AWS A5.12.pdf

AWS A5.12M/A5.12:2009 (ISO 6848:2004 MOD) An American National Standard

Specification for Tungs ungsten ten and Oxide Dispersed Tungsten Electrodes for Arc Welding and Cutting

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Copyright American Welding Society Provided by IHS under license with AWS No reproduction or networking permitted without license from I HS

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AWS AWS A5.12M/A5.12:2009 (ISO 6848:2004 6 848:2004 MOD) An American National Standard Approved by the American National Standards Institute April 17, 2009

Specification for Tungsten and Oxide Dispersed Tungsten Electrodes Electrodes for Arc Welding and Cutting

7th Edition

Supersedes ANSI/AWS A5.12/A5.12M-98

Prepared by the American Welding Welding Society (AWS) A5 Committee on Filler Metals and Allied Materials Under the Direction of the AWS Technical Activities Committee Approved by the AWS Board of Directors

Abstract This specification prescribes the requirements for the classification of bare tungsten and oxide dispersed tungsten electrodes for gas tungsten arc welding and cutting and plasma arc welding and cutting. Classification is based upon the chemical composition of the electrode. Standard sizes, finish, lengths, quantities, product identification, color coding, and chemical composition limits are specified. This specification makes use of both U.S. Customary Units and the International System of Units (SI). Since these are not equivalent, each system must be used independently of the other. This specification adopts the requirements of ISO 6848:2004 and incorporates the provisions of earlier versions of AWS A5.12, allowing for classifications classifications under both specifications.

550 N.W. LeJeune Road, Miami, FL 33126 Copyright American Welding Society Provided by IHS under license with AWS No reproduction or networking permitted without license from I HS


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AWS AWS A5.12M/A5.12:2009 (ISO 6848:2004 6 848:2004 MOD) An American National Standard Approved by the American National Standards Institute April 17, 2009

Specification for Tungsten and Oxide Dispersed Tungsten Electrodes Electrodes for Arc Welding and Cutting

7th Edition

Supersedes ANSI/AWS A5.12/A5.12M-98

Prepared by the American Welding Welding Society (AWS) A5 Committee on Filler Metals and Allied Materials Under the Direction of the AWS Technical Activities Committee Approved by the AWS Board of Directors

Abstract This specification prescribes the requirements for the classification of bare tungsten and oxide dispersed tungsten electrodes for gas tungsten arc welding and cutting and plasma arc welding and cutting. Classification is based upon the chemical composition of the electrode. Standard sizes, finish, lengths, quantities, product identification, color coding, and chemical composition limits are specified. This specification makes use of both U.S. Customary Units and the International System of Units (SI). Since these are not equivalent, each system must be used independently of the other. This specification adopts the requirements of ISO 6848:2004 and incorporates the provisions of earlier versions of AWS A5.12, allowing for classifications classifications under both specifications.

550 N.W. LeJeune Road, Miami, FL 33126 Copyright American Welding Society Provided by IHS under license with AWS No reproduction or networking permitted without license from I HS


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AWS A5.12M/A5.12:2009 (ISO 6848:2004 MOD)

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International Standard Book Number: 978-0-87171-747-4 American Welding Society 550 N.W. LeJeune Road, Miami, FL 33126 © 2009 by American Welding Society All rights reserved Printed in the United States of America Photocopy Rights. No Rights. No portion of this standard may be reproduced, stored in a retrieval system, or transmitted in any form, including mechanical, photocopying, photocopying, recording, or otherwise, without the prior written permission of the copyright owner. Authorization to photocopy items for internal, personal, or educational classroom use only or the internal, personal, or educational classroom use only of specific clients is granted by the American Welding Society provided that the appropriate fee is paid to the Copyright Clearance Center, 222 Rosewood Drive, Danvers, Danvers, MA 01923, tel: (978) 750-8400; Internet: .

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AWS A5.12M/A5.12:2009 (ISO 6848:2004 MOD)

Statement on the Use of American Welding Society Standards All standards (codes, specifications, recommended practices, methods, classifications, and guides) of the American Welding Society (AWS) are voluntary consensus standards that have been developed in accordance with the rules of the American National Standards Institute (ANSI). When AWS American National 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 be approved by the governmental body having statutory jurisdiction before they can become a part of those laws and regulations. In all cases, these standards carry the full legal authority of the contract or other document that invokes the AWS standards. Where this contractual relationship exists, changes in or deviations from requirements of an AWS standard must be by agreement between the contracting parties. AWS American National Standards are developed through a consensus standards development process that brings together volunteers representing varied viewpoints and interests to achieve consensus. While the AWS administers the process and establishes rules to promote fairness in the development of consensus, it does not independently test, evaluate, or verify 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 special, indirect, consequential, or compensatory, directly or indirectly resulting from the publication, use of, or reliance on this standard. AWS also makes no guarantee or warranty as to the accuracy or completeness of any information published herein. In issuing and making this standard available, AWS is neither undertaking to render professional or other services for or on behalf of any person or entity, nor is AWS undertaking to perform any duty owed by any person or entity to someone else. Anyone using these documents should rely on his or her own independent judgment or, as appropriate, seek the advice of a competent professional in determining the exercise of reasonable care in any given circumstances. It is assumed that the use of this standard and its provisions are entrusted to appropriately qualified and competent personnel. This standard may be superseded by the issuance of new editions. Users should ensure that they have the latest edition. Publication of this standard does not authorize infringement of any patent or trade name. Users of this standard accept any and all liabilities for infringement of any patent or trade name items. AWS disclaims liability for the infringement of any patent or product trade name resulting from the use of this standard. Finally, the 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 posted on the AWS web page (www.aws.org).

