Weld Procedures for Cryogenic Service_SNC_LAVALIN

POLSKIE LNG LIQUIFIED NATURAL GAS REGASIFICATION TERMINAL IN SWINOUJSCIE POLAND

Contract Nº: FW Doc. Nº: SNCL Doc. Nº: Revision: Date: Page:

1DD5528A DD5528A-88A1 017923-0000-45EG-0302_PB

0 October, 2008 Page 2 of 8

CONTENTS

PARA.

SUBJECT

I.

SCOPE

II.

REFERENCE DOCUMENTS

III.

REQUIREMENTS FOR CRYOGENIC SERVICE

EXHIBIT "A"

ACCEPTABLE WELDING PROCESSES

EXHIBIT "B"

ACCEPTABLE FILLER METALS FOR JOINING AUSTENITIC STAINLESS STEEL

THIS DOCUMENT CONTAINS FW IBERIA S.A.U. CONFIDENTIAL TECHNICAL INFORMATION


I.

II.

1DD5528A DD5528A-88A1 017923-0000-45EG-0302_PB


SCOPE A.

This document is a complement to general Welding Specification 017923-000045EG-XXXX for welding of stainless steel in cryogenic service. General requirements in Specification 017923-0000-45EG-XXXX are applicable, unless specifically amended hereinafter.

B.

LNG cryogenic service refers to operating temperatures down to -170ºC.

C.

This Specification is applicable to welding of stainless steel vessels, exchangers, machinery, piping and piping components in cryogenic service. Welding of non pressure parts is not within the scope of this specification.

D.

Compliance with this standard does not relieve the manufacturer or the vendor of the responsibility for supplying material and workmanship of proper quality and fully suitable for all the specified operating conditions.

REFERENCE DOCUMENTS •

III.


ASME Boiler & Pressure Vessels Code, all applicable Sections (hereafter referred to as the ASME Code) and, specially, Section II-C, Material Specifications Welding Rods, Electrodes and Filler Metals, Section VIII, Pressure Vessels and Section IX, Welding & Brazing Qualifications.

•

ASME B31.3 Process Piping

•

EN 1473 Installation and equipment for LNG. Onshore installations.

•

NFPA 59A Production, storage and handling of LNG.

•

European Directive 97/23/EC

REQUIREMENTS FOR CRYOGENIC SERVICE A.

Procedures Submittal Requirements Welding procedures shall be prepared as required by ASME Code, Section IX, latest revision including all addenda officially issued by ASME at the date of purchase order. The qualification of welding procedures and of welders shall be in accordance with ASME Code, Section IX and performed at the presence of a recognized independent Agency, as required by Pressure Equipment Directive 97/23/EC.



B.

C.

D.


1DD5528A DD5528A-88A1 017923-0000-45EG-0302_PB


Base Metal Preparation 1.

Joint preparation for welding may be performed by machining, grinding, thermal cutting, or combination thereof. Excessively deep or sharp irregularities in joint edges shall be removed by machining or by grinding. Joint edges shall be crack and lamination free prior to welding.

2.

Prior to welding, all oil, grease, dirt, rust and all loose scale shall be removed from the surfaces of the joint and the adjacent base metal within one inch from the edge of the joint. Oil and grease shall not be removed by heating with a torch.

3.

Only tools and brushes made of stainless steel shall be used. Additionally, all solvents, cleaners, markers, etc., must be chloride free.

Preheat and Interpass Temperature 1.

When, before welding, the base metal temperature is below 0ºC, the base metal shall be preheated to at least 20ºC, and this minimum temperature maintained during welding.

2.

Welding shall not be done when the ambient temperature is lower than 18ºC.

3.

Welding shall not be performed when condensation occur on the metal surfaces; appropriate heating shall be provided. Welding shall not be done if the materials to be welded are at a temperature less than 20ºC.

4.

For all thicknesses of austenitic stainless steel, preheat and max. interpass temperature shall not exceed 175ºC.

Welding Process 1.

The welding processes listed in EXHIBIT "A" "Acceptable Welding Processes" of this specification are acceptable for fabrication subject to the limitations stated therein. Request to use any other welding process shall be submitted to client for approval.

2.

Unless otherwise allowed in writing by client, all butt joints which are accessible from both sides shall back gouged or ground to sound metal after welding the first side and then back welded on the reverse side.



E.


1DD5528A DD5528A-88A1 017923-0000-45EG-0302_PB


3.

Where access or wall thickness precludes the use of double welded butt joints, single welded joints shall be made using a root pass deposited by the GTAW.

4.

All welds of nozzles, manways, and their reinforcement to equipment shell, heads, skirts and/or piping shall be full penetration.

Welding Filler Materials 1.

All filler materials used must be manufactured following the rules of ASME Section II, Part C.

2.

