aws d3.7 hull welding.pdf

Guide forAluminum HullWelding

AWS D3.7:2004An American National Standard

Copyright American Welding Society Provided by IHS under license with AWS Licensee=ConocoPhillips WAN/5919206100

Not for Resale, 03/31/2005 06:16:44 MSTNo reproduction or networking permitted without license from IHS

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Reproduced by Global Engineering Documents With the Permission of AWS Under Royalty Agreement

550 N.W. LeJeune Road, Miami, Florida 33126

AWS D3.7:2004An American National Standard

Approved byAmerican National Standards Institute

December 17, 2003

Guide for

Aluminum Hull Welding

Supersedes ANSI/AWS D3.7-90

Prepared byAWS D3 Committee on Welding in Marine Construction

Under the Direction ofAWS Technical Activities Committee

Approved byAWS Board of Directors

AbstractThis guide provides information on the welding of sea going aluminum hulls and other structures in marine construction.Included are sections on hull materials, construction preparation, welding equipment and processes, qualificationrequirements, welding techniques, and safety precautions.

Key Words—Aluminum hull welding, ship welding, hull welding, aluminum hulls, boats, crafts, ships



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Statement on Use of AWS American National StandardsAll 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 standards are either incorporated in, or made part of,documents that are included in federal or state laws and regulations, or the regulations of other governmental bodies,their provisions carry the full legal authority of the statute. In such cases, any changes in those AWS standards must beapproved by the governmental body having statutory jurisdiction before they can become a part of those laws andregulations. In all cases, these standards carry the full legal authority of the contract or other document that invokes theAWS standards. Where this contractual relationship exists, changes in or deviations from requirements of an AWSstandard must be by agreement between the contracting parties.

International Standard Book Number: 0-87171-690-9

American Welding Society, 550 N.W. LeJeune Road, Miami, FL 33126

© 2004 by American Welding Society. All rights reservedPrinted in the United States of America

Reprinted: June 2004

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, whether spe-cial, indirect, consequential or compensatory, directly or indirectly resulting from the publication, use of, or reliance on thisstandard. AWS also makes no guaranty or warranty as to the accuracy or completeness of any information published 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 the adviceof 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. AWS disclaims liability for the infringementof any patent resulting from the use or reliance on 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 (www.aws.org).

Official interpretations of any of the technical requirements of this standard may only be obtained by sending a request, in writ-ing, to the Managing Director, Technical Services Division, American Welding Society, 550 N.W. LeJeune Road, Miami, FL33126 (see Annex C). With regard to technical inquiries made concerning AWS standards, oral opinions on AWS standardsmay be rendered. However, such opinions represent only the personal opinions of the particular individuals giving them. Theseindividuals do not speak on behalf of AWS, nor do these oral opinions constitute official or unofficial opinions or interpreta-tions of AWS. In addition, oral opinions are informal and should not be used as a substitute for an official interpretation.

This standard is subject to revision at any time by the AWS D3 Committee on Welding in Marine Construction. It mustbe reviewed every five years, and if not revised, it must be either reaffirmed or withdrawn. Comments (recommenda-tions, additions, or deletions) and any pertinent data that may be of use in improving this standard are required andshould be addressed to AWS Headquarters. Such comments will receive careful consideration by the AWS D3 Committeeon Welding in Marine Construction and the author of the comments will be informed of the Committee’s response to thecomments. Guests are invited to attend all meetings of the AWS D3 Committee on Welding in Marine Constructionto express their comments verbally. Procedures for appeal of an adverse decision concerning all such comments areprovided in the Rules of Operation of the Technical Activities Committee. A copy of these Rules can be obtained fromthe American Welding Society, 550 N.W. LeJeune Road, Miami, FL 33126.

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iii

Dedication

Paul B. Dickerson1926–2004

The AWS D3 Committee on Welding in Marine Construction dedicates this edition ofAWS D3.7, Guide for Aluminum Hull Welding, to the memory of Paul B. Dickerson. Paulwas an AWS Fellow and contributed unselfishly to several technical committees of theAmerican Welding Society. His knowledge of aluminum alloy welding was prodigious,and Paul freely shared this knowledge with anyone that needed his help. Paul will begreatly missed by his family, friends, peers, and associates.



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Personnel

AWS D3 Committee on Welding in Marine Construction

R. D. Holdsworth, Chair Management Systems TechnologyK. Masubuchi, Vice Chair Mass Institute of Technology

A. Davis, Secretary American Welding SocietyG. M. Cain Oxylance Corporation

C. B. Champney Nelson Stud Welding*S. A. Collins Maine Maritime Academy

D. Cottle DC FabricatorsJ. H. Devletian Oregon Graduate Institute

**P. D. Dickerson ConsultantC. E. Grubbs Global DiversW. Hanzalek ABS Americas

*L. D. Holt The ESAB GroupA. W. Johnson A W. Johnson & AssociatesL. G. Kvidahl Ingalls Shipbuilding

*C. L. Null NAVSEAS. E. Pollard Machinists, Incorporated

J. M. Sawhill, Jr. Newport News ShipbuildingA. T. Sheppard The DuRoss Group, IncorporatedM. J. Sullivan NASSCO-National Steel & Shipbuilding

AWS D3A Subcommittee on Aluminum Hull Welding

**P. B. Dickerson, Chair ConsultantA. Davis, Secretary American Welding Society

*T. Anderson AlcoTec Wire CorporationC. B. Champney Nelson Stud Welding

B. Christy Alcan International LimitedS. A. Collins Marine Maritime Academy

A. W. Johnson A. W. Johnson & AssociatesL. Milacek Textron Marine

S. E. Pollard Machinists, Incorporated*G. Rowe AlcoTec Wire Corporation

*Advisor**Deceased



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Foreword

(This Foreword is not a part of AWS D3.7:2004, Guide for Aluminum Hull Welding,but is included for informational purposes only.)

This guide has been developed to aid the boat and craft builder using aluminum as the primary metal for construction.An effort has been made to include principal design elements as well as construction details that experience has provento be suitable for welded aluminum marine structures. This guide, along with thorough training in aluminum weldingprocedures including qualification of welding procedures and personnel, are of prime importance in maintaining highquality construction.

This guide was originally developed by the Aluminum Association Technical Committee on Welding and Joiningafter identifying the need to assist the builders of aluminum hulls, boats, crafts and ships with proven construction tech-niques. Their work was presented to the American Welding Society in 1979 and became the ANSI/AWS publicationD3.7-83, Guide for Aluminum Hull Welding. The first revision was ANSI/AWS D3.7-90.

This second revision, D3.7:2004, includes recent advances in welding equipment and techniques along with theinclusion of approximate mathematical equivalents in the International System of Units (SI).

Comments and suggestions for the improvement of this standard are welcome. They should be sent to the Secretary,AWS D3 Committee on Welding in Marine Construction, American Welding Society, 550 N.W. LeJeune Road, Miami,FL 33126.

Official interpretations of any of the technical requirements of this standard may be obtained by sending a request, inwriting, to the Managing Director, Technical Services Division, American Welding Society. A formal reply will beissued after it has been reviewed by the appropriate personnel following established procedures.



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Table of Contents

Page No.

Personnel .................................................................................................................................................................... iiiForeword ......................................................................................................................................................................vList of Tables ...............................................................................................................................................................ixList of Figures...............................................................................................................................................................x

1. General ..................................................................................................................................................................11.1 Scope............................................................................................................................................................11.2 Welding Processes .......................................................................................................................................11.3 Comparison of Welding Processes ..............................................................................................................11.4 Serviceability of Welded Aluminum Hulls .................................................................................................11.5 Workmanship...............................................................................................................................................21.6 Sources of Information ................................................................................................................................2

2. Aluminum Hull Materials .....................................................................................................................................22.1 General.........................................................................................................................................................22.2 Marine Aluminum Alloys............................................................................................................................22.3 Temper Designations ...................................................................................................................................32.4 Aluminum Product Forms ...........................................................................................................................42.5 Welding Filler Metals ..................................................................................................................................42.6 Filler Metal Selection ..................................................................................................................................8

3. Preparation for Construction .................................................................................................................................83.1 General.........................................................................................................................................................83.2 Handling and Storage ..................................................................................................................................83.3 Cutting and Edge Preparation....................................................................................................................123.4 Backgouging ..............................................................................................................................................143.5 Finishing and Contouring ..........................................................................................................................143.6 Cleaning for Welding ................................................................................................................................163.7 Forming and Bending ................................................................................................................................163.8 Preheat .......................................................................................................................................................16

4. Welding Processes and Equipment .....................................................................................................................174.1 General.......................................................................................................................................................174.2 Gas Metal Arc Welding .............................................................................................................................184.3 Gas Tungsten Arc Welding .......................................................................................................................204.4 Mechanized Welding .................................................................................................................................224.5 Stud Welding .............................................................................................................................................22

5. Qualification Procedures for Welding.................................................................................................................245.1 General.......................................................................................................................................................245.2 Procedure Qualification .............................................................................................................................245.3 Typical Test Coupon..................................................................................................................................265.4 Performance Qualification.........................................................................................................................265.5 Record Keeping .........................................................................................................................................26

6. Welding Procedure and Techniques....................................................................................................................266.1 General.......................................................................................................................................................266.2 Fitting, Aligning, and Assembling ............................................................................................................26



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Page No.

6.3 Weld Backing ............................................................................................................................................276.4 Butt Joints ..................................................................................................................................................286.5 Fillet Welds................................................................................................................................................296.6 Plug and Slot Welds ..................................................................................................................................326.7 Inserts and Doublers ..................................................................................................................................326.8 Snipes and Scallops ...................................................................................................................................336.9 Oil and Water Stops...................................................................................................................................346.10 Coamings ...................................................................................................................................................346.11 Avoiding Joint Corrosion ..........................................................................................................................356.12 Strongbacks................................................................................................................................................376.13 Clamping ...................................................................................................................................................386.14 Tack Weld Placement and Size .................................................................................................................386.15 Residual Welding Stresses and Distortion.................................................................................................386.16 Welding Sequence .....................................................................................................................................406.17 Angular Distortion .....................................................................................................................................416.18 Interpass Temperature ...............................................................................................................................416.19 Welding Stress Relief ................................................................................................................................426.20 Inspection of Welds ...................................................................................................................................436.21 Repair of Welds .........................................................................................................................................476.22 Metal Straightening ...................................................................................................................................496.23 Repair Welding of Aluminum Hulls..........................................................................................................496.24 Welding Power Connections .....................................................................................................................51

7. Safety...................................................................................................................................................................537.1 Introduction................................................................................................................................................537.2 Fumes and Gases .......................................................................................................................................537.3 Radiation....................................................................................................................................................547.4 Electrical Hazards......................................................................................................................................557.5 Fire Prevention...........................................................................................................................................567.6 OSHA Regulations ....................................................................................................................................59

Metric Conversion Factors.........................................................................................................................................59

Nonmandatory Annexes..............................................................................................................................................61Annex A—Codes and Other Standards.......................................................................................................................61Annex B—Quantity of Filler Metal Required for Welded Joints in Aluminum Made by65Annex B—GMAW and GTAW Processes ...................................................................................................................65Annex C—Guidelines for Preparation of Technical Inquiries for AWS Technical Committees ................................71

List of AWS Documents on Welding in Marine Construction ....................................................................................73



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List of Tables

Table Page No.

1 Chemical Composition Limits of Aluminum Alloys Used for Marine Construction....................................52 Minimum Mechanical Properties of Marine Aluminum Alloy Sheet and Plate............................................53 Minimum Mechanical Properties of Extruded Marine Aluminum Alloys ....................................................54 Minimum Mechanical Properties of Forged Aluminum Alloys ....................................................................75 Minimum Mechanical Properties of Cast Aluminum Alloys for Marine Use...............................................76 Chemical Compositions of Aluminum Welding Filler Metals ......................................................................77 Aluminum Welding Filler Metal Selection Guide.........................................................................................98 Minimum As-Welded Mechanical Properties of Gas-Shielded Arc Welds in Marine

Aluminum Alloys.........................................................................................................................................109 Approximate Minimum Bend Radii for 90° Cold Bends in Aluminum Alloys ..........................................17

10 Guided Bend Test Diameters for Common Aluminum Alloys....................................................................2511 Typical Procedures for Gas Metal Arc Welding of Groove Welds in Aluminum Alloys

with Argon Shielding ...................................................................................................................................2912 Typical Procedures for Manual Gas Tungsten Arc Welding of Butt Joints in Aluminum

with AC and Argon Shielding......................................................................................................................3113 Typical Procedures for Gas Tungsten Arc Welding Aluminum Pipe in the Horizontal

Rolled Position.............................................................................................................................................3314 Typical Procedures for Gas Tungsten Arc Welding Aluminum Pipe in the Horizontal

Fixed Position ..............................................................................................................................................3515 Gas Tungsten Arc Welding Aluminum Pipe—Alternating Current in All Fixed Positions ........................3716 Typical Procedures for Gas Metal Arc Welding Aluminum Pipe in the Horizontal Rolled Position .........3817 Typical Procedures for Gas Metal Arc Welding of Fillet Welds in Aluminum Alloys with

Argon Shielding ...........................................................................................................................................4018 Typical Procedures for Manual Gas Tungsten Arc Welding of Fillet Welds in Aluminum

with AC and Argon Shielding......................................................................................................................42



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List of Figures

Figure Page No.

1 Typical Extrusion Shapes for Shipbuilding Applications..............................................................................62 Typical Joint Designs for Gas Shielded Arc Welding of Aluminum ..........................................................133 Typical Band Saw Blade Design for Aluminum .........................................................................................134 Teeth Arrangements for Circular Saws for Aluminum................................................................................135 Vixon File for Aluminum ............................................................................................................................146 Chisel Designs Suitable for Aluminum .......................................................................................................157 Typical Semiautomatic Gas Metal Arc Welding Guns................................................................................198 Typical Water-Cooled Gas Tungsten Arc Welding Torch ..........................................................................219 Equipment Setup for Arc Stud Welding of Aluminum................................................................................23

10 Wrap-Around Guided Bend Test Jig ...........................................................................................................2511 Design of Master Weld Joints to Provide for Fit-up in Position..................................................................2712 Typical Joint Designs for Arc Welding of Aluminum.................................................................................2813 Sizes of Double Fillet Welds to Fully Connect As-Welded 5086-H116 Members at Right Angles ...........4414 Size of Double Fillet Welds to Fully Connect A5s-Welded 6061-T6 Members at Right Angles ...............4515 Welding Sequence for Large Doubler Plate ................................................................................................4616 General Design of an Insert Plate ................................................................................................................4717 Proper Design of Snipes and Scallops .........................................................................................................4818 Welded Oil or Water Stop at Intersecting Members....................................................................................4919 Typical Strongbacks for Maintaining Alignment During Welding .............................................................5020 Welding Sequence for Plate Butt and Adjacent Seams ...............................................................................5121 Typical Welding Sequence for Plate Butts and Seams where Butts are Staggered .....................................5222 Welding Sequence at the Intersection of Plate Butts and Seams.................................................................5323 Typical Welding Sequence for Plate Butt and Adjacent Seams where Internal Framing is Attached ........5424 Typical Welding Sequence for Large Subassembled Plate Panels ..............................................................5425 Placement of Starting and Stopping Tabs at the Ends of a Repair Weld Groove........................................5426 Correction of Distortion in a Panel by Welding on the Concave Side, Using a Predetermined Pattern .....5427 Welding Sequence for Side Shell Plate Repair ............................................................................................5628 Technique for Repairing a Crack by Welding .............................................................................................5629 Nomograph for Copper Ground Cable Size.................................................................................................5730 Nomograph for Copper Electrode Lead Cable Size.....................................................................................58B1 Double-Square-Groove Welds, Convex Beads............................................................................................65B2 Single-V-Groove Welds, No Root Opening, Welded Flush........................................................................65B3 Single-V-Groove Welds, 1/8 in. (3.2 mm) Root Opening, Welded Flush...................................................66B4 Double-V-Groove Welds .............................................................................................................................66B5 Single-V-Groove Welds, 45° Groove Angles, with Backing Strip..............................................................67B6 Single-V-Groove Welds, 60° Groove Angle, with Backing Strip ...............................................................67B7 Single-V-Groove Welds, 75° Groove Angle, with Backing Strip ...............................................................68B8 Single-V-Groove Welds, 90° Groove Angle, with Backing Strip ...............................................................68B9 Single- and Double-Bevel-Groove Welds ...................................................................................................69B10 Single-U-Groove Welds...............................................................................................................................69B11 Filler Metal Requirements for Fillet Welds with Equal Leg Lengths..........................................................70



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1. General1.1 Scope. This standard makes sole use of U.S. Custom-ary Units. Approximate mathematical equivalents in theInternational System of Units (SI) are provided for com-parison in parentheses or in appropriate columns intables and figures.

This guide provides information on proven processes,techniques, and procedures for welding aluminum hullsand related ship structures. The information presentedapplies chiefly to the welding of aluminum hulls that areover 30 ft (9 m) in length and made of sheet and plate1/8 in. (3.2 mm) thick and greater. Thin-gage aluminumwelding usually requires specific procedures in the areaof fixturing, welding sequence, and other techniques fordistortion control that are not necessarily applicable tothick plates. Similarly, the choice of welding processor applicable process conditions, or both, also differsaccording to thickness.

1.2 Welding Processes. The inert gas shielded weldingprocesses have been employed as the principal joiningmethod for the majority of aluminum naval and merchantship structures built since the early 1950s. In their basicforms, these processes employ two distinct types of elec-trodes, although both use a protective shield of inert gasto prevent oxidation of the hot metal in the weld zone.

1.2.1 Gas Tungsten Arc Welding (GTAW).1 Thefirst inert gas welding process to be developed was gastungsten arc welding which is sometimes referred to asTIG welding. Introduced in 1941, this process uses a non-consumable tungsten electrode. Inert gas is fed throughthe welding torch while filler metal, when required, isadded into the weld pool separately by hand or machine.

1.2.2 Gas Metal Arc Welding (GMAW).2 The sec-ond process, gas metal arc welding, which is sometimes

1. Refer to AWS C5.5/C5.5M, Recommended Practices forGas Tungsten Arc Welding, and the Welding Handbook, Vol. 2,8th Ed. 73–108.2. Refer to AWS C5.6, Recommended Practices for Gas Metal ArcWelding, and the Welding Handbook, Vol. 2, 8th Ed. 109–156.

referred to as MIG welding, is employed for over 90% ofthe joining in a welded aluminum hull because it is muchfaster than GTAW. This process also uses an inert gasshield, but employs a continuous aluminum wire elec-trode that provides filler metal as it is fed mechanicallythrough a welding gun. Introduced in 1948, GMAW issuitable for production welding of aluminum of 1/16 in.(1.6 mm) thickness and greater.

1.3 Comparison of Welding Processes. The gasshielded arc welding processes GMAW and GTAWoffer speed, good weld strength, and ease of operation inall positions on a wide range of aluminum thicknessesand joint types.

Inert gas shielded arc welded joints in aluminumalloys, generally recommended for marine use, retain ahigh percentage of the original base metal strength. Sim-ilarly, properly made welded joints, produced with thecorrect filler metals have virtually the same corrosionresistance as the base metal.

Oxyfuel gas and shielded metal arc welding are notsuitable for aluminum ship structures because weld qual-ity is inadequate, and the residual chlorides from the fluxmust be removed.

1.4 Serviceability of Welded Aluminum Hulls. Servicerecords of welded aluminum craft and other marinestructures are excellent. Maintenance and repair costrecords of hulls, which have been in service for 20 yearsor more, are impressive.

In many respects, preparation of aluminum hull platefor welding is simpler and more flexible than preparationof steel plate. Portable routers and radial saws, operatingat relatively high speeds, and plasma arc cutting arewidely used to advantage in cutting aluminum.

Machining operations to provide the required jointgeometry for sound welds usually can be done with thesame equipment employed for steel, but the cutting toolsshould be designed for aluminum. Shipyards alreadyequipped with plate milling and planing machines, forexample, employ the equipment for aluminum edgepreparation using tools properly shaped for cuttingaluminum.

Guide for Aluminum Hull Welding



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1.5 Workmanship. Proper fit-up should be maintainedfor sound aluminum welds and should be more precisethan that normally required for welded steel construc-tion. For most ship structures, no root opening in thejoint is preferred. However, where base metal thicknessor other conditions demand, proper root openings arewell defined. Aligning procedures generally follow thoseused in steel practice.

Many shipyards have discovered that the best fittersfor aluminum construction come from carpentry shops.This is due primarily to the fact that most aluminumcutting is done with similar mechanical equipment. Aworkman with woodworking experience is more likely tofollow the cutline more accurately than is a workerversed in steel ship construction where moderately loosefits may be tolerated.

1.6 Sources of Information. Data and opinions pre-sented in this manual are based on the experience ofshipyards, aluminum producers, naval architects andengineers, and welding equipment suppliers. The follow-ing subjects are covered in sufficient detail to providereliable and practical guidelines:

(1) Marine aluminum alloy, temper, and shapeavailabilities

(2) Edge preparations(3) Forming(4) Cleaning for welding(5) Welding processes(6) Welder training and qualification(7) Fitting, aligning, and assembling(8) Types of joints and assemblies(9) Welding procedures

(10) Stress relief(11) Inspection and testing of welds(12) Repair of weldsAdditional information is available from the aluminum

producers as well as from various comprehensive publi-cations covering structural data, specifications, welding,and related subjects. A number of applicable publicationsare available from the Aluminum Association, AmericanWelding Society, Society of Naval Architects and MarineEngineers, American Bureau of Shipping, and U.S. NavalShip Systems Command. These and other organizationsof interest are listed in Annex A, together with pertinentcodes, specifications, and regulations.

2. Aluminum Hull Materials2.1 General. In the early 1950s, several weldable,medium-to-high strength 5000 series aluminum-magnesium alloys became available, which were suitablefor corrosion-resistant, light-weight ship hulls andrelated structures. These alloys became known as marine

alloys. Their as-welded minimum tensile strengths rangefrom 25 ksi–42 ksi (170 MPa–290 MPa), and theirminimum yield strengths from 15 ksi–25 ksi (100 MPa–170 MPa). The 5000 series marine alloys have excellentcorrosion resistance and retain good weld strength with-out postweld thermal treatment.

2.2 Marine Aluminum Alloys. To understand the spe-cial characteristics of the principal marine aluminumalloys, a brief description of aluminum alloy groups ishelpful. The addition of specific alloying elements toaluminum produces two distinct alloy groups: nonheattreatable, represented by the 5000 series mentionedabove, and heat treatable, represented by the 6000 seriesaluminum-magnesium-silicon alloys. Alloy 6061, anexample of the latter, is used primarily for extrudedstructural members.

The mechanical properties of heat treatable aluminumalloys depend upon the specific combinations of alloyingelements and the applied thermal and mechanical treat-ments. Such treatments include solution heat treatment,quenching, cold working, and artificial or natural aging,depending upon the specific alloy. The mechanical prop-erties of nonheat treatable alloys depend upon their alloycompositions and the amount of strain hardening or coldwork introduced during production and fabrication.

2.2.1 Heat Treatable Alloys. The principal heat treat-able wrought aluminum alloy used for marine applica-tions is 6061. It is employed for some extruded structuralmembers and also for extruded pipes. For welded con-struction, allowance should be made for reduced as-welded strength and ductility as compared with the prop-erties of heat-treated, unwelded base metal. This allow-ance for design purposes is given for some heat treatablealloys in Table 8; values for other alloys can be found inreference books.

Since the as-welded strength of heat treatable alloysvaries with time at temperature (heat input) in the heat-affected zone, welding heat input can significantly affectthe as-welded tensile strength of these alloys.

2.2.2 Nonheat Treatable Alloys. The principal non-heat treatable marine aluminum alloys are 5052, 5083,5086, 5454, and 5456. Alloy 5052 was one of the firstcommercial aluminum-magnesium marine alloys and isstill in use for small pleasure craft. However, it is notnormally employed for structures in commercial or mili-tary craft because of its lower strength.

Where operating temperatures in excess of 150°F(65°C) are anticipated, 5454 alloy is used to avoid theproblem of stress corrosion cracking found in aluminumalloys with higher magnesium content. It is useful instack enclosures and similar applications.

Alloys 5083, 5086, and 5456, in the H116 temper, arethe chief aluminum materials used in hulls and other



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marine structures. These alloys are specifically recom-mended in the Technical and Research Bulletin No. 2-15,Guide for the Selection of Wrought Aluminum Plate andShapes for Ship Structure, published by the Society ofNaval Architects and Marine Engineers (SNAME).

Alloy 50863 is recommended for most marine con-struction. The nonheat treatable aluminum alloy in theaforementioned SNAME bulletin, designated as GradeA, is termed “a general purpose material for ship struc-ture requiring a comparatively medium-strength, lower-magnesium-content, weldable alloy having good “corro-sion-resistance and fabrication characteristics.” Typicalapplications of this alloy include hull, deck, and bulk-head plate and shapes, towers, masts, bulwarks, tanks,and similar components.

Alloys 50833 and 5456 are also employed for com-mercial marine construction. Designated as Grade “B,”non-heat treatable aluminum alloys in the aforemen-tioned SNAME Bulletin, 5083 and 5456 alloys aredescribed as recommended material “for components ofship structure which require a higher-strength, higher-magnesium content, weldable alloy having goodcorrosion resistance and moderately good fabricationcharacteristics.” Typical applications of these alloysinclude structures requiring a high strength-to-weightratio, such as hydrofoil hulls, surface-effect craft,amphibious vehicles, and similar components. Alloy5456 has been widely used in naval and crewboatconstruction.