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Official interpretations of any of the technical requirements of this standard may only be obtained by sending a request, in writing, to the appropriate technical committee. Such requests should be addressed to the American Welding Society, Attention: Managing Director, Technical Services Division, 550 N.W. LeJeune Road, Miami, FL 33126 (see Annex C). With regard to technical inquiries made concerning AWS standards, oral opinions on AWS standards may be rendered. These opinions are offered solely as a convenience to users of this standard, and they do not constitute professional advice. Such opinions represent only the personal opinions of the particular individuals giving them. These individuals do not speak on behalf of AWS, nor do these oral opinions constitute official or unofficial opinions or interpretations 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 A5 Committee on Filler Metals and Allied Materials. It must be reviewed every five years, and if not revised, it must be either reaffirmed or withdrawn. Comments (recommendations, additions, or deletions) and any pertinent data that may be of use in improving this standard are required and should be addressed to AWS Headquarters. Such comments will receive careful consideration by the AWS A5 Committee on Filler Metals and Allied Materials and the author of the comments will be informed of the Committee’s response to the comments. Guests are invited to attend all meetings of the AWS A5 Committee on Filler Metals and Allied Materials to express their comments verbally. Procedures for appeal of an adverse decision concerning all such comments are provided in the Rules of Operation of the Technical Activities Committee. A copy of these Rules can be obtained from the American Welding Society, 550 N.W. LeJeune Road, Miami, FL 33126.

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AWS A5.12M/A5.12:2009 (ISO 6848:2004 MOD)

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AWS A5.12M/A5.12:2009 (ISO 6848:2004 MOD)

Personnel AWS A5 Committee on Filler Metals and Allied Materials Chevron Arcos Industries, LLC Naval Surface Warfare Center American Welding Society ESAB Welding and Cutting Products Department of the Navy RSB Alloy Applications, LLC Hobart Brothers Company The Lincoln Electric Company Consultant ESAB Welding and Cutting Products Consultant The Lincoln Electric Company Foster Wheeler North America ESAB Welding and Cutting Products The Lincoln Electric Company Naval Surface Warfare Center Böhler Welding Group USA, Incorporated Lucas-Milhaupt, Incorporated Deltak J. W. Harris Company, Incorporated Special Metals Concurrent Technologies Corporation Damian Kotecki Welding Consultants Northrop Grumman Ship Systems Canadian Welding Bureau Consultant Chrysler LLC The Lincoln Electric Company Stoody Company HyperTech Research, Incorporated ABS Americas Materials Department Polymet Corporation Siemens Power Generation, Incorporated Consultant Consultant Wall Colmonoy Corporation Hydril Company Consultant Det Norske Veritas (DNV) Consultant ESAB Welding and Cutting Products NASSCO—National Steel and Shipbuilding ATI Wah Chang

J. S. Lee, Chair H. D. Wehr, 1st Vice Chair J. J. DeLoach, Jr. 2nd Vice Chair R. K. Gupta, Secretary T. Anderson J. M. Blackburn R. S. Brown J. C. Bundy D. D. Crockett D. A. DelSignore J. DeVito H. W. Ebert D. M. Fedor J. G. Feldstein S. E. Ferree D. A. Fink G. L. Franke R. D. Fuchs C. E. Fuerstenau J. A. Henning R. M. Henson S. D. Kiser P. J. Konkol D. J. Kotecki L. G. Kvidahl A. Y. Lau A. S. Laurenson W. A. Marttila T. Melfi R. Menon M. T. Merlo D. R. Miller B. Mosier A. K. Mukherjee C. L. Null M. P. Parekh R. L. Peaslee K.C. Pruden S. D. Reynolds, Jr. P. K. Salvesen K. Sampath W. S. Severance M. J. Sullivan R. C. Sutherlin

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AWS A5.12M/A5.12:2009 (ISO 6848:2004 MOD)

AWS A5 Committee on Filler Metals and Allied Materials (Continued) Euroweld, Limited Care Medical, Incorporated U.S. Steel Corporation

