Ù«•…»”–ﬁ˛––‹ —¿››É»·…•†„–” —•°»É•‹‚–«‹ Þ¿‰µ•†„materialstandard.com/.../uploads/2019/08/AWS-D10.11M_D10.11-2007.pdf ·

Ugravelaquomiddotfrac14raquo ordmplusmnreg Icircplusmnplusmnnot

ETHiquestshyshy Eacuteraquoacutefrac14middotsup2sup1 plusmnordm

ETHmiddotdegraquo Eacutemiddotnotcedilplusmnlaquonot

THORNiquestfrac12micromiddotsup2sup1

szligEacuteIacute UumliumlethograveiumliumlOacutentildeUumliumlethograveiumliumlaeligicircethetheacute

szligsup2 szligsup3raquoregmiddotfrac12iquestsup2 Ograveiquestnotmiddotplusmnsup2iquestacute Iacutenotiquestsup2frac14iquestregfrac14

Yacuteplusmndegsectregmiddotsup1cedilnot szligsup3raquoregmiddotfrac12iquestsup2 Eacuteraquoacutefrac14middotsup2sup1 Iacuteplusmnfrac12middotraquonotsect ETHregplusmnordfmiddotfrac14raquofrac14 frac34sect timesOslashIacute laquosup2frac14raquoreg acutemiddotfrac12raquosup2shyraquo copymiddotnotcedil szligEacuteIacute Ocircmiddotfrac12raquosup2shyraquoraquoatildeEumlsup2middotordfraquoregshymiddotnotsect plusmnordm Igraveraquoumliquestshy Icircraquoordfmiddotshyraquofrac14 Iacutelaquofrac34 szligfrac12frac12plusmnlaquosup2notntildeeumlecircicircethethethiumliumliumligrave

Ograveplusmnnot ordmplusmnreg Icircraquoshyiquestacuteraquoocirc ethegraventildeicircccedilntildeicircethiumlicirc icirciacuteaeligigraveeacuteaeligigraveiuml OacuteUumlIgraveOgraveplusmn regraquodegregplusmnfrac14laquofrac12notmiddotplusmnsup2 plusmnreg sup2raquonotcopyplusmnregmicromiddotsup2sup1 degraquoregsup3middotnotnotraquofrac14 copymiddotnotcedilplusmnlaquonot acutemiddotfrac12raquosup2shyraquo ordmregplusmnsup3 timesOslashIacute

oacuteoacuteAgraveocircocircAgraveocircocircAgraveocircocircocircocircocircAgraveAgraveAgraveocircocircocircAgraveAgraveocircocircAgraveocircAgraveAgraveAgraveocircocircoacuteAgraveoacuteAgraveocircocircAgraveocircocircAgraveocircAgraveocircocircAgraveoacuteoacuteoacute

550 NW LeJeune Road Miami FL 33126

szligEacuteIacute UumliumlethograveiumliumlOacutentildeUumliumlethograveiumliumlaeligicircethetheacuteszligsup2 szligsup3raquoregmiddotfrac12iquestsup2 Ograveiquestnotmiddotplusmnsup2iquestacute Iacutenotiquestsup2frac14iquestregfrac14

szligdegdegregplusmnordfraquofrac14 frac34sect notcedilraquoszligsup3raquoregmiddotfrac12iquestsup2 Ograveiquestnotmiddotplusmnsup2iquestacute Iacutenotiquestsup2frac14iquestregfrac14shy timessup2shynotmiddotnotlaquonotraquo

Ntildefrac12notplusmnfrac34raquoreg iumliacuteocirc icircethethecirc

Ugravelaquomiddotfrac14raquo ordmplusmnreg

Icircplusmnplusmnnot ETHiquestshyshy Eacuteraquoacutefrac14middotsup2sup1 plusmnordm

ETHmiddotdegraquo Eacutemiddotnotcedilplusmnlaquonot THORNiquestfrac12micromiddotsup2sup1

3rd Edition

Supersedes AWS D1011-87

Prepared by theAmerican Welding Society (AWS) D10 Committee on Piping and Tubing

Under the Direction of theAWS Technical Activities Committee

Approved by theAWS Board of Directors

szligfrac34shynotregiquestfrac12not

This standard presents guidelines for welding the root pass of metal pipe butt joints with an open root or a consumableinsert Joint designs assembly consumable insert configurations base metals filler metals and purging are discussedApplicable arc welding processes and techniques are described




ii


International Standard Book Number 0-87171-644-5American Welding Society

550 NW LeJeune Road Miami FL 33126copy 2007 by American Welding Society

All rights reservedPrinted in the United States of America

Photocopy Rights No portion of this standard may be reproduced stored in a retrieval system or transmitted in anyform including mechanical photocopying recording or otherwise without the prior written permission of the copyrightowner

Authorization to photocopy items for internal personal or educational classroom use only or the internal personal oreducational classroom use only of specific clients is granted by the American Welding Society provided that the appropriatefee is paid to the Copyright Clearance Center 222 Rosewood Drive Danvers MA 01923 tel (978) 750-8400 Internetltwwwcopyrightcomgt




iii


Iacutenotiquestnotraquosup3raquosup2not plusmnsup2 notcedilraquo Eumlshyraquo plusmnordm szligsup3raquoregmiddotfrac12iquestsup2 Eacuteraquoacutefrac14middotsup2sup1 Iacuteplusmnfrac12middotraquonotsect Iacutenotiquestsup2frac14iquestregfrac14shy

All standards (codes specifications recommended practices methods classifications and guides) of the AmericanWelding Society (AWS) are voluntary consensus standards that have been developed in accordance with the rules of theAmerican National Standards Institute (ANSI) When AWS American National Standards are either incorporated in ormade part of documents that are included in federal or state laws and regulations or the regulations of other govern-mental bodies their provisions carry the full legal authority of the statute In such cases any changes in those AWSstandards must be approved by the governmental body having statutory jurisdiction before they can become a part ofthose laws and regulations In all cases these standards carry the full legal authority of the contract or other documentthat invokes the AWS standards Where this contractual relationship exists changes in or deviations from requirementsof an AWS standard must be by agreement between the contracting parties

AWS American National Standards are developed through a consensus standards development process that bringstogether volunteers representing varied viewpoints and interests to achieve consensus While AWS administers the processand establishes rules to promote fairness in the development of consensus it does not independently test evaluate orverify the accuracy of any information or the soundness of any judgments contained in its standards

AWS disclaims liability for any injury to persons or to property or other damages of any nature whatsoever whetherspecial indirect consequential or compensatory directly or indirectly resulting from the publication use of or relianceon this standard AWS also makes no guaranty or warranty as to the accuracy or completeness of any informationpublished herein

In issuing and making this standard available AWS is not undertaking to render professional or other services for or onbehalf of any person or entity Nor is AWS undertaking to perform any duty owed by any person or entity to someoneelse Anyone using these documents should rely on his or her own independent judgment or as appropriate seek theadvice of a competent professional in determining the exercise of reasonable care in any given circumstances

This standard may be superseded by the issuance of new editions Users should ensure that they have the latest edition

Publication of this standard does not authorize infringement of any patent or trade name Users of this standard acceptany and all liabilities for infringement of any patent or trade name items AWS disclaims liability for the infringement ofany patent or product trade name resulting from the use of this standard

Finally AWS does not monitor police or enforce compliance with this standard nor does it have the power to do so

On occasion text tables or figures are printed incorrectly constituting errata Such errata when discovered are postedon the AWS web page (wwwawsorg)

Official interpretations of any of the technical requirements of this standard may only be obtained by sending a requestin writing to the Managing Director Technical Services Division American Welding Society 550 NW LeJeune RoadMiami FL 33126 (see Annex A) With regard to technical inquiries made concerning AWS standards oral opinionson AWS standards may be rendered However such opinions represent only the personal opinions of the particularindividuals giving them These individuals do not speak on behalf of AWS nor do these oral opinions constitute officialor unofficial opinions or interpretations of AWS In addition oral opinions are informal and should not be used as asubstitute for an official interpretation

This standard is subject to revision at any time by the AWS D10 Committee on Piping and Tubing It must be reviewedevery five years and if not revised it must be either reaffirmed or withdrawn Comments (recommendations additionsor deletions) and any pertinent data that may be of use in improving this standard are required and should be addressedto AWS Headquarters Such comments will receive careful consideration by the AWS D10 Committee on Piping andTubing and the author of the comments will be informed of the Committees response to the comments Guests areinvited to attend all meetings of the AWS D10 Committee on Piping and Tubing to express their comments verballyProcedures for appeal of an adverse decision concerning all such comments are provided in the Rules of Operation ofthe Technical Activities Committee A copy of these Rules can be obtained from the American Welding Society 550NW LeJeune Road Miami FL 33126




This page is intentionally blank

iv





v


ETHraquoregshyplusmnsup2sup2raquoacute

Advisor

AWS D10 Committee on Piping and Tubing

D J Connell Chair Detroit EdisonM P Lang 1st Vice Chair United Association Local 501

W F Newell Jr 2nd Vice Chair W F Newell and Associates IncorporatedB C McGrath Secretary American Welding Society

T Anderson ESAB Welding and Cutting ProductsR E Avery Nickel Development InstituteW L Ballis Consultant

A S Beckett Alyeska Pipeline Service CompanyC J Bishop Medical Gas Management Incorporated

C J Bloch Boyle Energy Services amp TechnologyD Brown Applied Energy Systems Incorporated

W A Bruce Edison Welding InstituteD Ciarlariello Mannings USA

K K Coleman EPRIH W Ebert Consultant

J G Emmerson Magnatech Limited PartnershipA L Farland Brookhaven National LaboratoryS J Findlan Electric Power Research InstituteD A Flood TRI TOOL INC

G Frederick Electric Power Research InstituteR Gatlin Global Industries

E A Harwart ConsultantB K Henon Arc Machines Incorporated

G K Hickox ConsultantJ Hill Heat Treatment Consultant

R B Kadiyala ConsultantD C Klingman The Lincoln Electric Company

M J LeRoy Swagelok CorporationM J Ludwig Bath Iron Works

B B MacDonald United AssociationP A Michalski Dominion East Ohio

J S Pastorok Kiewit Industrial CompanyE Piet Med Con

M Porter TRI TOOL INCW L Roth Procter amp Gamble IncorporatedJ R Scott Consultant