2.3 Temper Designations. Temper designations formarine aluminum alloys indicate the level of strengthachieved by a specific sequence of metallurgical treat-ments. Basic tempers are indicated by a letter, with sub-divisions of basic tempers indicated by one or moredigits following the letter. Heat treatable alloy temperdesignations begin with “T,” and non-heat treatablealloys with “H.” The letter “O” denotes fully annealedmaterial, and the letter “F” denotes “as fabricated” tem-pers, which are common to both groups of alloys.

Temper designations of nonheat treatable wroughtaluminum alloys consist of the letter “H” in conjunctionwith two or more digits; e.g., H34, H116. The first digitindicates the process as follows:

(1) H1 Strain Hardened(2) H2 Strain Hardened and Partially Annealed(3) H3 Strain Hardened followed by StabilizationThe second digit indicates the degree of work harden-

ing as follows:(1) 1 is 1/8 hard

3. The International Organization for Standardization (ISO)equivalent for 5083 and 5086 alloys are AlMg4.5Mn0.7 andAlM4, respectively.

(2) 2 is 1/4 hard(3) 4 is 1/2 hard(4) 6 is 3/4 hard(5) 8 is fully hardenedSometimes a third digit is used to designate special

conditions of tempering and hardening. The third digitindicates a variation of the two digit “H” temper. It isused to control the degree of temper or the mechanicalproperties that are different from, but are close to, thecorresponding two digit “H” temper to which it is added.

For marine aluminum alloys 5083, 5086, and 5456,mildly cold-worked tempers provide the most desirablecombination of mechanical properties and corrosionresistance for welded ship structures.

For general hull construction, and particularly forplate in the bilge areas, these marine alloys are now sup-plied in the H116 temper. This temper makes them pre-dominately free of continuous grain boundary networks.Such grain boundary networks found in other temperscould, under continuous exposure to stagnant or brackishwater, render the metal susceptible to exfoliation orintergranular corrosion. Federal specification QQ-A-250describes the requirements for the H116 temper for 5083,5086, and 5456 alloys.

Heat treatable wrought aluminum alloys respond toheat treatment to give strengths that are higher thanobtained by work hardening only. The heat of weldingthese alloys reduces the mechanical properties, but maybe subsequently heat treated to bring the weldment backto original properties.

Heat treated tempers are indicated by the letter Tfollowed by a number. The first number indicates thesequence of operations as follows:

(1) T1 cooled from an elevated temperature processand naturally aged to a substantially stable condition

(2) T2 cooled from an elevated temperature process,cold worked, and naturally aged to a substantially stablecondition

(3) T3 solution heat-treated, cold-worked, and natu-rally aged to a substantially stable condition

(4) T4 solution heat-treated and naturally aged to asubstantially stable condition

(5) T5 cooled from an elevated temperature processand then artificially aged

(6) T6 solution heat-treated and then artificially aged(7) T7 solution heat-treated and stabilized(8) T8 solution heat-treated, cold worked, and then

artificially aged(9) T9 solution heat-treated, artificially aged, and

then cold worked(10) T10 cooled from an elevated temperature process,

cold worked, and then artificially agedSometimes second and third digits are used for varia-

tions in the same basic sequence of operations that result



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AWS D3.7:2004

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in minor changes in mechanical properties; e.g., T54,T451.

Typical marine application of heat treatable alloys arewrought 6061, 6063, and casting alloy 356.0. These met-als are normally used in the T4 or T6 temper or a varia-tion thereof.

2.4 Aluminum Product Forms.4 All product forms ofaluminum are used in marine construction, includingplate, extrusions, forgings, and castings. Sheet metalgages, electrical conductors, bar, rod, and wire also areemployed in various ship fittings. The chemical com-position limits of aluminum alloys generally used formarine construction are given in Table 1.

2.4.1 Plate and Sheet. Flat-rolled aluminum productof 0.25 in. (6.4 mm) thickness and over is referred toas plate, while that from 0.006 in.–0.249 in. (0.15 mm–6.4 mm) thick is called sheet. (The term strip is not usedfor aluminum.) Aluminum plate is used in hulls, decks,shell strakes, bulkheads, flat brackets, and other appli-cations. Specific alloy selection depends upon severalfactors including design and service requirements.

The marine alloys are available as plate through 6 in.(150 mm) thickness, and widths through 186 in. (4.72 m).Combined width and maximum length per plate are afunction of thickness, with a limiting weight determinedby the initial ingot size. Availability of specific platesizes may vary among different suppliers. Extra-wideplate, at a premium price, may provide a significant netsavings if a sufficient number of welded joints are elimi-nated. Minimum mechanical properties of marine alu-minum alloy sheet and plate are given in Table 2.5

2.4.2 Extrusions. Aluminum also has unique versatil-ity in boat and ship use in the form of extruded sections.Both standard and special extruded shapes may be usedto obtain maximum structural and fabrication economicbenefits. A typical use of extrusions is in longitudinallyframed hulls where the longitudinal stiffeners and shellplate, complete with beveled edges for welding, areextruded in a single shape. Virtually all interior supportstiffeners, angles, bulb angles, and tees are extrusions.When structural shapes are too long for the availableextrusion press capacity or quantities are too small tojustify an extrusion run, aluminum shapes are often fab-ricated from formed and rolled sections or made ofwelded sections.

4. Information on wrought aluminum alloy compositions,tempers, designations, and physical and mechanical propertiesof various mill products is provided in Aluminum Standardsand Data, published by the Aluminum Association.5. Refer to ASTM B209, Standard Specification for Aluminumand Aluminum Alloy Sheet and Plate.

Typical of the many extruded aluminum shapes thathave been used for marine construction are those shownin Figure 1. Minimum mechanical properties of extrudedmarine aluminum alloys are given in Table 3.6

2.4.3 Forgings. Aluminum forgings are used to anadvantage in marine applications, particularly for struc-tural or mechanical parts requiring higher strengths thancan be obtained in castings. Three aluminum alloys com-monly employed for marine structural components are5083, 6061, and 6151. Minimum mechanical propertiesof forged aluminum alloys are given in Table 4.7

2.4.4 Castings. Cast aluminum is used extensively inmarine applications for bits, chocks, fairleads, pad eyes,handrail sockets, blocks, pulleys, electrical boxes, instru-ment cases, and many other items. Commonly usedcasting alloys for marine applications include 356.0,A356.0, 514.0, 520.0, and 535.0.

Minimum mechanical properties of cast aluminumalloys for marine use are given in Table 5.8

2.5 Welding Filler Metals. Aluminum alloy filler metalsare supplied as wire electrodes on spools or in coils, andas welding rods.9 General availability includes spoolswith nominal weights of 1, 16, 20, 30, 125, and 165 lb(0.45, 6.8, 9.1, 14.6, 56, and 80 kg). The same alloys arealso available as 36 in. (0.91 m) straight lengths in pack-ages of 5, 10, 25, and 50 lb (2.3, 4.5, 11, and 23 kg).Sizes range from 0.030 in.–3/16 in. (0.8 mm–4 mm) di-ameter for spooled electrode, and 1/16 in.–1/4 in.(1.6 mm through 6.4 mm) diameter for straight lengthwelding rods. Chemical compositions of aluminum fillermetals recommended for welding marine aluminum al-loys are given in Table 6. Aluminum filler metals arehigh quality wire products and are usually packaged toprevent surface contamination from moisture or foreignmatter. ANSI/AWS A5.01, “Filler Metal ProcurementGuidelines,” should be consulted for defining lot sizeand any testing desired by the purchaser. Although notthe only cause of weld porosity, the hydrated surface ofthe filler metal can be a major cause.

6. Additional extrusion alloy data are given in ASTM B 221,Standard Specification for Aluminum Alloy Extruded Bar, Rod,Wire, Shape, and Tube.7. Additional data given in ASTM B247, Standard Specifica-tion for Aluminum Alloy Die and Hand Forgings.8. Additional data for sand, die, permanent mold, and invest-ment castings are given in ASTM Standard Specification B 26,B 85, B 108, and B 618, respectively. Also aluminum castinginformation is provided in “Standards for Aluminum Sandand Permanent Mold Castings” published by the AluminumAssociation, Inc.9. Aluminum filler metals are produced in accordance withAWS A5.10.



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Table 1Chemical Composition Limits of Aluminum Alloys Used for Marine Construction

Composition (Weight Percent)(1), (2)

Alloy Si Fe Cu Mn Mg Cr Zn Ti

Others

AlEach Totals

508250835086545454566061606361516351356.0A356.0514.0520.0535.0

0.250.400.400.250.25

0.40–0.800.20–0.600.6–1.20.7–1.36.5–7.56.5–7.5

0.350.250.15

0.400.400.500.400.400.700.351.000.500.600.200.500.300.15

0.100.100.100.100.10

0.15–0.400.100.350.100.250.200.150.250.05

0.100.40–1.00.20–0.70.50–1.00.50–1.0

0.150.100.200.100.350.100.350.15

0.10–0.25

2.2–2.84.0–4.93.5–4.52.4–3.04.7–5.50.8–1.2

0.45–0.900.45–0.800.40–0.800.20–0.400.20–0.403.5–4.59.5–10.66.2–7.5

0.15–0.350.05–0.250.05–0.250.05–0.200.05–0.200.04–0.35

0.100.15–0.35

——————

0.100.250.250.250.250.250.100.250.200.350.100.150.15—

—0.150.150.200.200.150.100.150.200.250.200.250.25

0.10–0.25

0.050.050.050.050.050.050.050.050.050.050.050.050.050.05

0.150.150.150.150.150.150.150.150.150.150.150.150.150.15

RemainderRemainderRemainderRemainderRemainderRemainderRemainderRemainderRemainderRemainderRemainderRemainderRemainderRemainder

Notes:(1) Single values are maximum limits.(2) Registered with the Aluminum Association.

Table 2Minimum Mechanical Properties of Marine Aluminum Alloy Sheet and Plate

Alloy Temper

Thickness

Minimum StrengthMinimum ElongationTensile Yield

in. mm ksi MPa ksi MPa% in 2 in. (51 mm)

5052 H112H320H340

1/2 to 3/01/8 to 2/01/8 to 1/0

13 to 76.3.2 to 51.3.2 to 25.

253134

170210230

.0 9.52326

65160180

1297

5083 H112H116H323H343

0-1/4 to 1-1/20-1/8 to 1-1/2

1/8 to 1/41/8 to 1/4

6.4 to 38.3.2 to 38.3.2 to 6.43.2 to 6.4

40444550

280300310340

18313439

120210230270

1210108

5086 H112H116H340

1/2 to 1/01/8 to 2/01/8 to 1/0

13 to 253.2 to 51.3.2 to 25.

354044

240280300

162834

110190230

1086

5454 H112H320H340

1/2 to 3/01/8 to 2/01/8 to 1/0

13 to 763.2 to 51.3.2 to 25.

313639

210250270

122629

83180200

1186

5456 H112H116H323H343

0-1/4 to 1-1/20-1/8 to 1-1/4

1/8 to 1/41/8 to 1/4

6.4 to 38.3.2 to 32.3.2 to 6.43.2 to 6.4

42464853

290320330370

19333641

130230250280

121088

6061 T451T651

1/4 to 3/01/8 to 4/0

6.4 to 76.3.2 to 100.

3042

210290

1635

110240

189



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Figure 1—Typical Extrusion Shapes for Shipbuilding Applications

Table 3Minimum Mechanical Properties of Extruded Marine Aluminum Alloys

Alloy Temper

Minimum StrengthMinimumElongationUltimate Yield

ksi MPa ksi MPa % in 2 in. (51 mm)

5083 H111H112

4039

280270

2416

170110

1212

5086 H111H112

3635

250240

2114

14096

1212

5454 H111H112

3331

230210

1912

13083

1212

6061 T4, T4511T6, T6511

2638

180260

1635

110240

1610

6063 T5, T52 22 150 15 100 8

6351 T54 30 210 20 150 10

KEEL

INTERLOCKING DECKHOUSE PLANKS INTERLOCKING DECKHOUSE PLANKS

BULKHEAD TANK TOPS CHINE STIFFENED BUTT JOINTS

INTEGRALLY STIFFENED DECKING



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Table 4Minimum Mechanical Properties of Forged Aluminum Alloys

Alloy Temper Test Direction

Minimum StrengthMinimum ElongationUltimate Yield

ksi MPa ksi MPa % in 4D(1)

5083 H111 LongitudinalLong Transverse

4239

290270

2220

150140

1412

H112 LongitudinalLong Transverse

4039

280270

1816

120110

1614

6061 T6T6

LongitudinalLong Transverse

3838

260260

3535

240240

75

6151 T6 LongitudinalLong Transverse

4444

300300

3737

250250

106

Note:(1) D is the specimen diameter.

Table 5Minimum Mechanical Properties of Cast Aluminum Alloys for Marine Use

Alloy Temper Product

Minimum Strength(1)

MinimumElongationUltimate Yield

ksi MPa ksi MPa % in 2 in. (51 mm)

A356.0A356.0A356.0A514.0A520.0A535.0

T60T60T61F00T40F00

Permanent mold castingSand castingPermanent mold castingSand castingSand castingSand casting

333437224235

230230250150290240

2224269

2218

15017018060

150120

3.3.556

129

Note:(1) Values represent properties obtained from separately cast test bars.

Table 6Chemical Compositions of Aluminum Welding Filler Metals

Composition, Weight Percent(1)

Filler Metal Si Fe Cu Mn Mg Cr Zn Ti

Others(2)

AlEach Total

ER4043ER5183ER5356ER5554ER5556ER5654

4.5–6.00.400.250.250.25

[Note (3)]

0.80.400.400.400.40

[Note (3)]

0.300.100.100.100.100.05

0.050.50–1.0

0.05–0.200.50–1.00.50–1.0

0.01

0.054.3–5.24.5–5.52.4–3.04.7–5.53.1–3.9

—0.05–0.250.05–0.200.05–0.200.05–0.200.15–0.35

0.100.250.100.250.250.20

0.200.15

0.06–0.200.05–0.200.05–0.200.05–0.15

0.050.050.050.050.050.05

0.150.150.150.150.150.15

RemainderRemainderRemainderRemainderRemainderRemainder

Notes:(1) Single values are maximum.(2) Beryllium: 0.0003% maximum.(3) Silicon + iron: 0.45% maximum.



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Proper storage of aluminum filler metals is impor-tant for production of sound welds. They should be keptin a heated, dry storage area with a relatively uniformtemperature to prevent condensation on the metalsurface. Once a package has been opened, it is goodpractice to return the filler metal to its package and thento the storage area if it will not be used for an extendedperiod. It is also good practice during times of highrelative humidity to have a heated compartment for thespool on the welding machine to prevent condensationduring use. When welding wire used for applicationsthat require volumetric NDT, it is good practice toperform a fillet weld break test and to examine thefractured surface for excessive porosity. An overheadfillet weld break test is best for determining wirequality. Any contamination on the wire will show asporosity in the weld. This will assure that the filler met-als and techniques used will produce the desired weldquality.

2.6 Filler Metal Selection. The choice of filler metalfor welding various marine aluminum alloys should bemade with consideration given to weld strength, weldductility, corrosion resistance, use at sustained elevatedtemperatures above 150°F (65°C), and relative freedomfrom cracking during welding. The aluminum weldingfiller metal selection guide are given in Table 7 andrates suggested filler metals for welding wroughtand cast aluminum alloys to themselves or to eachother, depending upon the desired characteristics.Filler metal requirements in pounds per foot of jointfor typical welded joints in aluminum are shown inAnnex B.

The correct choice of filler metal is of vital impor-tance because the mechanical properties of welded alu-minum joints are affected by the composition of the weldmetal, as well as other factors. As previously pointed out,aluminum mill products of 6061 alloy, like those of otherheat treatable alloys, lose appreciable tensile strength asa result of the heat of welding. Ductility is also reduced.When this alloy is welded with ER4043 filler metal,proper postweld heat treatment nearly restores tensilestrength to that of the unwelded base metal, but ductilityis reduced further.

On the other hand, nonheat treatable alloysretain approximately 90% of their original strengthsin the as-welded condition. Their as-welded yieldstrengths are reduced to about 60% of that of theunwelded base metals, but their ductility remains largelyunchanged.

Table 8 gives the expected minimum as-weldedmechanical properties for marine aluminum alloyswelded with the gas tungsten arc (GTAW) or gas metalarc process (GMAW).

3. Preparation for Construction3.1 General. In a shipyard, careful preparation of prop-erly selected material is essential to sound structures,good workmanship, and overall economy. Aluminumstock preparation begins when the metal arrives in goodcondition at the shipyard. Proper handling practices andadequate storage facilities are required to maintain themetal in good condition so that special operations willnot be necessary prior to edge and surface preparationsfor welding.

Hull plates and extrusions should be cut to size,formed as required, edges prepared, cleaned, and prop-erly fitted to other components before welding. Each ofthese steps should be carried out correctly in order tomake sound welds economically.

3.2 Handling and Storage. Care of aluminum beginswhen a shipment of hull plate or extrusions is unloaded.Porous outer wrappings and interleaving should alwaysbe removed if there is a possibility of humid conditionsor direct contact with water. Prolonged contact of suchmaterials with the aluminum is likely to cause waterstaining of the metal surface. In case of doubt, it is gener-ally good practice to remove such packing.

Special techniques are not required for handling alu-minum mill products used in hull construction. However,good handling practices are required to avoid deepscratches, dents, and bent edges.

Preferably, storage facilities should be indoors, dry,clean, and well ventilated to avoid the possibility ofstaining from a combination of condensation and dirt.Where plates or shapes are stored on edge or end andseparated for good air circulation, the danger of waterstaining is minimized. However, if the metal has beenshipped during cold weather, it often is advisable toplace it in a dry, moderately-heated storage area for atime before it is moved to a heated shop having relativelyhigh humidity. This is particularly necessary when platesare stored in stacks rather than on edge.

If storage areas are heated by individual combustionunits, the units should be vented to the outdoors to avoidsulfurous combustion products that can affect the metalfinish in the presence of moisture.

Storing plates and shapes on edge can also reduce thechance of surface abrasions. Grit on the floor or trappedbetween plates can be a major source of scratching andgouging when aluminum plates are stacked flat. In addi-tion, storing on edge greatly reduces the possibility ofstoring other materials on the aluminum. Free access ofair to all surfaces of edge-stored aluminum can be pro-vided by placing nonporous plastic strips or other suit-able inert material between the metal and the floor, andbetween plates along their top edges.



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Table 7Aluminum Welding Filler Metal Selection Guide

BaseMetal

505250835456 5086

514.0520.0535.0 5454

6061606361516351

356.0A356.0

FillerMetal

Characteristics(1)

WSDCT(2) WSDCT WSDCT WSDCT WSDCT WSDCT WSDCT

356.0A356.0

40435356

ABAAABABB–

——

——

ABBA–AAAB–

ABBAAAAAB–

AAAAA—

AAAAA—

6061606361516351

404351835356555455565654

ADCAABABC–BBAC–CCABABABC–CCAB–

—AABA–ABAA–BCAA–AABA–BCAA–


ADCA–BABC–BBAC–CCAB–BABC–CCAB–

ADCBABABC–BBAC–CCAAABABC–CCAB–

ACBAABAAC–BBAC–CBABBBAAC–CBAB–

5454 404351835356555455565654

ADCCAAAAB–ABAB–CCAAAAABB–BCAB–

—AABB–ABAB–BCAA–AABB–

—

—AABB–ABAB–BCAA–AABB–

—

—AABB–ABAB–BCAA–AABB–BCAA–

—AABB–ABAB–BCAAAAABB–BCAB–

514.0520.0535.0

404351835356555455565654

ADCC–AABB–ABAB–CCAA–AABB–BCAA–



—AABB–ABAB–BCAA–AABB–BCAA–

5086 51835356555455565654

AABA–ABAA–CCAA–AABA–BCAA–

AABA–ABAA–

—AABA–

—

AABA–ABAA–

—AABA–

—

50835456

51835356555455565654

AABA–ABAA–CCAA–AABA–BCAA–

AABA–A-AA–

—AABA–

—

5052 404351835356555455565654

ADCBAAABC–ABAC–CCAAAAABC–BCAB–

Notes:(1) A, B, C, and D are relative ratings in decreasing order of merit. The ratings have relative meaning only within a given block. Combinations having

no rating are not usually recommended. Ratings do not apply when the alloys are to be heat-treated after welding.(2) Legend: Filler metals are rated on the following characteristics:Symbol CharacteristicW Ease of welding (relative freedom from weld cracking).S Strength of welded joint in as-welded condition. Rating applies particularly to fillet welds. All rods and electrodes rated should develop

presently specified minimum strengths for butt welds.D Ductility. Rating is based upon free bend elongation of the weld.C Corrosion resistance in continuous or alternate immersion in fresh or salt water.T Recommended for service at sustained temperatures above 150°F (6°C).



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Table 8Minimum As-Welded Mechanical Properties of Gas-Shielded Arc Welds

in Marine Aluminum Alloys (U.S. Customary Units)

Alloy and Temper

Product and Thickness Range,

in.

Property(1)

Tension Compression Shear Bearing

Ftuw(2)

ksiFtyw(3)

ksiFcyw(4)

ksiFsuw(5)

ksiFsyw(6)

ksiFbuw(7)

ksiFbyw(8)

ksi

5052-H32, H34 All 25 13 13 16 .0 7.5 50 19

5083-H111-H321

-H321

-H323, H343

ExtrusionsSheet & Plate0.188–1.500

Plate, 1.501–3.000

Sheet

3940

39

40

2124

23

24

2024

23

24

2324

24

24

1214

13

14

7880

78

80

3236

34

36

5086-H111-H112

-H112

-H112

-H116, H32, H34

ExtrusionsPlate,

0.250–0.499Plate,

0.500–1.000Plate,

1.001–2.000Sheet & Plate

3535

35

35

35

1817

16

14

19

1717

16

14

19

2121

21

21

21

10.0 9.5

9

8

11

7070

70

70

70

2828

28

28

28

5454-H111-H112-H32, H34

ExtrusionsExtrusions

Sheet & Plate

313131

161216

151216

191919

.0 9.57

.0 9.5

626262

242424

5456-H116, H3215456-H111, H321

-H116, H321

-H323, H343

Sheet & PlateExtrusions

0.188–1.500Plate,

1.501–3.000Sheet

4241

41

42

2624

24

26

2422

23

26

2524

25

25

1514

14

15

8482

82

84

3838

36

38

6061-T6, T651(9)

-T6, T651(10)

6063-T5, T526151-T6(9)

-T6(10)

6351-T5k-T5(10)

356.0-T6A356.0-T6514.0-F535.0-F

All(9)

Over 0.375(10)

AllAll(9)

Over 0.375(10)

All(9)

Over 0.375(10)

CastingsCastingsCastingsCastings

2424172424242423232235

20151120152015

20151120151215

15151115155015

129

.0 6.5129

129

50503450505050

30302230303030

Notes:(1) Welding filler metals are those recommended in Table 7.(2) Ultimate tensile strength across a butt joint. Strengths are AWS and ASME weld qualification test values.(3) Yield strength across a butt joint, 0.2% offset in a 10 in. gage length.(4) Compressive yield strength across a butt joint, 0.2% offset in a 10 in. gage length.(5) Ultimate shear strength within 1 in. of a weld.(6) Yield strength in shear within 1 in. of a weld.(7) Ultimate bearing strength within 1 in. of a weld.(8) Bearing yield strength within 1 in. of a weld.(9) For all thicknesses when welded with 5183, 5356, or 5556 filler metal, and for thicknesses of 0.275 in. and under when welded with 4043, 5554,

or 5654 filler metal.(10) Apply when welded with 4043, 5554, or 5654 filler metals.



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Table 8Minimum As-Welded Mechanical Properties of Gas-Shielded Arc Welds

in Marine Aluminum Alloys (Metric Units)

Property(1)

Alloy and Temper

Product andThickness Range,

in.

Tension Compression Shear Bearing

Ftuw(2)

MPaFtyw(3)

MPaFcyw(4)

MPaFsuw(5)

MPaFsyw(6)

MPaFbuw(7)

MPaFbyw(8)

MPa

5052-H32, H34 All 172 90 90 110 51 345 131

5083-H111-H321

-H321

-H323, H343

ExtrusionsSheet & Plate0.188–1.500

Plate, 1.501–3.000

Sheet

269276

269

276

145165

159

165

138165

159

165

159165

165

165

8396

90

96

538552

538

552

221248

234

248

5086-H111-H112

-H112

-H112

-H116, H32, H34

ExtrusionsPlate,

0.250–0.499Plate,

0.500–1.000Plate,

1.001–2.000Sheet & Plate

241241

241

241

241

124117

110

96

131

117117

110

96

131

145145

145

145

145

6965

62

55

76

483483

483

483

483

193193

193

193

193

5454-H111-H112-H32, H34

ExtrusionsExtrusions

Sheet & Plate

214214214

11083

110

10383

110

131131131

6511765

427427427

165165165

5456-H116, H3215456-H111, H321

-H116, H321

-H323, H343

Sheet & PlateExtrusions

0.188–1.500Plate,

1.501–3.000Sheet

290283

283

290

179165

165

179

165152

159

179

172165

172

172

10396

96

103

579565

565

579

262262

248

262

6061-T6, T651(9)

-T6, T651(10)

6063-T5, T526151-T6(9)

-T6(10)

6351-T5(9)

-T5(10)

356.0-T6A356.0-T6514.0-F535.0-F

All(9)

Over 0.375(10)

AllAll(9)

Over 0.375(10)

All(9)

Over 0.375(10)

CastingsCastingsCastingsCastings

165165117165165165165159159152241

13810376

138103138103

13810376

138103138103

10310376

103103103103

83624583628362

345345234345345345345

207207152207207207207

Notes:(1) Welding filler metals are those recommended in Table 7.(2) Ultimate tensile strength across a butt joint. Strengths are AWS and ASME weld qualification test values.(3) Yield strength across a butt joint, 0.2% offset in a 250 mm gage length.(4) Compressive yield strength across a butt joint, 0.2% offset in a 250 mm gage length.(5) Ultimate shear strength within 25 mm of a weld.(6) Yield strength in shear within 25 mm of a weld.(7) Ultimate bearing strength within 25 mm of a weld.(8) Bearing yield strength within 25 mm of a weld.(9) For all thicknesses when welded with 5183, 5356, or 5556 filler metal, and for thicknesses of 9.52 mm and under when welded with 4043, 5554,

or 5654 filler metal.(10) Apply when welded with 4043, 5554, or 5654 filler metals.