R. A. Swain K. P. Thornberry M. D. Tumuluru

Advisors to the AWS A5 Committee on Filler Metals and Allied Materials R. L. Bateman R. A. Daemen J. P. Hunt S. Imaoka M. A. Quintana E. R. Stevens E. S. Surian

Electromanufacturas, S. A. La Grande Tuiliere Consultant Kobe Steel Limited The Lincoln Electric Company Stevens Welding Consulting National University of Lomas de Zamora

AWS A5I Subcommittee on Tungsten Electrodes W. S. Severance, Chair R. K. Gupta, Secretary S. G. Caldwell M. E. Gedgaudas R. A. Swain

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ESAB Welding and Cutting Products American Welding Society ATI Firth Sterling Arc Machines, Incorporated Euroweld, Limited

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AWS A5.12M/A5.12:2009 (ISO 6848:2004 MOD)

Foreword This foreword is not part of AWS A5.12M/A5.12:2009 (ISO 6848:2004 MOD), Specification for Tungsten and Oxide Dispersed Tungsten Electrodes for Arc Welding and Cutting , but is included for informational purposes only.

This document is the first AWS adoption of ISO 6848:2004, Arc welding and cutting — Nonconsumable tungsten electrodes — Classification. With its insertion of references and additional informative annexes it replaces ANSI/AWS A5.12/A5.12M-98, Specification for Tungsten and Tungsten-Alloy Electrodes for Arc Welding and Cutting . The “MOD” in the designation of this document shows that this is a modified adoption of the ISO document. All changes are listed in Annex D. The modifications to ISO 6848:2004 are shown in Italic font. Color code for classification EWCe-2 has been changed from orange to grey. Color code for classification EWG used to be grey, but now the manufacturer may select any color for this classification not already in use. Please note that ISO uses commas (,) and AWS uses periods (.) for decimals. The ISO decimal commas have been replaced by periods in this document for consistency.

Document Development The current document is the sixth revision of the initial AWS/ASTM document issued in 1 955. The evolution took place as follows: ASTM B297-55T AWS A5.12-55T

Tentative Specifications for Tungsten Arc-Welding Electrodes

ASTM B297-65T AWS A5.12-65T

Tentative Specifications for Tungsten Arc-Welding Electrodes

ANSI/AWS A5.12-69 W3.12-73

Specification for Tungsten Arc-Welding Electrodes

ANSI/AWS A5.12-80

Specification for Tungsten Arc Welding Electrodes

ANSI/AWS A5.12-92

Specification for Tungsten and Tungsten Alloy Electrodes for Arc Welding and Cutting

ANSI/AWS A5.12/A5.12M-98 Specification for Tungsten and Tungsten Alloy Electrodes for Arc Welding and Cutting Attention is drawn to the possibility that some of the elements of this part of ISO 6848 may be the subject of patent rights. AWS and ISO shall not be held responsible for identifying any or all such patent rights. Comments and suggestions for the improvement of this standard are welcome. They should be sent to the Secretary, AWS A5 Committee on Filler Metals and Allied Materials, American Welding Society, 550 N.W. LeJeune Road, Miami, FL 33126.

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AWS A5.12M/A5.12:2009 (ISO 6848:2004 MOD)

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AWS A5.12M/A5.12:2009 (ISO 6848:2004 MOD)

Table of Contents Page No. Personnel ......................................................................................................................................................................v Foreword .....................................................................................................................................................................vii List of Tables.................................................................................................................................................................x List of Figures ...............................................................................................................................................................x

1. Scope.....................................................................................................................................................................1 2. Normative references ..........................................................................................................................................1 3. Classification ........................................................................................................................................................2 4. Acceptance ...........................................................................................................................................................2 5. Chemical analysis ................................................................................................................................................2 6. Retest ....................................................................................................................................................................2 7. Marking................................................................................................................................................................2

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8. Standard sizes and tolerances ............................................................................................................................8 8.1 Electrode diameters, lengths, and tolerances...............................................................................................8 8.2 Finish ...........................................................................................................................................................9 8.3 Electrode straightness..................................................................................................................................9 8.4 Electrode roundness.....................................................................................................................................5 9. Rounding-off procedure......................................................................................................................................5 10. Electrode quality..................................................................................................................................................5 11. Packaging .............................................................................................................................................................5 11.1 Marking of packages....................................................................................................................................5 11.2 Packing ........................................................................................................................................................ 6 11.3 Marking of overpacking...............................................................................................................................6 11.4 Warning label...............................................................................................................................................6 Annex A (informative)—Conditions of use .............................. ............... .............................. ................ ............... ....... 7 National Annexes Annex B (Informative)— Guide to AWS Specification for Tungsten and Oxide Dispersed Tungsten Annex B (Informative)— Electrodes for Arc Welding and Cutting ............................................................................11 Annex C (Informative)—Guidelines for the Preparation of Technical Inquiries ............... ............... ............... .......... 19 Annex D (Informative)—List of Deviations from ISO 6848:2004............................. ............................. ................ .. 21 AWS Filler Metal Specifications by Material and Welding Process............................... .............................. ............. 23 AWS Filler Metal Specifications and Related Documents.........................................................................................25