W J Sperko Sperko Engineering ServicesP A Tews AcergyJ Tidwell Fluor Daniel

D J Tillack Tillack Metallurgical




vi


Advisor

AWS D10S Subcommittee on Purging and Root Pass Welding

W J Sperko Chair Sperko Engineering ServicesB C McGrath Secretary American Welding Society

H W Ebert ConsultantM P Lang United Association Local 501L LeBlanc Moody International Incorporated

P A Michalski Dominion East OhioJ S Pastorok Kiewit Industrial Company

J R Scott Consultant




vii


Uacuteplusmnregraquocopyplusmnregfrac14

This foreword is not part of AWS D1011MD10112007 Guide for Root Pass Weldingof Pipe Without Backing but is included for informational purposes only

The AWS D10 Committee on Piping and Tubing has been in existence since 1958 during which time a great deal ofinformation on many aspects of pipe welding has been published The first document on root pass welding and gas purgingwas approved in February 1980 and published as AWS D1011-80 Recommended Practices for Root Pass Welding andGas Purging

This publication was intended to be a how to guide in the use of open root and consumable insert welding techniquesfor root pass welding of groove welds joining metal pipe Joint designs fitting techniques consumable insert configurationsfiller and base metal combinations purging and welding processes were discussed This publication made no provisionfor joints which include backing rings

The first edition of D1011 published in 1980 was extensively revised and updated for the second edition which waspublished in 1987 The 1987 edition was reaffirmed in 1992 This latest edition AWS D1011MD10112006 Guide forRoot Pass Welding of Pipe Without Backing has been extensively revised and updated to provide the user with the latestavailable information

Comments and suggestions for the improvement of this standard are welcome They should be sent to the SecretaryAWS D10 Committee on Piping and Tubing American Welding Society 550 NW LeJeune Road Miami FL 33126





viii





ix


Igraveiquestfrac34acuteraquo plusmnordm Yacuteplusmnsup2notraquosup2notshy

ETHiquestsup1raquo Ograveplusmnograve

Personnel vForeword viiList of Figuresxi

1 Scope 111 Introduction112 Units of Measure1

2 Normative References 1

3 Terms and Definitions2

4 Preparations for Welding 241 Cleanliness242 Purging343 Purge Gas Containment 3

5 Purging Prior to Welding 451 Step 1 452 Step 2 553 Purge Time Estimates 554 Recommended Residual Oxygen Levels 5

6 Purging During Welding 761 Flow Rate Reduction 762 Flow Rates for Open-Root Welds and for Joints with Consumable Inserts 763 Purge Maintenance for Subsequent Weld Layers7

7 Tack Welding771 Preparation and Spacing 772 Inspection Removal of Discrepancies and Cleaning 7

8 Welding Using GTAW Without Consumable Inserts781 General782 Tungsten Electrode Type and Configuration783 Joint Design 884 Purge Containment 885 Arc Initiation886 Welding TechniqueOpen Root Groove 887 Welding TechniqueGroove with Zero Root Opening 1088 Welding Pipe in Various Positions 1089 Stop and Start Areas 10

9 Welding Using GTAW with Consumable Inserts 1291 Description and Specifications of Consumable Inserts 1292 Welding Techniques for Consumable Inserts1393 Pipe Axis Horizontal13

10 GTAW of Stainless Steels with Flux Cored Filler Metals and Backing Fluxes13101 Flux Cored Filler Metals13




x



102 Backing Fluxes 13103 Limitations13

11 Welding Carbon and Low Alloy Steels with SMAW and GMAW13111 Introduction13112 Shielded Metal Arc Welding (SMAW) with Cellulosic Covered Electrodes 13113 Low Hydrogen (Basic) SMAW for Open Gap Root Pass Welding 14114 Shielded Metal Arc Welding (SMAW) with Rutile Covered Electrodes16115 Gas Metal Arc Welding (GMAW) 16

12 Intermediate Weld Layers 16121 Inspection and Purging 16122 Processes and Limitations16

13 Welding of Aluminum Alloys 17131 Characteristics of Aluminum that Affect Welding Techniques 17132 Welding Techniques 17

14 Welding Equipment 17141 GTAW Torches 17142 Gas Nozzles 17143 Gas Lenses 17144 Power Supplies 17145 Machine and Automatic Welding Equipment 18

Annex A (Informative)Guidelines for the Preparation of Technical Inquiries 21

List of AWS Documents on Piping and Tubing23




xi


Ocircmiddotshynot plusmnordm Uacutemiddotsup1laquoregraquoshy

Uacutemiddotsup1laquoregraquo ETHiquestsup1raquo Ograveplusmnograve

1 Purging Fixtures 42 Preweld Purge Time for 300 mm [12 in] Length of Pipe of Various Sizes 63 Typical Open Root Joint Design84 Angular Relations Between Pipe Torch and Filler Metal for Open Root Welding 95 Feeding Filler Metal Through the Root Opening in Limited Access Areas 106 Groove Design Dimensions and Tolerances for Use with Consumable Inserts 117 Assembly Tolerances for Welding Pipe Using Five Classes of Consumable Inserts 128 Steps for Root Pass Welding with Classes 1 2 3 and 5 Consumable Inserts 149 Steps for Root Pass Welding with Class 4 Consumable Inserts 15

10 Eccentric Positioning of Classes 3 and 5 Consumable Inserts in 5G Position (Axis HorizontalPipe Not Rotated During Welding) to Prevent Sag 16

11 Joint Design for Aluminum Pipe 17





xii






1

1 Scope

This document describes how to make root weld passeson circumferential pipe groove welds using open rootjoints with filler metal additions tightly-fitted jointswithout the addition of filler metal and joints with con-sumable inserts Joint designs fitting techniques con-sumable insert configurations filler and base metalcombinations purging and welding processes are dis-cussed This publication does not address joints madeusing backing rings and techniques applicable to mecha-nized orbital welding

Safety and health issues and concerns are beyond thescope of this standard and therefore are not fullyaddressed herein Safety and health information is avail-able from other sources including but not limited toANSI Z491 Safety in Welding Cutting and Allied Pro-cesses and applicable federal and state regulations SeeClauses 2 and 15 and Annex A for additional safety andhealth references

11 Introduction When the pipe system designer hasdetermined that the use of backing rings is unacceptabledue to service conditions and that complete joint penetra-tion including a continuous root side surface is neededbutt joints may be made from one side using the groovedesigns and techniques described in this documentAlthough gas tungsten arc welding (GTAW) is mostcommonly used for precise control in root pass weldingshielded metal arc welding (SMAW) and gas metal arcwelding (GMAW) are also widely used

12 Units of Measure This standard makes use of boththe International System of Units (SI) and US Custom-ary Units The latter are shown within brackets [ ] or inappropriate columns in tables and figures The measure-ments may not be exact equivalents therefore eachsystem must be used independently

To identify nominal pipe sizes in both SI and US Cus-tomary Units the following designations are used

1 DN (Diameter Nominal) is the SI designation

2 NPS (Nominal Pipe Size) is the US Customarydesignation

2 Normative ReferencesThe following standards contain provisions whichthrough reference in this text constitute provisions ofthis AWS standard For undated references the latest edi-tion of the referenced standard shall apply For dated ref-erences subsequent amendments to or revisions of anyof these publications do not apply

AWS Documents1

1 AWS A30 Standard Welding Terms and Definitions

2 AWS A51A51M Specification for Carbon SteelElectrodes for Shielded Metal Arc Welding

3 AWS A55A55M Specification for Low AlloySteel Electrodes for Shielded Metal Arc Welding

4 AWS A512A512M Specification for Tungsten andTungsten Alloy Electrodes for Arc Welding and Cutting

5 AWS A530A530M Specification for Consum-able Inserts

6 AWS A532A532M Specification for WeldingShielding Gases

7 AWS C55C55M Recommended Practices forGas Tungsten Arc Welding

8 AWS C510C510M Recommended Practices forShielding Gases for Welding and Plasma Arc Cutting

9 AWS D104 Recommended Practices for WeldingAustenitic Chromium-Nickel Stainless Steel Piping andTubing

1 AWS standards are published by the American WeldingSociety 550 NW LeJeune Road Miami FL 33126

Ugravelaquomiddotfrac14raquo ordmplusmnreg Icircplusmnplusmnnot ETHiquestshyshyEacuteraquoacutefrac14middotsup2sup1 plusmnordm ETHmiddotdegraquo Eacutemiddotnotcedilplusmnlaquonot THORNiquestfrac12micromiddotsup2sup1





2

10 AWS D106D106M Recommended Practices forGas Tungsten Arc Welding Titanium Piping and Tubing

11 AWS D107MD107 Guide for the Gas ShieldedArc Welding of Aluminum and Aluminum Alloy Pipe

12 AWS D108 Recommended Practices for Weld-ing Chromium-Molybdenum Steel Piping and Tubing

13 AWS D1012MD1012 Guide for Welding MildCarbon Steel Pipe

14 AWS F11M Methods for Sampling AirborneParticulates Generated by Welding and Allied Processes

15 AWS F13 Sampling Strategy Guide for Evaluat-ing Contaminates in the Welding Environment

16 AWS F32M Ventilation Guide for Welding

17 AWS F41 Recommended Safe Practices forPreparation for Welding and Cutting of Containers andPiping

18 AWS Safety and Health Fact Sheets

American National Standards Institute (ANSI) Documents2

1 ANSI Z491 Safety in Welding Cutting and AlliedProcesses (published by American Welding Society)

2 NSI Z871 Practice for Occupational and Educa-tional Eye and Face Protection

3 Terms and DefinitionsTerms used in this document should be interpreted inaccordance with AWS A30 Standard Welding Termsand Definitions except for those not defined by that stan-dard or where these terms require further definition toclarify their usage in this standard

air-cooled torch A nonstandard term for a gas cooledtorch

gas-cooled torch A welding torch where the primarycooling medium of the torch is the flow of shieldinggas

keyhole welding A standard term for the technique inwhich a concentrated heat source penetrates partiallyor completely through a workpiece forming a hole(keyhole) at the leading edge of the weld pool As theheat source progresses the molten metal fills inbehind the hole to form the weld bead