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3.3 Cutting and Edge Preparation. Sawing, machining,and other mechanical methods are most commonly usedfor cutting aluminum.10 Aluminum is easily andsmoothly cut by such methods, provided the equipmentis in good condition. Although edge preparations are cutdry whenever possible, cutting lubricants may be usedwhere necessary. Cutting wax is not recommended foruse on blades because of the difficulty in complete re-moval before welding. In either case, correct tool rakeand clearance angles are essential. Proper cutting condi-tions are similar to those required for wood. Many wood-cutting power tools of adequate rating and speeds may besuccessfully used on aluminum.

Plasma arc cutting is fast and accurate, but equipmentcost is relatively high.11 The process may be adaptable tocutting thick aluminum plate and complex plate shapes.However, sawing and automatic or template-controlledrouting or milling of pieces that can be readily handledare often more economical.

3.3.1 Edge Preparation. Preparation of the edgesmay often be done as the sheet or plate is cut to size andshape. Below 3/16 in. (4.8 mm) thickness, a square edgemay be satisfactory. Above this thickness, a single- ordouble-bevel- or J-shaped edge is generally required.Butt joints are frequently used for welding aluminumhull plates. Typical butt joint configurations with squareand V-groove designs are shown in Figure 2.

Edge preparation should be in accordance with thewelding procedure specification to achieve the desiredresults.

Edge preparation can be done in a number of ways:high-speed milling machines, routers, planers, and vari-ous types of saws. The equipment should be adapted tosuit the job. Normal heavy-duty industrial tools are rec-ommended, as they are expected to operate for extendedperiods of time. Air-operated tools have a high efficiencyrating. However, care should be taken to use an air sup-ply free of oil, moisture, and dirt to prevent contamina-tion of the joint from the air exhaust and subsequent weldporosity upon fabrication.

The use of sanding or grinding for edge preparation isnot generally recommended. Where employed, abrasivesshould be approved for the job and properly used. Anyresidue from sanding or grinding should be removedfrom the aluminum surfaces to avoid weld contaminationand porosity.

10. For additional information on machining, refer to the ASMHandbook, Vol. 16: Machining., ASM International, MetalsPark, Ohio, 1989: 761–804.11. Plasma arc cutting is described in the Welding Handbook,Vol 2, 8th Ed., 329-350, and also in AWS C5.2, RecommendedPractices for Plasma Arc Cutting.

Where a cutting operation leaves a rough surface, asecondary operation, such as milling, planing, routing,sanding, polishing, or filing, should follow to provideadequate smoothness for proper cleaning before welding.

3.3.2 Sawing. The main requirements for sawingaluminum are blades that have relatively coarse teethand the use of high blade speeds. Band saws, which arecommonly used for cutting pieces small enough to bemanipulated by hand, should have 2–4 teeth per in. (0.8–1.6 teeth per cm) and a blade speed of at least6000 ft/min (1800 m/min) under load. A typical bandsaw blade for aluminum is shown in Figure 3.

Hand-held or stationary circular saws that are fittedwith high-speed steel blades are run at 8000 surfaceft/min (2400 m/min) or faster, and at 4000–6000 surfaceft/min (1200–1800 m/min) with other tool steel blades.Carbide tipped blades are particularly suitable wherelubrication on the blade is not allowed. The carbide bladespeeds should be a minimum of 10 000 surface ft./min.Two types of circular saw blades are shown in Figure 4.The tooth side-rake angle should be about 15 degrees forthe type shown in Figure 4(A). Circular saws are versa-tile for cutting plate, as well as for straight or angularcut-off of extrusions. Jig or saber saws are convenient forcutting holes or intricate shapes in pieces that are toolarge to be cut with a band saw.

Clean, as-sawed edges are often suitable for welding.If they need cleaning, they should be smoothed first byfiling, planing, routing, sanding, polishing, or milling toremove entrapped oxide, contaminants or lubricants atfolds.

3.3.3 Shearing. The shear should be clean andsharp with the correct clearances between blades for themetal thicknesses. Properly sheared edges can be weldedsatisfactorily with sheet thicknesses up to 3/16 in.(4.8 mm). However, sheared edges, and other weld sur-faces, should be clean whether they are welded “assheared” or after dressing. Sheared edges should bedressed by filing, planing, sanding, or routing beforewelding to eliminate entrapped oxide or contaminants atfolds.

Shearing is not recommended for aluminum alloyscontaining 3.5% or more of Mg (5086, 5083, and 5456)because the edges can become sensitive to stress-corrosion cracking. However, sheared edges that areeither entirely melted during welding or buttered forwelding are satisfactory.

3.3.4 Nibbling. A nibbler cuts material by a shearingaction, and the resultant edge may require dressingbefore welding. A nibbler is advantageous for cuttingcurved edges and holes.



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General Note: Joint spacing is increased in A and B when a permanent backing is used.

Figure 2—Typical Joint Designs for Gas Shielded Arc Welding of Aluminum

Figure 3—Typical Band Saw Blade Design for Aluminum

Figure 4—Teeth Arrangements for Circular Saws for Aluminum

60˚–100˚

60˚–100˚60˚–90˚

3/16 MIN0–3/32 in.(0–2.4 mm)

0–1/8 in.(0–3.2 mm)

1/16–1/8 in.(1.6–3.2 mm)

0–1/8 in.(0–3.2 mm)

1/16–1/8 in.(1.6–3.2 mm)

5/16 in.(8 mm) MIN

0–3/16 in.(0–4.8 mm)

BACKGOUGEDAND WELDED

1/2T + 1/16

B

DC

A

5/16 in.(8 mm) MIN

90˚

45˚

RAKER (NO SET)

SET TO RIGHTSET TO LEFT

UNTEMPERED BAND CHIP CLEARANCEBETWEEN TEETH

SOFT GULLET

HARDENED TIP

TEMPERED TOOTH

ROTATION

ROTATION

(A) ALTERNATE SIDE–RAKE TEETH

(B) CHIP-BREAKER TEETH BETWEEN SQUARE TEETH



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3.3.5 Filing. A vixon or autobody file, shown inFigure 5, is the most suitable type for aluminum. It hasproper tooth shape and spacing for free cutting actionand produces a smooth surface that can be readilycleaned.

3.3.6 Routing. Pin, radial-arm, or hand routers areuseful tools for cutting and preparing the edges of alumi-num sheet and plate for shipbuilding. They are wellsuited for use with templates of irregular shapes and forstack cutting several sheets simultaneously. Special cut-ters can be used to cut and bevel at the same time. Thecut edges are ready for welding after cleaning.

3.3.7 Planing/Milling. Portable air-powered weldshavers are available to gouge and finish joints and buttwelds. They are fast and effective when properly usedand produce smoothly finished, easily cleaned surfaces.Depth of cuts are adjustable and various cutter configura-tions are available, including a flat cutter blade toremove weld bead reinforcement and a vee blade withvarious angles and bottom radii for making bevels.

3.3.8 Chipping. Chipping is seldom used for edgepreparation because it is slow, noisy, and difficult to con-trol. It is chiefly used for weld metal removal and forback gouging. For optimum chipping speed and cleancutting action, the chisel shapes should be similar tothose shown in Figure 6. They are quite different fromthose normally used for steel.

Significant aspects of these chisel designs are asfollows:

(1) Large rake angle to help control depth of cut andto lift the chip free of the joint

(2) Shaped cutting edges to provide better tracking(3)Proper design and width to obtain the required

groove depth and angle

3.3.9 Sanding. When used, care should be taken toselect nonloading type sanding discs specificallyintended for aluminum, and to maintain them free oflubricants and other foreign material. Discs of 36-80 gritwill remove heavy oxide and leave a smooth acceptablesurface finish. Polishing pads can be used for light oxideremoval, however a final solvent clean is sometimesdesirable if a residue of the binder is left on the joint.

3.3.10 Grinding. Grinding of aluminum, except asa final weld contouring and finishing operation, is dis-couraged because it leaves a rough, torn metal surfacethat is difficult to clean. When used, care should be takento select nonloading type grinding discs specificallyintended for aluminum and to maintain them free oflubricants and other foreign material.

Grinding has been employed for back gouging andweld metal removal for repairs. Satisfactory weld qualitycan be obtained when care is taken to maintain cleanli-ness of the grinding discs and the aluminum surfacesprior to welding.

3.4 Backgouging. Backgouging of joints for welding thesecond side should be of adequate depth to ensure com-plete root fusion. Standard air hammers fitted with prop-erly shaped chisels can be used. If the metal chip splits toform a “ram’s horn,” the root of the first weld has notbeen reached. The operator can maintain chipping on thecenter of the joint by observing the size of each part ofthe “ram’s horn.” A single, unsplit chip usually indicatesthat sound metal has been reached. The resulting grooveshould be smooth and readily cleaned. With the propertorch and nozzle, plasma gouging can be successfullyemployed for back gouging the non-heat treatable alumi-num alloys.

Backgouging can also be accomplished using portablepower saws with small cutters or portable milling cutters.Die and disk grinders with appropriate wheels are alsoused.

3.5 Finishing and Contouring. Finishing of welds isseldom required. When specified, weld finishing can bereadily accomplished by grinding or sanding, providedcare is taken to avoid damaging or thinning the basemetal adjacent to the weld. Chipping with pneumaticchisels or portable milling equipment along with finallight disc sanding or polishing is often the most econom-ical method of finishing welds.Figure 5—Vixon File for Aluminum



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Figure 6—Chisel Designs Suitable for Aluminum

8 in. (203 mm)1-1/2 in.(38 mm)

1-1/8 in. (28.5 mm)

8 TO 10 RAD.

3/16 in. (4.8 mm)

8 in. (203 mm)

1-1/2 in.(38 mm)

1-1/8 in. (28.5 mm)

8–10 RAD.

3/16 in. (4.8 mm)

1/2 in. (13 mm)

8 in. (203 mm)1-1/4 in.(32 mm) 5/16 in. (8 mm)

1 in. (25 mm)

4–6 RAD.

4–6 RAD.

8 in. (203 mm)1-1/8 in. (28.5 mm)

3/8 in. (9.5 mm)

1/2 in. (13 mm)

(D) GOUGE CHISEL

(C) GOUGE CHISEL

(B) FLAT-EDGED CHISEL

(A) FLAT CHISEL



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3.6 Cleaning for Welding. Shipyard cleaning proce-dures most commonly used for aluminum welding con-sist of degreasing followed by hand or power wirebrushing or sanding of the joint surfaces and adjacentsurfaces just prior to assembly and welding. When sand-ing is employed, it is necessary to remove all sandingdust, prior to welding, with a clean stainless steel brush.

Degreasing is usually done with a commercial solventby wiping, spraying, dipping, or vapor degreasing. Suchsolvents may be toxic, and the cleaning and weldingareas should always be well ventilated.12 Always followthe safe handling guidelines provided by the chemicalmanufacturer. Vapors that are heavier than air can accu-mulate in lower areas of the structure.

Wire brushes should have stainless steel bristles offrom 0.005 in.–0.015 in. (0.13 mm–0.38 mm) diameter.They should be degreased periodically to prevent con-tamination of the aluminum surface. Pressure on thebrush should be light to avoid burnishing the surface andembedding the oxide or foreign matter.

For more tightly adhering contaminants or very thickoxide, other cleaning methods may be used. Mechanicalmethods include machining, scraping, filing, grindingand sanding. Chemical methods include the use of caus-tic soda, acids, and proprietary solutions. It is alwaysimportant to remember that when mixing any solutions,the chemical should always be added slowly into thewater or solvent while stirring.

Cleaning should be done before fit-up of the jointbecause it is difficult to remove solvents or solutionsfrom assembled joints.

Weld joint surfaces and adjacent surfaces maybecome contaminated again if they are exposed to theshop atmosphere for an extended period. An effectiveway to prevent this is to cover the joints with strips ofstrong paper, 2 in.–3 in. (51 mm–76 mm) wide, taped inplace along their length. Tape should not be applieddirectly to the joint faces, or within 1 in. (25 mm) oneither side, because the adhesive may be difficult toremove. Any residue on the joint faces may cause poros-ity in the weld. It is also important to remember that theaddition of strong paper will not stop oxidation or mois-ture on the joint surface.

Compressed air is useful for cleaning joints of dust ormetal particles that may have collected, but it should befree from water and oil. It should come from a reliablesupply of dry, clean air, and there should be no lubrica-tors in the lines. Always follow safe practices whenusing compressed air.

Rough, contaminated surfaces are very difficult toclean properly. They require a dressing operation, such

12. Refer to ANSI Z49.1, Safety in Welding, Cutting, andAllied Processes, published by the American Welding Society.

as milling, routing, smooth sanding, polishing, or filing,before they are cleaned.

Cleaning should not be limited to the joint faces. Suf-ficient adjacent surface areas should be cleaned toremove any oil or grease that could flow into the joint orvaporize into the inert gas shield during welding. It isgood practice to degrease all surfaces for a distance of3 in.–6 in. (76 to 150 mm) from the joint edge. Wirebrushing, sanding, and polishing should be limited to thejoint faces and other areas that will be exposed to thearc.13

3.7 Forming and Bending. Many aluminum shapes canbe formed cold. Table 9 gives the minimum bend radiifor 90-degree cold bends in principal marine aluminumalloys. For more severe forming, heat may be used, butprecautions need to be taken to avoid undesirablechanges in the metal properties. The effects of cold workand of heating are different for nonheat treatable and heattreatable alloys.

3.7.1 Nonheat Treatable Alloys. Alloys possessing3.5% or more of Mg should not be formed at temper-atures in the range of 150°F–400°F (66°C–204°C)because of the risk of causing the metal to becomesensitive to stress-corrosion cracking. Forming above400°F (204°C) affects the strength of work-hardenedmetal. The effect is more pronounced as the annealingtemperature of 650°F (343°C) is approached. Formingtemperatures should be carefully controlled, and the timeat forming temperature kept as short as possible.

3.7.2 Heat Treatable Alloys. Annealing 6061 alloyto completely remove the effects of hardening markedlyreduces its tensile strength. The annealing treatment forthis alloy is 2–3 hours at 775°F (413°C) followed by aslow cool of 50°F (28°C) per hour down to 500°F(260°C). It is generally used only where required to formthe part, and then only when the part can be heat-treatedto restore or obtain maximum strength. When it isdesired to partially remove the effects of cold working orheat treatment to make the metal more formable, 6061alloy is heated to 650°F (343°C), followed by rapid cool-ing. Time at elevated temperature is critical for 6061alloy.

3.8 Preheat. Temperature changes can result in conden-sation. Therefore, it is almost a universal practice amongshipyards to heat and dry off aluminum componentsbefore welding during early morning hours. Tempera-

13. Additional information may be found in the ASM Handbook,Volume 05: Surface Engineering, ASM International, MetalsPark, Ohio, 1994.



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tures for drying need not exceed 150°F (66°C); i.e., handwarm.

Clean-burning gas is used in torches that are adjustedto produce a soft, reducing flame. Local overheatingshould be avoided. It is essential to monitor temperaturewith pyrometric instruments or temperature-indicatingcrayons or paint. A maximum temperature of 250°F(121°C) should not be exceeded, and time at temperatureshould not exceed 15 minutes.

The use of resistance heater bars is another alternateway to preheat the base metal before welding iscommenced.

4. Welding Processes andEquipment

4.1 General. The gas metal arc welding (GMAW) pro-cess is recommended for over 90% of the welding inmarine construction because welds can be produced athigh speeds as a result of the high heat input and thecontinuous feeding of filler metal. It is used for semi-automatic, machine, and automatic welding operations.The process can be used to weld sheet as thin as 0.050 in.(1.3 mm) with pulsed power, and about 0.070 in.(1.8 mm) with continuous power.

Table 9Approximate Minimum Bend Radii for 90° Cold Bends in Aluminum Alloys

AlloyTemper in.

(mm)

Minimum Bend Radius(1)

Base Metal Thickness, t

1/64(0.4)

1/32(0.8)

1/16(1.6)

1/8(3.2)

3/16(4.8)

1/4(6.4)

3/8(9.5)

1/2(13)

5052

0H32H34H36H38

0001t1t

001t1t

1.5t

00.5t1.5t1.5t2.5t

0.5t1t2t

2.5t3t

1t1.5t2t3t4t

1t1.5t2.5t3.5t5t

1.5t1.5t2.5t4t

5.5t

1.5t2t3t

4.5t6.5t

5083

0H116H321H243H343

—————

—0.5t———

0.5t1t1t

1.5t1.5t

1t1.5t1.5t2t

2.5t

1t2t

1.5t2.5t3t

1t2.5t1.5t3t

3.5t

1.5t3t2t——

1.5t4t

2.5t——

5086

0H116H32H34H36

0—0

1.5t1.5t

00.5t0.5t1t2t

0.5t1t1t

1.5t2.5t

1t1.5t1.5t2t3t

1t2t

1.5t2.5t3.5t

1t2.5t2t3t4t

1.5t3t

2.5t3.5t4.5t

1.5t4t3t4t5t

54540

H32H34

00.5t0.5t

0.5t0.5t1t

1t1t

1.5t

1t2t2t

1t2t

2.5t

1.5t2.5t3t

1.5t3t

3.5t

2t4t4t

5456

0H116H321H323H343

—————

—0.5t———

—1t—

2.5t3t

1t1.5t2t3t

3.5t

1.5t2t2t

3.5t4t

1.5t2.5t2.5t4t

4.5t

2t3t3t——

2t4t

3.5t——

60610

T4T6

001t

001t

01t

1.5t

1t1.5t2.5t

1t2.5t3t

1t3t

3.5t

1.5t3.5t4.5t

2t4t5t

Note:(1) The radii listed are the minimum recommended for bending sheets and plates without fracturing in a standard press brake with air bend dies. Other

types of bending operations may require larger radii or permit smaller radii. The minimum permissible radii will also vary with the design andcondition of the tooling.



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Gas tungsten arc welding (GTAW) can be used forjoining aluminum parts with small cross-sections, suchas piping, handrails, and similar fittings that have curvedor relatively inaccessible joints. This process is suitablefor welding aluminum ranging from thin sheet gauges toa practical maximum thickness of approximately 3/8 in.(9.5 mm). Proper application requires a high degree oftorch maneuverability and welder skill.

Stud welding is used extensively by shipyards tofasten aluminum studs to aluminum hulls, decks, andbulkheads for the attachment of insulation; hangers forelectrical brackets, cable troughs and pipe; and othersimilar applications.

4.2 Gas Metal Arc Welding. In gas metal arc welding,filler metal can be transferred from the electrode to theworkpiece in two ways:

(1) Discrete droplets are moved across the arc underthe influence of gravity and electromagnetic forces.Transfer can be either globular (large droplets) or spraytype (small droplets). The pulsed spray process variationis gaining wider usage on thin base metals.

(2) The electrode contacts the weld pool, therebycreating a short circuit. This is known as short-circuitingtransfer.

Short-circuiting and globular transfer are not recom-mended for welding aluminum because of the danger ofincomplete fusion in the welded joint as well as exces-sive porosity. Spray transfer is recommended for allGMA welding of aluminum and pulsed power will pro-vide this for low current welding of the thinner sheetthicknesses.

The GMAW process employs an aluminum wire elec-trode and an inert gas shield. With some GMAW equip-ment, electrode feed starts the instant the arc is initiatedand stops when the arc is stopped. With other types, elec-trode feed is controlled by the welder. Gas flow is simi-larly controlled. The arc is produced by direct currentflowing between the electrode at positive and the work atnegative polarity (dcep).

4.2.1 Shielding Gas. Argon and helium, or mixturesof the two gases, are used exclusively for welding alumi-num. The purity and moisture content of the inert shield-ing gas is extremely important. Gas suppliers exercisegreat care to ensure that commercial welding grades arefree from moisture, oils and other contaminants. Thedewpoint of the gas should be below –76°F (–60°C) forArgon and –71°F (–57°C) for Helium (per AWS A5.32/A5.32M) at the manifold or cylinder and -40°F (–40°C)at the nozzle as a minimum. All welding machine, shop,and yard pipelines and hoses should be kept clean andfree of moisture and other contaminants that cause weldporosity. Hoses that were previously used for other thanwelding grade inert gas should not be used with welding

equipment. When high quality welds are called for,oxyfuel gas hoses should not be used, and synthetichoses like PVC are recommended.

Weld quality and economy for a given set of weldingconditions are markedly affected by the type of inert gasemployed. The primary function of the inert gas is toexclude oxygen, nitrogen, and hydrogen from the moltenmetal. It also provides an ionized path for the electricaltransfer of energy and a stable arc action.

Either argon, helium, or a mixture of the two is usedfor GMAW of aluminum. Pure argon is usually preferredfor welding plate in thicknesses up to about 3/4 in.(19 mm). Argon is most effective in oxide removalwhen used with a direct current, electrode positive arc.

A direct current, electrode positive arc, operating atany given amperage, has a higher voltage with heliumshielding than with argon shielding. For joining thickaluminum plate, mixtures of argon and helium are oftenemployed with GMAW to obtain the higher arc energyassociated with helium and the good cleaning action withargon. Helium-argon mixtures are also recommended forout-of-position welding of hull plates. Mixtures of 50%–75% helium are commonly used to take advantage of thegood penetration characteristics and weld metal sound-ness particularly when using a 5XXX alloy electrode.Most dealers supply cylinders with a mixture of 75%helium and 25% argon. In addition, mixing valves andgas proportioners are commonly employed to produceany desired mixture of these gases.

4.2.2 Equipment. Gas metal arc welding equipment isavailable in a range of capacities for both semiautomaticand automatic operation. Several basic designs of semi-automatic GMAW guns are available to fit variouscombinations of electrode wire feed and power sourceequipment. Typical semiautomatic GMAW guns areshown in Figure 7. Pull-type guns, Figure 7(D), andpush-pull guns, Figure 7(C), may be used with remotewire feeders to reach distant welding locations andshould be used to feed 3/64 in. (1.2 mm) diameter andsmaller electrodes. Most welding guns rated for higherthan 150 A need to be water-cooled for high duty cyclealuminum welding. Factors controlling the suitability ofthe arc welding gun design and wire feed system includeaccessibility, electrode diameter, and distance from theelectrode wire supply to the location of welding.

Wire feeders usually are located some distance fromthe welding power supply. Depending on the systememployed, the GMAW gun can be used at extended dis-tances from the electrode supply to enhance the mostefficient use of the equipment. Control of welding cur-rent or arc voltage, depending upon the type of powersupply being employed, can be provided at the weldingstation with a remote pendant.



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4.2.3 Power Sources. Several types of DC powersources are available for semiautomatic, machine, andautomatic gas metal arc welding (GMAW). Semiauto-matic welding requires welding currents up to about400A. Machine and automatic welding generally requirecurrents in the range of 250 A–600 A.

Important factors in selecting a GMAW power sourcefor aluminum include size of the weld, electrode diame-ter, welding position, amount of welding to be done,desired production rate, and other factors.

Power is generally supplied for GMAW by singleoperator, dc rectifiers, motor-driven generators, invert-ers, or pulsing type power sources. Rectifiers have higherelectrical efficiency and lower noise level. Motor-drivengenerators are not affected by normal line voltage fluctu-ations. Engine-driven generators are used essentiallyaway from power lines and, if properly maintained, givelong, dependable service. For semiautomatic GMAW ofaluminum, three types of dc power sources are normallyused, namely:

(1) Constant Potential (CP) having flat or slightlydrooping volt-ampere characteristic (1 V–3 V/100 A)

(2) Constant Current (CC) having a drooping volt-ampere characteristic (1V/5 A–10 A)

(3) Pulsed direct current (PA) with characteristics ofeither (1) or (2).

Modifications of these types are also used formachine and automatic GMAW.

The principal differences in performance of thesepower sources when welding aluminum are manifestedwhen specific welding variables are adjusted. A primefactor in choosing a given type of power source is, there-fore, the type of welding to be done. Electrode feedcontrol requirements are different for constant-currentand constant-potential machines.

With a constant-current machine, the electrode feedis not initiated until the arc is established by touchingthe electrode to the work. Alternatively, a slow run-inwire feed can be used. Attempts to start the arc by feed-ing the electrode into the work at normal speed usuallyfail.

