WEM-SU-5246

November 2009 2009 Chevron U.S.A. Inc. All rights reserved. 1 of 8

This document is the confidential property of Chevron U.S.A. Inc. Neitherthe whole nor any part of this document may be disclosed to any thirdparty without the prior written consent of Chevron U.S.A. Inc. Neither thewhole nor any part of this document may be reproduced, stored in anyretrieval system or transmitted in any form or by any means (electronic,mechanical, reprographic, recording or otherwise) without the priorwritten consent of Chevron U.S.A. Inc.

WEM-SU-5246

USE OF NON-PRESSURE-TESTED CLOSURE WELDS

APPLICATION: ONSHORE, TOPSIDES, LNG

Rev Date Description Author Sponsor 11/09 Initial Release RSHC RSHC

Use of Non-Pressure-Tested Closure Welds WEM-SU-5246


CONTENTS

1.0 Scope ..........................................................................................................................32.0 References ..................................................................................................................3

2.1 ......Purchaser Documents ......................................................................................32.2 ......Industry Codes and Standards .........................................................................3

3.0 Terminology ................................................................................................................33.1 ......Acronyms .........................................................................................................33.2 ......Definitions .........................................................................................................4

4.0 Purchaser Applications and Limits ..........................................................................45.0 Quality Control ...........................................................................................................5

5.1 ......Specific Requirements for Carbon Steel Piping ...............................................55.2 ......Specific Requirements for Austenitic Stainless Steel .......................................65.3 ......Specific Requirements for Other Alloy Piping Systems ....................................65.4 ......Inspection and Examination Requirements ......................................................6

6.0 Documentation ...........................................................................................................7



1.0 SCOPEThis document defines non-pressure-tested closure welds, the basis for use of such welded joints, their application limits, and the quality control (QC) required to install such joints.

2.0 REFERENCES1. The following documents are referenced herein and are considered part of this specification. 2. Use the edition of each document referenced below unless otherwise specified.

2.1 Purchaser DocumentsNone.

2.2 Industry Codes and StandardsAmerican Society of Mechanical Engineers (ASME)B31.3 Process PipingB31.4 Pipeline Liquid Petroleum Transportation Systems for Hydrocarbons and

Other LiquidsB31.8 Gas Transmission and Distribution Piping Systems

Boiler and Pressure Vessel Code (BPVC) Section II, Part C Specifications for Welding Rods, Electrodes, and Filler MetalsSection V Nondestructive ExaminationSection IX Welding and Brazing Qualifications

American Society for Nondestructive Testing (ASNT)SNT-TC-1A Standard Topical Outlines for Qualification of Nondestructive Testing

Personnel

American Welding Society (AWS)QC1 Standard for AWS Certification of Welding Inspectors

National Society of Corrosion Engineers (NACE)MR0175 Materials for Use in H2S Containing Environments in Oil and Gas

Production

3.0 TERMINOLOGY

3.1 AcronymsDNDiameter Nominal

FCAWFlux Cored Arc Welding

GTAWGas Tungsten Arc Welding

GMAWGas Metal Arc Welding

IDInside Diameter

MTMagnetic Partial Examination



NBNominal Bore

ODOutside Diameter

PMIPositive Material Identification

PTLiquid Penetrant Examination

PQRProcedure Qualification Record

QCQuality Control

RTRadiographic Examination

SMAWShielded Metal Arc Welding

TOFDTime of Flight Diffraction

UTUltrasonic Examination

VTVisual Examination

WPSWelding Procedure Specification

3.2 DefinitionsClosure WeldsThe final weld joining pressure-tested piping systems to each other, to pressure vessels, and other piping or pipeline components which have been successfully pressure and leak tested.

Piping SystemsInterconnected piping subject to the same set or sets of design conditions.

4.0 PURCHASER APPLICATIONS AND LIMITS1. Typical Purchaser applications are described as follows:

a. Offshore process module-to-module tie-ins and pipeline riser tie-ins to module process piping.

b. LNGprocess module-to-module tie-ins, piping to rotating equipment, and balance of plant piping systems.

c. Skid mounted equipment or pressure vessel hook-upsfrequently connected using closure welds because of pressure limitation of the vessel or introducing water into the vessel will cause damage. Pneumatic testing is more hazardous and is typically avoided except for LNG piping which is typically pneumatic tested to avoid ice formation during cooldown of the cryogenic systems.