2 ANSI standards are published by the American National Stan-dards Institute 25 West 43rd Street 4th Floor New York NY10036-7406

nozzle weld A nonstandard term for a weld between twopipes in which a hole is made in one pipe and theother pipe is welded onto the first pipe at the hole at apredetermined angle to provide an alternate fluid path

purge A standard term for the introduction of a gas toremove contaminants from a system or provide back-ing during welding

purge caps Devices made of any suitable material thatcan be used to seal the ends of pipes for purging

purge dams Barriers made of any suitable material thatcan be placed inside pipes to contain the purge gaseswithin the weld area They may be water soluble or ofsome other type

walking-the-cup A technique for manipulating thetorch when manually welding groove welds With thistechnique the electrode extension is adjusted to allowthe proper arc length while the edge of the shieldinggas nozzle rests on both groove faces of the joint Thetorch is manipulated using a wrist motion in which thenozzle (cup) is rotated at a slight angle to the axis ofthe root opening increased pressure is exerted on theleading groove face while the nozzle is rotated caus-ing forward progression Subsequently the nozzle isrotated and increased pressure is exerted on theopposing groove face The nozzle is again rotatedcausing further forward progression This motion isrepeated so that the cup appears to be walking alongthe groove faces while the arc oscillates smoothlyacross the joint

water-cooled torch A welding torch where the primarycooling medium is the flow of water or other liquidcoolant through the torch

4 Preparations for Welding41 Cleanliness Cleanliness is important in all weldingoperations but it is especially important in root passwelding Cleaning should be done on the groove facesand a minimum of 25 mm [1 in] of the base metal onboth the inside and outside surfaces of the pipe All partsof the joint should be free of grease and oil which shouldbe removed by use of a suitable solvent A suitable sol-vent is one that does not leave a residue and is not harm-ful to the welder or to the weldment Most solventsrequire good ventilation and many are flammable there-fore proper precautions should be taken Grinding orother mechanical means should be used to remove allpaint scale rust and dirt

Grinding and cleaning operations should be done justprior to welding After cleaning the pipe should be han-dled so as to preserve cleanliness





3

42 Purging

421 Purging Applications An internal gas purge isrequired for stainless and nonferrous piping systems(except aluminum) if a smooth root surface is to beobtained Carbon steels and low alloy steels containingless than 5 chromium can be welded using an open rootgroove without the use of an internal gas purge How-ever purging of joints is highly recommended when thechromium content of the weld metal exceeds 2 or whenusing a consumable insert since purging reduces theoccurrence of defects and the excessive oxidation of theresultant root bead Inert backing gas should always beused for consumable inserts of any material other thancarbon steel and when using Class 1 or 2 inserts

It should be noted that purging will increase weldingspeed significantly when used during welding steels thatdo not normally require purging such as carbon and lowalloy steel

422 Purging Gases Argon is most often used forinternal purging and may be safely used for all materialsHelium may also be used for all materials although it ismore expensive than argon For some materials nitrogenis a suitable purge gas Nitrogen can be used at lowercost than argon for specific applications but it shouldbe demonstrated as suitable by testing prior to use inproduction

The purging gases should be specified according to AWSA532A532M Specification for Welding ShieldingGases or AWS C510 Recommended Practices forShielding Gases for Welding and Plasma Arc CuttingArgon (AWS A532A532M Class SG-A) helium (SG-He) and nitrogen (SG-N) should have a purity of betterthan 99995 and have a dew point of 51degC [67degF] orlower

The purging procedures in this document are based onthe use of argon as the purging gas If nitrogen or heliumis used modifications to the purging procedure may benecessary because both gases are less dense than argon

43 Purge Gas Containment

431 General Requirements and Some Contain-ment Methods Purging requires an entrance openingthrough which the purge gas can enter the weld joint areaat a controlled rate and an exit opening through whichoxygen-containing gas can leave Purge gas hoses shouldnot be rubber or other porous material since these areable to aspirate air when high flow rates are used Theuse of plastic teflon or other nonporous hoses is recom-mended For piping where both ends can be cappedproperly sized wood or plastic disks can be taped to thepipe ends Plastic caps that are used to prevent damage topipe ends during shipment are commonly used as purge

caps Note When welding austenitic stainless steel thetape used should have a water-soluble fluoride chlorideand other halogen compound content below 50 ppm

The cap on the end of the assembly where the purge gasis introduced obviously requires a hole to receive thepurge gas hose The other cap requires a hole largeenough to prevent build-up of gas pressure Since air isless dense (lighter) than argon the exit hole should be ata higher elevation to minimize the entrapment of air Allleak paths between the gas entrance and the exit holeshould be blocked branch pipes and other areas whereair may be entrapped should also be vented Purge capsof the type discussed here are most commonly used whena large subassembly or an entire system is purged

432 Other Containment Methods

4321 Other purge containment techniques can beused where purging the entire system is impractical Oneof these is the use of water soluble paper and tape fromwhich dams can be formed to contain the purge gasThese commercially available dams are in the form ofwater soluble paper disks that can be fastened inside thepipes on both sides of a weld joint prior to assembly Forsmall diameter piping or tubing the soluble paper can becrumpled into a ball and stuffed into the pipe thus elimi-nating the need for taping in place After welding thepaper can be dissolved with a water rinse or left in to bedissolved during hydrostatic testing Soluble dams areparticularly advantageous because they reduce the vol-ume which must be purged and this represents a signifi-cant cost savings on large piping systems Moreimportantly they do not have to be physically removedafter welding

4322 When the weld will be postweld heattreated cardboard disks held in place with masking tapeare also suitable for use as purge dams since they willburn to ashes during heat treating

4323 Hinged collapsible or rubber gasketed disksof the types shown in Figure 1 can also be fabricated andfitted into piping The purging techniques are similar tothose used with soluble dams At least one end of thepipe system must be left open for removal of the disksafter welding

4324 Commercially available inflatable bladderscan be used as localized purge containment devices whenan opening is available to remove the bladders afterwelding One bladder is inserted on each side of the jointto be welded The bladders are inflated with purge gas orair after which purging of the volume between the damscan proceed

4325 Purge dams should be far enough awayfrom the groove to prevent burning melting or other





4

damage to dams from the heat of welding Typically adistance of 150 mm [6 in] is adequate Whenever pre-heating is used this distance should be increased to keepthe metal temperature at the dam no higher than 150degC[300degF] However some purge dam materials are avail-able for service up to 300degC [570degF] Extra considerationshould be taken in the case of higher preheat tempera-tures and the method chosen for the heat source becausethe heat applied may be higher at the outer boundaries ofthe weld area than that at the weld groove this wouldrequire additional spacing of the purge dams Careshould also be taken when removing dams that the weldarea is cool enough to prevent heat damage to any blad-ders rubber or plastic parts and to ensure that personneldo not burn their skin

4326 In addition to sealing branch connectionsand open ends of the pipe it is also necessary to preventthe purging gas from escaping through the root opening

at the weld groove itself This is commonly done bywrapping a single layer of tape around the outside of thejoint Tape contact with the groove face should be mini-mized and all adhesive residues should be removed priorto depositing subsequent passes Care should be taken toseal off all leak paths before introducing the purge gasinto the piping system All root openings in the systembetween the purge gas exit and entrance point should betaped closed

5 Purging Prior to Welding51 Step 1

511 Purging a piping system is a two-step operationDuring the first step prior to tack welding the purge gasis used to displace the air in the pipe at relatively highflow rates This high flow rate is maintained until the gasinside the pipe reaches an acceptably low oxygen level

Figure 1Purging Fixtures





5

512 The time required for the first stage of purgingdepends on the maximum oxygen level permitted by thewelding procedure the volume of the system beingpurged and the purge gas flow rate However the rela-tionship between purge gas flow rates and time is not lin-ear ie a system that can be purged in one hour at a flowrate of 25 Lmin [50 ft3h] will not be purged to the samedegree in one-half hour if the flow rate is increased to50 Lmin [100 ft3h] An increase in the purge flow rateincreases the turbulence within the system which resultsin an increase in the mixing of air and the purge gas Thisrequires additional volume changes of gas within thepipe to achieve the desired level of oxygen removal

52 Step 2

521 During the second stage the purge gas flow rateis reduced so that the purge maintains a slight positivepressure on the inside of the pipe This reduced gas flowis maintained to eliminate air re-entry into the pipe andminimize oxidation of the root surface while the rootpass is welded

522 At lower flow rates less mixing occurs and theheavier argon forces air upward and out of the pipe sys-tem To take advantage of this the argon gas inlet shouldbe at the lowest point in the volume to be purged and thegas outlet should be at the highest point Higher purgeflow rates will decrease the time required for preweldpurging due to increased mixing but increase the amountof gas required

53 Purge Time Estimates

531 Generally reasonable preweld flow rates andtimes can be derived from simple calculations of thesystem volume and by applying a time factor

The time for one volume change of the system is foundby dividing the volume by the gas flow rate For exam-ple the prepurge time for one volume change in a 6 m[20 ft] length of 450 DN [18 NPS] diameter pipeprepurged at 25 Lmin [50 ft3h] would be

Volume = 0785 I (pipe diameter)2 I length

SI 0785 I (0457 m)2 I 6 m = 0984 m3

US Customary Units

0785 I (15 ft)2 I 20 ft = 353 ft3

3 30984 m 1000 Lm = 39 minutes25 Lm

I

3

3353 ft = 071 hour or 42 minutes50 ft h

A general rule is to preweld purge at flow rates and timesthat will produce 5 to 6 volume changes In the exampleabove one volume change occurs approximately every40 minutes Six changes would require 240 minutes orabout 4 hours

532 Figure 2 shows minimum preweld purge time inminutes per 300 mm [12 in] of pipe for varying pipediameters at 25 Lmin [50 ft3h] flow rate Suggestedpreweld purge times can be calculated quickly and easilyfrom this graph

54 Recommended Residual Oxygen Levels

541 While the use of calculations and graphs such asthose discussed above can simplify estimates for preweldpurge applications it is recommended that the residualoxygen level be measured prior to initiation of weldingThis can be done quickly and easily with commerciallyavailable oxygen analyzers which are small durableaccurate and easy to use The following oxygen limits arerecommended