The reason for this is that the heat developed by thelimited welding amperage is insufficient to initiate melt-ing of the electrode tip. With a constant-potentialmachine, a large surge of current takes place when theelectrode touches the workpiece. The electrode meltsback rapidly, and the arc is established readily. However,a slow run-in feed is advantageous for improving the

Figure 7—Typical Semiautomatic Gas Metal Arc Welding Guns

(A) GAS-COOLED, CURVED-NECK GUNFOR PUSH WIRE FEED

(B) WATER-COOLED PISTOL-GRIP GUNFOR PUSH WIRE FEED

(C) PUSH-PULL TYPE GUNS (D) GUN WITH SELF-CONTAINED WIRE DRIVE AND SPOOL

GAS TUBECOMPOSITECABLE

ELECTRODE GUIDE TUBE

GUN HANDLE

GUN SWITCHNOZZLE

CURRENT CONTACT TUBEWELDING ELECTRODE



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soundness of the weld metal at starts. It also helpsprovide better contact tube life by limiting the startingcurrent surge. Since the resistance heating of the alumi-num electrode is much less than ferrous electrodes, gunswith long contact tubes should be used to provide consis-tent electrical transfer.

As the gun-to-work distance is changed, a constant-potential machine will tend to maintain a constant arclength by allowing the welding amperage to vary. With aconstant-current (CC) machine, larger changes in arclength will be noted, but the amperage change will beless than with a constant-potential (CP) machine. Oscil-lation should be minimized or avoided when using a CPpower supply with aluminum, due to the wide fluctua-tions in heat input that may lead to lack of fusion in deepgroove and fillet welds. A drooping volt-ampere char-acteristic power supply (CC) is generally preferred forsound welds in aluminum when the arc is manipulated.Proper welding procedures should be developed andfollowed for each type of power supply. A shorter arcgives deeper penetration and is generally used for thefirst pass. Longer arcs are used for cover passes andwelds, where deep penetration is not required. However,arc length that is too long or too short causes inadequateinert gas shielding, creating excessive weld porosity andspatter.

Power sources are available for pulsed spraywelding. A pulsed, direct-current power source pulsesthe welding amperage from a low background value toa high peak value. The steady, background amperage istoo low to produce spray transfer, however, it maintainsa continuous arc cleaning action. The peak amperage,which is superimposed upon the background amperageat regulated intervals, is well above the spray transitionamperage. Consequently, one droplet of metal isusually transferred during each pulse. The combinationof the two levels of amperage produces a steady arcwith axial spray transfer at average welding amperagebelow those required for conventional spray arcwelding. Now available are synergic controllers thatinclude the adjustment of peak and background amper-age, along with voltage and pulse rate, with a singleknob.

Because the heat input is lower than normal spray arcwelding, this variation of GMAW is capable of weldingthinner base metal than is practical with conventionalspray transfer. It is useful for welding aluminum of0.08 in. (2 mm) or less in thickness. This type of powersource also makes it possible to weld groove and filletwelds having relatively poor joint fit-up in either thehorizontal or vertical position. Finally, it permits the useof an electrode at least one size larger than can be usedwith a steady amperage, so as to improve the feedingcharacteristics when welding sheet gauges.

4.2.4 Wire Feed Units. Selection of an appropriatewire feed system is important. Desirable features of asystem are as follows:

(1) An adjustable constant-speed drive;(2) A slow run-in or touch-start initial wire feed speed

starting system compatible with the appropriate type ofpower source;

(3) Crater fill and burnback controls;(4) Radius-groove top and bottom wire drive rolls.

Self-contained wire guns [Figure (7D)] may also useknurled feed rolls, but they are not recommended forother systems with long wire liners to the gun that canbecome clogged with aluminum shavings;

(5) Nonmetallic liners and guides for the electrode;e.g., nylon, teflon, etc.;

(6) Water and gas solenoid valves.To protect the aluminum welding wire from dirt and

to reduce the incidence of weld porosity, it is desirable tohave a spool enclosure. Additional protection can beachieved with an electric heater in the enclosure to mini-mize condensation.

4.3 Gas Tungsten Arc Welding. A nonconsumabletungsten electrode is used for gas tungsten arc welding(GTAW). Both the electrode and the molten weld poolare protected by an inert gas shield. When required, fillermetal is added by hand or by a mechanical wire feeder.

Even though the tungsten electrode is nonconsumableunder normal operating conditions, the weld metal canbe contaminated with tungsten if the electrode is allowedto touch the molten weld metal or filler rod, or if thewelding current is excessive for the electrode size.GTAW is suitable for welding aluminum in all positions.Weld beads are characteristically smooth. A typicalwater-cooled welding torch is shown in Figure 8. GTAWis often the only suitable process where joint accessibil-ity is limited because a wide variety of welding torchdesigns are available, including miniature sizes. Also,some low-current models are air cooled and easier tomanipulate than water cooled types.

4.3.1 Types of Welding Current. Aluminum can begas tungsten arc welded using conventional sinusoidal-wave ac (60 Hz), balanced sinusoidal-wave (bwac) andsquare-wave ac (swac), square-wave with adjustable bal-ance, and dc with the electrode either negative or positive.

Surface cleaning of the aluminum takes place whenthe electrode is positive, but penetration is poor. Con-versely, penetration is good with a negative electrode,but there is no cleaning action. Alternating current canprovide good cleaning action and acceptable penetration,particularly with swac of variable frequency and pulsewidth. Direct current can provide good penetration orgood cleaning, but not both conditions simultaneously.



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4.3.2 Electrodes. The choice of tungsten electrodedepends upon the type of welding current selected for theapplication. With conventional ac, better arc action is ob-tained when the electrode has a hemispherical-shapedtip. AWS Classes EWP (pure tungsten) and EWZr (tung-sten-zirconia) electrodes retain this tip shape well. ClassEWTh (tungsten-thoria) electrodes may also be usedwith some sacrifice in arc stability and fine tungsten in-clusions in the weld.14 The electrode should be tapered tofacilitate melting the tip to form a hemispherical shape.

Class EWTh-l and EWTh-2 (tungsten-thoria) elec-trodes are preferred for use with dc power. Both havehigher emissivity, better current carrying capacity, easierstarting characteristics, and longer life than do EWPelectrodes. Class EW Th-1 and EW Th-2 electrodes arenot preferred for AC welding of aluminum. When theseelectrodes are used with ac on aluminum, there is anincreased tendency for rectification of the arc, reducedarc cleaning action and arc stability, as well as increasedloss of tungsten compared to the EWP and EWZr elec-trode types.

In recent years the thorium oxide tungsten alloys arefalling out of favor due to their mild radioactivity. Theyare being replaced by electrodes containing lanthanum orcerium oxides.

4.3.3 Shielding Gases. Argon is the most commonlyused shielding gas, particularly for manual welding withAC. Helium additions are used in special cases. Arc volt-age characteristics with argon permit greater arc lengthvariations with minimal effect on arc power than helium.

14. Refer to AWS A5.12, Specification for Tungsten Arc Weld-ing Electrodes, published by the American Welding Society.

Argon also provides better arc starting characteristicsand improved cleaning action, especially with alternatingcurrent.

Helium is used primarily for machine welding withDCEN power. It permits welding at higher travel speedor with greater penetration than argon.

Helium-argon mixtures are sometimes used to takeadvantage of the higher heat inputs with helium whilemaintaining the favorable arc characteristics of argon.Mixtures of 25%–50% helium will permit higher travelspeeds with ac power. Cleaning action is still acceptable.A mixture of 90% He–10% Ar will provide better arcstarting characteristics with dc power than pure helium.

4.3.4 Alternating Current Power. When ac is usedin conjunction with shielding of argon or an argon-helium mixture, the surface oxide is removed by arcaction. However, this cleaning action may not be satis-factory when the mixture contains high percentages ofhelium and preweld cleaning is usually necessary. Purehelium shielding is seldom used with alternating currentbecause the arc characteristics are poor.

The oxide removal action takes place only during theportion of the ac cycle when the electrode is positive.This action tends to rectify the ac power. To assure arcinitiation during this half cycle, the power source shouldhave either a high open-circuit voltage or an auxiliarycircuit to superimpose high voltage on the welding cir-cuit. The arc should be initiated by some means otherthan touching the electrode to the workpiece to avoidtungsten contamination. High frequency arc starting iscommonly used in this regard.

The magnitude of the current will be greater when theelectrode is negative unless the power source containsappropriate electrical circuitry to balance the ac wave.For this reason, balanced-waved ac power sources arerecommended for welding aluminum. Proper gas shield-ing and arc cleaning action are indicated by a bright weldbead with silvery borders on each side. An oxidized weldbead may be a result of an unstable arc, low welding cur-rent, poor gas shielding, or excessive arc length.

4.3.5 Direct Current, Electrode Negative Power.Gas tungsten arc welding with direct current, electrodenegative (DCEN) has distinct advantages compared to acpower, particularly with machine welding. The deeppenetration possible with helium shielding is particularlyuseful for welding thick sections. Preheating is notnormally required. With thin sections, DCEN permitsmuch higher travel speed than does alternating current,and the arc length should be carefully controlled whenusing helium shielding gas.

The surface appearance of a weld made with DCENwill be dull rather than bright because the cleaning actionof the electrode positive half-cycle of ac is absent. A thin

Figure 8—Typical Water-CooledGas Tungsten Arc Welding Torch

COLLETHANDLE

GAS IN

NOZZLEELECTRODE

WATER INWATER OUT

POWER CABLE



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oxide film accounts for this appearance, but it is easilyremoved by wire brushing. Thorough preweld cleaningis essential, as is interpass cleaning with multiple-passwelds.

Argon shielding may be used with DCEN, but pene-tration will be less than with helium. Arc length controlwill not be so critical, and this may be beneficial whenmanually welding thin base metal.

4.3.6 Direct Current, Electrode Positive Power.Welding with DCEP provides good surface cleaningaction and permits welding of thin aluminum base metalwith sufficient current to maintain a stable arc. The weldbead tends to be wide, and penetration is shallow. Appli-cation is limited to base metal of about 0.050 in.(1.3 mm) thickness and under, or for tack welding, becauseof tungsten electrode overheating. Argon shieldingshould be used. Helium or argon-helium mixtures wouldcontribute to electrode overheating. Edge or square-groove joint geometries with filler metal are applicable.

4.3.7 Square-Wave Alternating Current Power.Square-wave alternating current (swac) power suppliesdiffer from conventional ac sinusoidal wave power withrespect to the current wave form. The SWAC powersource is designed to produce dc power and rapidly shiftthe polarity to produce a square alternating wave form ofadjustable frequency available in some models. In addi-tion, the relative percentage of time for each polaritywithin one cycle of current can be adjusted within limits.

This type of power combines the advantages of sur-face cleaning associated with conventional ac power anddeep penetration obtainable with DCEN power. How-ever, one is gained with some sacrifice in the other. Iflonger electrode-positive time is needed for acceptablecleaning, penetration will decrease with a specific weld-ing current and frequency.

The square-wave shape enhances arc reignition dur-ing polarity reversal. Often, superimposed high fre-quency voltage is needed only to start the arc, rather thanbeing needed continuously during welding to stabilizethe arc.

Welding techniques similar to those for conventionalac welding are suitable with swac welding, as is the elec-trode tip shape. Argon shielding is preferred, but argon-helium mixtures can provide deeper penetration at somesacrifice in cleaning action.

4.3.8 Wire Feed Units. Mechanized GTAW employsa wire feed unit for the addition of filler metal. Modelsrange from the conventional machine-mounted type tospecial-purpose units. The guide that directs the fillerwire into the molten weld pool is usually mounted nextto the welding torch. Controls operate and regulate thewire feed. The wire is supplied on spools identical tothose for gas metal arc welding bare wire electrodes.

4.4 Mechanized Welding. High welding currents andtravel speeds can be used, resulting in greater productiv-ity with this method. Mechanized welding is employedin two ways.

4.4.1 Mechanically Aided Welding. The arc weldinggun is normally mounted either on a tracked or tracklesspacing carriage or on a boom. Both mountings may carrythe equipment alone, or may be large enough to accom-modate the welder also. In either case, the welder manu-ally regulates welding machine settings, travel speed,wire entry position, and torch position. Such mechanicalaids improve efficiency, when welding long joints.

4.4.2 Machine Welding. Machine welding employscompletely mechanized equipment. The welding opera-tor monitors the welding and manually adjusts seamtracking and welding variables, such as welding current,arc voltage, wire feed rate and travel speed. Resultingweld beads are accurate and uniform within the processcapability. Shipyard use of machine welding is economi-cal for long joints in hull plates, prefabrication of panels,welding tubular and other hollow components of super-structure, hatch covers, ship-fabricated bulkheads, andsimilar applications. Machine welding should be con-sidered for shipyard use wherever the work can be posi-tioned for welding in the flat, horizontal, or verticalposition.

4.5 Stud Welding. There are two types of stud weldingthat employ an arc to obtain fusion. These are gasshielded drawn arc and capacitor discharge stud welding.Aluminum studs can be joined to aluminum componentswith both types of equipment.15 Friction stud welding isa new technology that may be considered. Stud weldingis used to join various mechanical fasteners to structuralsections.

4.5.1 Arc Stud Welding. Arc stud welding equip-ment consists of a stud welding gun, a timing controldevice, a dc power source, and a gas adapter foot thatholds a ceramic ferrule around the stud and conductsshielding gas to the joint. The ferrule confines the weldmetal and aids in forming a fillet at the base of thewelded stud.

The stud welding gun is also equipped with a dampen-ing device to control the plunging rate of the stud at thecompletion of the weld time. Argon is generally used forshielding, but helium may be useful with large studs totake advantage of the higher arc energy. An equipmentarrangement is shown in Figure 9. This equipment is usedwith the stud (electrode) positive and the work negative.

15. Stud welding is discussed in AWS C5.4, RecommendedPractices for Stud Welding, and Vol. 2 of the Welding Hand-book, 8th Ed. published by the American Welding Society.



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AW

S D

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23

Figure 9—Equipment Setup for Arc Stud Welding of Aluminum

Copyright A

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Provided by IH

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An aluminum stud differs from a steel stud in that noflux is used on the welding end. A cylindrical- or cone-shaped projection is used on the base of the stud. Theprojection dimensions on the welding end are designedfor each size of stud to give the best arc action. The pro-jection serves to initiate the long arc used for aluminumstud welding.

Studs have weld base diameters of 1/4 in.–1/2 in.(6.4 mm–13 mm). Their sizes and shapes are similarto steel studs. They are commonly made of aluminum-magnesium alloys, including 5183, 5356, and 5556, thathave a typical tensile strength of 40 ksi (280 MPa).These alloys have high strength, good ductility, and theyare metallurgically compatible with the majority of alu-minum alloys used in the shipbuilding industry.

4.5.2 Capacitor Discharge Stud Welding. With thisprocess, DC arc power is produced by a rapid dischargeof stored electrical energy with pressure applied duringor immediately following the electrical discharge. Theprocess uses an electrostatic storage system as a powersource in which the weld energy is stored in capacitors.

There are three different types of capacitor dischargestud welding: initial contact, initial gap and drawn arc.They differ primarily in the manner of arc initiation. Ini-tial contact and initial gap stud welding utilize studs hav-ing a small, specially designed projection (tip) on thewelding end of the stud. Drawn arc stud welding createsa pilot arc as the stud is lifted off the workpiece by thestud gun, similar to arc stud welding.

The process is best suited for welding studs to rela-tively thin base metal. Neither ferrules nor shielding gasis normally required to protect the weld metal becausethe welding time is very short. However, argon shieldingshould be used with the drawn arc method because thewelding time is long enough for oxidation to take place.

Studs for capacitor discharge welding commonlyhave bases ranging from 0.062 in.–0.187 in. (1.6 mm–4.75 mm) diameter. The drawn arc technique is com-monly used for 1/4 in.–1/2 in. (6.4 mm–13 mm) diame-ter. Studs are commonly made from 1100, 4043, 5183,5356, and 5556 alloys, and are readily welded to 5XXX(except 4043) and 6XXX alloys.

Arc times are significantly shorter and welding cur-rents are much higher than those used for arc stud weld-ing. It is the very short weld time that accounts for theshallow weld penetration into the workpiece and also thesmall stud melt-off distance.

Depending upon stud size and type of equipmentused, the peak welding current can vary from about600 A–20 000 A. The total time to make a weld dependson the welding method used. For the drawn arc method,weld time is in the range of 6 ms–15 ms.

4.5.3 Quality Control. Aluminum stud weldingrequires attention to the following points to assure goodreliability:

(1) Correctly designed studs and proper matching ofstud and base metal (see Table 7)

(2) Power source and welding equipment of sufficientcapacity for the stud size

(3) Surfaces that are clean and free of lubricants,oxides, and other contaminants

(4) Proper positioning of the stud welding gun on thework surface, and correct stud lift and plunge settings

Visual inspection of aluminum stud welds for accep-tance is limited because the appearance of the weld filletdoes not necessarily indicate soundness. Therefore,visual inspection of aluminum stud welds is recom-mended only to determine complete fusion and absenceof undercut around the periphery of the weld.

Aluminum studs can be tested to establish acceptablewelding procedures using a bend test. If the stud bends to15° from the original axis without breaking the stud orweld, the stud welding techniques should be consideredsatisfactory. Production studs should not be bent andthen straightened because of possible damage to them. Inthis case, the torque test or separate qualification testplates may be substituted.

Torque testing of threaded aluminum studs is done inthe same manner as that used for steel studs. Torque isapplied to a predetermined value or until the stud fails.For a particular application, the acceptable proof loadshould be established by suitable laboratory tests, relat-ing applied torque to tensile loading.

5. Qualification Procedures for Welding

5.1 General. Standards for welding aluminum shipstructures routinely call for qualification of the weldingprocedures to be used and the qualification of weldersand welding operators to produce sound welds. Suchqualification is recommended in every case and is man-datory for all hulls that are to be welded to codes andspecifications of cognizant governmental and commer-cial agencies. The principal agencies are included inAnnex A.

It is essential that the builder and owner agree uponsuitable standards for welding procedure and perfor-mance. Welders and welding inspectors who are experi-enced and qualified in welding aluminum (preferably inmarine applications) should be employed for ship struc-tures. Most shipyards conduct training programs forwelding and inspection personnel.

5.2 Procedure Qualification. Procedure qualificationpractices for welding may not be defined in the contract



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for the vessel to be constructed. However, the contractfor a Navy or Coast Guard ship, for example, will proba-bly refer to NAVSEA S9074-AQ-G1B-010/048,Requirements for Welding and Brazing Procedure andPerformance Qualification. This document describes indetail the procedure and performance qualificationrequirements for vessel construction.

In the absence of specification requirements in thecontract, the Navy or Coast Guard will normally requestthat welding procedures be qualified in a manner similarto the requirements of either the ASME Boiler and Pres-sure Vessel Code, Section IX; the American Bureau ofShipping Rules; or AWS D1.2, Structural WeldingCode—Aluminum, or AWS B2.1, Specification for Weld-ing Procedure and Performance Qualification. Thesedocuments require that a welded test plate be preparedusing the basic joint design, material preparation, weld-ing process, procedures, equipment, plate thickness, andwelding position that will be used during construction ofthe vessel. The weld shall be postweld heat-treated, ifrequired by the design requirements of the vessel. Ten-sile or bend test specimens, or both, cut from the testweld need to meet the minimum requirements of thespecification. Minimum weldment strengths for marinealuminum alloys are given in Table 8.

Weld bend tests are commonly conducted in twotypes of jigs.16 One is the standard plunger-type guidedbend test. The other is the wrap-around guided bend jigshown in Figure 10. It is preferred for aluminum becauseit produces a more uniform bending across the weldmetal and heat-affected zone than does the plunger type.Table 10 describes bend test requirements specified byAWS D1.2 and B2.1 specifications for wrought alumi-num alloys. Cast aluminum alloys are not bend tested.AWS D1.2 uses a “nick-break” test, while AWS B2.1uses a macro-etch in lieu of the guided bend test forwelds involving castings.

Welding and testing of procedure plates are usuallywitnessed by the designated Navy or Coast Guardinspector, or the ABS surveyor. Details of the proce-dures, similar to that outlined in Section IX of the ASMEBoiler and Pressure Vessel Code, or NAVSEA S9074-AQ-G1B-010/048, Requirements for Welding and Braz-ing Procedure and Performance Qualification, are pre-sented to the surveillance agency. Upon approval by thatagency, the procedure may be used in fabrication of thevessel. The ranges of base metal thickness, alloy, weld-ing positions, and other conditions qualified by eachprocedure qualification are designated in the particularcode specification or document.

16. Refer to Rules for Building and Classing Aluminum Vessels,American Bureau of Shipping, or AWS B4.0, Standard Methodsfor Mechanical Testing of Welds, American Welding Society.

The U.S. Navy, U.S. Coast Guard, and AmericanBureau of Shipping normally require that copies of pro-cedure qualification test data and weld procedure specifi-cations be submitted for review and approval. It shouldbe recognized that, when this is required, productionwelding is not allowed to proceed prior to receiving thisapproval.

Note: Diameter A is selected to produce the required bend radiusin the specimen.

Figure 10—Wrap-AroundGuided Bend Test Jig

Table 10Guided Bend Test Diameters

for Common Aluminum Alloys

Base AlloysBend Specimen

ThicknessBend

Diameter

3003, 5052, 5454 3/8 in. (9.5 mm)or less

4t

5083, 5086, 5456 andAnnealed 6XXXSpecimens(1)

3/8 in. (9.5 mm)or less

6-2/3t

As-welded 6XXXSpecimens and all4043 welds

1/8 in. (3.2 mm)or less

16-1/2t

7005(2) 3/8 in. (9.5 mm)or less

8t

Notes:(1) 6XXX alloys are annealed before bending. Annealing practice:

Hold for 2–3 hrs at 775°F (410°C) and cool at 50°F (28°C) perhr to 500°F (260°C). Rate of cooling below 500°F (260°C) isunimportant.

(2) Bend testing of 7005 should be conducted within 2 weeks ofwelding.

MOVABLE ROLLER(ANY DIAMETER)

STATIONARYPIN

A

CLAMP

B = 1/2 A

WELD

SPECIMEN



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5.3 Typical Test Coupon. A typical set of weld testspecimens consists of two reduced-section tensile testspecimens and two each of root-bend and face-bend testspecimens. These are obtained from a groove-weld, buttjoint test plate of adequate size. Appropriate specimenlocations in the test plate are designated by the qualifica-tion document.

The tensile specimens should fracture at or above theminimum specified strength (see Table 8) or as otherwiserequired by the applicable code. The bend specimenshould bend over a designated radius with no cracksexceeding 1/8 in. (3.2 mm) in length on the convex side.

Additional tests may include visual, penetrant, radio-graphic inspection or macroscopic examination of weldcross sections.

5.4 Performance Qualification. Welder and weldingoperator performance qualification may be designated tobe in accordance with Section IX of the ASME Boilerand Pressure Vessel Code, NAVSEA S9074-AQ-G1B-010/048, Requirements for Welding and Brazing Proce-dure and Performance Qualification, Section 30 of theRules for Building and Classing Aluminum Vessels, pub-lished by the American Bureau of Shipping, AWS D1.2Structural Welding Code—Aluminum, or AWS B2.1,Specification for Welding Procedure and PerformanceQualification.

5.5 Record Keeping. Records of procedure and per-formance qualification tests for welding componentscovered by ABS, military, government agency, ASME,AWS, or similar specifications should be kept by thefabricator.

6. Welding Procedure and Techniques

6.1 General. The technology of fabricating welded alu-minum hulls is well developed and is similar, in manyrespects, to that established for other marine materials.This knowledge, combined with the good formability ofaluminum, enables fitters and welders to produce soundhulls exhibiting a high degree of craftsmanship.

6.2 Fitting, Aligning, and Assembling. After degreas-ing and heavy oxide removal from anticipated joint sur-faces, the next step in vessel fabrication is to assembleflat plates and subsections for welding of the butt joints.Plates are tack welded together, welded on one side, andthen turned for back chipping or gouging and welding onthe other side. Some shipyards make the tack welds andthe first weld on the same side; others weld the sideopposite to the tack welds first.

Joint edges that have been accurately measured andprepared on milling or planing machines, or by other pre-

cision cutting methods can be easily fit-up with a mini-mum of fixturing.

Fit-up requirements for welded aluminum construc-tion are generally more restrictive than those normallyemployed for welded steel construction. Root openingsshould be as small as possible, and accurately maintainedduring welding to ensure sound welds.

Procedures used in aligning component pieces aregenerally similar to those used for steel. Small aluminumparts can be hand-held in position while being tackwelded. Larger components can be aligned by the use ofwelded strong-backs or clips, or positioned by weldedtabs and come-alongs. Judicious use can be made ofshims and wedges.

Edges to be welded should be maintained in align-ment with a uniform root opening in accordance with thespecific welding procedure. When developing weldingprocedures, it is important to use small, uniform rootopenings to minimize distortion. Wherever practicable, atight-fitted butt joint should be used. When mechanizedwelding is used, very uniform alignment and root open-ing is necessary for optimum weld quality.

After assembling and welding, flat-plate stiffenersand attachments are fitted and tack welded to the plates.Tack welding or fixturing may be used to hold the platesor other joint members in alignment for welding. Tackwelds are used most frequently, although fixturing maybe used to advantage on subassemblies or on hulls ofsmall boats in large production runs. For complexshapes, tack welds are generally used.