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AWS A5.12M/A5.12:2009 (ISO 6848:2004 MOD)

List of Tables Table 1 2 A.1 A.2

Page No. Chemical composition requirements for tungsten electrodes .......................................................................3 Standard diameters and lengths ....................................................................................................................4 Suitability of current supply type.................................................................................................................. 7 Approximate current ranges depending upon the electrode diameter ..........................................................9

List of Figures Figure 1

Page No. Measurement procedure for straightness ......................................................................................................5

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AWS A5.12M/A5.12:2009 (ISO 6848:2004 MOD)

Specification for tungsten and oxide dispersed tungsten electrodes for arc welding and cutting

1 Scope This standard specifies requirements for classification of nonconsumable tungsten electrodes for inert gas shielded arc welding, and for plasma welding, cutting, and thermal spraying. This specification makes use of both International System of Units (SI) and the U.S. Customary Units. The measurements are not exact equivalents; therefore, each system must be used independently of the other without combining in any way when referring to material properties. The specification designated A5.12M uses SI Units; and the specification designated A5.12 uses U.S. Customary Units. The later units are shown within brackets [ ] or in appropriate columns in tables and figures. Standard dimensions based on either system may be used for sizing of tungsten electrodes or packaging or both under A5.12M or A5.12 specification.

2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. 2.1 The following AWS standard 1 is referenced in the mandatory sections of this document:

AWS A5.01M/A5.01 (ISO 14344 MOD), Procurement Guidelines for Consumables—Welding and Allied Processes—Flux and Gas Shielded Electrical Welding Processes 2.2 The following ANSI standard 2 is referenced in the mandatory sections of this document:

ANSI Z49.1, Safety in Welding, Cutting, and Allied Processes 2.3 The following ASTM standards 3 are referenced in the mandatory sections of this document:

ASTM E 29, Standard Practice for using Significant Digits in Test Data to Determine Conformance with Specifications ASTM F 288, Standard Specification for Tungsten Wire for Electron Devices and Lamps 2.4 The following ISO standard 4 is referenced in the mandatory sections of this document:

ISO 31-0:1992, Quantities and units — Part 0: General principles; and Annex B, Rule A 1 AWS

standards are published by the American Welding Society, 550 N.W. LeJeune Road, Miami, FL 33126. ANSI standard is published by the American Welding Society, 550 N.W. LeJeune Road, Miami, FL 33126. 3 ASTM standards are published by the American Society for Testing and Materials, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959. 4 ISO standards are published by the International Organization for Standardization, 1, rue de Varembé, Case postale 56, CH-1211 Geneva 20, Switzerland. 2 This

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AWS A5.12M/A5.12:2009 (ISO 6848:2004 MOD)

3 Classification 3.1 Classification of a tungsten electrode is based upon its chemical composition. 3.2 The tungsten and oxide dispersed tungsten electrodes covered by this specification are classified using a system that is independent of the U.S. Customary Units and the International System of Units (SI). Classification is according to the chemical composition of the electrode as specified in Table 1. See Clause B7 for classification descriptions. 3.3 Electrodes classified under one classification shall not be classified under any other classification in this specification. 3.4 No electrode meeting the requirements of any other classification, shall be classified under EWG. 3.5 The electrodes classified under this specification are intended for gas tungsten arc welding (GTAW), gas tungsten arc cutting (GTAC), plasma arc welding (PAW), or plasma arc cutting (PAC), but that is not to prohibit their use with any other process for which they are found suitable.

See Clause B2 for an explanation of the classification system.

4 Acceptance Acceptance of the electrodes shall be in accordance with the provisions of AWS A5.01M:A5.01 (ISO 14344 MOD). See Annex Clause B3 for further information concerning acceptance and testing of material shipped.

5 Chemical analysis Chemical analysis shall be performed on specimens of the electrode being classified. Any analytical technique may be used but, in cases of dispute, reference shall be made to established published methods. The referee method shall be ASTM F 288. The results of the analysis shall meet the requirements of Table 1 for the classification of electrode under test.

6 Retests If any test fails to meet the requirement, that test shall be repeated twice. The results of both retests shall meet the requirements. Specimens for retesting may be taken from the original test sample or from a new test sample. For chemical analysis, retests need only be for those specific elements that failed to meet their test requirement. If the results of one or both retests fail to meet the requirement, the material under test shall be considered as not meeting the requirements of this speci fication for that classification.

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In the event that, during preparation or after completion of any test, it is clearly determined that prescribed or proper procedures were not followed in preparing the test specimen, or in conducting the tests, the test shall be considered invalid, without regard to whether the test was actually completed, or whether the test results met, or failed to meet, the requirement. That test shall be repeated, following proper prescribed procedures. In this case, the requirement for doubling the number of test specimens does not apply.