For carbon and low alloy steels 2 [20 000 ppm]

For stainless steels 12 [5000 ppm]

For nickel alloys 12 [5000 ppm]

For titanium and zirconium alloys 14 [2500 ppm]

542 It should be noted that a lower oxygen level maybe required to achieve cleaner root side surfaces In addi-tion care should be taken that the pipe inside diameter isdry since moisture will contaminate the purge gas andthat the inside pipe surfaces near the weld are free ofhydrocarbon contamination since hydrocarbons will burnand discolor the root side surface even in the presence ofpure argon An oxygen limit of 12 [5000 ppm] willcreate a higher level weld discoloration (heat-tint oxide)than is acceptable for services requiring high purity con-ditions (food dairy pharmaceutical biotech etc) andmaximum corrosion resistance in a number of environ-ments For such applications a weld discoloration levelguide such as shown in AWS D181 Specification forWelding of Austenitic Stainless Steel Tube and Pipe Sys-tems in Sanitary (Hygienic) Applications may be usefulin establishing the required oxygen level

543 It should also be noted that in some shopsstainless steel welds are made using GMAW withoutbacking gas This is done using machine welding inwhich the pipe is rotated beneath a fixed torch and a suf-ficient supply of shielding gas is fed into the root open-ing to provide adequate shielding of the root surfaces tominimize oxidation





6

Igraveplusmn frac12iquestacutefrac12laquoacuteiquestnotraquo notcedilraquo degregraquodeglaquoregsup1raquo notmiddotsup3raquo ordmplusmnreg iquestsup2sect acuteraquosup2sup1notcedil plusmnordm copyraquoacutefrac14 oslashOcircdivideocirc sup3laquoacutenotmiddotdegacutesect notcedilraquo ordfiquestacutelaquoraquo plusmnfrac34notiquestmiddotsup2raquofrac14 ordmregplusmnsup3 notcedilraquo frac12cediliquestregnot oslashEcircdivide frac34sect notcedilraquo acuteraquosup2sup1notcedil plusmnordmnotcedilraquo degmiddotdegraquo frac14middotordfmiddotfrac14raquofrac14 frac34sect ethograveiacute sup3 Aringiumlicirc middotsup2 plusmnreg iuml ordmnotAtildeaelig

Igravemiddotsup3raquo atilde Ecirc I oslashOcircntildeethograveiacute sup3divide ordmplusmnreg degmiddotdegraquo acuteraquosup2sup1notcedilshy middotsup2 sup3raquonotraquoregshy AringEcirc I oslashOcircntildeiumlicirc middotsup2divide ordmplusmnreg degmiddotdegraquo acuteraquosup2sup1notcedilshy middotsup2 middotsup2frac12cedilraquoshyocirc plusmnreg Ecirc I oslashOcircntildeiuml ordmnotdivide ordmplusmnreg degmiddotdegraquo acuteraquosup2sup1notcedilshymiddotsup2 ordmraquoraquonotAtilde

Ucircumliquestsup3degacuteraquoaelig Igraveplusmn frac12iquestacutefrac12laquoacuteiquestnotraquo notcedilraquo notmiddotsup3raquo regraquomacrlaquomiddotregraquofrac14 ordmplusmnreg degregraquodeglaquoregsup1middotsup2sup1 ecirceth sup3 Aringicircetheth ordmnotAtilde plusmnordm UumlOgrave iumlicirceuml AringOgraveETHIacute eumlAtilde degmiddotdegraquoaelig

iumlograve Uacuteregplusmnsup3 notcedilraquo frac12cediliquestregnotocirc notcedilraquo notmiddotsup3raquo regraquomacrlaquomiddotregraquofrac14 ordmplusmnreg degregraquodeglaquoregsup1middotsup2sup1 ethograveiacute sup3 Aringiumlicirc middotsup2 plusmnreg iuml ordmnotAtilde plusmnordm UumlOgrave iumlicirceuml AringOgraveETHIacute eumlAtilde degmiddotdegraquo atilde iuml sup3middotsup2laquonotraquoicircograve OcircntildeIacute atilde ecirceth sup3ntildeethograveiacute sup3 atilde icircetheth plusmnreg icircetheth ordmnotntildeiuml ordmnot atilde icircethethiacuteograve Igravecedillaquoshyocirc Ecirc I OcircntildeIacutedivide atilde iuml sup3middotsup2laquonotraquo I icircetheth atilde icircetheth sup3middotsup2laquonotraquoshy plusmnreg iacute cedilplusmnlaquoregshy iquestsup2frac14 icirceth sup3middotsup2laquonotraquoshy

Ograveplusmnnotraquoaelig iuml Ocircntildesup3middotsup2 atilde icircograveiuml ordmnotiacutentildecedilregograve

Figure 2Preweld Purge Time for 300 mm [12 in] Length of Pipe of Various Sizes





7

6 Purging During Welding61 Flow Rate Reduction Once the required oxygenlevel inside the pipe has been achieved the flow rate ofthe entering purge gas should be reduced before root passwelding begins to eliminate excessive pressure on theinside of the pipe Joint tape can be removed as weldingprogresses (see 83) Excessive pressure will causeunacceptable root surface concavity or holes through theroot bead The proper purge flow rate during welding isone that is barely detectable at the gas exit port

62 Flow Rates for Open-Root Welds and for Jointswith Consumable Inserts

621 With open root welds flow rates of 4 Lmin to6 Lmin [8 ft3h to 12 ft3h] are typical It is usually nec-essary to reduce the flow rate as the root is closed toprevent blowout of the weld metal Higher flow rates willbe required for open groove welds For small diameterpiping or tubing it may be necessary to reduce flow ratesbelow the values recommended above

622 With consumable inserts the unfused insertseals the root and prevents the escape of gas and flowrates of approximately 2 Lmin to 3 Lmin [4 ft3h to 6 ft3h]are recommended

63 Purge Maintenance for Subsequent Weld LayersIt is normal practice to maintain the purge for the secondand third layers of weld deposit to minimize internal oxi-dation during reheating of the root pass This is particu-larly important when welding reactive metals such astitanium (see AWS D106D106M)

7 Tack Welding71 Preparation and Spacing Tack welding should bedone with care because the tack welds normally becomepart of the final weld For this reason tack welding is notusually performed until preweld purging (when purgingis used) has been completed At least four tack weldsshould be made at 90deg intervals around the pipe For250 DN [10 NPS] and larger diameters tacks should bemade at least every 150 mm [6 in] around the pipe andthey should be 20 mm to 25 mm [075 in to 10 in] longto resist weld shrinkage forces which will try to pull theroot closed during root pass welding When weldingstainless steel (see AWS D104 and D108] tacks shouldbe spaced more closely

72 Inspection Removal of Discrepancies and Clean-ing Tack welds should be cleaned prior to root passwelding For open root welds both ends of each tackweld should be carefully ground and tapered to simplifycomplete fusion of the remainder of the root face during

root pass welding When using an open root the root sideof tack welds should be examined by shining a flashlightthrough the root opening and looking at the root side ofthe tack through the root opening If the root pass is notmade immediately after tack welding the joint should becovered with a clean rag tape or other suitable coveringto maintain its cleanliness To prevent misalignment tackwelds should be checked by the welder as he or shewelds around the joint to be sure that they remain intactCracked tack welds should be carefully ground outbefore proceeding

8 Welding Using GTAW Without Consumable Inserts

81 General The highest quality root welds are usuallyobtained by using the GTAW process The following fac-tors should be considered when welding with thisprocess

82 Tungsten Electrode Type and Configuration

821 For direct current electrode negative (DCEN)2 or 1 thoriated tungsten electrodes (see AWSA512A512M Specification for Tungsten and TungstenAlloy Electrodes for Arc Welding and Cutting EWTh-2or EWTh-1) have traditionally been used but other com-positions such as lanthanated and ceriated are also avail-able and work well During grinding of thoriatedtungsten electrodes radioactive dust is created posingthe potential hazard of internal radiation exposure byinhalation or ingestion unless care is taken to control thedust (see AWS Safety and Health Fact Sheet No 27Thoriated Tungsten Electrodes) The end of the electrodeshould be tapered at about 31 to a point and then thepoint should be ground off to form a flat face Althoughone can weld using a pointed tungsten electrode thepoint will frequently melt off and contaminate the weldpool The flat face on the tungsten electrode should beapproximately 05 mm [0020 in] for a 24 mm or 32 mm[332 in or 18 in] diameter size electrode For a 15 mm[116 in] diameter tungsten electrode the flat face can besomewhat smaller

822 When welding aluminum AC current and puretungsten electrodes are usually used Rather than thetapered and truncated electrode geometry describedabove a balled end is typically used The balled end isproduced by striking an arc on a metal plate and increas-ing the current until a ball forms at the electrode tip (SeeAWS C55C55M Recommended Practices for GasTungsten Arc Welding for additional details on electrodepreparation)





8

83 Joint Design

831 Open Root Joint A typical groove design foropen root welding is shown in Figure 3 Internal align-ment (15 mm [006 in] maximum) is very important Itis usually necessary to counterbore or grind heavy-walled pipe to achieve the correct internal surface matchWeld metal can also be added to the inside surface of thepipe prior to machining or grinding to achieve therequired internal alignment The open root groove designmay be used for both butt welds and nozzle welds

832 Root OpeningOpen Root Groove Theamount of root opening is determined by the method tobe used in adding filler metal A root opening equal to orslightly smaller than the filler metal wire diameter isused with the keyhole technique In this technique thefiller metal is introduced intermittently as necessary tofill the gap

A larger opening is used with the continuous feed tech-nique in which the filler metal is always in the openingand can be melted continuously if desired Welders whoprefer the continuous method should also be able to usethe keyhole technique since it is sometimes requiredwhen weld shrinkage decreases the root opening as theroot pass is made In either case the filler metal can beused as a spacer or guide in determining the openingprior to tack welding However it should be noted thatshrinkage during solidification and cooling of any tackweld will reduce this spacing The amount of shrinkagevaries with the coefficient of expansion of both the baseand filler metals and with changes in total heat input Forexample a stainless steel tack weld will shrink more thana carbon steel tack weld made under similar conditions

since austenitic stainless steel has a larger coefficient ofthermal expansion than ferritic steel