Each lot or heat of stainless steel welding materials will be tested to verify that the requirements of ASME Section VIII (UHA-51) are fulfilled.

3.

In general the tensile strengths of deposited weld metal shall be at least equal to the specified minimum tensile strength of the materials being welded.

4.

When joining similar materials the chemical composition of the deposit weld metal shall mach that of the base metal as closely as possible. Any deviation shall be reported and approved by Client. This shall not prelude the use of welding materials containing alloying elements of different type or in different amounts than those in the base materials provide these is not evidence that such elements are not harmful and the only way to achieve desirable weld metals properties such as adequate tensile strength of adequate impact strength al low temperatures.

5.

When filler metal designated under AWS classification "G" is used, both WPS and PQR must use filler metal of the same manufacturer and brand name.

6.

Unless otherwise authorized in writing by Client, filler metals for joining similar and dissimilar stainless steel shall meet the requirements of EXHIBIT "B", "Acceptable Filler Metals for Joining Austenitic Stainless Steels" of this Technical Specification, including notes.

7.

PWHT of solid austenitic stainless steel components shall not be performed unless specifically required by Material Requisition/Drawing. PWHT procedure shall be submitted by Client for review and acceptance.



F.


1DD5528A DD5528A-88A1 017923-0000-45EG-0302_PB


Toughness 1.

Procedure qualification: only welding procedures that have been qualified for impact properties using the Charpy V-notch method at a temperature not higher than that specified on individual material requisition are acceptable.

2.

When design temperature is colder than -104ºC, PQR for austenitic steel welds must include impact tests at weld zone and HAZ, in order to ensure impact properties. Impact tests will be performed at temperature equal or lower than MDMT, and PQR must be qualified using the same manufacturer brand and filler metal type than used for production welding.

3.

Acceptance criteria is based on lateral expansion, which shall not be less than 0.38 mm for all specimen sizes.

4.

To achieve an optimum between toughness properties at cryogenic temperatures and hot cracking susceptibility, ferrite content must be maintained between 3-8 FN. PQR shall include ferrite measurements.



EXHIBIT "A"


1DD5528A DD5528A-88A1 017923-0000-45EG-0302_PB


ACCEPTABLE WELDING PROCESSES

WELDING PROCESS

Restriction (see below) (1) (2)

SMAW

-

Shielded Metal Arc

GTAW

-

Gas Tungsten Arc

3, 9

SAW

-

Submerged Arc

4, 5, 6, 7, 8

RESTRICTIONS: Unless otherwise authorized in writing by Client use of these welding processes is subject to indicated restrictions: 1.

Individual beads deposited by standard automatic processes shall not exceed 6mm deep.

2.

Backing rings will not be used unless approved by Client.

3.

Internal purging with inert gas is required for root and second passes of single welded butt joints in stainless steel. Purity of inert gas will be 99.99% minimum.

4.

The use of neutral flux (non-voltage sensitive) is required for submerged arc welding.

5.

The use of alloy wire and neutral flux, rather than alloying through the flux, is required where an alloy weld deposit is desired. Alloy, semiactive or active flux is not allowed. Fluxes that compensates for small losses of alloying elements are permitted.

6.

Use of manual submerged arc welding is not permitted.

7.

Start and run off pads of same material as base material shall be used on all longitudinal seams.

8.

The flux and wire combination actually used shall be the same manufacturer and grade than used in the procedure qualification. The manufacturer and brand name or grade shall be specified in WPS and PQR.

9.

When this welding process is used for field welding, suitable precautions shall be taken to shield the welding area from wind or drafts which could interfere with the shielding as protection.



EXHIBIT "B"

ACCEPTABLE FILLER MATERIALS STAINLESS STEEL (1) (2) (3)

Mater. to be Welded

304

304L

304

308

308

304L

308L

309 309S 310 310S 316 316L 316Ti 317 317L


309 309S 308 309 308 309

310 310S 308 309 308 309

309

309 310

FOR

1DD5528A DD5528A-88A1 017923-0000-45EG-0302_PB


JOINING

316

316L

316Ti

317

317L

321

347

348

308

308

308

308

308

308

308

308

308L

308L

308L

308L

308L

308L

308L

308L

309 316 309 316

309 316 309 316

309 318 309 318

309 317

309 317

309 321

309 347

309 348

309

309

309

309

309

316

316

316

316

316

316

316

316

316L

316L

316L

316L

316L

316L

316L

318

317 318

317L 318

317

317

318 321 317 321 317L 321

318 347 317 347 317L 347

321

347

318 348 317 348 317L 348 347 348 347 348

317L

321

AUSTENITIC

347

347

348

348

NOTES: (1)

321 filler metal only exists as rod (ER321). For coated electrode use E347.

(2)

Low carbon filler wires will result in lower tensile strengths. Refer to par. III.E.3.


Weld Procedures for Cryogenic Service_SNC_LAVALIN

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