7 Marking In accordance with Table 1, tungsten electrodes shall be marked on the basis of their chemical composition, with one color ring near one end of the electrode. The width of the color ring shall be at least 3 mm [1/8 in]. Such color coding shall have no adverse effect on the operation or use of the electrode. Alternatively, tungsten electrodes may have their classification symbols marked on the surface of the electrode near at least one end of the electrode.



AWS A5.12M/A5.12:2009 (ISO 6848:2004 MOD)

Table 1 — Chemical composition requirements for tungsten electrodes Classification symbol (ISO 6848 Classification)

Chemical composition requirements Oxide addition

Tungsten, mass percent

Colour code, RGB colour value and colour samplea

Principal oxide

Mass percent

EWP (WP)

None

bN.A.b

0.5 max.

99.5 min.

Green #008000

EWCe-2 (WCe 20)

CeO2

1.8 to 2.2

0.5 max.

Balance

Grey (formerly orange) #808080

EWLa-1 (WLa 10)

La2O2

0.8 to 1.2

0.5 max.

Balance

Black #000000

Balance

Gold #FFD700

EWLa-1.5 (WLa 15)

La2O2

1.3 to 1.7

0.5 max.

EWLa-2 (WLa 20)

La2O2

1.8 to 2.2

0.5 max.

Balance

Blue #0000FF

EWTh-1 (WTh10)

ThO2

0.8 to 1.2

0.5 max.

Balance

Yellow #FFFF00

Balance

Red #FF0000

Balance

Violet #EE82EE

EWTh-2 (WTh 20)

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Impurities, mass percent

ThO2

(WTh 30)

ThO2

1.7 to 2.2

0.5 max.

2.8 to 3.2

0.5 max.

EWZr-1 (WZr 3)

ZrO2

0.15 to 0.50

0.5 max.

Balance

Brown #A52A2A

EWZr-8 (WZr 8)

ZrO2

0.7 to 0.9

0.5 max.

Balance

White #FFFFFF

EWG

The manufacturer must identify all additions.

The manufacturer must state the nominal quantity of each addition.

0.5 max.

Balance

The manufacturer may select any color not already in use.

NOTE Intentional additions of “doping oxides” other than indicated for a particular electrode classification is prohibited. a b

RGB color values and color samples can be found at the following website: http://msdn2.microsoft.com/en-us/library/ms531197.aspx N.A. = Not applicable.

8 Standard sizes and tolerances 8.1 Electrode diameters, lengths and tolerances Standard electrode diameters, lengths , and tolerances are given in Table 2. Other diameters, lengths , and tolerances may be as agreed upon between the purchaser and supplier.



AWS A5.12M/A5.12:2009 (ISO 6848:2004 MOD)

Table 2 — Standard diameters and lengths Size

a b

Length

Diameter mm

Tolerance ±mm

Diameter in

Tolerance ±in

Length mm

Tolerance mm

0.25b

0.02

0.010

0.001

50b

±1.5

0.30b

0.02

75b

0.50b

0.05

0.020

0.002

1.00b

0.05

0.040

1.50b

0.05

a0.060a

1.60b

Length in

Tolerance ±in

-1.0, +2.5

3

1/16

150b

-1.0, +4.0

6

1/16

0.002

175b

-1.0, +6.0

7

1/8

0.002

300b

-1.0, +8.0

12

1/8

0.05

450b

-1.0, +8.0

18

1/8

2.00b

0.05

600b

-1.0, +13.0

24

1/8

2.40b

0.08

2.50b

0.08

3.00b

0.10

3.20b

0.093 (3/32)

0.003

0.10

0.125 (1/8)

0.003

4.00b

0.10

0.156 (5/32)

0.003

4.80b

0.10

0.187 (3/16)

0.003

5.00b

0.10

6.30b

0.10

6.40b

0.10

0.250 (1/4)

0.003

8.00b

0.10

10.00b

0.10

Although the metric size 1.6 mm [0.063 in] is closer to 1/16 in [0.0625 in], it has been common industry practice to refer to the U.S. customary size 0.060 in as 1/16 in. Standard sizes and lengths in ISO 6848, though tolerances may be tighter in some cases.

8.2 Finish Electrodes shall be supplied with a ground finish. The ground finish designates that the electrode has been cleaned of impurities after it has been centerless ground to a uniform size. It shall be supplied with a bright, polished surface. The maximum surface roughness shall be 0.8 µmRa [32 µin AARH].

8.3 Electrode straightness The electrodes shall be straight such that any element of its surface, over a specified length, must lie between two parallel lines of a specified spacing where the two lines and the nominal axis of the electrode share a common plane, as shown in Figure 1. The specified spacing is 0.5 mm [0.020 in] over a length of 100 mm [4 in].