84 Purge Containment The weld opening should becovered with tape on the outside surface of the pipe toprevent the escape of the purge gas During the weldingof the root pass the welder should peel the tape off thejoint in short increments just prior to welding that incre-ment Any tape residue should be removed prior toapplying the reinforcement or cap pass

85 Arc Initiation High frequency starting is used foreasiest arc ignition However caution is advised sincehigh-frequency emissions may interfere with electroniccomponents in the vicinity of or attached to the work-piece and may be prohibited at some work sites Wherehigh frequency is not available and the touch-startingmethod is used the arc should always be initiated againsta groove face or a striking bar not against the base metaloutside the groove The arc should then be moved intothe root and held stationary until the root faces just beginto melt

86 Welding TechniqueOpen Root Groove Whenthe arc is established the filler metal should be intro-duced to the leading edge of the arc forming the weldpool The filler metal may then be fed into the pool asdescribed in the following sections The basic angularrelationships between the workpieces filler metal andtorch are shown in Figure 4 other relationships may bedeveloped for specific situations The method of addingfiller metal depends upon which of two following tech-niques is used

861 Keyhole Method The wire filler metal shouldalways rest on the joint root ahead of the leading edge of

Figure 3Typical Open Root Joint Design





9

the weld pool When additional filler metal is requiredthe wire filler metal is moved back into the leading edgeof the weld pool and a segment is melted off The wirefiller metal is then retracted while the pool is movedbetween the groove faces with an oscillating motionWith practice welders can learn to dab wire into thepool and then retract the end of the wire far enough fromthe leading edge of the arc to prevent melting but yetremain within the inert gas shield to prevent oxidation ofthe wire tip Should the end of the filler metal becomecontaminated or oxidized that end should be cut off orabrasively cleaned before further welding

862 Continuous Feeding of Filler Metal This tech-nique allows continuous feeding of the wire into the mol-ten weld pool The filler metal wire fits in between theroot faces and is fed continuously into the weld pool Thefiller metal wire is melted as the arc passes over it keep-ing the pool width to a minimum and still achieving com-plete penetration The amount of root reinforcementvaries with the amount of filler metal that is fed into thepool The root reinforcement on the inside pipe surface

should not be larger than 15 mm [006 in] Excess rootreinforcement is a detriment and should be avoided thesame as excess reinforcement on the face of the weldWhere a joint is being made in close quarters a helpfultechnique is to feed the wire filler metal through the rootopening into the pool adding it from the root side sur-face instead of adding it from the more conventional faceside surface (see Figure 5)

863 Walking-the-Cup Method Similar to the key-hole method the filler metal should always rest on thejoint root however it is rarely moved towards or awayfrom the weld pool Rather it is held stationary and thetorch cup (nozzle) is rotated or walked in forward pro-gressive fashion consuming the filler metal similar to aconsumable insert Occasionally the filler metal may bemoved towards the weld pool when a void or gouge inthe bevel edge is encountered Alternately the fillermetal may be moved away from the weld pool whenshrinkage has occurred or poor tacking techniques wereused which cause the root opening to be significantlyless than the width of the electrode

Figure 4Angular Relations Between Pipe Torch and Filler Metal for Open Root Welding





10

87 Welding TechniqueGroove with Zero RootOpening Groove Types A and C shown in Figure 6may be used with a root opening of zero (tight butt) forwelding stainless steels and silicon killed carbon steels asan alternative to adding filler metal or using consumableinserts When this technique is used the root opening Gshould not exceed 08 mm [003 in] With Groove TypeC the arc should be located over the joint root and heldstationary until the weld pool width is two-thirds thewidth of the bottom of the groove The torch should thenbe moved smoothly around the joint holding the poolwidth constant Filler metal should be added only wherethe root opening is greater than zero For Groove Type Cthe root pass weld should be made using a stringer beadtechnique and the minimum pool width possible the fur-ther up the radius of the end preparation the weld poolextends the more root concavity will be formed Careshould be taken to keep the tungsten electrode centeredover the joint root

88 Welding Pipe in Various Positions Welding shouldbe done in the upward direction from all orientationsfrom when the pipe is in the horizontal fixed position(5G) to within 20p of vertical (Refer to AWS A30 Stan-dard Welding Terms and Definitions for welding posi-tions) This normally requires starting the weld at thelowest point of the joint and proceeding uphill from thatpoint Other starting points can also be used to controlshrinkage distortion When the pipe axis is within 20p ofvertical welding may start at any location around thegroove and proceed using the forehand welding tech-nique in either direction

89 Stop and Start Areas As the welder progressesaround the pipe he or she may have to stop welding forrepositioning A foot control or a manual remote currentis the best way to gradually reduce the current level priorto extinguishing the arc If such equipment is not avail-able the arc should be slowly moved up the groove face

Figure 5Feeding Filler Metal Through the Root Opening in Limited Access Areas





11

Figure 6Groove Design Dimensions and Tolerances for Use with Consumable Inserts

Ocircraquosup1raquosup2frac14 Ugraveregplusmnplusmnordfraquo Igravesectdegraquo

Oumlplusmnmiddotsup2not Uumlmiddotsup3raquosup2shymiddotplusmnsup2shy iquestsup2frac14 Igraveplusmnacuteraquoregiquestsup2frac12raquoshy ordmplusmnreg Eumlshyraquo copymiddotnotcedil Yacuteplusmnsup2shylaquosup3iquestfrac34acuteraquo timessup2shyraquoregnot Yacuteacuteiquestshyshyraquoshy

Yacuteacuteiquestshyshyraquoshy iuml iquestsup2frac14 igrave Yacuteacuteiquestshyshy icirc Yacuteacuteiquestshyshyraquoshy iacute iquestsup2frac14 euml

Ugrave szligocirc THORNocirc Yacute Eacute otildeethograveegrave sup3sup3 Aringethograveethiacute middotsup2Atilde OacuteszligEgraveograve Eacute otildeethograveegrave sup3sup3 Aringethograveethiacute middotsup2Atilde OacuteszligEgraveograve Eacute otildeethograveigrave sup3sup3 Aringethograveethicirc middotsup2Atilde OacuteszligEgraveograve

Ccedil szlig eth notplusmn ethograveegrave sup3sup3 Aringethograveethiacute middotsup2Atilde OacuteszligEgraveograve iumlograveeuml sup3sup3 Aringethograveethecirc middotsup2Atilde OacuteszligEgraveograve eth sup3sup3 notplusmn ethograveegrave sup3sup3 Aringethograveethiacute middotsup2Atilde OacuteszligEgraveograve

Ccedil THORNocirc Yacute eth notplusmn ethograveegrave sup3sup3 Aringethograveethiacute middotsup2Atilde OacuteszligEgraveograve eth sup3sup3 notplusmn iumlograveeuml sup3sup3 Aringethograveethecirc middotsup2Atilde OacuteszligEgraveograve eth sup3sup3 notplusmn icircograveigrave sup3sup3 Aringethograveethccedil middotsup2Atilde OacuteszligEgraveograve

Icirc Yacute icircograveigrave sup3sup3 notplusmn iacuteograveicirc sup3sup3 Aringethograveethccedil notplusmn ethograveiumliacute middotsup2Atilde

Ocirc THORN icircograveigrave sup3sup3 otildeethocirc ethograveegrave sup3sup3 Aringethograveethccedil middotsup2 otildeethocirc ethograveethiacute middotsup2Atilde

Oacute Yacute icircograveigrave sup3sup3 o ethograveigrave sup3sup3 Aringethograveethccedil middotsup2 o ethograveethicirc middotsup2Atilde

Egrave Yacute ograveetheuml sup3sup3 Aringethograveicirceth middotsup2Atilde

AElig Yacute iacuteograveicirc sup3sup3 Aringethograveiumliacute middotsup2Atilde





12

at increasing travel speed so that the size of the weld poolis as small as possible before extinguishing the arcExtinguishing the arc rapidly without using one of thesetechniques may produce crater cracks

9 Welding Using GTAW with Consumable Inserts

91 Description and Specifications of Consumable Inserts

911 Consumable inserts are used for root pass weld-ing of pipe where high quality welds are consistentlyrequired with minimum repairs or rejects Detailed infor-mation on chemical composition dimensions sizes andstyles are given in AWS A530A530M Specificationfor Consumable Inserts The five shapes of consumableinserts (Classes 1 through 5) are illustrated in Figure 6Recommended groove designs for inserts are also shownin Figure 6

With consumable inserts consideration should be givento the unusually large effect of dilution As much as onehalf (50) of the weld root pass is comprised of fused

base metal compared with 25 or less fused base metalfor the remainder of the weld fill passes Factors such aseffects on mechanical properties and crack and corrosionresistance should be considered when consumable insertsare used

For aluminum pipe inserts are not recommended

912 For wall thicknesses of 5 mm [020 in] or lessthe smaller insert sizes are generally used ie 32 mm[012 in] size for Classes 1 2 and 4 and 15 mm[006 in] I 32 mm [012 in] size for Classes 3 and 5There is no thickness where the use of one insert sizeabruptly becomes unfeasible and another size becomesmandatory There are ranges of thicknesses where twodifferent sizes of the same shape of insert may be usedThe choice may depend upon fabricator preferencewelder training the pipe chemical composition andavailability

913 For carbon low alloy and stainless steel weld-ing assembly tolerances for the various shape inserts areshown in Figure 7 In some critical applications thefabricators internal process specifications for assembly

Figure 7Assembly Tolerances for Welding Pipe Using Five Classes of Consumable Inserts





13

tolerances may be more restrictive than those listed inFigure 6 Some alloys such as copper-nickel or nickel-copper require closer tolerances for successful use of theinserts Assembly tolerances may also be related specifi-cally to wall thickness as shown in Figure 6

914 All insert shapes are supplied in a wide varietyof alloys covering many weldable pipe compositionsNormally the chemical composition of the consumableinserts meets the same specification limits for filler metalused with inert gas welding processes

915 For carbon steel inserts properly deoxidizedmaterial should be used to assure sound low-porositywelds especially if a purge gas is not used Contamina-tion of Class 1 inserts (see AWS A530A530M Specifi-cation for Consumable Inserts Inverted T-shape) andClass 2 inserts (see AWS A530A530M J-shape) bydirt or hydrocarbons is a common source of porositytherefore inserts should be cleaned thoroughly using asolvent immediately prior to being tack welded in placeOnce inserts are tacked in place the groove should becovered to prevent dirt and dust from collecting betweenthe insert and the pipe root faces