2. Use of non-pressure-tested weld joints shall be per ASME B31.3.a. ASME B31.3 Section 345 provides the basis for allowing non-pressure-tested (non-leak

tested) weld joints to be used. Paragraph 345.2.3.(c) Special Provisions for Testing (closure welds) allows such welds, provided they are examined in-process per paragraph 344.7 and have 100 percent radiographic examination (RT) or ultrasonic examination (UT).

b. Per ASME B31.3 code interpretations 20-07 and 20-24, there are no restrictions on fluid service or the number of closure welds, provided they are joining components that have been pressure tested.



3. Purchaser limits are as follows:a. The number of closure weld joints shall be kept to a minimum.

1) Goal shall be to have only one per piping system where feasible. If not feasible, the number of closure weld joints shall be limited to as few as possible for each system

2) Where pressure testing can be practicably (feasible as well as usable) engineered and safely executed, pressure testing of all weld joints shall be done.

b. Only full penetration butt weld joints in full compliance with ASTM B31.3 shall be used.c. Minimum pipe diameter shall be NPS 2 in. (DN 50).

1) Minimum wall thickness shall be schedule 40 for all carbon steel pipe diameters. 2) For NPS 2 in. (DN 50) pipe diameter, minimum wall thickness shall be 0.218 in.

(5.02 mm).3) For LNG austenitic stainless steel piping, minimum wall thickness shall be

schedule 10s.d. Brazed or socket welded systems shall not use closure welds. These systems shall be

pressure tested.e. All module piping systems exclusive of closure welds joining two or more large sub-

assembly modules for final assembly of the module to be shipped shall be pressure tested at the fabrication yard or shop.

f. Field run or stick built piping shall not use closure welds. 1) These systems shall be tested per Section 4.0, item a, 2 as a general rule. 2) If pressure testing cannot be feasibly engineered and safely done, closure welds may

be used per Section 4.0, item a, 1.

5.0 QUALITY CONTROL1. Non-pressure-tested closure welds shall be treated as requiring the highest quality. The welds

shall be made with detailed and tightly controlled fabrication, welding and nondestructive examinations as specified in Section 5.0 item 2.

2. As a minimum, all welding procedures shall meet the requirements of ASME BPVC Section IX plus the referencing code ASME B31.3, 31.4, and/or 31. 8 as is applicable. a. In addition, for closure welds that will be in sour service, the welding procedures shall

meet NACE MR0175 requirements. b. Hardness testing shall be by Vickers method using 10 kilogram load (Hv10) or less.c. Rockwell test method is not acceptable. d. Welding consumables shall meet the requirements of ASME BPVC Section II, Part C.

5.1 Specific Requirements for Carbon Steel Piping1. Minimum diameter shall be NPS 2 in. (DN 50).2. Minimum wall thickness shall be Sch.40 or 0.218 in. (5.02 mm) for any pipe diameter,

whichever is thicker. 3. Pipe diameters of NPS 4 in. (DN 100) or less shall be 100 percent welded using the gas

tungsten arc welding (GTAW) process.



4. Root and hot passes in all pipe diameters shall be welded using the GTAW process.5. Shielded metal arc welding (SMAW), flux cored arc welding (FCAW), and gas metal arc

welding (GMAW) (spray arc mode only) may be used for fill and cap welding of pipe wall thickness, 3/8 in. (10 mm) and greater.

6. Welds shall be completed with a minimum of 3 passes (root, hot fill/cap).

5.2 Specific Requirements for Austenitic Stainless Steel1. Minimum diameter shall be NPS 2 in. (DN 50).2. Minimum wall thickness shall be Sch. 10s for any pipe diameter. 3. Pipe diameters of NPS 4 in. (DN 100) or less shall be 100 percent welded using the GTAW

process.4. Root and hot passes in all pipe diameters shall be welded using the GTAW process.5. Back purging maintenance with 100 percent Argon of the root and hot pass plus one fill pass

(~1/4 inch [6 mm] of weld deposit) is required.6. Flux-coated filler metal or flux-cored filler metal may be used with Purchaser acceptance for

root pass welding requiring no back purging. These filler metals shall not be used upstream of mechanical equipment such that any remaining slag could damage the equipment for piping systems requiring high internal cleanliness.

7. SMAW, FCAW, and GMAW (spray arc mode only) may be used for fill and cap welding of pipe wall thickness, 3/8 inch (10 mm) and greater.

8. Welds shall be completed with a minimum of 3 passes (root, hot fill/cap), except for wall thicknesses of 0.120 in. (5.72 mm) or less, which shall be completed in two passes.