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AWS A5.12M/A5.12:2009 (ISO 6848:2004 MOD)

Figure 1 — Measurement procedure for straightness

8.4 Electrode roundness Electrodes shall fit through ring gages sized for their maximum allowable diameter according to Table 2.

9 Rounding-off procedure For purposes of determining compliance with the requirements of this Standard, the actual test values obtained shall be subjected to the rounding-off rules of ISO 31-0:1992, Annex B, Rule A or ASTM E 29. If the measured values are obtained by equipment calibrated in units other than those of this Standard, the measured values shall be converted to the units of this Standard before rounding off. If an average value is to be compared to the requirements of this Standard, rounding-off shall be done only after calculating the average. In the case where the testing standard cited in the normative references of this Standard contains instructions for rounding off that conflict with the instructions of this Standard, the rounding-off requirements of the testing standard shall apply. The rounded-off results shall fulfill the requirements of the appropriate table for the classification under test.

10 Electrode quality The electrode surface shall be free of impurities, undesirable films, foreign inclusions, slivers, cracks, scale and other defects. Electrodes shall be internally free of foreign inclusions or anything else that would adversely affect the operation of the electrode. Oxide additions shall be sufficiently uniformly distributed throughout the electrode so that the operation of the electrode is not adversely affected.

11 Packaging 11.1 Marking of packages The following information, as a minimum, shall be legibly marked so as to be visible from the outside of each package: a) the number of this Standard, i.e., AWS A5.12M/A5.12:2009 (ISO 6848:2004 MOD); ` ` ` , ` , ` , ` ` , ` ` , ` , , ` ` ` ` ` , ` , ` , , , ` ` , , ` , , ` , ` , , ` -

b) electrode classification symbol in accordance with Table 1; c) electrode diameter; d) electrode length; e) net quantity of electrodes; f) supplier’s name and trade designation; g) lot, control, or heat number.



AWS A5.12M/A5.12:2009 (ISO 6848:2004 MOD)

11.2 Packing Tungsten electrodes shall be packed so that their surfaces are protected from all damage or staining when they are properly transported and stored.

11.3 Marking of overpacking Marking of any, or all, overpacking of unit packages with items listed in 11.1 shall be optional with the manufacturer.

11.4 Warning label The appropriate precautionary information 5 as given in ANSI Z49.1, latest edition (as a minimum) or its equivalent, shall be prominently dispayed in legible print on all packages of electrodes, including individual unit packages enclosed within a larger package.

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5 Typical

examples of “warning labels” are shown in figures in ANSI Z49.1 for some common or specific consumables used with certain processes.



AWS A5.12M/A5.12:2009 (ISO 6848:2004 MOD)

Annex A (informative)

Conditions of use

A.1 Influence of the type of current A.1.1 General The electric arc may be supplied with either direct current or alternating current. Table A.1 indicates which type of current is generally more suitable to the type of metal or alloy to be welded.

A.1.2 Direct current supply The arc behavior is different depending on whether the electrode is connected to the positive or negative terminal of the power source. With electrode positive (d.c. +) polarity, there is greater output heat at the electrode and less penetration of the work than with electrode negative (d.c. −) polarity. The current-carrying capacity of an electrode of a given size wi ll therefore be lower wit h positive polarity than wi th negative polarity.

A.1.3 Alternating current supply With alternating current (a.c.) supply, the current changes direction each half-cycle. The arc alternates between electrode positive polarity and electrode negative polarity. The current-carrying capacity of an electrode is then less than when it is used with electrode negative polarity, but greater than when it is used with electrode positive polarity.

Table A.1 — Suitability of current supply type Direct current Type of metal or alloy to be welded

Alternating current

Electrode negative (–)

Electrode positive (+)

Aluminium and its alloys, thickness ≤ 2.5 mm [0.10 in]

Acceptable

Acceptable

Best

Aluminium and its alloys, thickness > 2.5 mm [0.10 in]

Acceptable

aN.R.a

Best

Magnesium and its alloys

N.R.

Acceptable

Best

Non-alloy (carbon) steels and low alloy steels

Best

N.R.

N.R.

Stainless steels

Best

N.R.

N.R.

Copper

Best

N.R.

N.R.

Bronze

Best

N.R.

Acceptable

Acceptable

N.R.

Best

Silicon bronze

Best

N.R.

N.R.

Nickel and its alloys

Best

N.R.

Acceptable

Titanium and its alloys

Best

N.R.

Acceptable

Aluminium bronze

a

N.R. = Not recommended.