92 Welding Techniques for Consumable Inserts

921 Figures 8 and 9 illustrate typical steps requiredfor root pass welding with consumable inserts Arc initi-ation should be as previously described ie either highfrequency starting or striking the arc on the groove face

922 The electrode should be kept perpendicular tothe work and be pointed radially toward the center of thepipe An arc length of about 3 mm [012 in] is satisfac-tory Forward progression is governed by the melting rateof the consumable insert and the characteristics of theweld pool Evidence of sufficient melting is shown by theincreased fluidity and wetting flow increase in weldpool diameter andor silicone island stirring When thisoccurs the arc is gradually moved forward around thegroove As the arc is extinguished care should be exer-cised to prevent crater cracks (see 88)

93 Pipe Axis Horizontal When the pipe axis is hori-zontal and the pipe is not rotated flat inserts (A530A530M Class 3 and 5) are positioned eccentrically topromote good weld bead shape on the internal surface ofthe pipe Figure 10 illustrates this

10 GTAW of Stainless Steels with Flux Cored Filler Metals and Backing Fluxes

101 Flux Cored Filler Metals Recent product develop-ments provide another option for protecting the root side

of the joint for a limited number of chemical composi-tions when using GTAW this involves the use of fluxcored filler metals During welding a thin layer of slagwill cover the root side of the bead This eliminates theneed for back purging provided the heat-tint oxide in theheat-affected zone (HAZ) is acceptable for the intendedservice However it is important that adequate root gapsare provided or keyhole welding are utilized to ensuresome of the flux will reach the underside of the bead andform a slag covering

At this time the existence of welding rods appears to belimited to the following deposit compositions but othersmay become available in the future 308L 316L 309Land 347

102 Backing Fluxes Similar success has also beenobtained using powdered flux that is mixed with a sol-vent and painted on the inside surfaces of pipe endsbefore assembly and tack welding Such fluxes preventthe severe oxidation of stainless steel that occurs whenwelding without backing gas but like flux cored wires aresidual flux is left on the inside surfaces of the pipe andthe presence of that flux must be acceptable to the enduser of the piping system

103 Limitations Depending upon the specific servicethe slag and heat-tint oxide may have to be removed fromthe pipe root surface since it may interfere with the purityof the product andor the corrosion resistance of thealloy The end user of the piping system should beadvised that residual flux and oxidized heat-affectedzones will be present when either flux-containing wiresor paint-on backing fluxes are used Also this type offiller metal has not been designed for fill passes and thusshould not be used for any application other than rootpasses

11 Welding Carbon and Low Alloy Steels with SMAW and GMAW

111 Introduction Both the shielded metal arc weldingprocess and the gas metal arc welding process are fre-quently used for open root welding of carbon and somelow alloy steels For additional information see the latestedition of AWS D1012MD1012 Guide for WeldingMild Steel Pipe

112 Shielded Metal Arc Welding (SMAW) with Cellu-losic Covered Electrodes

1121 E6010 and E6011 electrodes are frequentlyused for welding the root pass of low-carbon steel pipeThese and other higher-strength cellulosic electrodessuch as (E7010-A1 EXX10-P1 and EXX11-A1 as clas-sified in AWS A55A55M Specification for Low Alloy





14

Figure 8Steps for Root Pass Welding with Classes 1 2 3 and 5 Consumable Inserts





15

Steel Electrodes for Shielded Metal Arc Welding) mayalso be used for root pass welding of higher strength pipewhere hydrogen cracking is not a particular concern SeeAWS D1012MD1012 Guide for Welding Mild SteelPipe

1122 The SMAW process is not recommended forroot pass welding of alloys such as chromium-molybdenumsteels stainless steels nickel or copper alloys becausemost SMAW electrodes for these base metals are of thelow hydrogen type and complete joint penetration is dif-ficult to obtain Purging of SMAW open root joints is notdone because the turbulence of the arc defeats the effec-tiveness of gas shielding on the underside of the rootbead by aspirating large amounts of air into the weld andnegating the effects of the purge

113 Low Hydrogen (Basic) SMAW for Open GapRoot Pass Welding

1131 Some low hydrogen electrodes are designed forvertical up root pass welding with an open gap The rootpasses are generally welded with small diameter elec-trodes (25 mm to 32 mm) [332 in to 18 in] with lowcurrent and DC straight (electrode negative) polarity Aswith vertical down cellulosic SMAW (EXX10 andEXX11) electrodes a keyhole technique is used Weld-ing proceeds vertically upward with the electrode coatingtouching the pipe edges The electrode angle and the cur-rent are controlled to maintain a small keyhole behindthe arc The crater is normally ground before starting anew electrode Better results are seen when faster travelspeeds are used than with slow travel speeds as the root

Figure 9Steps for Root Pass Welding with Class 4 Consumable Inserts





16

reinforcement is smaller and there is less chance of burn-through

1132 The recommended joint preparation is a 25 mm[332 in] root opening with a 20 mm to 25 mm [564 into 332 in] root face with a 60deg included angle A 25 mm[332 in] diameter electrode would normally be weldedwith 70 amps while a 32 mm [18 in] diameter electrodewould be welded with 100 amps

1133 Vertical down low hydrogen electrodes are cur-rently available as AWS classifications E8045-P2E9045-P2 and E10045-P2 They are not generally rec-ommended for root pass welding These basic coatedelectrodes have very little arc force other than that pro-vided by the welding machine so joint preparation iscritical to assure full root penetration Very little align-ment mismatch (highlow) can be tolerated These elec-trodes are designed to freeze very quickly to enable themto run downhill As a result they do not wet in verywell This limits the tolerance for variable gap openingsand there is a higher risk of either burning through orinternal lack of fusion or internal undercut

114 Shielded Metal Arc Welding (SMAW) withRutile Covered Electrodes

1141 Some rutile-type covered electrodes (such asE6013) are designed for root pass welding of pipe Theseelectrodes are identified by the manufacturer as suitable

for root pass welding of piping They exhibit more pene-tration than ordinary E6013 but not as much as E6010Because of the reduced penetration a root opening of2 mm to 4 mm [008 in to 016 in] and a root face thick-ness of about 15 mm [006 in] is recommended whenusing a 32 mm [012 in] electrode and either uphill ordownhill progression

1142 These types of covered electrodes are alsoavailable in electrodes that will produce low-alloy steelweld metal with strengths up to 550 MPa [80 ksi] mini-mum tensile strength However when using these elec-trodes the higher preheat that would be used forcellulosic covered electrodes such as E7010-G E7010-A1or E7010-P1 should be used since rutile-type coveredelectrodes are not low hydrogen electrodes

115 Gas Metal Arc Welding (GMAW)

1151 Root passes can also be made using GMAW inthe short-circuiting transfer mode and an open root jointdesign when using an argonCO2 shielding gas mixtureWelding voltages of 17 V to 19 V and wire feed speedsin the vicinity of 64 mms [150 inmin] will provide agood starting point in the development of the weldingprocedure when using 09 mm [0035 in] diameter wireWhere a complex waveform machine is used the manu-facturers recommended settings should be used as astarting point for procedure development (see 1443)Progression of vertical welds for root pass welding isusually downward Purging is recommended for stainlessand low alloy steels and nonferrous alloys except alumi-num A V-groove design with a 75deg groove angle nomi-nal 24 mm [009 in] root face and a 24 mm [009 in]root opening is recommended Heat input and travelspeed should be controlled to prevent excessive rootreinforcement The arc should be kept at the leading edgeof the pool to ensure complete joint penetration

1152 When welding aluminum copper or nickelalloy pipe using GMAW the normal practice is to weldthe root using GTAW and fill the weld using GMAW

12 Intermediate Weld Layers121 Inspection and Purging Once the root has beenwelded visual inspection is recommended Care shouldbe taken to minimize melting through the root whendepositing the second and third weld layers Gas purgingwhen used should be maintained until at least two addi-tional layers have been deposited Maintaining the purgefor these two layers is necessary regardless of whichwelding process is used for the fill layers

122 Processes and Limitations These intermediatelayers may be made with the GTAW SMAW FCAW or

Figure 10Eccentric Positioning of Classes3 and 5 Consumable Inserts in 5G Position

(Axis Horizontal Pipe Not RotatedDuring Welding) to Prevent Sag





17

GMAW process To prevent lack of fusion the useof GMAW-S should be limited to a maximum pipewall thickness of 10 mm [039 in] and fill passes shouldbe made using uphill progression when in the verticalposition

13 Welding of Aluminum Alloys131 Characteristics of Aluminum that Affect Weld-ing Techniques Techniques for welding aluminum alloypipe should be designed around the fundamental charac-teristics of aluminum The most relevant ones are

1 the high melting temperature of aluminum oxide

2 the low melting temperature of the aluminum

3 the tenacious attachment of the oxide to the metaland its rapid reformation when removed

4 the high thermal conductivity of aluminumabout25 times that of steel

5 the high fluidity of molten aluminum and

6 the ability of molten aluminum to dissolve largequantities of hydrogen gas which causes porosity

132 Welding Techniques Successful techniques havebeen developed using the gas shielded arc welding pro-cesses (GTAW PAW and GMAW) which remove theoxide and prevent its reformation by shielding the weldpool under an inert gas They are high energy processesso that they permit relatively high welding speeds toovercome the effects of high thermal conductivity andfluidity of the molten weld metal

A joint design consisting of a V-groove with a wide bot-tom (Figure 11) has been developed to permit control ofthe root pass and to ensure that a sound weld can bemade with the gas tungsten or plasma arc welding pro-cesses Control of porosity is mainly a matter of ensuring

thorough joint cleanliness before welding Any residualoily substance or moisture will cause porosity For thisreason the pipe ends should be carefully cleaned with asolvent just before assembly and wire brushed to removethe oxide just before welding The details of these andall other necessary factors are given in AWS D107Recommended Practices for Gas Shielded Arc Weldingof Aluminum and Aluminum Alloy Pipe