5.3 Specific Requirements for Other Alloy Piping Systems1. Purchaser shall provide the specific requirements upon request by Supplier. 2. Piping systems of low alloy, nickel or copper based, aluminum, etc., need to be reviewed on a

case-by-case basis.

5.4 Inspection and Examination Requirements1. The following inspections and examinations shall be performed by qualified personnel:

a. Verify that the correct pipe materials are to be joined by reviewing material certifications and by performing positive material identification (PMI) using portable material analyzer equipment.

b. Verify that the correct welding procedure specification (WPS) for the pipe materials is to be used by review of the WPS and welding procedure qualification record (PQR).

c. Verify that the correct welding consumables are selected and available. 1) Austenitic stainless steel and other high alloy welding consumables shall be

confirmed by material certification and by PMI.2) Carbon steel welding consumables shall be confirmed by review of material

certification.d. Weld bevels dimensions shall be checked and visually examined for cleanliness prior to

joint fit-up.



e. During and after fit-up of the closure joint, verify internal cleanliness, inside diameter (ID) alignment (centerline offset and Hi-Lo), root gap, and outside diameter (OD) mismatch.

f. Verify required minimum preheat temperature is reached before welding is begun including tack welding operations.

g. During joint weld-out, verify that the minimum preheat is maintained and the maximum interpass temperature is not exceeded.

h. Perform visual examination (VT) of all weld passes.i. Perform magnetic partial examination (MT) or liquid penetrant examination (PT) after

completion of root, hot pass, each additional 1/4 inch (6 mm) of fill passes, and cap passes.

Note Carbon steel cap pass exam is to be performed a minimum of 24 hours after the weld joint has cooled to ambient for the as-welded condition. For joints requiring PWHT, the cap pass exam may be performed after cooling to ambient from PWHT.

j. Perform 100 percent volumetric exam by radiography (RT) and ultrasonic (UT) methods. 1) Time of flight diffraction (TOFD) or phased array modes are preferred. 2) RT and UT procedures shall be acceptable to Purchaser. 3) UT procedures must demonstrate full volumetric coverage of each joint configuration.4) RT procedures shall use fine grain, high contrast, high definition film and the exposed

film shall meet a film density range of 2.0 to 3.5 (3.0 preferred) as verified by calibrated densitometer. Film developing and processing techniques shall be of the highest quality for film viewing and evaluation.

2. Nondestructive examination personnel shall be certified to ASNT SNT-TC-1A requirements or Purchaser-accepted alternate certification system.

3. Welding inspectors shall be certified to AWS QC1 or Purchaser-accepted alternate certification system. Welding inspectors shall be acceptable to Purchaser.

4. Visual, magnetic particle, liquid penetrant, radiography, and ultrasonic examination procedures shall comply with the applicable requirements of ASME BPVC Section V. Acceptance criteria shall meet the applicable code of construction and Purchaser specifications.

6.0 DOCUMENTATION1. Each closure weld location shall be identified on piping layout drawings. A tabular list shall be

submitted to Purchaser for review. 2. The tabular list shall include the following:

a. Line numberb. Pipe material typesc. Pipe diameter and wall thickness for each side of the closure jointd. Method for weld bevel preparatione. Weld bevel detail in sketch formf. WPS to be usedg. Schedule dates for joint fit-up and welding



3. In addition to the tabular list, the WPS and PQR shall be submitted, if not submitted previously.

4. After joint completion, the inspections and exams performed per Section 5.0 above shall be included in the final QC records package required for each line number.

5. Each final closure joint record shall include completed NDE documentation for all PMI, PT, MT, RT, VT, and UT exams. In addition, a separate tabular sign-off sheet for inspectors and NDE personnel shall be completed for the following minimum operations and/or exams:a. PMI or verification of base and filler materialb. Joint prep and cleanlinessc. Preheat and interpass tempsd. Fit up, joint clearance, and internal alignmente. Variables specified by welding proceduref. VT and PT or MT results as required after weld passes (VT to note, among other

conditions, slag removal and weld condition)g. Appearance of finished jointh. Review of final 100 percent UT or RT

Contents1.0 Scope2.0 References2.1 Purchaser Documents2.2 Industry Codes and Standards

3.0 Terminology3.1 Acronyms3.2 Definitions

4.0 Purchaser Applications and Limits5.0 Quality Control5.1 Specific Requirements for Carbon Steel Piping5.2 Specific Requirements for Austenitic Stainless Steel5.3 Specific Requirements for Other Alloy Piping Systems5.4 Inspection and Examination Requirements

6.0 Documentation