All cold welding starts and oversize or unsound tackwelds should be chipped out or ground, or subsequentweld defects will occur at these places. Tack weldsshould be of sufficient size to hold the joint in alignmentand to resist both spring back of parts and thermalstresses during welding. Tack welds should have bothends ground for incorporation into the final weld.

Major subassemblies are erected on the shipways oron the platen in accordance with the erection schedule.Although some yards fabricate subassemblies to exactdimensions and no trimming is necessary when they arefitted to the hull, it is sometimes desirable to provideexcess base metal on one side of the master joint for fit-up, as shown in Figure 11. The plate can be trimmed,while in position in the ways, to mate with the adjoiningsection. Structural members, such as longitudinals,should extend beyond the edge of one plate for a distanceof at least 12 in. (300 mm) and remain unwelded for adistance of about 12 in. (300 mm) back from that edge.The structural sections on the adjacent plate ends about12 in. (300 mm) from the edge (see Figure 11). Thestructural sections can also be trimmed during fit-up.Another method used would leave the stiffeners cut back



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a minimum of 12 in. (300 mm) on both sides of the erec-tion butt joint.

The final closing joint of a series of subassembliesusually requires trimming. Sometimes the joint is over-lapped, and then cut and beveled for welding on the ves-sel. In other instances, the opening is surveyed, and thecutting for proper fit-up is done in the subassembly area.A build-up of tolerances and weld shrinkage may occurin ship construction that requires fitting a “margin” plate.The use of margin plates that are less than 8 in. (200 mm)wide should be avoided. The minimum width of marginplates will depend on the actual design and productioncondition, including plate thickness, frame spacing andlocation of welding.

As a general rule, a master butt joint should not fall ona transverse frame. The distance of a butt joint from aframe should not be less than the sum of (1) the distancefrom the web of the frame section to the edge of the out-standing flange, and (2) the width of the welding gunbeing used. Locating the joint at a reasonable distancefrom the flange permits the welder to make the weld witha minimum of difficulty. Adequate access to the weldalso makes repair welding easier, should it be needed.

6.3 Weld Backing. Backing is frequently used to supportthe molten weld metal at the root of a weld to preventexcessive melt-through. Backing may be either tempo-rary or permanent and, in any case, it should be cleanedprior to welding.

Temporary backing is generally used for machine orautomatic welding of thin sections at relatively highspeeds. It can be made of anodized aluminum, ceramic,copper or austenitic stainless steel, and may be water-cooled. Carbon steel backing may be used when specialattention is paid to prevent and remove rust. If non-anodized aluminum is used temporarily, it can be tackwelded in place and cut off after welding. Backing ofother metals including hard coat anodized aluminummay be clamped in place. Copper is recommended forbacking only when the arc does not impinge on itbecause it may contaminate the weld and result in subse-quent corrosion in service.

Temporary backing may be flat, in which case theweld should be back-gouged and welded on the secondside. The backing may also be grooved to provide forroot reinforcement when the weld is to be made from oneside only.

Special fiberglass and ceramic backing tapes arecommercially available. They are particularly usefuland cost effective on nonuniform curved surfaces aswell as the groove weld joints (A), (E), and (F) shown inFigure 12.

Permanent backing forms part of the joint and shouldbe made of the same alloy as the base metal. Where thepossibility of crevice corrosion exists, permanent back-ing should be joined to the base metal with continuousfillet welds to prevent moisture entrapment between the

Figure 11—Design of Master Weld Joints to Provide for Fit-up in Position

CUT TO FIT

EXTRA STOCKPANEL A PANEL B

12 in.(305 mm)

12 in.(305 mm)

12 in.(305 mm)



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two. Disadvantages of permanent backing are increasedweight and cost of the structures.

6.4 Butt Joints. Several types of butt joints are used inwelded aluminum ship construction. Typical jointdesigns are shown in Figure 12. Joint designs (C), (D),and (E) should be back-chipped to sound metal beforewelding the second side.

Typical procedures for gas metal arc welding of buttjoints are shown in Table 11, and for gas tungsten arcwelding in Table 12. Subassemblies GMA machine-

welded in the flat position, square-groove welds arecommonly used in thicknesses of 3/16 in.–3/8 in.(4.8 mm–9.5 mm). For 3/8 in. (9.5 mm), a 1/8 in.–1/4 in.(3.2 mm–6.4 mm) bevel is used on each side of the jointto reduce the weld reinforcement.

For semiautomatic GMA welded butt joints, a singleV-groove joint with a wide root face is usually preferred.The V-groove is located on the inside of the vessel sothat initial welding is done on the inside. Back gougingof the joint can be done on the outside without inter-ference from frames, stiffeners and other obstructions.

Figure 12—Typical Joint Designs for Arc Welding of Aluminum

TEMPORARYBACKING

TEMPORARYBACKING

2t

r

t/4

t

t

60˚–90˚

r

60˚–90˚

60˚

60˚

r

r

0.19 in.(4.8 mm)

or 110˚

r

r

r

0.06–0.09 in.(1.5–2.3 mm)

0.06–0.09 in.(1.5–2.3 mm)

0.06 in.(1.5 mm)

0.06–0.09 in.(1.5–2.3 mm)

0.5 in.(13 mm)

t/4

t

1.5 in.(38 mm)

t [MAX. 0.38 in.(9.7 mm)]

PERMANENTBACKINGSTRIP

PERMANENTBACKINGSTRIP

tt

(A) (B)

(C) (D)

(E) (F)

(G) (H)

1.5 in.(38 mm)

t [MAX. 0.38 in.(9.7 mm)]



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AWS D3.7:2004

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The second weld is then made on the outside of thevessel.

Automatic or machine welding is preferred to semiau-tomatic welding because it generally reduces the numberof weld passes required and, thus, the distortion. Typicalaluminum pipe welding procedures for manual GTAWare given in Tables 13–15, and further information about“extended land”bevel joints can be obtained by referringto AWS D10.7, Recommended Practices for GasShielded Arc Welding of Aluminum and Aluminum Alloy

Pipe, Table 16 gives typical procedures for semi-automatic GMA welding of pipe in the horizontal rolledposition. Approximate filler metal requirements for typi-cal groove welds in aluminum are given in Annex B.

6.5 Fillet Welds. Usually, the greatest footage of weld inship construction consists of fillet welds that are nor-mally employed to attach stiffeners and beams to hull,deck, and bulkhead plates. Fillet welds also are used forattaching bulkheads and for welding all attachments,

Table 11Typical Procedures for Gas Metal Arc Welding of Groove Welds

in Aluminum Alloys with Argon Shielding (U.S. Customary Units)

SectionThickness

in.Welding

Position(1)Joint

Geometry(2)

Root (r)Opening

in.

No. ofWeldPasses

ElectrodeDiameter

in.

WeldingCurrent(3)

A

ArcVoltage(4)

V

ArgonFlowft3/hr

TravelSpeedin./min

0.062 FF

AG

00–0.094

11

0.0300.030

70–11070–110

15–2015–20

2525

25–4525–45

0.094 FF, V, H, O

AG

00–0.125

11

0.030–0.0470.030

90–150110–130

18–2218–23

3030

25–4523–30

0.125 F, V, HF, V, H, O

AG

0–0.0940–0.188

11

0.030–0.0470.030–0.047

120–150110–135

20–2419–23

3030

24–3018–28

0.188

F, V, HF, V, H

OF, VH, O

BFFHH

0–0.0620–0.0620–0.062

0.094–0.1880–0.188

1F, 1R1

2F23

0.030–0.0470.0470.047

0.047–0.0620.047

130–175140–180140–175140–185130–175

22–2623–2723–2723–2723–27

3535603560

24–3024–3024–3024–3025–35

0.250

FF

V, HO

F, VO, H

C–60°FFFHH

0–0.0940–0.0940–0.0940–0.094

0.125–0.2500–0.250

1F, 1R2

3F, 1R3F, 1R

2–34–6

0.047–0.0620.047–0.062

0.0470.047–0.0620.047–0.0620.047–0.062

175–200185–225165–190180–200175–225170–200

24–2824–2925–2925–2925–2925–29

404045604060

24–3024–3025–3525–3524–3025–40

0.375

FF

V, HO

F, VO, H

C–90°FFFHH

0–0.0940–0.0940–0.0940–0.094

0.250–0.3750–0.375

1F, 1R2F, 1R3F, 1R5F, 1R

48–10

0.0620.0620.0620.0620.0620.062

225–290210–275190–220200–250210–290190–260

26–2926–2926–2926–2926–2926–29

505055805080

20–3024–3024–3025–4024–3025–40

0.750

FF

V, H, OF

V, H, O

C–60°FFEE

0–0.0940–0.1250–0.0620–0.0620–0.062

3F, 1R4F, 1R8F, 1R3F, 3R6F, 6R

0.062–0.0940.0940.0620.0620.062

240–400325–375240–300270–330230–280

26–3126–3126–3026–3026–30

6060806080

14–2016–2024–3016–2416–24

General Note: 5XXX filler alloys will use upper portion of range for current and lower portion of voltage range. 4XXX filler alloys employ the lowerportion of the current range, and the upper portion of the voltage range.

Notes:(1) F—flat; V—vertical; H—horizontal; O—overhead.(2) Refer to Figure 12.(3) Values for constant current (no pulsing).(4) Voltage measured between contact tube and work.



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AWS D3.7:2004

30

such as bitts, chocks, handrails, ladders, padeyes, andother fittings, during construction.

Two important factors to consider are the size of thefillet welds17 and whether the welds are to be intermittent

17. The size of a fillet weld with equal legs is the leg length ofthe largest isosceles right triangle that can be inscribed withinthe weld cross section. With unequal legs, the weld size is theleg length of the largest right triangle that can be inscribed inthe weld cross section.

or continuous. Typical fillet weld procedures for gasmetal arc welding of aluminum are given in Table 17,and for gas tungsten arc welding in Table 18.

Where intermittent welding is employed, weld cratersat ends of beads must be avoided by reversing the direc-tion of welding for a short distance at those points. Thisis done to avoid crater cracks, which may lead to failureof the weld. However, it is always recommended that thenumber of arc starts and stops be kept to a minimum forthe technique used.

Table 11Typical Procedures for Gas Metal Arc Welding of Groove Welds

in Aluminum Alloys with Argon Shielding (Metric Units)

SectionThickness

mmWelding

Position(1)Joint

Geometry(2)

Root (r)Opening

mm

No. ofWeldPasses

ElectrodeDiameter

mm

WeldingCurrent(3)

A

ArcVoltage(4)

V

ArgonFlowL/min

TravelSpeedmm/s

1.6 FF

AG

02.4

11

0.80.8

70–11070–110

15–2015–20

1212

10.6–19.010.6–19.0

2.4 FF, V, H, O

AG

03.2

11

0.8–1.20.8

90–150110–130

18–2218–23

1414

10.6–19.09.7–12.7

3.2 F, V, HF, V, H, O

AG

.00–2.44.8

11

0.8–1.20.8–1.2

120–150110–135

20–2419–23

1414

10.2–12.77.6–11.8

4.8

F, V, HF, V, H

OF, VH, O

BFFHH

.00–1.6

.00–1.6

.00–1.62.4–4.8

4.8

1F, 1R1

2F23

0.8–1.21.21.2

1.2–1.61.2

130–175140–180140–175140–185130–175

22–2623–2723–2723–2723–27

1717281728

10.2–12.710.2–12.710.2–12.710.2–12.710.6–14.8

6.4

FF

V, HO

F, VO, H

C–60°FFFHH

.00–2.4

.00–2.4

.00–2.4

.00–2.43.2–6.4

6.4

1F, 1R2

3F, 1R3F, 1R

2–34–6

1.2–1.61.2–1.6

1.21.2–1.61.2–1.61.2–1.6

175–200185–225165–190180–200175–225170–200

24–2824–2925–2925–2925–2925–29

191921281928

10.2–12.710.2–12.710.6–14.810.6–14.810.2–12.710.6–16.9

9.6

FF

V, HO

F, VO, H

C–90°FFFHH

.00–2.4

.00–2.4

.00–2.4

.00–2.46.4–9.6

9.6

1F, 1R2F 1R3F, 1R5F, 1R

48–10

1.61.61.61.61.61.6

225–290210–275190–220200–250210–290190–260

26–2926–2926–2926–2926–2926–29

242426382438

8.5–12.710.2–14.810.2–12.710.6–16.910.2–12.710.6–16.9

19

FF

V, H, OF

V, H, O

C–60°FFEE

.00–2.4

.00–3.2

.00–1.6

.00–1.6

.00–1.6

3F, 1R4F, 1R8F, 1R3F, 3R6F, 6R

1.6–2.42.41.61.61.6

240–400325–375240–300270–330230–280

26–3126–3126–3026–3026–30

2828382838

5.9–8.56.8–8.5

10.2–12.76.8–10.26.8–10.2

General Note: 5XXX filler alloys will use upper portion of range for current and lower portion of voltage range. 4XXX filler alloys employ the lowerportion of the current range, and the upper portion of the voltage range.

Notes:(1) F—flat; V—vertical; H—horizontal; O—overhead.(2) Refer to Figure 12.(3) Values for constant current (no pulsing).(4)Voltage measured between contact tube and work.



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AWS D3.7:2004

31

Consideration should be given to the economy ofusing continuous, double fillet welds rather than intermit-tent fillet welds. All factors should be weighed, includingthe time required to mark off an intermittent weld pattern,the actual versus theoretical length of weld, the actualversus theoretical size of the fillet weld, the normallylarger fillet sizes at the ends of each intermittent weld asa result of starting and stopping and any increased qualityrequirements. However, double continuous fillet weldsmay cause greater distortion, particularly in the thinnerplates. Filler metal requirements for typical fillet welds inaluminum are given in Annex B, Figure B11.

Whether economy can be obtained is predicated, to acertain extent, on the specified fillet weld sizes. Atpresent, there is some controversy regarding the properfillet weld size to use. The U.S. Navy, in some cases,

requires fillet weld sizes beyond normal commercialstandards. For commercial work, however, the generalrule is to use a continuous full fillet weld, the size ofwhich is equal to the thickness of the thinner memberjoined. Sizes of double fillet welds that fully connectmembers of a 5000-series marine alloy at right angles aregiven in Figure 13. Similar data for as-welded 6061-T6alloy are given in Figure 14. The data are based on thefollowing conditions:

(1) Typical base metal tensile and shear strengths areused.

(2) Weld shear values used are 80% of typical.(3) Welded connections are intended to be strong

enough to force failure to occur in the web rather than inthe welds, or in the base metal by shear parallel with thefusion lines of the welds.

Table 12Typical Procedures for Manual Gas Tungsten Arc Welding of Butt Joints

in Aluminum with AC and Argon Shielding (U.S. Customary Units)

SectionThickness

in.Welding

Position(1)Joint

Geometry(2)

Root (r)Opening

in.

No. ofWeldPasses

Filler RodDiameter

in.

EW-PElectrodeDiameter

in.

WeldingCurrent

A

CupDiameter

in.

ArgonFlowft3/hr

TravelSpeedin./min

0.062 F, V, HO

BB

0–0.0620–0.062

11

0.062–0.0940.094

0.062–0.0940.062

60–8060–75

0.380.38

2025

8–108–10

0.094F

V, HO

BBB

0–0.0940–0.0940–0.094

111

0.1250.094–0.1250.094–0.125

0.094–0.1250.094

0.094–0.125

95–11585–11090–110

0.380.380.38

202025

8–108–108–10

0.125F

V, HO

BBB

0–0.1250–0.0940–0.094

1–21–21–2

0.125–0.1560.125

0.125–0.156

0.1250.1250.125

125–150110–140115–140

0.440.440.44

202025

10–1210–1210–12

0.188

FVHO

D–60°D–60°D–90°D–110°

0–0.1250–0.0940–0.0940–0.094

2222

0.156–0.1880.1560.1560.156

0.156–0.1880.1560.1560.156

170–190160–175155–170165–180

0.44–0.50.440.440.44

25252530

10–1210–1210–1210–12

0.250

FVHO

D–60°D–60°D–90°D–110°

0–0.1250–0.0940–0.0940–0.094

22

2–32

0.1880.188

0.156–0.1880.188

0.188–0.250.188

0.156–0.1880.188

220–275200–240190–225210–250

0.50.50.50.5

30303035

8–108–108–108–10

(3)0.375(3)

FFV

V, H, OHO

D–60°E

D–60°E

D–90°D–110°

0–0.1250–0.0940–0.0940–0.0940–0.0940–0.094

223233

0.188–0.250.188–0.25

0.1880.1880.1880.188

0.250.25

0.188–0.250.188–0.250.188–0.250.188–0.25

315–375340–380260–300240–300240–300260–300

0.630.630.630.630.630.63

353535353540

8–108–108–108–108–108–10

Notes:(1) F—flat; V—vertical; H—horizontal; O—overhead.(2) See Figure 12. Angle dimension is the appropriate groove angle.(3) May be preheated.



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AWS D3.7:2004

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Some ship structure designs call for a larger size offillet weld for a distance of 18 in.–24 in. (460 mm–610 mm) back from the ends of stiffeners. This is oftenaccomplished with a second weld pass in these areas.

6.6 Plug and Slot Welds. Plug and slot gas metal arcwelds are primarily used for attaching plates to decks, asshown in Figure 15. Similar applications could be fordoubler plates around sea chests, hatch corner reinforce-ments, and doubler plates on machine foundations.

Plug and slot welds can pose a problem with gasmetal arc welding. The hole or slot should be largeenough to properly maneuver the welding gun for com-plete fusion of the fillet weld placed in the corner of thejoint if allowed by the owner’s specification and afterinspection.

Wherever possible, slot welds are recommended overplug welds. The slots should be at least 4 in. (100 mm)long and of sufficient width to permit the welder toobtain good fusion when making the fillet weld passaround the periphery of the slot.

It is not always necessary to fill the entire slot forstrength. Where a smooth surface is desired or requiredto avoid retention of moisture and dirt, the welded slotcan be filled flush with a suitable mastic filler if allowedby the owner’s specification and after inspection.

6.7 Inserts and Doublers. Large openings in the hull ordeck, such as hatches, scuttles, elevator shafts and doors,and also load-bearing fittings generally require reinforce-ment in the form of thicker plate, either as an insert or asa doubler. Generous radii, (R), are recommended for

Table 12Typical Procedures for Manual Gas Tungsten Arc Welding

of Butt Joints in Aluminum with AC and Argon Shielding (Metric Units)

SectionThickness

mmWelding

Position(1)Joint

Geometry(2)

Root (r)Opening

mm

No. ofWeldPasses

Filler RodDiameter

mm

EW-PElectrodeDiameter

mm

WeldingCurrent

A

CupDiameter

mm

ArgonFlowL/min

TravelSpeedmm/s

1.6 F, V, HO

BB

0–1.60–1.6

11

1.6–2.42.4

1.6, 2.41.6

60–8060–75

9.69.6

912

3.4–4.23.4–4.2

2.4F

V, HO

BBB

0–2.40–2.40–2.4

111

3.22.4, 3.22.4–3.2

2.4, 3.22.4

2.4, 3.2

95–11585–11090–110

9.69.69.6

99

12

3.4–4.23.4–4.23.4–4.2

3.2F

V, HO

BBB

0–3.20–2.40–2.4

1–21–21–2

3.2–4.03.2

3.2–4.0

3.23.23.2

125–150110–140115–140

11.211.211.2

99

12

4.2–5.14.2–5.14.2–5.1

4.8

FVHO

D–60°D–60°D–90°D–110°

0–3.20–2.40–2.40–2.4

2222

4.0–484.04.04.0

4.0–4.84.04.04.0

170–190160–175155–170165–180

11.18, 12.711.211.211.2

12121214

4.2–5.14.2–5.14.2–5.14.2–5.1

6.4

FVHO

D–60°D–60°D–90°D–110°

0–3.20–2.40–2.40–2.4

22

2–32

4.84.8

4.0–4.84.8

4.8–6.44.8

4.0–4.84.8

220–275200–240190–225210–250

12.712.712.712.7

14141417

3.4–4.23.4–4.23.4–4.23.4–4.2

(3)9.6(3)

FFV

V, H, OHO

D–60°E

D–60°E

D–90°D–110°

0–3.20–2.40–2.40–2.40–2.40–2.4

223233

4.8–6.44.8–6.4

4.84.84.84.8

6.46.4

4.8–6.44.8–6.44.8– 6.44.8–6.4

315–375340–380260–300240–300240–300260–300

16.016.016.016.016.016.0

171717171719

3.4–4.23.4–4.23.4–4.23.4–4.23.4–4.23.4–4.2

Notes:(1) F—flat; V—vertical; H—horizontal; O—overhead.(2) See Figure 12. Angle dimension is the appropriate groove angle.(3) May be preheated.



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AWS D3.7:2004

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inserts and doublers, where applicable, as shown inFigure 16. A V-groove weld should be used to join thedeck to the insert. The insert plate should be tapered tothe thickness of the deck plate at the joint to avoid stressconcentration at the weld. The use of insert plates is pre-ferred to doublers because the stress concentrationsinherent in fillet welds are avoided. The peripheralgroove weld should have complete joint penetration touniformily distribute the stress at the transition in platethickness.

Doubler plates are normally attached by slot welding.When the doubler has been properly prepared and thefaying surface cleaned, it is tack welded in position.Welding progresses, as shown in Figure 15, by first mak-ing the slot welds, then any groove welds in the doublerplates, and finally the fillet weld around the edges of the

doubled section. The primary purpose of continuouslywelding the edges to the plate is to eliminate the possibil-ity of crevice corrosion between the doubler and the deckplate.

6.8 Snipes and Scallops. Where snipe-type cuts are per-mitted in the design, they should be large enough toallow clearance for the welding gun to properly termi-nate the weld, as shown in Figure 17(A). Because of thesize of the welding gun nozzle for aluminum, the 3/4 in.(19 mm) snipes common in steel construction are toosmall for aluminum fabrication. Wherever possible,snipes of 1-1/2 in. (38 mm) or larger should be used,depending upon the depth of the member, as shown inFigure 17(B).

Table 13Typical Procedures for Gas Tungsten Arc Welding

Aluminum Pipe in the Horizontal Rolled Position (U.S. Customary Units)

NominalPipe Size

WallThickness

in.

TungstenElectrodeDiameter

in.

Gas NozzleDiameter

in.

FillerRod

Diameterin.

WeldingCurrenta.c. A

ArgonFlowft3/h

BackingRing (T)

Thicknessin.

No. ofPasses(2)

11-1/41-1/2

22-1/2

33-1/2

4568

1012

0.1330.1400.1450.1540.2030.2160.2260.2370.2580.2800.3220.3650.406

1/81/81/81/81/81/81/83/163/163/163/163/163/16

7/167/167/167/167/161/21/21/21/21/21/21/21/2

3/32–1/81/81/81/8

1/8–5/321/8–5/321/8–5/321/8–5/321/8–3/16

5/32–3/165/32–3/165/32–3/165/32–3/16

100–115110–135115–140125–150140–180150–190160–200170–210190–230210–250220–260240–280250–290

25–4025–4025–4025–4030–4030–4030–4030–4030–4035–4035–4035–4035–40

0.0720.0720.0720.0930.0930.0930.0930.1250.1250.1870.1870.1870.187

1–21–21–21–2222222

2–32–32–3

Notes:(1) R = 0 for no backing ring or removable backing ring, 1/4 in. max for integral backing ring.(2) Root opening = 0. More passes are required when R = 1/4 in.

T

75˚

BACKINGRING

R(1)

1/16

1-1/2



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AWS D3.7:2004

34

6.9 Oil and Water Stops. Liquid-tight welded alumi-num bulkheads, along with water, and oil tanks or com-partments, require the use of welded stops. These consistof complete joint penetration welds, about 3 in. (76 mm)long, at intersecting members, as shown in Figure 18.

The procedure for positioning and welding of stops inaluminum is similar to that for steel. Their principal pur-pose is to isolate any leaks in welds that are disclosedduring hydrostatic testing of watertight compartments,thus facilitating leak location and repair. It also does notallow the liquid to run the length of a fillet weld orlapped member.

The conventional steel practice of building up ratherlarge weld pads in corners and other locations to avoidleaks has not proved generally effective on aluminumfabrication.

The recommended repair procedure is to chip orgrind out the aluminum weld metal in the leak area,clean and dry the surfaces thoroughly, and reweld. Analternate method is to clean and dry the surfaces, removethe oxide coating, and then remelt the weld metal, withAC or DCEN power using the GTAW method. How-ever, the exact nature of the discontinuity is the keyfactor in selecting the repair procedure and weldingmethod.

6.10 Coamings. Weld joint designs for protective andreinforcement coamings in aluminum hulls and decks varywith specific design details and anticipated service re-quirements. The designs should be developed as required.A common half-round coaming is frequently attached tothe top of the shear strake with a single V-groove weld on


Aluminum Pipe in the Horizontal Rolled Position (Metric Units)

NominalPipe Size

WallThickness

mm


mm

Gas NozzleDiameter

mm

FillerRod

Diametermm


ArgonFlowL/min

BackingRing (T)

Thicknessmm

No. ofPasses(2)

25304050607590

100125150200250300

3.383.553.683.915.165.495.746.026.557.118.189.27

10.31

3.23.23.23.23.23.23.24.8 4.84.84.84.84.8

11.111.111.111.111.112.712.712.712.712.712.712.712.7

2.4–3.23.23.23.2

3.2–4.03.2–4.03.2–4.03.2–4.84.0–4.84.0–4.84.0–4.84.0–4.84.0–4.8

100–115110–135115–140125–150140–180150–190160–200170–210190–230210–250220–260240–280250–290

12–1912–1912–1912–1914–1914–1914–1914–1914–1917–1917–1917–1917–19

1.81.81.82.42.42.42.43.23.24.84.84.84.8

1–21–21–21–2222222

2–32–32–3

Notes:(1) R = 0 for no backing ring or removable backing ring, 6.4 mm max for integral backing ring.(2) Root opening = 0. More passes are required when R = 6.4 mm.