14 Welding Equipment141 GTAW Torches An assortment of gas tungsten arctorches is readily available from welding equipment sup-pliers Torches are either air-cooled or water-cooled Formost root pass welding an air-cooled torch is adequateThe water-cooled torches require an auxiliary water sup-ply Water-cooled torches should be considered wheneverhigh currents are used such as for fill passes in largediameter piping and for aluminum or copper welding

142 Gas Nozzles Gas nozzles are available in varioussizes and configurations including those with long noz-zles for reaching into deep groove joints For most rootpass welding applications gas nozzles with 10 mm to13 mm [039 in to 05 in] (6 to 12) orifice diametersshould be used

143 Gas Lenses A gas lens is a screen insert which islocated between the torch body and the gas nozzle Theselenses promote lamellar flow of the shielding gas andreduce turbulence and mixing of shielding gas with air asthe gas exits the torch This reduces the risk of porosityand provides a cleaner weld surface Gas lenses arewidely used in welding critical systems particularlywhere radiographic inspection is required

144 Power Supplies

1441 Standard Power Supplies Standard DC(direct current) power supplies with drooping volt-ampere curves (the type commonly used for shieldedmetal arc welding) are used for gas tungsten arc weldingMachines best suited for gas tungsten arc welding of rootpasses are those in which the 10 V to 15 V and 75 A to150 A ranges are well within the operating capacity ofthe power supply Power supplies equipped with highfrequency arc initiation and current upslope and downs-lope capabilities or a remote current control (eg a footpedal) make it easier to achieve high quality welds andshould be used whenever possible

While constant current power supplies are used for theGTAW and the SMAW processes they are not suitablefor GMAW The latter requires a constant potential (con-stant voltage) power supply This applies to both auto-matic and semiautomatic applicationsFigure 11Joint Design for Aluminum Pipe





18

1442 Pulsed Power Supplies GTAW and GMAWpower supplies with pulsed current capabilities are avail-able These power supplies rapidly alternate the weldingcurrent from a low background level to a high peak levelThe pulsing frequency and current wave shapes varyamong different types of power supplies The pulsed cur-rent provides easier control of the weld pool It alsoallows the use of a lower total heat input which reducesdistortion especially in stainless steel and cracking ten-dencies in alloys that are subject to cracking of the weldbead down its centerline during solidification (ie hotshort alloys) like UNS N08020 (Alloy 20Cb3 or 320)For GMAW of aluminum constant current power sup-plies are usually recommended

1443 Multiprocess Power Sources Power sourcesare available that can offer output in CV CC ACDCpulsed modes andor complex waveform modes Thisequipment uses high-speed electronics to control the out-put wave form and shape enabling one to affect the beadshape penetration tie-in and the level of spatter Whenusing such power supplies one may not be able todirectly transfer settings from one manufacturers modelto another model or to a similar power supply made byanother manufacturer

145 Machine and Automatic Welding Equipment

1451 Equipment is commercially available for weld-ing root and fill passes for pipe that is in a fixed positionor being rolled Equipment for welding pipe that can berolled is mounted on a boom or a side-beam carriage andthe pipe is rotated beneath it

1452 Equipment for welding in fixed positions ismore sophisticated and the application must be carefullyevaluated to ensure that the productive gains justify thecapital expenditure for the work to be done Mostdesigns have a motorized orbital welding head which isfastened to the pipe Voltage sensing and automatic torchoscillating capabilities are available

1453 Automatic voltage control is essential formaintaining a constant arc length when the surface of theworkpiece is uneven Oscillation of the welding headallows the use of weaving instead of stringer beads Thismay reduce the number of weld passes required to fill thejoint The total welding time may thereby be reducedPulsed current equipment is also available It is espe-cially useful for fixed position welding where greaterweld pool control is required





19

A1 IntroductionThe American Welding Society (AWS) Board of Directorshas adopted a policy whereby all official interpretationsof AWS standards are handled in a formal mannerUnder this policy all interpretations are made by thecommittee that is responsible for the standard Officialcommunication concerning an interpretation is directedthrough the AWS staff member who works with thatcommittee The policy requires that all requests for aninterpretation be submitted in writing Such requests willbe handled as expeditiously as possible but due to thecomplexity of the work and the procedures that must befollowed some interpretations may require considerabletime

A2 ProcedureAll inquiries shall be directed to

Managing DirectorTechnical Services DivisionAmerican Welding Society550 NW LeJeune RoadMiami FL 33126

All inquiries shall contain the name address and affilia-tion of the inquirer and they shall provide enough infor-mation for the committee to understand the point ofconcern in the inquiry When the point is not clearlydefined the inquiry will be returned for clarification Forefficient handling all inquiries should be typewritten andin the format specified below

A21 Scope Each inquiry shall address one single provi-sion of the standard unless the point of the inquiryinvolves two or more interrelated provisions The provi-sion(s) shall be identified in the scope of the inquiry

along with the edition of the standard that contains theprovision(s) the inquirer is addressing

A22 Purpose of the Inquiry The purpose of theinquiry shall be stated in this portion of the inquiry Thepurpose can be to obtain an interpretation of a standardsrequirement or to request the revision of a particular pro-vision in the standard

A23 Content of the Inquiry The inquiry should beconcise yet complete to enable the committee to under-stand the point of the inquiry Sketches should be usedwhenever appropriate and all paragraphs figures andtables (or annex) that bear on the inquiry shall be cited Ifthe point of the inquiry is to obtain a revision of the stan-dard the inquiry shall provide technical justification forthat revision

A24 Proposed Reply The inquirer should as aproposed reply state an interpretation of the provisionthat is the point of the inquiry or provide the wording fora proposed revision if this is what the inquirer seeks

A3 Interpretation of Provisions of the Standard

Interpretations of provisions of the standard are made bythe relevant AWS technical committee The secretary ofthe committee refers all inquiries to the chair of the par-ticular subcommittee that has jurisdiction over the por-tion of the standard addressed by the inquiry Thesubcommittee reviews the inquiry and the proposed replyto determine what the response to the inquiry shouldbe Following the subcommittees development of theresponse the inquiry and the response are presented tothe entire committee for review and approval Uponapproval by the committee the interpretation is an official

szligsup2sup2raquouml szlig oslashtimessup2ordmplusmnregsup3iquestnotmiddotplusmnsup2iquestacutedivide

Ugravelaquomiddotfrac14raquoacutemiddotsup2raquoshy ordmplusmnreg notcedilraquo ETHregraquodegiquestregiquestnotmiddotplusmnsup2 plusmnordm Igraveraquofrac12cedilsup2middotfrac12iquestacute timessup2macrlaquomiddotregmiddotraquoshy

This annex is not part of AWS D1011MD10112007 Guide for Root Pass Weldingof Pipe Without Backing but is included for informational purposes only





20

interpretation of the Society and the secretary transmitsthe response to the inquirer and to the Welding Journalfor publication

A4 Publication of InterpretationsAll official interpretations will appear in the WeldingJournal and will be posted on the AWS web site

A5 Telephone InquiriesTelephone inquiries to AWS Headquarters concerningAWS standards should be limited to questions of a gen-eral nature or to matters directly related to the use of thestandard The AWS Board Policy Manual requires thatall AWS staff members respond to a telephone requestfor an official interpretation of any AWS standard withthe information that such an interpretation can be

obtained only through a written request Headquartersstaff cannot provide consulting services However thestaff can refer a caller to any of those consultants whosenames are on file at AWS Headquarters

A6 AWS Technical CommitteesThe activities of AWS technical committees regardinginterpretations are limited strictly to the interpretation ofprovisions of standards prepared by the committees or toconsideration of revisions to existing provisions on thebasis of new data or technology Neither AWS staff northe committees are in a position to offer interpretive orconsulting services on (1) specific engineering problems(2) requirements of standards applied to fabricationsoutside the scope of the document or (3) points notspecifically covered by the standard In such cases theinquirer should seek assistance from a competent engi-neer experienced in the particular field of interest





21

Ocircmiddotshynot plusmnordm szligEacuteIacute Uumlplusmnfrac12laquosup3raquosup2notshy plusmnsup2 ETHmiddotdegmiddotsup2sup1 iquestsup2frac14 Igravelaquofrac34middotsup2sup1

Designation Title

D104 Recommended Practices for Welding Austenitic Chromium Nickel Stainless Steel Piping and Tubing

D106D106M Recommended Practices for Gas Tungsten Arc Welding Titanium Piping and Tubing

D107MD107 Recommended Practices for Gas Shielded Arc Welding Aluminum and Aluminum Alloy Pipe

D108MD108 Guide for Welding Chromium Molybdenum Steel Piping and Tubing

D1010D1010M Recommended Practices for Local Heating of Welds in Piping and Tubing

D1011MD1011 Recommended Practices for Root Pass Welding

1012MD1012 Guide for Welding Mild Steel Pipe

D1013D1013M Recommended Practices for Brazing of Copper Pipe and Tubing for Medical Gas Systems





22








550 NW LeJeune Road Miami FL 33126

szligEacuteIacute UumliumlethograveiumliumlOacutentildeUumliumlethograveiumliumlaeligicircethetheacuteszligsup2 szligsup3raquoregmiddotfrac12iquestsup2 Ograveiquestnotmiddotplusmnsup2iquestacute Iacutenotiquestsup2frac14iquestregfrac14

szligdegdegregplusmnordfraquofrac14 frac34sect notcedilraquoszligsup3raquoregmiddotfrac12iquestsup2 Ograveiquestnotmiddotplusmnsup2iquestacute Iacutenotiquestsup2frac14iquestregfrac14shy timessup2shynotmiddotnotlaquonotraquo

Ntildefrac12notplusmnfrac34raquoreg iumliacuteocirc icircethethecirc

Ugravelaquomiddotfrac14raquo ordmplusmnreg

Icircplusmnplusmnnot ETHiquestshyshy Eacuteraquoacutefrac14middotsup2sup1 plusmnordm

ETHmiddotdegraquo Eacutemiddotnotcedilplusmnlaquonot THORNiquestfrac12micromiddotsup2sup1