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A.2 Arc amperage The electrode size should be selected so that the current value is high enough for the arc to cover the whole area of the electrode tip, which is then heated up to a temperature approaching its melting temperature. If the current is too low for the electrode size selected, the arc may be erratic. If, however, the current is too high, it will cause the electrode to overheat and its tip to melt. Drops of molten tungsten may fall into the weld, and the arc will become erratic and unstable. Table A.2 provides recommended current ranges depending on the type of power supply and electrode diameter. A high current value provides, in addition to a more stable arc, a higher concentration of heat, but this is limited depending on the conditions of use. An adequate degree of taper of the electrode tip with d.c.-polarity permits improvement of these conditions; e.g., the degree of taper of the electrode tip should be chosen according to the current used. A more obtuse angle is recommended at higher currents for a given electrode diameter. Tungsten electrodes when used with alternating current or with direct current positive polarity will form a molten ball on the arcing end of the electrode. A pure tungsten electrode may produce tungsten inclusions in the weld when used on a.c. or d.c.+ without having accurate control of amperage and arc length. The use of zirconiated tungsten will alleviate this problem. Many modern a.c. welding power supplies allow the balance between the d.c.+ and d.c.– portions of the current cycle to be varied. When the d.c.+ portion of the cycle is increased relative to the d.c.– portion, the recommended average current is decreased somewhat from the ranges given in Table A.2. Conversely, when the d.c.– portion is increased relative to the d.c.+ portion, the recommended average a.c. current is increased somewhat from the ranges given in Table A.2.

A.3 Further remarks The choice of an electrode type and size and of the welding current is influenced by the type and thickness of the parent metal to be welded or cut. The capacity of tungsten electrodes to carry current is dependent upon a number of other factors, in particular, the type of equipment used (gas- or water-cooled), the extension of the electrode beyond the nozzle and the welding position used. An electrode of a given size will have its greatest current-carrying capacity with direct current, electrode negative; less with alternating current, and still less with direct current, electrode positive. Table A.2 lists some typical current values that may be used with argon shielding. However, the other factors mentioned above should be carefully considered before selecting an electrode for a specific application.

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AWS A5.12M/A5.12:2009 (ISO 6848:2004 MOD)

Table A.2 — Approximate current ranges depending upon the electrode diametera

Electrode diameter

Direct current A Electrode negative (–)

Alternating current A

Electrode positive (+)

mm

in

Pure tungsten

Tungsten with oxide additives

Pure tungsten


Pure tungsten


0.25

0.010

up to 15

up to 15

not applicable

not applicable

up to 15

up to 15

up to 15

up to 15

not applicable

not applicable

up to 15

up to 15

0.30 0.50

0.020

2 to 20

2 to 20

not applicable

not applicable

2 to 15

2 to 15

1.0

0.040

10 to 75

10 to 75

not applicable

not applicable

15 to 55

15 to 70

1.5

0.060

60 to 150

60 to 150

10 to 20

10 to 20

45 to 90

60 to 125

1.6

60 to 150

60 to 150

10 to 20

10 to 20

45 to 90

60 to 125

2.0

75 to 180

100 to 200

15 to 25

15 to 25

65 to 125

85 to 160

120 to 220

150 to 250

15 to 30

15 to 30

80 to 140

120 to 210

2.5

130 to 230

170 to 250

17 to 30

17 to 30

80 to 140

120 to 210

3.0

150 to 300

210 to 310

20 to 35

20 to 35

140 to 180

140 to 230

2.4

0.093 (3/32)

3.2

0.125 (1/8)

160 to 310

225 to 330

20 to 35

20 to 35

150 to 190

150 to 250

4.0

0.156 (5/32)

275 to 450

350 to 480

35 to 50

35 to 50

180 to 260

240 to 350

4.8

0.187 (3/16)

380 to 600

480 to 650

50 to 70

50 to 70

240 to 350

330 to 450

5.0

400 to 625

500 to 675

50 to 70

50 to 70

240 to 350

330 to 460

6.3

550 to 875

650 to 950

65 to 100

65 to 100

300 to 450

430 to 575

575 to 900

750 to 1 000

70 to 125

70 to 125

325 to 450

450 to 600

6.4

0.250 (1/4)

8.0

650 to 830

10.0 NOTE a

If no value is given, no recommendation is available.

The current values are based on the use of argon gas, and these values may vary depending on the type of shielding gas, type of equipment, and application.

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National Annexes

Annex B (Informative) Guide to AWS Specification for Tungsten and Oxide Dispersed Tungsten Electrodes for Arc Welding and Cutting This annex is not part of AWS A5.12M/A5.12:2009 (ISO 6848:2004), Specification for Tungsten and Oxide Dispersed Tungsten Electrodes for Arc Welding and Cutting, but is included for informational purposes only.

B1. Introduction B1.1 The purpose of this guide is to correlate the electrode classifications with their intended applications so the specification can be used effectively. B1.2 Tungsten electrodes are nonconsumable in that they do not intentionally become part of the weld metal as doelectrodes used as filler metals. The function of a tungsten electrode is to serve as one of the terminals of an arc which supplies the heat required for welding or cutting.