T

75˚

BACKINGRING

R(1)

1.6

38.1



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AWS D3.7:2004

35

top and a fillet weld on the underside. The groove weld isusually ground flush to the contour of the coaming piece.

6.11 Avoiding Joint Corrosion. Properly welded jointsmade in marine aluminum with the correct filler metalare highly corrosion resistant. The aluminum alloys usedfor marine construction form a tenacious oxide film ontheir surface that protects the material against the corro-sive environment. It is only in the event that this film isconstantly removed or disturbed, that progressive oxida-tion can take place. For this reason, local corrosionshould be expected in regions subject to extreme scrub-bing action, such as that caused by turbulent flow adja-

cent to projections from underwater hulls, over ruddersand related surfaces. These surfaces should be protectedby coatings and these coatings maintained to prevent pit-ting.

Galvanic corrosion is probably the greatest source ofcorrosion damage to aluminum structures and should beconstantly guarded against by using care in constructionand maintenance. The same priority given by thedesigner to avoiding sharp interior corners, crevices, andother voids during the design and location of structuralcomponents should also be extended to welded joints andweld surfaces. Although galvanic corrosion normallyoccurs when moisture is in contact with two different


Aluminum Pipe in the Horizontal Fixed Position (U.S. Customary Units)

NominalPipe Size

WallThickness

in.


in.

Gas NozzleDiameter

in.

FillerRod

Diameterin.


ArgonFlow(3)

ft3/h

BackingRing (T)

Thicknessin.

No. ofPasses(4)

11-1/41-1/2

22-1/2

33-1/2

4568

1012

0.1330.1400.1450.1540.2030.2160.2260.2370.2580.2800.3220.3650.406

1/81/81/81/81/81/81/83/163/163/163/163/163/16

1/21/21/21/21/21/21/21/21/21/21/21/21/2

3/321/81/81/8

1/8–5/321/8–5/321/8–5/321/8–3/16

5/32–3/165/32–3/165/32–3/165/32–3/165/32–3/16

90–110100–120110–130120–140130–150145–165150–170160–180180–190195–205210–220230–240245–255

30–8030–8030–8030–8030–8030–8030–8035–8035–8050–8050–8050–8050–80

0.0720.0720.0720.0930.0930.0930.0930.1250.1250.1870.1870.1870.187

1–21–21–21–2222222

2–32–32–3

Notes:(1) 110° angle required on bottom 90° of pipe; can be applied to full 360°.(2) R = 0 for no backing ring or removable backing ring, 1/4 in. max for integral backing ring.(3) The higher flow rate is required for the overhead quadrant.(4) Greater number of passes are required for bottom 90° of weld, and when R ≤ 1/4 in. with integral backing.

T

75˚OR

110˚(1)

BACKINGRING

R(2)

1/16

1-1/2



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AWS D3.7:2004

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metals to form an electrical circuit, it also can take placewhen members of the same alloy are involved, if a moistcontaminant includes metallic salts. Good drainageshould always be provided.

Smooth, rounded weld beads that are free of incom-plete fusion, undercut, overlap and cracks are necessaryto avoid crevices that may hold dirt and moisture.Uneven, heavily rippled or dimpled weld beads shouldbe machined flush, repaired or replaced. Avoidance orcorrection of such potential trouble spots helps eliminatethe possibility of crevice entrapment and concentration-cell corrosion.

Wherever weld beads are intermittent and exposed tomoisture, frequent or continual entrapment of wateroccurs. If drainage is not adequate, corrosion is likely tobe caused by air- or sea-borne salts dissolved in thewater. This corrosion is accelerated because the wet filmexcludes oxygen from the aluminum surface and pre-vents formation of the protective aluminum oxide. Allweld surfaces and crevices should be protected againstmoisture entrapment with a suitable joint compound orpaint coating, particularly when they are located in thebilge or other confined and generally contaminatedareas. In general, butt joints are preferred to lap joints toavoid the possibility of crevice corrosion in the lapped


Aluminum Pipe in the Horizontal Fixed Position (Metric Units)

NominalPipe Size

WallThickness

mm


mm

Gas NozzleDiameter

mm

FillerRod

Diametermm


ArgonFlow(3)

L/min

BackingRing (T)

Thicknessmm

No. ofPasses(4)

25304050607590

100125150200250300

3.383.553.683.915.165.495.746.026.557.118.189.27

10.31

3.23.23.23.23.23.23.24.84.84.84.84.84.8

12.712.712.712.712.712.712.712.712.712.712.712.712.7

2.43.23.23.2

3.2–4.03.2–4.03.2–4.03.2–4.84.0–4.84.0–4.84.0–4.84.0–4.84.0–4.8

90–110100–120110–130120–140130–150145–165150–170160–180180–190195–205210–220230–240245–255

14–3814–3814–3814–3814–3814–3814–3817–3817–3824–3824–3824–3824–38

1.81.81.82.42.42.42.43.23.24.84.84.84.8

1–21–21–21–2222222

2–32–32–3

Notes:(1) 110° angle required on bottom 90° of pipe; can be applied to full 360°.(2) R = 0 for no backing ring or removable backing ring, 6.4 mm max for integral backing ring.(3) The higher flow rate is required for the overhead quadrant.(4) Greater number of passes are required for bottom 90° of weld, and when R ≤ 6.4 mm with integral backing.

T

75˚OR

110˚(1)

BACKINGRING

R(2)

1.6

38.1



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AWS D3.7:2004

37

area and continuous fillet welds in lieu of intermittentfillet welds.

6.12 Strongbacks. Aluminum strongbacks of variousdesigns are used to hold large plates, shapes or heavyassemblies, so that the joints remain in alignment duringwelding. Typical designs are shown in Figure 19. Astrongback system employing weld studs is also veryeffective for use during assembly. Design and placementof strongbacks should be selected to assure adequateallowance for expansion and contraction of the work dur-ing production welding. Excessive restraint of transverseweld shrinkage is generally avoided by using an arrange-ment similar to those shown in Figures 19(A), 19(B),19(E), 19(F), and 19(G).

Strongbacks are particularly effective in maintaininga flat, smooth surface by preventing vertical or angulardistortion at groove welds in heavy plate. Sometimes, it

is adequate to tack weld one side of the strongback only;the pressure alone exerted on the other plate being suffi-cient. T-joints can be held in alignment with temporarybraces, as shown in Figure 19(D). Similar holdingdevices are clips, wedges, and saddles that are used tohold stiffeners to deck sections.

The strongbacks in Figures 19 (E–H) are attached bythe stud welding process. Stud welds are machine con-trolled and have uniform heat input over a small area.These strongback assemblies are easily removed andreusable. Threaded studs or short headed studs up to1/2 in. diameter can be used. The threads on the stud orstrongback permit complete control of the plate align-ment. Figure 19(H) shows a jacking screw used to drawassemblies into position.

Although steel strongbacks are sometimes knockedoff with a hammer, this practice is not recommended foraluminum. Aluminum strongbacks, including studs,

Table 15Gas Tungsten Arc Welding Aluminum Pipe—Alternating Current in All Fixed Positions

Nominal Pipe Size Wall Thickness Filler Rod Diameter Current ac Argon Flow F

in. mm in. mm in. mm amp cfh l/m in. mm

011-1/41-1/2

022-1/2

033-1/2

040506081012

25304050607590

100125150200250300

0.1330.1400.1450.1540.2030.2160.2260.2370.2580.2800.3220.3650.406

3.383.553.683.915.165.495.746.026.557.118.189.27

10.31

3/323/323/323/321/81/81/8

1/8–5/321/8–5/321/8–5/32

5/32–3/165/32–3/165/32–3/16

2.42.42.42.43.23.23.2

3.2–4.03.2–4.03.2–4.04.0–4.84.0–4.84.0–4.8

80–11080–11080–12080–13080–140

135–155135–160135–170135–190135–205135–220135–240135–255

30–8030–8030–8030–8030–8030–8030–8035–8035–8050–8050–8050–8050–80

14–3814–3814–3814–3814–3814–3814–3817–3817–3824–3824–3824–3824–38

1/161/161/161/161/163/323/323/323/323/323/323/323/32

1.61.61.61.61.62.42.42.42.42.42.42.42.4

General Notes:• Tungsten electrode diameter is 1/8 in. (3.2 mm) for 1 in.–3-1/2 in. (25 mm–89 mm) pipe size and 3/16 in. (4.8 mm) for 4 in.–12 in. (102 mm–305 mm)

pipe size.• Gas nozzle orifice diameter is 1/2 in. (12.7 mm).• Number of passes is 3 to 6 for 1 in.–12 in. (25 mm–305 mm) pipe size.• Low range of current is based upon first weld pass through F thickness.

60˚

3/16 in. (4.8 mm) F

EDGE PREPARATION



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AWS D3.7:2004

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should be removed by chipping or other cutting to avoidbase metal scarring, which would require repair.

6.13 Clamping. Small clamps, clips, weights, shims, andmechanical, or pneumatic hold-down fixtures, ranging insize from hand-held to crane-manipulated, are employedto hold parts in alignment for welding. Piping and rail-ings of all types usually are held for tack welding bystandard pipe-alignment clamps.

6.14 Tack Weld Placement and Size. Placement ofaluminum tack welds is similar to the practices used forsteel ship structures. Tack welding is done by theGMAW or GTAW process. GTAW may be used for tackwelding thin sections, and GMAW for thick sections. Aqualified production tack welder should make the tackwelds.

The tack welds should be of sufficient length andsoundness, including tapering the starts and stops, so thatthey can remain as part of the production weld. Nor-mally, tack welds are 2 in.–3 in. (50 mm–75 mm) longand spaced 4 in.–6 in. (100 mm–150 mm) apart forsections 3/8 in. (9.5 mm) thick and under, and 3 in.–6 in.

(75 mm–150 mm) long, spaced 6 in.–12 in. (150 mm–300 mm) apart for thicker sections. However, the numberof tack welds used should be the minimum required tomaintain joint alignment. Intersecting joints should betack welded within 12 in.–15 in. (300 mm–375 mm) oftheir intersection.

For both fillet and groove welds, it is important tokeep tack weld beads as small as possible, consistentwith the required tack weld strength. This permits pro-duction of sound welds and smooth beads by machineand automatic welding without chipping out the tackwelds as welding progresses along the joint.

Manual welding of tack welded joints may be accom-plished in a similar manner. Tapering by grinding etc. orchipping out both ends of tack welds prior to welding isrecommended. Tack welds that are cracked, or are other-wise of poor quality, should always be removed orrepaired prior to making the weld.

6.15 Residual Welding Stresses and Distortion. Theheat of welding causes expansion and contraction of thebase metal and some shrinkage at the joint where the

Table 16Typical Procedures for Gas Metal Arc Welding

Aluminum Pipe in the Horizontal Rolled Position (U.S. Customary Units)

NominalPipe Size

Wall Thicknessin.

ElectrodeDiameter

in.

Approximate Welding Current,

dcep, AmpArgon Flow

ft3/hNumber

of Passes(2)

4568

1012

0.2370.2580.2800.3220.3650.406

3/643/643/641/161/161/16

200215220225225250

454545505050

222333

Notes:(1) Root opening = O for no backing or removable backing ring, and 1/4 in. for any permanent backing.(2) For root opening = O. More passes are required when the root opening = 1/4 in.

1-1/4–1-1/2

1/16

75˚

5/32–3/16

0–1/4 MAX(1)

BACKINGRING



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AWS D3.7:2004

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metal has melted and resolidified. The thermal expansioncoefficient of aluminum is about twice that of steel, witha melting point of about half that of steel, and the thermalconductivity is greater. The total amount of thermalexpansion varies inversely with the speed of welding. Arule of thumb is to apply or design the welding fixturesso that plate alignment will accommodate twice thedimensional change normally expected for welding asimilar steel component.

Some shipyards insist that stiffeners be welded todecks and bulkheads in the flat-assembly-bay area usinga backstep welding sequence outward from the center ofeach stiffener, as described later. Where production war-rants the investment, ship builders employ multiple,machine-mounted welding heads to weld simultaneouslyall stiffeners to a panel from one end to the other.

Welding of stiffeners to panels causes an overallshrinkage of the center portion of the panel. This fre-quently causes the periphery of the panel to warp intolarge waves, “called oil canning,” which when the thirdweld is made in proper sequence, the plates on either sideare still relatively free to draw together. It is essential for

assemblies containing but joints that run from side toside (of the boat or ship) and weld (but) seams, that eachbutt weld is completed up to the seam before the longitu-dinal seam is welded. However, attempts to clamp theouter edges to stiffeners are generally unsuccessful,because the warps instantly appear when the clamps arereleased. However, two adjacent subassembly panelssimilarly welded will have approximately the sameamount of shrinkage within the panel. When these twosections are fitted and welded, the weld shrinkage of thejoint compensates to some extent for the excess length atthe edges.

The cost of correcting distortion can be significant.Marine aluminum does respond to flame heating withsubsequent water quench shrinking, but it could be usedon heavy sections with controlled procedures. Thin sec-tions should not be flame straightened. Some acceptableprocedures used to remove unwanted distortion in alumi-num assemblies include slotting and rewelding, weld-bead overlay, and the welding of additional stiffeners.Such welding techniques used for shrinking metal arequite expensive. Additional stiffeners, that are employed

Table 16Typical Procedures for Gas Metal Arc Welding

Aluminum Pipe in the Horizontal Rolled Position (Metric Units)

NominalPipe Size

Wall Thicknessmm

ElectrodeDiameter

mm

ApproximateWelding Current,

dcep, AmpArgon Flow

L/minNumber

of Passes(2)

102125150200250300

6.026.557.118.189.27

10.31

1.21.21.21.61.61.6

200215220225225250

212121242424

222333

Notes:(1) Root opening = O for no backing or removable backing ring, and 6.4 mm for any permanent backing.(2) For root opening = O. More passes are required when the root opening = 6.4 mm.

32–38

1.6

75˚

4.0–4.8

0–6.4 MAX(1)

BACKINGRING



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AWS D3.7:2004

40

to correct for distortion, increase the weight and cost ofthe ship needlessly. Prevention of distortion by followingcontrolled procedures and sequence is, of course, muchmore satisfactory and economical than any correctionalprocedure.

6.16 Welding Sequence. Planning the optimum weldingsequence to minimize distortion and meet specified toler-ances varies with the assembly to be welded, the thick-ness of the base metals, the fixturing and experienceavailable at the shipyard, and the type of weldingemployed. The goal in making the plan is to minimizedistortion of the completed subassembly, hull, or entireship structure. While no specific formula encompassingall factors and applying to all assemblies is available, thefollowing general practices have proved helpful to manybuilders.

(1) In large panels consisting of a number of plates,the butt seams should be welded before the panel seams.In that way, the shrinkage caused by the many smaller

joints has taken place prior to final alignment andwelding of the long panel seams, as shown in Figures 20and 21.

(2) Welding of panels constructed of multiple platesshould progress from the center toward the outer edges.

(3) Starting at the center of a seam and weldingoutward with a backstep sequence has proven helpful inspecific instances.

When the third weld is made in proper sequence, theplates on either side are still relatively free to drawtogether. It is essential for assemblies containing buttjoints that run from side to side (of the boat or ship), andwell (both) seams, so that each butt weld is completed upto the seam before the longitudinal seam is welded.

When the concept shown in Figure 22 is applied toa plate structure, the order of welding is as shown inFigure 20. On a broader scale, the sequence for astaggered butt arrangement takes on an orderly form thatis easy to follow, as shown in Figure 21. There are

Table 17Typical Procedures for Gas Metal Arc Welding of

Fillet Welds in Aluminum Alloys with Argon Shielding (U.S. Customary Units)

SectionThickness

in.Welding

Position(1)No. of

Passes(2)

ElectrodeDiameter

in.

Welding Current

dcepA

ArcVoltage

V

ArgonFlowft3/h

TravelSpeedin./min

0.094 F, V, H, O 1 0.030 100–130 18–22 30 24–30

0.125F

V, HO

111

0.030–0.0470.030

0.030–0.047

125–150110–130115–150

20–2419–2320–24

303040

24–3024–3024–30

0.188F

V, HO

111

0.0470.030–0.0470.030–0.047

180–210130–175130–190

22–2621–2522–26

303545

24–3024–3024–30

0.250F

V, HO

111

0.047–0.0620.047

0.047–0.062

170–240170–210190–220

24–2823–2724–28

404560

24–3024–3024–30

0.375F

H, VO

133

0.0620.0620.062

240–300190–240200–240

26–2924–2725–28

506085

18–2524–3024–30

0.750F

H, VO

44–6100

0.0940.0620.062

360–380260–310275–310

26–3025–2925–29

607085

18–2524–3024–30

General Note: 5XXX filler alloys will use upper portion of range for current, and lower portion of voltage range. 4XXX filler alloys employ the lowerportion of the current range, and the upper portion of the voltage range.

Notes:(1) F—flat; V—vertical; H—horizontal; O—overhead.(2) Number of weld passes for minimum leg size fillet weld only.



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AWS D3.7:2004

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several joints that can be welded at the same time, asindicated by the numbering system.

Figure 23 shows the same basic arrangements as inFigure 20 with the addition of internal framing or stiffen-ers. As mentioned previously, the internal framing andother supports should be welded only to within about12 in. (300 mm) of panel edges. After the butt jointbetween the panels is welded, the unwelded portions ofthe internal structures can be aligned and welded.

Figure 24 shows this principle applied to the assemblyof large plate panels. If the internal members were firstwelded completely out to the panel edges, they wouldoffer rather severe restraint to the shrinkage of the tie-ingroove welds.

6.17 Angular Distortion. In addition to the lineardimensional changes resulting from the characteristicexpansion and contraction of the weld, angular distortionabout the weld axis may occur when joining sections thatare relatively free to move. The rotation amounts to

approximately two degrees per weld pass. Angular dis-tortion can be minimized by symmetrical joint designand welding procedures, welding with minimum heatinput, and avoiding deposition of excess filler metal.Angular distortion normally is not a problem when weld-ing relatively large and thick sections, where proper useis made of strongbacks to provide control.

6.18 Interpass Temperature. While the mechanicalproperties of the 5000 series aluminum alloys are not soadversely affected by the heat of welding as are those ofthe heat treatable 6061 alloy, it is always desirable tolimit the size of the heat-affected zones. Also, to avoidpossible hot cracking of aluminum weld metal, the inter-pass temperature should be maintained at a level suitablefor the specific alloy. Overheated weld metal results inlarge grain size and high shrinkage stresses.

A generally observed rule is not to exceed an inter-pass temperature of 150°F (66°C); the weld should becool enough to touch briefly with the hand. Out-of-posi-

Table 17Typical Procedures for Gas Metal Arc Welding of

Fillet Welds in Aluminum Alloys with Argon Shielding (Metric Units)

SectionThickness

mmWelding

Position(1)No. of

Passes(2)

ElectrodeDiameter

mm

Welding Current

dcepA

ArcVoltage

V

ArgonFlowL/min

TravelSpeedmm/s

2.4 F, V, H, O 1 0.8 100–130 18–22 14 10.2–12.7

3.2F

V, HO

111

0.8–1.20.8

0.8–1.2

125–150110–130115–150

20–2419–2320–24

141419

10.2–12.710.2–12.710.2–12.7

4.8F

V, HO

111

1.20.8–1.20.8–1.2

180–210130–175130–190

22–2621–2522–26

141721

10.2–12.710.2–12.710.2–12.7

6.4F

V, HO

111

1.2–1.61.2

1.2–1.6

170–240170–210190–220

24–2823–2724–28

192128

10.2–12.710.2–12.710.1–12.7

9.6F

H, VO

133

1.61.61.6

240–300190–240200–240

26–2924–2725–28

242840

7.6–10.610.2–12.710.2–12.7

19.0F

H, VO

44–610

2.41.61.6

360–380260–310275–310

26–3025–2925–29

283340

7.6–10.610.2–12.710.2–12.7

General Note: 5XXX filler alloys will use upper portion of range for current, and lower portion of voltage range. 4XXX filler alloys employ the lowerportion of the current range, and the upper portion of the voltage range.

Notes:(1) F—flat; V—vertical; H—horizontal; O—overhead.(2) Number of weld passes for minimum leg size fillet weld only.



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AWS D3.7:2004

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tion welds, particularly, are apt to be of poor quality ifthe interpass temperature exceeds 150°F (66°C). Typicalaluminum alloys used for marine application are alsosubject to corrosion through exfoliation, when heatedlong enough in the sensitizing range of 200°F–500°F(93°C–260°C). This time frame may be upwards of oneweek. Therefore these alloys are not recommended forheated holding tanks.

6.19 Welding Stress Relief. As previously pointed out,the best method of controlling welding stresses isthrough the use of the appropriate welding process,welding conditions, filler metal, weld sequence for theparticular section thickness, joint design, and assemblysequence. Residual stresses in welded assemblies can beas high as the yield strength of the metal when consider-ation is not given to the above.

Post heating at a temperature of 450°F–525°F(232°C–274°C) will materially reduce the residual weld-ing stresses with little reduction in the strength of

wrought 5000 series alloys. As stated previously, alloysthat contain 3% or more of magnesium should not beheated for extended periods of time because they maybecome sensitized to stress corrosion cracking or exfolia-tion corrosion. Therefore, the total heating time for suchalloys should not exceed about 30 minutes.

Thermal stress relief methods for heat treatable alloys,such as 6061-T6, generally result in as much or greaterdecrease in mechanical properties as in the residual stresslevels. Therefore, thermal stress relief is used only whena heat treatable alloy weldment can subsequently besolution treated and aged to restore mechanical proper-ties. The manufacturer's recommendation for thermaltreatment should be followed.

Mechanical peening of weld metal is often preferredover thermal stress relief to effect limited redistributionof weld stresses. Peening may be accomplished by shotpeening with a multiple-point peening gun or withspecially designed flapper wheels. Generally, the depthof cold work by shot peening is greater than that obtain-

Table 18Typical Procedures for Manual Gas Tungsten Arc Welding of

Fillet Welds in Aluminum with AC and Argon Shielding (U.S. Customary Units)

SectionThickness

in.Welding

Position(1)

No. ofWeldPasses

Filler Rod Diameter

in.

EW-P(2)

ElectrodeDiameter

in.

WeldingCurrent

A

Gas CupDiameter

in.

ArgonFlowft3/h

TravelSpeedin./min

0.062 F, H, VO

11

0.062, 0.0940.062, 0.094

0.062, 0.0940.062, 0.094

70–11065–90

0.380.38

1620

8–108–10

0.094 FH, V

O

111

0.094, 0.1250.0940.094

0.125–0.1560.094–0.1250.094–0.125

110–14590–125

110–135

0.380.380.38

181820

8–108–108–10

0.125 FH, V

O

111

0.1250.1250.125

0.125–0.1560.094–0.1250.094–0.125

135–175115–145125–155

0.440.380.44

202025

10–128–108–10

0.188 FH, V

O

111

0.1560.1560.156

0.156–0.1880.156–0.1880.156–0.188

190–245175–210185–225

0.50.50.5

252530

8–108–108–10

0.250 FH, V

O

111

0.1880.1880.188

0.188–0.250.1880.188

240–295220–265230–275

0.50.50.5

303035

8–108–108–10

(2)0.375(3) FVHO

2233

0.1880.1880.1880.188

0.2500.188–0.250.188–0.250.188–0.25

325–375280–315270–300290–335

0.630.630.630.63

35353540

8–108–108–108–10

Notes:(1) F—flat; H—horizontal; V—vertical; O—overhead.(2) Zirconia tungsten (EW-Zr) can be used.(3) May be preheated.



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AWS D3.7:2004

43

able with a multiple-point gun. Peening of aluminumweld metal should not be attempted, however, untilcareful inspection has revealed no surface weld defects,such as incomplete fusion or cracks. Such defects couldbe covered-up by the peening operation and thus leftundetected.

6.20 Inspection of Welds

6.20.1 Visual. Visual inspection of aluminum welds isthe first and most important quality control procedure.Inspectors should be well versed in aluminum weldingso that they can properly evaluate the appearance ofwelds. Considerations relative to visual inspection are asfollows:

(1) Groove weld beads should be smooth and prop-erly contoured, with a minimum amount of undercut asallowed by the design agency.

(2) Welds may exhibit some surface porosity, but thepresence of large or gross surface porosity usually iscause for rejection.

(3) Excessive melt-through, overlap, incompletefusion, and visible inclusions are obvious defects.

(4) Crater cracks in any location, including tackwelds, root passes of welds, and at starts and stops offinal production welds, are defects.

Inspectors can use a low-power (3X) magnifyingglass to aid in visual examination of doubtful weld areas.