3rd Edition

Supersedes AWS D1011-87

Prepared by theAmerican Welding Society (AWS) D10 Committee on Piping and Tubing

Under the Direction of theAWS Technical Activities Committee

Approved by theAWS Board of Directors

szligfrac34shynotregiquestfrac12not

This standard presents guidelines for welding the root pass of metal pipe butt joints with an open root or a consumableinsert Joint designs assembly consumable insert configurations base metals filler metals and purging are discussedApplicable arc welding processes and techniques are described




ii










iii

















iv





v



Advisor























vi


Advisor









vii












viii





ix


















x













xi











xii






1

1 Scope









AWS Documents1
















2






























3

42 Purging




















4











5


52 Step 2







SI 0785 I (0457 m)2 I 6 m = 0984 m3

US Customary Units

0785 I (15 ft)2 I 20 ft = 353 ft3

3 30984 m 1000 Lm = 39 minutes25 Lm

I

3
















6











7


















8

83 Joint Design














9










10









11

















12















13






















14






15










16



















17















144 Power Supplies







18











19



















20










21


Designation Title













22








ii










iii

















iv





v



Advisor























vi


Advisor









vii












viii





ix


















x













xi











xii






1

1 Scope









AWS Documents1
















2






























3

42 Purging




















4











5


52 Step 2







SI 0785 I (0457 m)2 I 6 m = 0984 m3

US Customary Units

0785 I (15 ft)2 I 20 ft = 353 ft3

3 30984 m 1000 Lm = 39 minutes25 Lm

I

3
















6











7


















8

83 Joint Design














9










10









11

















12















13






















14






15










16



















17















144 Power Supplies







18











19



















20










21


Designation Title













22








iii

















iv





v



Advisor























vi


Advisor









vii












viii





ix


















x













xi











xii






1

1 Scope









AWS Documents1
















2






























3

42 Purging




















4











5


52 Step 2







SI 0785 I (0457 m)2 I 6 m = 0984 m3

US Customary Units

0785 I (15 ft)2 I 20 ft = 353 ft3

3 30984 m 1000 Lm = 39 minutes25 Lm

I

3
















6











7


















8

83 Joint Design














9










10









11

















12















13






















14






15










16



















17















144 Power Supplies







18











19



















20










21


Designation Title













22









iv





v



Advisor























vi


Advisor









vii












viii





ix


















x













xi











xii






1

1 Scope









AWS Documents1
















2






























3

42 Purging




















4











5


52 Step 2







SI 0785 I (0457 m)2 I 6 m = 0984 m3

US Customary Units

0785 I (15 ft)2 I 20 ft = 353 ft3

3 30984 m 1000 Lm = 39 minutes25 Lm

I

3
















6











7


















8

83 Joint Design














9










10









11

















12















13






















14






15










16



















17















144 Power Supplies







18











19



















20










21


Designation Title













22








v



Advisor























vi


Advisor









vii












viii





ix


















x













xi











xii






1

1 Scope









AWS Documents1
















2






























3

42 Purging




















4











5


52 Step 2







SI 0785 I (0457 m)2 I 6 m = 0984 m3

US Customary Units

0785 I (15 ft)2 I 20 ft = 353 ft3

3 30984 m 1000 Lm = 39 minutes25 Lm

I

3
















6











7


















8

83 Joint Design














9










10









11

















12















13






















14






15










16



















17















144 Power Supplies







18











19



















20










21


Designation Title













22








vi


Advisor









vii












viii





ix


















x













xi











xii






1

1 Scope









AWS Documents1
















2






























3

42 Purging




















4











5


52 Step 2







SI 0785 I (0457 m)2 I 6 m = 0984 m3

US Customary Units

0785 I (15 ft)2 I 20 ft = 353 ft3

3 30984 m 1000 Lm = 39 minutes25 Lm

I

3
















6











7


















8

83 Joint Design














9










10









11

















12















13






















14






15










16



















17















144 Power Supplies







18











19



















20










21


Designation Title













22








vii












viii





ix


















x













xi











xii






1

1 Scope









AWS Documents1
















2






























3

42 Purging




















4











5


52 Step 2







SI 0785 I (0457 m)2 I 6 m = 0984 m3

US Customary Units

0785 I (15 ft)2 I 20 ft = 353 ft3

3 30984 m 1000 Lm = 39 minutes25 Lm

I

3
















6











7


















8

83 Joint Design














9










10









11

















12















13






















14






15










16



















17















144 Power Supplies







18











19



















20










21


Designation Title













22









viii





ix


















x













xi











xii






1

1 Scope









AWS Documents1
















2






























3

42 Purging




















4











5


52 Step 2







SI 0785 I (0457 m)2 I 6 m = 0984 m3

US Customary Units

0785 I (15 ft)2 I 20 ft = 353 ft3

3 30984 m 1000 Lm = 39 minutes25 Lm

I

3
















6











7


















8

83 Joint Design














9










10









11

















12















13






















14






15










16



















17















144 Power Supplies







18











19



















20










21


Designation Title













22








ix


















x













xi











xii






1

1 Scope









AWS Documents1
















2






























3

42 Purging




















4











5


52 Step 2







SI 0785 I (0457 m)2 I 6 m = 0984 m3

US Customary Units

0785 I (15 ft)2 I 20 ft = 353 ft3

3 30984 m 1000 Lm = 39 minutes25 Lm

I

3
















6











7


















8

83 Joint Design














9










10









11

















12















13






















14






15










16



















17















144 Power Supplies







18











19



















20










21


Designation Title













22








x













xi











xii






1

1 Scope









AWS Documents1
















2






























3

42 Purging




















4











5


52 Step 2







SI 0785 I (0457 m)2 I 6 m = 0984 m3

US Customary Units

0785 I (15 ft)2 I 20 ft = 353 ft3

3 30984 m 1000 Lm = 39 minutes25 Lm

I

3
















6











7


















8

83 Joint Design














9










10









11

















12















13






















14






15










16



















17















144 Power Supplies







18











19



















20










21


Designation Title













22








xi











xii






1

1 Scope









AWS Documents1
















2






























3

42 Purging




















4











5


52 Step 2







SI 0785 I (0457 m)2 I 6 m = 0984 m3

US Customary Units

0785 I (15 ft)2 I 20 ft = 353 ft3

3 30984 m 1000 Lm = 39 minutes25 Lm

I

3
















6











7


















8

83 Joint Design














9










10









11

















12















13






















14






15










16



















17















144 Power Supplies







18











19



















20










21


Designation Title













22









xii






1

1 Scope









AWS Documents1
















2






























3

42 Purging




















4











5


52 Step 2







SI 0785 I (0457 m)2 I 6 m = 0984 m3

US Customary Units

0785 I (15 ft)2 I 20 ft = 353 ft3

3 30984 m 1000 Lm = 39 minutes25 Lm

I

3
















6











7


















8

83 Joint Design














9










10









11

















12















13






















14






15










16



















17















144 Power Supplies







18











19



















20










21


Designation Title













22









1

1 Scope









AWS Documents1
















2






























3

42 Purging




















4











5


52 Step 2







SI 0785 I (0457 m)2 I 6 m = 0984 m3

US Customary Units

0785 I (15 ft)2 I 20 ft = 353 ft3

3 30984 m 1000 Lm = 39 minutes25 Lm

I

3
















6











7


















8

83 Joint Design














9










10









11

















12















13






















14






15










16



















17















144 Power Supplies







18











19



















20










21


Designation Title













22









2






























3

42 Purging




















4











5


52 Step 2







SI 0785 I (0457 m)2 I 6 m = 0984 m3

US Customary Units

0785 I (15 ft)2 I 20 ft = 353 ft3

3 30984 m 1000 Lm = 39 minutes25 Lm

I

3
















6











7


















8

83 Joint Design














9










10









11

















12















13






















14






15










16



















17















144 Power Supplies







18











19



















20










21


Designation Title













22









3

42 Purging




















4











5


52 Step 2







SI 0785 I (0457 m)2 I 6 m = 0984 m3

US Customary Units

0785 I (15 ft)2 I 20 ft = 353 ft3

3 30984 m 1000 Lm = 39 minutes25 Lm

I

3
















6











7


















8

83 Joint Design














9










10









11

















12















13






















14






15










16



















17















144 Power Supplies







18











19



















20










21


Designation Title













22









4











5


52 Step 2







SI 0785 I (0457 m)2 I 6 m = 0984 m3

US Customary Units

0785 I (15 ft)2 I 20 ft = 353 ft3

3 30984 m 1000 Lm = 39 minutes25 Lm

I

3
















6











7


















8

83 Joint Design














9










10









11

















12















13






















14






15










16



















17















144 Power Supplies







18











19



















20










21


Designation Title













22









5


52 Step 2







SI 0785 I (0457 m)2 I 6 m = 0984 m3

US Customary Units

0785 I (15 ft)2 I 20 ft = 353 ft3

3 30984 m 1000 Lm = 39 minutes25 Lm

I

3
















6











7


















8

83 Joint Design














9










10









11

















12















13






















14






15










16



















17















144 Power Supplies







18











19



















20










21


Designation Title













22









6











7


















8

83 Joint Design














9










10









11

















12















13






















14






15










16



















17















144 Power Supplies







18











19



















20










21


Designation Title













22









7


















8

83 Joint Design














9










10









11

















12















13






















14






15










16



















17















144 Power Supplies







18











19



















20










21


Designation Title













22









8

83 Joint Design














9










10









11

















12















13






















14






15










16



















17















144 Power Supplies







18











19



















20










21


Designation Title













22









9










10









11

















12















13






















14






15










16



















17















144 Power Supplies







18











19



















20










21


Designation Title













22









10









11

















12















13






















14






15










16



















17















144 Power Supplies







18











19



















20










21


Designation Title













22









11

















12















13






















14






15










16



















17















144 Power Supplies







18











19



















20










21


Designation Title













22









12















13






















14






15










16



















17















144 Power Supplies







18











19



















20










21


Designation Title













22









13






















14






15










16



















17















144 Power Supplies







18











19



















20










21


Designation Title













22









14






15










16



















17















144 Power Supplies







18











19



















20










21


Designation Title













22









15










16



















17















144 Power Supplies







18











19



















20










21


Designation Title













22









16



















17















144 Power Supplies







18











19



















20










21


Designation Title













22









17















144 Power Supplies







18











19



















20










21


Designation Title













22









18











19



















20










21


Designation Title













22









19



















20










21


Designation Title













22









20










21


Designation Title













22









21


Designation Title













22









22









