleaned to a near-white metal finish, standard Sa 2-1/2, and have this finish at the time of casting.

8.

Inspection Inspection during and after fabrication of anodes shall be carried out by the contractor. Inspection shall cover the following as a minimum: a)

Dimension of cracking, identification, weight, and quality of castings on at least 5% of the number of anodes from each cast.

b)

Quality of steel inserts before casting, and surface preparation on at least 5% of inserts for batch of anodes from cast.

c)

9.

Inspection of results of chemical analysis and potential tests done by supplier.

Acceptance and Rejection Where any of the requirements, mentioned in this specification, are not met, the anodes and relevant batch of anodes will be rejected.

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