6.20.2 Radiographic. One of the better methods ofdetermining weld quality is radiographic inspection.However, because some cracks and incomplete fusionmay escape detection due to the relative positions of thedefect and the X-ray source, inspection requires profes-sional radiographers and interpretation. Industry-wideradiographic standards of aluminum weld quality havebeen established for commercial marine work. For exam-ple, radiographs made in accordance with ABS Rules forNondestructive Inspection of Hull Welds, which showany of the following discontinuities, indicate unaccept-able welds that need to be repaired:

Table 18Typical Procedures for Manual Gas Tungsten Arc Welding of

Fillet Welds in Aluminum with AC and Argon Shielding (Metric Units)

SectionThickness

mmWelding

Position(1)

No. ofWeldPasses

FillerRod Diameter

mm

EW-P(2)

ElectrodeDiameter

mm

WeldingCurrent

A

Gas CupDiameter

mm

ArgonFlowL/min

TravelSpeedmm/s

1.6 F, H, VOF

111

1.6, 2.41.6, 2.42.4, 3.2

1.6, 2.41.6, 2.43.2–4.0

70–11065–90

110–145

9.69.69.6

898

3.4–4.23.4–4.23.4–4.2

2.4 H, VOF

111

2.4 2.43.2

2.4–3.22.4–3.23.2–4.0

90–125110–135135–175

9.69.6

11.2

899

3.4–4.23.4–4.24.2–4.1

3.2 H, VOF

111

3.23.24.0

2.4–3.22.4–3.24.0–4.8

115–145125–155190–245

9.611.212.7

91212

3.4–4.23.4–4.23.4–4.2

4.8 H, VOF

111

4.04.04.8

4.0–4.84.0–4.84.8–6.4

175–210185–225240–295

12.712.712.7

121414

3.4–4.23.4–4.23.4–4.2

6.4 H, VOF

112

4.84.84.8

4.84.86.4

220–265230–275325–375

12.712.716.0

141717

3.4–4.23.4–4.23.4–4.2

(3)9.6(3) VHO

233

4.84.84.8

4.8–6.44.8–6.44.8–6.4

280–315270–300290–335

16.016.016.0

171719

3.4–4.23.4–4.23.4–4.2

Notes:(1) F—flat; H—horizontal; V—vertical; O—overhead.(2) Zirconia tungsten (EW-Zr) can be used.(3) May be preheated.



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Figure 13—Sizes of Double Fillet Welds to Fully ConnectAs-Welded 5086-H116 Members at Right Angles

105 15 20 25 30 35 40 45 5050

45

40

35

30

25

20

15

10

5

0.25 0.50 0.75 1.0 1.25 1.50 1.75 2.0

2.0

1.75

1.50

1.25

1.0

0.75

0.50

0.25

105 15 20 25 30 35 40 45 5050

45

40

35

30

25

20

15

10

5

0.25 0.50 0.75 1.0 1.25 1.50 1.75 2.0

2.0

1.75

1.50

1.25

1.0

0.75

0.50

0.25

FILLET SIZE, s, mm

FILLET SIZE, s, in.

PLA

TE

TH

ICK

NE

SS

, T, i

n.

PLA

TE

TH

ICK

NE

SS

, T, m

m

FILLET SIZE, s, mm

FILLET SIZE, s, in.

PLA

TE

TH

ICK

NE

SS

, T, i

n.

PLA

TE

TH

ICK

NE

SS

, T, m

m

(A) LOADING IN TRANSVERSE SHEAR

(B) LOADING IN LONGITUDINAL SHEAR

T

S 5556

FIL

LER M

ETAL

5183

5356

FIL

LER M

ETAL

5654 FILLER META

L

5556

FIL

LER M

ETAL 51

8353

56

5654

FILL

ER META

L



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Figure 14—Size of Double Fillet Welds to Fully ConnectAs-Welded 6061-T6 Members at Right Angles

105 15 20 25 30 35 40 45 5050

45

40

35

30

25

20

15

10

5

0.25 0.50 0.75 1.0 1.25 1.50 1.75 2.0

2.0

1.75

1.50

1.25

1.0

0.75

0.50

0.25

105 15 20 25 30 35 40 45 5050

45

40

35

30

25

20

15

10

5

0.25 0.50 0.75 1.0 1.25 1.50 1.75 2.0

2.0

1.75

1.50

1.25

1.0

0.75

0.50

0.25

FILLET SIZE, s, mm

FILLET SIZE, s, in.

PLA

TE

TH

ICK

NE

SS

, T, i

n.

PLA

TE

TH

ICK

NE

SS

, T, m

m

FILLET SIZE, s, mm

FILLET SIZE, s, in.

PLA

TE

TH

ICK

NE

SS

, T, i

n.

PLA

TE

TH

ICK

NE

SS

, T, m

m

(A) LOADING IN TRANSVERSE SHEAR

(B) LOADING IN LONGITUDINAL SHEAR

T

s

5654

, 535

6, 5

183,

AN

D 5

556

FILL

ER M

ETAL

S

4043

FIL

LER M

ETAL

5183

AN

D 5

556

FILL

ER

ME

TALS

4043

FIL

LER

MET

AL

5356

5654



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(1) Any type of crack(2) Incomplete fusion exceeding allowable lengths or

aggregate amount per unit length of weld(3) Incomplete penetration exceeding allowable

lengths or aggregate amounts per unit length of weld(4) Porosity or tungsten inclusions exceeding the

amounts indicated in the applicable construction standardThe amount of radiography required on a vessel is

determined by the contract, the judgment of the fabrica-tor, or both.

Low kilovoltage (150 kV) portable X-ray equipmentis readily available from a number of manufacturers.Generally, radioisotope sources are not used on alumi-num because the film image of discontinuities lacks con-

trast, compared with that obtainable with an X-raymachine. This makes detection of discontinuities moredifficult. The isotopes Ytterbium 160 and Iridium 192are used on aluminum for specific applications. The lat-ter is particularly useful for aluminum thicknesses above3 in. (76 mm), which is a practical maximum for 150 kVX-ray machines.

6.20.3 Ultrasonic. Ultrasonic inspection may be usedon aluminum and is particularly advantageous for detect-ing cracks and incomplete fusion. Its adoption and usenormally require initial justification for a specific job byX-ray and, perhaps, metallographic sectioning.

➀ Tack weld all slots.➁ Weld perimeter of each slot with specified fillet size and then fill all slots when required.➂ Groove weld doubler plates.➃ Fillet weld perimeters of doubler plates.

Figure 15—Welding Sequence for Large Doubler Plate

1 2 3 4

DECK PLATEDECK PLATE

DOUBLERPLATE

DOUBLERPLATE

DECK PLATE



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6.20.4 Penetrant. Dye-penetrant or fluorescent-penetrant inspection may be used after welding is com-pleted. However, it is not recommended on castings orunfinished weld joints where subsequent welding may bedone. This is due to the difficulty of removing the penetrantsolution from pores and crevices. Subsequent weld passeson such contaminated surfaces are likely to have excessiveporosity caused by hydrocarbons in the residual dye, mois-ture, or by both. If used for final inspection, the entire sur-face that was inspected should be thoroughly cleaned ofresidual dye before any repair welding is attempted.

6.21 Repair of Welds. Repairing of welds can be timeconsuming if not done properly. It is vitally important to

accurately determine the nature and exact location of adefect as indicated by X-ray or other means of inspec-tion. The most important decision on a butt joint is todetermine the side of the weld that the defect is nearestto. Ultrasonic and angulation X-ray inspection tech-niques can assist in locating a defect more precisely.

The normal method of metal removal is with a chip-ping gun. The operator should remove defective metaluntil sound metal is reached. A split chip is indicative ofincomplete fusion. High levels of porosity are easilydetected when sharp knife-edged chisels are used.

Primary problems with chipping as a means of weld-metal removal for repair welding are the following:

(1) Failure to follow the weld seam

Figure 16—General Design of an Insert Plate

A A

INSERT PLATE

R

DECK PLATE

3D–6D

D

DECK PLATE INSERT PLATE

SECTION A-A



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(2) Failure to remove all defective material to theproper depth

(3) Chipping a narrow, deep groove that makes pro-duction of a sound repair weld difficult

Metal can also be removed by some high-speed mill-ing tools, such as routers, or proprietary equipment, suchas hand-held milling tools. A principal drawback withthe use of this type of equipment is guiding a high-speedtool so that it follows the weld seam. Also, it should beadjusted so that the depth of cut reaches sound material.An additional problem is that it is impractical to examinechips or grindings visually to determine whether the joint

has been cleaned to sound metal. Inspection of a milledsurface for defects may be difficult because the cuttermay produce a “finish'' or relatively fine cutting pattern.A technique gaining acceptance to remove defectivewelds is plasma arc gouging.

Grooves should taper gradually to the surface at bothends, with a generous radius at the bottom of the excava-tion. Incomplete fusion may occur at these locations ifthe taper is too steep.

Cleaning joints prior to repair welding is important.Care should be taken while using chemical cleaners anddeoxidizers so that the liquid is not trapped within the

Note: Radius snipe allows access for gun to completeweld without crater formation.

(A)

(B)

Figure 17—Proper Design of Snipes and Scallops

Depth of Member, D Radius, R

Less than 6 in. (152 mm)6 in.–9 in. (152 mm–229 mm)Greater than 9 in. (229 mm)

.01.5 in. (38 mm)2 in. (51 mm)3 in. (76 mm)

1.5 in. (38 mm) R, MIN

WELDINGGUN

RADIUS R

TYPICAL MEMBER

SNIPE SCALLOP

D



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joint itself. After a welded joint has been chipped ormilled for repair, it is desirable to weld the repair areaduring the same working day to avoid the entrapment ofdebris, dust, and moisture. In some instances, it is prac-tical to temporarily cover the joint with a non-residueleaving tape in order to exclude debris. Scheduling canalso be helpful, like welding the top side of groove weldsand longitudinals first to minimize dirt entrapment.

Two critical conditions that may be encountered inrepair welding are incomplete fusion at the start of therepair weld, and an unacceptable crater condition at theend of a short repair weld bead. These can be readily pre-vented by using starting and stopping wedges at the endsof the area to be repaired, as shown in Figure 25. Thewedge blocks are cut off after welding, and the face ofthe weld dressed to match the remainder of the weld.

In the case of fillet welds, the necessity for repair isgenerally determined by visual inspection. Usually,defective fillet welds contain cracks, undercut, overlap orinsufficient weld metal. Cracks and overlaps should bechipped out, and the joint rewelded and reexamined.Undercutting and deficient weld metal frequently can be

repaired by depositing one or more weld beads in thedefective area.

All weld repair in aluminum requires completelyclean surfaces free of oil, grease, thick oxide film, andimbedded particles of any type. Either GMAW orGTAW is suitable for weld repairs. When welding onhull plates below the waterline, preheat or high weldingheat input is necessary to compensate for the chillingeffect of the water.

6.22 Metal Straightening. Straightening of aluminumplates or other members using spot heating with oxyfuelgas torches followed by quick water spray quenching (asis used with steel) is not generally recommended. How-ever, metal straightening, when rigidly controlled, can beused successfully on heavier thicknesses. For weldedseams that are too badly out of fair, one commonly usedstraightening method is to cut the seams apart. Strong-backs are applied to pull the metal out past fair. Theseams are then rewelded with “the backstep” or a bal-anced sequence, so that the resulting joint is straight.Excessive distortion sometimes occurs at the intersectionof four welds at a common point, as intersecting groovewelds.

For welded assemblies, deck or other panel structuresof thick plate, where an unbalanced welding procedurehas caused bowing or local warping of members,straightening may be effected by placing additional weldbeads on the concave side of the member. An example isshown in Figure 26. The specific weld bead pattern andwelding sequence to be used should be established bytests.

6.23 Repair Welding of Aluminum Hulls. Virtuallyany part of an aluminum hull or other ship structure,which can be freed of oil and moisture, can be repairedby welding at dockside. Proper grounding of weldingequipment is essential to protect the hull from greatlyaccelerated electrolytic corrosion during welding, partic-ularly when the craft is in salt water. Recommendedwelding machine grounding is discussed later.

Relatively large damaged panels or sections can becut out easily and replaced because the light weight ofaluminum permits handling of large prefabricated com-ponents with conventional dock cranes and trucks. Thealloy composition of the aluminum sections to berepaired or replaced should be determined, if practical.However, the 5000 series marine alloys are so univer-sally employed for aluminum hulls that it is likely thealloy in question is one of these. Also, one of the com-monly used filler metals for this series, such as 5356,may be used. This filler metal also may be used for weld-ing 6061 alloy. However, use of the correct filler metal toproduce optimum weld properties is always recom-mended where the composition of the base metal is

Figure 18—Welded Oil or Water Stopat Intersecting Members

FILLET WELDS

WELDED STOP

2 in.(51 mm)

3 in.(76 mm)

CONTINUOUS MEMBER

AB

BDECK OR SHELL

A

OR

SECTION B-B

PLAN VIEW A-A



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Figure 19—Typical Strongbacks forMaintaining Alignment During Welding



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known or can be determined. Either the GTAW orGMAW process may be used.

Proper preparation of aluminum surfaces to be repair-welded is essential. The principal steps to be taken are asfollows:

(1) The damaged sections of all components shouldbe removed.

(2) The original weld metal in new weld areas shouldbe removed to provide the correct plate edge shape andcontour.

(3) Patches and reinforcements should be fabricatedand formed to obtain proper close fit-up.

(4) All weld joint surfaces should be solvent cleaned,filed, and brushed.

(5) All surfaces in the weld area should be dried.(6) The patch should be positioned and clamped for

tack welding.(7) The patch should be tack welded in place.(8) Tack welds should be chipped out or tapered at

each end as required.(9) The proper weld sequence should be followed to

minimize residual stress.All permanent boatyard repairs should be equivalent

to the original construction. For extensive repairs, origi-nal specification and “as built'' drawings should beobtained from the builder by the repair yard.

Repairs of cracks or other defects in a weld are madeby chipping out the defective weld to sound metal andrepair welding, as described previously. If seams inwatertight compartments are improperly repaired,unfused areas within the weld metal are likely to causeleakage over a period of time. Small cracks can developat the sites of such internal voids. Welding over defectsshould be avoided, as cracks can propagate from theseareas.

Where damage is encountered or extensive repairs arerequired, replacement of entire panels or a larger sectionthan that actually affected is recommended. Such sec-tions may be removed with plasma arc cutting, with asaber saw, or with a carbide tipped circular saw, leavinglarge-radius corners. Edges of the opening end of newcut-to-size sections are prepared according to the thick-ness of the joint and welding processes to be used. If theplate thickness of the patch is greater than the originalplate, all edges should be tapered to the thickness of theadjacent plate (see Figure 16). The patch or insert shouldbe welded in place from both sides, if possible. If not,full penetration welds should be made using removableor permanent backing.

When it is necessary to weld sections under therestrained conditions usually encountered in repairjobs, the sequence should be similar to that shown inFigure 27. All adjacent seams in the existing structureshould be cut back about 12 in. (300 mm) from the open-ing to prevent or reduce restraint. Likewise, the framingof the old structure should be released for a distance ofabout 12 in. (300 mm) from the opening. Welds shouldnot be started or stopped at a corner.

Relatively minor cracks in base metal may be repairedby welding. Chipping to remove the crack prior to weld-ing is recommended in all cases. Preheating of the basemetal adjacent to the crack is suggested. Use of drilledholes at either end of the crack, as shown in Figure 28, toprevent extension is optional for aluminum. Weldingshould start on the base metal at each end of the repairand terminate at the midpoint. The second weld should befused completely with the first and the crater filled. Thebackstep method should be used on longer excavations.

6.24 Welding Power Connections. The possibility ofelectrolytic corrosion of aluminum hulls in water causedby welding and associated operations, can be overcomeby proper connection of the power leads from the weld-ing machines and accessory equipment.18 The arc weld-ing machines, electrode and work leads, and associatedcontrol equipment should be installed on the craft wherethe welding is to be done. A welding machine on onecraft with the work lead connected to that craft should notbe used to perform welding on another craft alongside.

If it is not possible to install the welding machine onboard, it should be installed on shore in a location asclose as possible to the craft. A shore-based weldingmachine work lead should not be connected to an earth

18. Based on the following published material: (1) U.S. NavyNAVSHIP NOTE 4700 (1969), derived from Care, Mainte-nance, Repair, and Operation Manual for U.S. Navy Aluminum(1968), by Sub-Committee on Marine Applications, The Alu-minum Association. (2) Roger, T. Howard, Marine Corrosion,Appendix 3, Earthing of Welding Machines, pp. 284–287.

➀ Weld butt➁ Weld seam➂ Weld seam

Figure 20—Welding Sequence forPlate Butt and Adjacent Seams

C

1

2A

B1 B2

3



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ground. It should be clamped directly to the work on thecraft where the welding is being done. Care should betaken to ensure that there is no intermediate contact ofthe electrode and work lead cables between the weldingmachine and the craft.

No work lead connections should be made betweenthe craft and the shore or between adjacent craft forwelding. Care should be taken to prevent cables fromhanging or sagging in the water between the craft andshore. It is essential that no welding current flowsthrough the sea water to or away from the metal hull; theship should not be part of an electrolytic cell.

Separate welding machines should be used whenwelding on more than one ship at dockside. The worklead from each machine should be connected only to thework on the one ship being served. If it is essential toweld on two or more ships using a single weldingmachine, separate work leads may be run from the shore-

based welding machine to each ship, but this arrange-ment is not recommended. It is preferred to connect asingle work lead or cable only to the craft being welded.

In addition to employing a correctly isolated weldingcircuit, as previously described, the following conditionsshould be checked to ensure corrosion protection fromstray welding current:

(1) Both electrode and work lead cables should be ofadequate size to carry the maximum welding current tobe used (see Figures 29 and 30).

(2) Care should be taken to make certain that mooringlines do not accidentally ground the power sourcebecause they may act as electrical conductors.

(3) A work lead of adequate length should be used sothat it can be clamped as closely as possible to the weld-ing site. Even if the circuit is isolated on the one ship,some current may flow through the water alongside if the

Figure 21—Typical Welding Sequence for Plate Butts and Seams where Butts are Staggered

87

5

5

2

5

5 5

5

5

5

7 7

7

7 7

778

8

8

8

6

6

6

6

6

63

3 3

8

3

4

4

5

1 2



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work lead is clamped to the vessel a long way from thewelding site.

(4) Inspect all cable connections regularly to ensurethey are clean and tight. A salt-laden atmosphere maycorrode any electrical contact, and cable movement mayloosen it.

For best electrical connections, the aluminum surfaceshould be ground or sanded to remove the oxide, andbolted or clamped lugs with an electrical sealer should beused.

7. Safety7.1 Introduction. In welding, safety precautions alwaysapply to the process being used, the equipment, thewelder's physical and mental condition, the type and con-dition of the welder's clothing, shop or yard conditions,and other factors. Welding safety also is affected by themetal being welded which may generate hazardousfumes and gases.

7.2 Fumes and Gases. Many welding, cutting and alliedprocesses produce fumes and gases which may be harm-ful to health. Fumes are solid particles which originatefrom welding consumables, the base metal, and anycoatings present on the base metal. Gases are producedduring the welding process or may be produced by theeffects of process radiation on the surrounding environ-ment. The amount and composition of these fumes andgases depend upon the composition of the filler metaland base metal, welding process, current level, arclength, and other factors.

The possible effects of over-exposure range from irri-tation of eyes, skin, and respiratory system to more severecomplications. Effects may occur immediately or at somelater time. Fumes can cause symptoms such as nausea,headaches, dizziness, and metal fume fever. The possibil-ity of more serious health effects exists when especiallytoxic metals are involved. In confined spaces, the gasesmight displace breathing air and cause asphyxiation.

Enough ventilation, exhaust at the arc, or both, shouldbe used to keep fumes and gases from the breathing zone

WELD FLUSH AND EVENWITH PLATE EDGES

(A)

(B) (C)

(D)(A)

(B) (C)

SEAM

BUTT BUTT

12 in.(300 mm)

Notes:1. Weld seam between (A) and (B) to within 12 in. (300 mm) of

butt joint.2. Weld butt between (B) and (C).3. Weld butt between (A) and (D).4. Complete welding seam.

(B) ALIGNED BUTTS

Figure 22—Welding Sequence at the Intersection of Plate Butts and Seams

Notes:1. Weld butt seam between (B) and (C).2. Weld seam.

(A) STAGGERED BUTTS



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and general area. In some cases, natural air movementwill provide enough ventilation. Where ventilation maybe questionable, air sampling should be used to deter-mine if corrective measures should be applied.

The following sources should be referred to for moredetailed information on fumes and gases produced by thevarious welding processes:

(1) The permissible exposure limits required byOSHA can be found at CFR Title 29, Chapter XVII, Part1910. The OSHA General Industry Standards are avail-able from the Superintendent of Documents, U.S.Government Printing Office, Washington, DC 20402.

(2) The recommended threshold limit values for thesefumes and gases may be found in Threshold Limit Valuesfor Chemical Substances and Physical Agents in theWorkroom Environment published by the AmericanConference of Governmental Industrial Hygienists(ACGIH), 1330 Kemper Meadow Drive, Cincinnati, OH45240.

(3) The results of an AWS funded study are availablein the report entitled Fumes and Gases in the WeldingEnvironment.

(4) The results of Aluminum Association WeldingFume studies:

(a) “Evaluation of Atmosphere at Welder’s Posi-tion When Gas Metal Arc Welding Several AluminumAlloys,” 1985.

(b) “Evaluation of Atmosphere at Operator’s Po-sition When Gas Metal Arc Welding, Gas Tungsten ArcWelding and Plasma Arc Cutting Selected AluminumAlloys,” 1991.

7.3 Radiation. Welding, cutting, and allied operationsmay produce radiant energy (radiation) harmful tohealth.

Notes:1. Weld frames (FR) and girder to plates within 12 in. (305 mm)

of all unwelded butts and seams.2. Weld butt complete.3. Weld unwelded portion of girder in way of butt.4. Weld lower seam to point 12 in. (305 mm) from next butt.5. Weld unwelded portion of frames in way of lower seam.6. Weld upper seam to point 12 in. (305 mm) from next butt.7. Weld unwelded portion of frames in way of upper seam.

Figure 23—Typical Welding Sequence for Plate Butt and Adjacent Seams where

Internal Framing is Attached

FR FRFRFR

BUTT

SIDE SHELL

LOWER SEAM A

C

GIRDER

UPPER SEAM

Notes:1. Panels 1 and 2 are complete with internals welded to within

12 in. (305 mm) of edges of panel.2. Weld panels together following the same general sequence

as indicated in Figures 22 and 23.

Figure 24—Typical Welding Sequence for Large Subassembled Plate Panels

Figure 25—Placement of Startingand Stopping Tabs at the Ends

of a Repair Weld Groove

PANEL 1 PANEL 1

WELD GROOVE

WEDGE-SHAPEDSTART AND STOP TABS



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Radiant energy may be ionizing (such as X-rays) ornonionizing (such as ultraviolet, visible light, or infra-red). Radiation can produce a variety of effects such asskin burns and eye damage, depending on the radiantenergy’s wavelength and intensity, if excessive exposureoccurs.

The intensity and wavelengths of nonionizing radiantenergy produced depend on many factors such as theprocess, welding parameters, electrode and base metalcomposition, fluxes, and any coating or plating on thebase metal. Most arc welding and cutting processes(except submerged arc when used properly), laser weld-ing and torch welding, cutting, brazing, or soldering canproduce sufficient quantities of nonionizing radiation tomake precautionary measures necessary.

Protection from possible harmful effects caused bynonionizing radiant energy from welding include the fol-lowing measures:

(1) The welding arcs should not be observed directlybut through welding filter plates which meet the require-ments of ANSI/ASC Z87.1, Practice for Occupationaland Educational Eye and Face Protection, published byAmerican National Standards Institute.

(2) Exposed skin should be protected with adequategloves and clothing as specified in ANSI/ASC Z49.1,Safety in Welding, Cutting, and Allied Processes, pub-lished by the American Welding Society.

(3) One should beware of reflections from weldingarcs, and all persons should be protected from intensereflections. (Note: paints using pigments of substantially

zinc oxide or titanium dioxide have a low reflectance forultraviolet radiation.)

(4) One should avoid exposing passersby to weldingoperations by the use of screens, curtains, or adequatedistance from aisles, walkways, etc.

(5) Safety glasses with UV protective side shieldshave been shown to provide some beneficial protectionfrom ultraviolet radiation produced by welding arcs.

7.4 Electrical Hazards. Electric shock can kill. How-ever, it can be avoided. Live electrical parts should notbe touched. The manufacturer’s instructions and recom-mended safe practices should be read and understood.Faulty installation, improper grounding, and incorrectoperation and maintenance of electrical equipment are allsources of danger.

All electrical equipment and the workpieces should begrounded. The work lead is not a ground lead. It is usedonly to complete the welding circuit. A separate connec-tion is required to ground the workpiece. The work leadshould not be mistaken for a ground connection.

The correct cable size should be used, since sustainedoverloading may cause cable failure and result in possi-ble electrical shock or fire hazard. All electrical connec-tions should be tight, clean and dry. Poor connectionscan overheat and even melt. Further, they can producedangerous arcs and sparks. Water, grease, or dirt shouldnot be allowed to accumulate on plugs, sockets, or elec-trical units. Moisture can conduct electricity. To preventshock, the work area, equipment, and clothing should bekept dry at all times. Dry gloves and rubber soled shoes

Figure 26—Correction of Distortion in a Panel by Weldingon the Concave Side, Using a Predetermined Pattern



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AWS D3.7:2004

56

should be worn, or one should stand on a dry board orinsulated platform.

Cables and connectors should be kept in good con-dition. Improper or worn electrical connections may setup conditions that could cause electrical shock or shortcircuits. Worn, damaged, or bare cables should not beused. Open circuit voltage should be avoided.

When several welders are working with arcs of differ-ent polarities, or when a number of alternating currentmachines are being used, the open circuit voltages can beadditive. The added voltages increase the severity of theshock hazard.

In case of electric shock, the power should first beturned off. If the rescuer must resort to pulling the victimfrom the live contact, nonconducting materials should beused. If the victim is not breathing, cardiopulmonaryresuscitation (CPR) should be administered as soon ascontact with the electrical source is broken. A physicianshould be called and CPR should be continued untilbreathing has been restored, or until a physician hasarrived. Electrical burns should be treated as thermalburns; that is, clean, cold (iced) compresses should beapplied. Contamination should be prevented and the

burns should be covered with a clean, dry dressing. Aphysician should be called.

7.5 Fire Prevention. Molten metal, sparks, slag, and hotwork surfaces are produced by welding, cutting, andallied processes. These can cause fire or explosion ifprecautionary measures are not followed.

Many of the fires associated with welding, cutting andapplied processes have been caused by sparks which cantravel up to 35 ft (11 m) in a horizontal direction from thework area. Sparks can pass through or become lodged incracks, clothing, pipe holes, and other small openings infloors or partitions. (Note: sparks and molten metal cantravel greater distances when falling.)

Typical combustible materials commonly involved infires are floors, partitions, roofs, and building contentssuch as wood, paper, clothing, plastics, chemical andflammable liquids, and gases. Outdoors, the combustiblematerials involved are dry leaves, grass, and brush.Explosions have occurred where welding or cutting hasbeen performed in spaces containing flammable gases,vapors, liquids, or dusts.

All combustible material should be removed from thework area. Where possible, the work should be moved toa location well away from combustible materials. If nei-ther action is possible, combustibles should be protectedwith a cover of fire resistant material. All combustiblematerials should be moved and made safe for a radius of35 ft (11 m) around the work area. All open doorways,windows, cracks, and other openings should be covered

Note that a release length of 12 in. (305 mm) is provided in thehorizontal seams at each corner of the insert plate.

Notes:1. Weld framing to within 12 in. (305 mm) of unwelded butts and

seams.2. Weld vertical butt ➁ complete.3. Weld vertical butt ➂ complete.4. Weld unwelded framing in way of vertical butts.5. Weld horizontal seam ➄ including release lengths.6. Weld horizontal seam ➅ including release lengths.7. Weld unwelded framing in way of horizontal screws.

Figure 27—Welding Sequencefor Side Shell Plate Repair

12 in. (305 mm)

12 in. (305 mm)

12 in. (305 mm)

12 in. (305 mm)

6

12 3

5

Figure 28—Technique forRepairing a Crack by Welding

DRILLED HOLE

FIRST WELD

FILLER CRATER

SECOND WELD



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Figure 29—Nomograph for Copper Ground Cable Size

500

450

400

375

350

325

300

275

250

225

200

175

150

125

100

90

802

1

1/0

2/0

3/0

4/0

66 696

85 037

105 880

133 392

169 519

212 594

NUMBER 1 CABLE IS THEMINIMUM SIZE TO BE USEDFOR ANY CURRENT OR LENGTH

LEN

GT

H, f

t

CU

RR

EN

T, A

300

275

250

225

200

175

150

125

100

90

80

70

60

50

A CM ft

BASED ON 1 000 000 CM/1000 AMPERES/100 ft

AR

EA

, CIR

CU

LAR

mils

1 500 0001 400 0001 300 000

1 200 000

1 100 000

1 000 000

900 000

800 000

700 000

600 000

550 000

500 000

450 000

400 000

350 000

300 000275 000

250 000

225 0004/0

3/0

2/0

1/0

1

200 000

175 000

150 000

125 000

100 000

90 000

80 000



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AWS D3.7:2004

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Figure 30—Nomograph for Copper Electrode Lead Cable Size

500

450

400

375

350

325

300

275

250

225

200

175

150

125

100

90

802

1

1/0

2/0

3/0

4/0

66 696

85 037

105 880

133 392

169 519

212 594

NUMBER 1 CABLE IS THEMINIMUM SIZE TO BE USEDFOR ANY CURRENT OR LENGTH

LEN

GT

H, f

t

CU

RR

EN

T, A

300

275

250

225

200

175

150

125

100

90

80

70

60

50

A CM ft

BASED ON 500 000 CM/1000 AMPERES/100 ft

AR

EA

, CIR

CU

LAR

mils

750 000700 000650 000

600 000

550 000

500 000

450 000

40 000

350 000

300 000

275 000

250 000

225 000

200 000

175 000

150 000137 500

125 000

112 500

4/0

3/0

2/0

1/0

1

100 000

87 500

75 000

62 5002

50 000



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AWS D3.7:2004

59

or blocked with fire resistant material. If possible, thework area should be enclosed with portable fire resistantscreens.

Combustible walls, ceilings, etc. should be protectedfrom sparks and heat with fire resistant covers. If work isto be performed on a metal wall, ceiling, etc., ignition ofcombustibles on the other side should be prevented bymoving the combustibles to a safe location. If this cannotbe done, someone should be designated to serve as a firewatch, equipped with a fire extinguisher during the weld-ing operation and for one half-hour after welding iscompleted.

Welding or cutting should not be performed on mate-rial having a combustible coating or combustible internalstructure, as in walls or ceilings, without an approvedmethod for eliminating the hazard. Hot slag should notbe disposed of in containers holding combustible mate-rial. A fire extinguisher should be kept nearby. A thor-ough examination for evidence of fire should be made.Easily visible smoke or flame may not be present forsome time after the fire has started.

Overloading and improper sizing can cause overheat-ing of electrical equipment. All electrical equipment andwiring should be installed properly with recommendedcircuit protection.

The work cable should be connected to the work asclose to the welding area as practical. Work cables con-nected to locations some distance from the welding areaincrease the possibility of the welding current passingthrough lifting chains, crane cables, or other alternatecircuits. This can create fire hazards or overheat liftingchains or cables until they fail.

Welding or cutting should not be done in atmospherescontaining dangerously reactive or flammable gases,vapors, liquids, or dust. Heat should not be applied to acontainer that has held an unknown substance or acombustible material whose contents when heated canproduce flammable or explosive vapors. Heat should notbe applied to a workpiece covered by an unknown sub-stance or whose coating can produce flammable, toxic,or reactive vapors when heated. Adequate proceduresshould be developed and proper equipment used to dothe job safely. Adequate ventilation should be provided

in work areas to prevent accumulation of flammablegases, vapors, or dusts. Containers should be cleaned andpurged before applying heat.

Closed containers, including castings, should bevented before preheating, welding, or cutting. Ventingwill prevent the buildup of pressure and possible explo-sion due to the heating and the resultant expansion ofgases.

7.6 OSHA Regulations. The OSHA regulations thatgovern safety practices are found in the Code of FederalRegulations, Title 29, Chapter XVII, Part 1915, “Safetyand Health Regulations for Ship Repairing.” Subpart Ddeals with “Welding, Cutting, and Heating” in situationsinvolving ship repairing, and Title 29 CFR 1910.252-Subpart Q “Welding, Cutting, and Brazing for GeneralIndustry” covers the general industry. These regulationsare supplemented by the following publications:

(1) National Electric Code, National Fire ProtectionAssociation.

(2) Oxygen-Fuel Gas Systems for Welding and Cut-ting, NFPA No. 51, National Fire Protection Association.

(3) Practice for Occupational and Educational Eyeand Face Protection, ANSI/ASC Z87.1, AmericanNational Standards Institute.

(4) Safety in Welding, Cutting, and Allied Processes,ANSI Z49.1, American Welding Society.

(5) Standard for Fire Prevention in the Use of Cuttingand Welding Processes, NFPA No. 51B, National FireProtection Association.

(6) Standard Welding Terms and Definitions, AWSA3.0, American Welding Society.

(7) Threshold Limit Values, American Conference ofGovernmental Industrial Hygienists.

Metric Conversion Factors:1 in. = 25.4 mm1 in./min = 25.4 mm/min and 0.423 mm/s1 ft/min = 305 mm/min and 5.1 mm/s1 lb = 0.45 kg1 ft3/h = 0.0283 m3/h and 0.472 L/min1 psi = 6.89 kPa1 ksi = 6.89 MPatC = 0.556 (tF

– 32)



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AWS D3.7:2004

61

A1. Issuing AgenciesAgencies that publish codes, specifications, recom-

mended practices, materials standards, and welding testsapplicable to welded aluminum ship structure are asfollows:

The Aluminum Association, Inc.900 19th Street, NWWashington, DC 20006

American Bureau of Shipping and Affiliated Companies16855 Northchase DriveHouston, TX 77060

American Conference of Governmental IndustrialHygienists

1330 Kemper Meadow DriveCincinnati, OH 45240

American National Standards Institute1819 L Street, N.W., Suite 600Washington, DC 20036

ASTM International100 Barr Harbor DriveP.O. Box C700West Conshohocken, PA 19428-2959

American Society of Mechanical EngineersThree Park AvenueNew York, NY 10016-5990

American Welding Society550 N.W. LeJeune RoadMiami, FL 33126

National Fire Protection Association, Inc.One Battery March ParkP.O. Box 9101Quincy, MA 02269-9101

Naval Publications and Forms CenterDefense Printing Service Detachment Office700 Robbins AvenuePhiladelphia, PA 19111-5094

Society of Naval Architects and Marine Engineers601 Pavonia Avenue, Suite 400Jersey City, NJ 07306-3881

United States Coast Guard2100 Second Street, SWWashington, DC 20593-0001

United States NavyNaval Sea Systems CommandNAVSEA 05MWashington, DC 20762

A2. StandardsPertinent governmental and commercial standards

and references are given in the following list.

A2.1 Federal

QQ-A-200/4—Aluminum Alloy 5083, Bar, Rod, Shapes,Tube and Wire, Extruded





Annex A

Codes and Other Standards(This Annex is not a part of AWS D3.7:2003, Guide for Aluminum Hull Welding,

but is included for informational purposes only.)

Nonmandatory Annexes



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62


QQ-A-225/7—Aluminum Alloy 5052, Bar, Rod, andWire; Rolled, Drawn, or Cold Finished

QQ-A-250/6—Aluminum Alloy 5083, Plate and Sheet





WW-T-700/5—Tube, Aluminum Alloy, Drawn, Seam-less, 5086

WW-T-700/6—Tube, Aluminum Alloy, Drawn, Seam-less, 6061

A2.2 Military

MIL-STD-0022—Welded Joint Design

MIL-STD-1595—Qualification of Aircraft, Missile andAerospace Fusion Welders

MIL-STD-1689—Fabrication, Welding, and Inspectionof Ships Structure

MIL-STD-2035 (SH)—Nondestructive Testing Accep-tance Criteria

MIL-STD-2219—Fusion Welding of AerospaceApplications

MIL-W-6858—Spot and Seam Welding of Aluminum,Magnesium, Non-Hardening Steels, Nickel andTitanium

MIL-W-10430—Preparation for Delivery of WeldingRods and Electrodes

MIL-W-22248—Weldments, Aluminum and AluminumAlloys

MIL-W-45205—Welding Aluminum Alloys, ExcludingArmor

MIL-W-45206—Welding Aluminum Alloy Armor

MIL-W-45210—Welding, Resistance, Spot; WeldableAluminum Alloys

MIL-W-45211—Welding, Stud, Aluminum

MIL-R-45774—Radiographic Inspection, Weld Sound-ness Standards

NAVSEA 0900-LP-006-3010—Ultrasonic InspectionProcedure and Acceptance Standards for Hull Struc-ture, Production and Repair Welds

NAVSEA 0900-LP-003-8000—Surface InspectionAcceptance Standards for Metals

NAVSEA S 9074-AQ-G1B-010/248—Requirements forWelding and Brazing Procedure and PerformanceQualification

US Coast Guard—Title 46, Code of Federal Regulations

US Coast Guard—Rules for Nondestructive Inspectionof Hull Welds

A2.3 Industrial

American Bureau of Shipping—ABS Rules for Buildingand Classing Aluminum Vessels

ASME Boiler and Pressure Vessel Code, Section IX,Qualification Standard for Welding and Brazing Pro-cedures, Welders, Brazers, and Welding and BrazingOperators

ANSI H35.1—Alloy and Temper Designation Systemfor Wrought Aluminum

ANSI H35.2—Dimensional Tolerances for AluminumMill Products

ANSI B96.1—Standard for Welded Aluminum AlloyStorage Tanks

ASTM B 26—Standard Specification for AluminumAlloy Sand Castings

ASTM B 108—Standard Specification for AluminumAlloy Permanent Mold Castings

ASTM B 209—Standard Specification for AluminumAlloy Sheet and Plate

ASTM B 210—Standard Specification for AluminumAlloy Drawn Seamless Tubes

ASTM B 211—Standard Specification for AluminumAlloy Bar, Red and Wire

ASTM B 221—Standard Specification for Aluminumand Aluminum Alloy Extruded Bars, Rods, Wire,Shapes and Tubes

ASTM B 241—Standard Specification for Aluminumand Aluminum Alloy Seamless Pipe and SeamlessExtruded Tube

ASTM B 247—Standard Specification for AluminumAlloy Die and Hand Forgings

ASTM B 308—Standard Specification for AluminumAlloy 6061-T6 Standard Structural Shapes, Rolled orExtruded

ASTM B 429—Standard Specification for AluminumAlloy Extruded Structural Pipe and Tube



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63

ASTM B 618—Standard Specification for Aluminumand Aluminum Alloy Investment castings

ASTM B 686—Standard Specification for AluminumAlloy Castings

ASTM E 94—Standard Recommended Practice forRadiographic Testing

ASTM E 142—Standard Method for Controlling Qualityof Radiographic Testing

ASTM E 185—Standard Practice for Liquid PenetrantInspection Method

AWS A5.01—Filler Metal Procurement Guidelines

AWS A5.10—Specification for Bare Aluminum andAluminum Alloy Welding Electrodes and Rods

AWS A5.12—Specification for Tungsten and TungstenAlloy Electrodes for Arc Welding and Cutting

AWS A5.32—Specification for Welding ShieldingGases

AWS B2.1—Standard for Welding Procedure and Per-formance Qualification

AWS C5.2—Recommended Practices for Plasma ArcCutting

AWS C5.4—Recommended Practices for Stud Welding

AWS C5.5—Recommended Practices for Gas TungstenArc Welding

AWS C5.6—Recommended Practices for Gas Metal ArcWelding

AWS D1.2—Structural Welding Code, Aluminum

AWS D10.7—Recommended Practices for Gas-Shielded-Arc Welding of Aluminum and AluminumAlloy Pipe

AWS QC1—Standard for Qualification and Certificationof Welding Inspectors

A2.4 Other Publications by the D3 Committee onMarine Construction

AWS D3.5—Guide for Steel Hull Welding

AWS D3.6—Specification for Underwater Welding



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AWS D3.7:2004

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Figure B1—Double-Square-Groove Welds, Convex Beads

Figure B2—Single-V-Groove Welds, No Root Opening, Welded Flush

3/4

1/2

1/4

0

15

20

10

5

0 0.1 0.2

0.30.1 0.2

PLA

TE

TH

ICK

NE

SS

, in.

PLA

TE

TH

ICK

NE

SS

, mm

lbs/ft OF JOINT

kg/m OF JOINT

PLA

TE

TH

ICK

NE

SS

, in.

PLA

TE

TH

ICK

NE

SS

, mm

lbs/ft OF JOINT

kg/m OF JOINT

0 1 2 3 4 5

10

20

30

40

502

0

1

1 2 3 4 5 6 7

A1/16 in.(1.6 mm)

A–45 ˚ A–60˚ A–75˚ A–90˚

Annex B

Quantity of Filler Metal Required for Welded Joints in Aluminum Made by GMAW and GTAW Processes

(This Annex is not a part of AWS 3.7:2003, Guide for Aluminum Hull Welding,but is included for informational purposes only.)



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Figure B3—Single-V-Groove Welds, 1/8 in. (3.2 mm) Root Opening, Welded Flush

Figure B4—Double-V-Groove Welds

PLA

TE

TH

ICK

NE

SS

, in.

PLA

TE

TH

ICK

NE

SS

, mm

lbs/ft OF JOINT

kg/m OF JOINT

0 1 2 3 4 5

10

20

30

40

502

0

1

1 2 3 4 5 6 7

A1/16 in.(1.6 mm)

A–45 ˚ A–60˚

A–75˚ A–90˚

1/8 in. (3.2 mm)

PLA

TE

TH

ICK

NE

SS

, in.

PLA

TE

TH

ICK

NE

SS

, mm

lbs/ft OF JOINT

kg/m OF JOINT

10

20

30

40

50

1-1/2

11/8 in. (3.2 mm)ROOT OPENING

1/8 in.(3.2 mm)

0.5 1.0 1.5 2.0 2.5

0.5 1 1.5 20

1/2

1

2

60˚

T 60˚



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AWS D3.7:2004

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Figure B5—Single-V-Groove Welds, 45° Groove Angles, with Backing Strip

Figure B6—Single-V-Groove Welds, 60° Groove Angle, with Backing Strip

PLA

TE

TH

ICK

NE

SS

, in.

PLA

TE

TH

ICK

NE

SS

, mm

lbs/ft OF JOINT

kg/m OF JOINT

1 2

10

20

30

1-1/2

1-1/4

0.5 1.0 1.5 2.0 2.5 3.0 3.5

R

R = 1/8 in. (3

.2 mm)

1

3/4

1/2

1/4

1/2 1-1/2 2-1/2

45˚R = 1/4 in. (6

.4 mm)

R = 3/8 in. (9.5 mm)

R = 1/2 in. (13 mm)

PLA

TE

TH

ICK

NE

SS

, in.

PLA

TE

TH

ICK

NE

SS

, mm

lbs/ft OF JOINT

kg/m OF JOINT

1 2

10

20

30

1-1/2

1-1/4

0.5 1.0 1.5 2.0 2.5 3.0 3.5

R

R = 1/8 in. (3

.2 mm)

1

3/4

1/2

1/4

1/2 1-1/2 2-1/2

60˚R = 1/4 in. (6.4 mm)

R = 3/8 in. (9.5 mm)

R = 1/2 in. (13 mm)



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AWS D3.7:2004

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PLA

TE

TH

ICK

NE

SS

, in.

PLA

TE

TH

ICK

NE

SS

, mm

lbs/ft OF JOINT

kg/m OF JOINT

1 2

10

20

30

1-1/4

1

0.5 1.0 1.5 2.0 2.5 3.0 3.5

R

R = 1/16 in. (1.6 mm)

3/4

1/2

1/4

1/2 1-1/2 2-1/2

75˚R = 1/4 in. (6.4 mm)

R = 3/8 in. (9.5 mm)

R = 1/2 in. (13 mm)

PLA

TE

TH

ICK

NE

SS

, in.

PLA

TE

TH

ICK

NE

SS

, mm

lbs/ft OF JOINT

kg/m OF JOINT

1 2

10

20

1

0.5 1.0 1.5 2.0 2.5 3.0 3.5

R

R = 1/8 in. (3

.2 mm)3/4

1/2

1/4

1/2 1-1/2 2-1/2

90˚

R = 1/4 in. (6.4 mm)

R = 3/8 in. (9.5 mm)

R = 1/2 in. (13 mm)



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Figure B9—Single- and Double-Bevel-Groove Welds

Figure B10—Single-U-Groove Welds

PLA

TE

TH

ICK

NE

SS

, in.

PLA

TE

TH

ICK

NE

SS

, mm

lbs/ft OF JOINT

kg/m OF JOINT

1 3

10

20

1 2 3 4 5

T

2-1/2

2

1-1/2

0 2 4

45˚

SINGLE BEVEL

DOUBLE BEVEL

30

40

50

60

70

1/2

1

3

45˚

1/8 in.(3.2 mm)

1/8 in. (3.2 mm)

45˚

3/8 in.(9.5 mm)

3/8 in.(9.5 mm)

T

PLA

TE

TH

ICK

NE

SS

, in.

PLA

TE

TH

ICK

NE

SS

, mm

lbs/ft OF JOINT

kg/m OF JOINT

1

10

20

0.5 1.0 1.5 2.5 3.02

1-1/2

0 2

18˚ 30

40

50

1/2

1

5/32 in.(4 mm)

2.0



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Figure B11—Filler Metal Requirements for Fillet Welds with Equal Leg Lengths

WE

LD S

IZE

, in.

WE

LD S

IZE

, mm

lbs/ft OF JOINT

kg/m OF JOINT

1 3

10

20

1.0 2.0 3.02

1-1/2

0 2

30

40

50

1/2

1



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C1. IntroductionThe AWS Board of Directors has adopted a policy

whereby all official interpretations of AWS standardswill be handled in a formal manner. Under that policy, allinterpretations are made by the committee that is respon-sible for the standard. Official communication concern-ing an interpretation is through the AWS staff memberwho works with that committee. The policy requires thatall requests for an interpretation be submitted in writing.Such requests will be handled as expeditiously as possi-ble but due to the complexity of the work and the proce-dures that must be followed, some interpretations mayrequire considerable time.

C2. ProcedureAll inquiries must be directed to:

Managing Director, Technical ServicesAmerican Welding Society550 N.W. LeJeune RoadMiami, FL 33126

All inquiries must contain the name, address, andaffiliation of the inquirer, and they must provide enoughinformation for the committee to fully understand thepoint of concern in the inquiry. Where that point is notclearly defined, the inquiry will be returned for clarifica-tion. For efficient handling, all inquiries should be type-written and should also be in the format used here.

C2.1 Scope. Each inquiry must address one single provi-sion of the standard, unless the point of the inquiryinvolves two or more interrelated provisions. That provi-sion must be identified in the scope of the inquiry, along

with the edition of the standard that contains the provi-sions or that the Inquirer is addressing.

C2.2 Purpose of the Inquiry. The purpose of theinquiry must be stated in this portion of the inquiry. Thepurpose can be either to obtain an interpretation of astandard requirement, or to request the revision of a par-ticular provision in the standard.

C2.3 Content of the Inquiry. The inquiry should beconcise, yet complete, to enable the committee to quicklyand fully understand the point of the inquiry. Sketchesshould be used when appropriate and all paragraphs, fig-ures, and tables (or the Annex), which bear on theinquiry must be cited. If the point of the inquiry is toobtain a revision of the Standard, the inquiry must pro-vide technical justification for that revision.

C2.4 Proposed Reply. The inquirer should, as a pro-posed reply, state an interpretation of the provision thatis the point of the inquiry, or the wording for a proposedrevision, if that is what inquirer seeks.

C3. Interpretation of Provisions of the Standard

Interpretations of provisions of the standard are madeby the relevant AWS Technical Committee. The secre-tary of the committee refers all inquiries to the chairmanof the particular subcommittee that has jurisdiction overthe portion of the standard addressed by the inquiry. Thesubcommittee reviews the inquiry and the proposed replyto determine what the response to the inquiry should be.Following the subcommittee’s development of theresponse, the inquiry and the response are presented tothe entire committee for review and approval. Upon

Annex C

Guidelines for Preparation of Technical Inquiries for AWS Technical Committees

(This Annex is not a part of AWS D3.7:2003, Guide for Aluminum Hull Welding,but is included for informational purposes only.)



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AWS D3.7:2004

72

approval by the committee, the interpretation will be anofficial interpretation of the Society, and the secretarywill transmit the response to the inquirer and to theWelding Journal for publication.

C4. Publication of InterpretationsAll official interpretations will appear in the Welding

Journal.

C5. Telephone InquiriesTelephone inquiries to AWS Headquarters concern-

ing AWS standards should be limited to questions of ageneral nature or to matters directly related to the use ofthe standard. The Board of Directors’ policy requires thatall AWS staff members respond to a telephone requestfor an official interpretation of any AWS standard with

the information that such an interpretation can beobtained only through a written request. The Headquar-ters staff cannot provide consulting services. The staffcan, however, refer a caller to any of those consultantswhose names are on file at AWS Headquarters.

C6. The AWS Technical CommitteeThe activities of AWS Technical Committees in regard

to interpretations, are limited strictly to the Interpretationof provisions of standards prepared by the Committee orto consideration of revisions to existing provisions on thebasis of new data or technology. Neither the committeenor the staff is in a position to offer interpretive or con-sulting services on: (1) specific engineering problems; or(2) requirements of standards applied to fabrications out-side the scope of the document or points not specificallycovered by the standard. In such cases, the inquirer shouldseek assistance from a competent engineer experienced inthe particular field of interest.



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AWS D3.7:2004

73

List of AWS Documents on Welding Marine Construction

Designation Title

D3.5 Guide for Steel Hull Welding

D3.6 Specification for Underwater Welding

D3.7 Guide for Aluminum Hull Welding

Additional Documents of Fundamental Subject Matter

A1.1 Metric Practice Guide for the Welding Industry

A2.4 Standard Symbols for Welding, Brazing, and Nondestructive Examination

A3.0 Standard Welding Terms and Definitions

B2.1 Standard for Welding Procedure and Performance Qualification

B4.0 Standard Methods for Mechanical Testing of Welds

For ordering information, contact Global Engineering Documents, an Information Handling Services (IHS) Groupcompany, 15 Inverness Way East, Englewood, Colorado 80112-5776; telephones: (800) 854-7179, (303) 397-7956; fax(303) 397-2740; Internet: www.global.ihs.com.



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