B2. Classification B2.1 The system for identifying the electrode classifications in this specification follows the standard pattern used in other AWS filler metal specifications. The letter “E” at the beginning of the classification designation stands for electrode. The “W” indicates that the electrode is primarily tungsten. The “P” indicates that the electrode is essentially pure tungsten and contains no intentionally added emission enhancing elements. The “Ce,” “La,” “Th,” and “Zr” indicate that the electrode is doped with oxides of cerium, lanthanum, thorium, or zirconium, respectively. The numeral at the end of some of the classifications indicates a different chemical composition level or product within a specific group. B2.2 “G” Classification B2.2.1 This specification includes electrodes classified as EWG. The “G” indicates that the electrode is of a general classification. It is “general” because not all of the particular requirements specified for each of the other classifications are specified for this classification. The intent in establishing this classification is to provide a means by which electrodes that differ in one respect or another (chemical composition, for example) from other classifications (meaning that the composition of the electrode—in the case of this example—does not meet the composition specified for any of the classifications in the specification) can still be classified according to the specification. The purpose is to allow a useful electrode—one that otherwise would have to await a revision of the specification—to be classified immediately, under the existing specification. This means, then, that two electrodes—each bearing the same “G” classification—may be quite different in some certain respect. To prevent the confusion that this situation could create, this specification requires the manufacturer to identify, on the label, the type and nominal content of each doping addition made in the particular product.



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B2.2.2 Request for Electrode Classification (1) When an electrode cannot be classified according to some classification other than a “G” classification, the manufacturer may request that a classification be established for that electrode. The manufacturer may do this by following the procedure given here. When the manufacturer elects to use the “G” classification, the A5 Committee on Filler Metals and Allied Materials recommends that the manufacturer still request that a classification be established for that electrode, as long as the electrode is of commercial significance. (2) A request to establish a new electrode classification must be a written request, and it needs to provide sufficient detail to permit the A5 Committee on Filler Metals and Allied Materials or the Subcommittee to determine whether the new classification or the modification of an existing classification is more appropriate, and whether either is necessary to satisfy the need. In particular, the request needs to include: (a) All classification requirements as given for existing classifications, such as, chemical composition ranges, mechanical property requirements, and usability test requirements. (b) Any conditions for conducting the tests used to demonstrate that the product meets the classification requirements. (It would be sufficient, for example, to state that welding conditions are the same as for other classifications.) (c) Information on Descriptions and Intended Use, which parallels that for existing classifications, for that clause of the Annex. (d) A request for a new classification without the above information will be considered incomplete. The Secretary will return the request to the requester for further information. (3) The request should be sent to the Secretary of the A5 Committee on Filler Metals and Allied Materials at AWS Headquarters. Upon receipt of the request, the Secretary will: (a) Assign an identifying number to the request. This number will include the date the request was received. (b) Confirm receipt of the request and give the identification number to the person who made the request. (c) Send a copy of the request to the Chair of the A5 Committee on Filler Metals and Allied Materials and the Chair of the particular Subcommittee involved. (d) File the original request. (e) Add the request to the log of outstanding requests. (4) All necessary action on each request will be completed as soon as possible. If more than 12 months lapse, the Secretary shall inform the requestor of the status of the request, with copies to the Chairs of the Committee and of the Subcommittee. Requests still outstanding after 18 months shall be considered not to have been answered in a “timely manner” and the Secretary shall report these to the Chair of the Committee on Filler Metals and Allied Materials, for action. (5) The Secretary shall include a copy of the log of all requests pending and those completed during the preceding year with the agenda for each Committee on Filler Metals and Allied Materials meeting. Any other publication of requests that have been completed will be at the option of the American Welding Society, as deemed appropriate.

B3. Acceptance Acceptance of all welding materials classified under this specification is in accordance with AWS A5.01M/A5.01 (ISO 14344 MOD), as the specification states. Any testing a purchaser requires of the supplier, for material shipped in accordance with this specification, shall be clearly stated in the purchase order, according to the provisions of AWS A5.01M/A5.01 (ISO 14344 MOD). In the absence of any such statement in the purchase order, the supplier may ship the material with whatever testing is normally conducted on material of that classification, as specified in Schedule F, Table 1, of AWS A5.01M/A5.01 (ISO 14344 MOD). Testing in accordance with any other Schedule in that Table must be specifically required by the purchase order. In such cases, acceptance of the material shipped will be in accordance with those requirements.

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AWS A5.12M/A5.12:2009 (ISO 6848:2004 MOD)

B4. Certification The act of placing the AWS specification and classification designations on the packaging enclosing the product, or the classification identification on the product itself, constitutes the supplier's (manufacturer's) certification that the product meets all of the requirements of the specification. The only testing requirement implicit in this certification is that the manufacturer has actually conducted the test required by the specification on material that is representative of that being shipped, and that that material met the requirements of the specification. Representative material, in this case, is any production run of that classification using the same formulation. “Certification” is not to be construed to mean that tests of any kind were necessarily conducted on samples of the specific material shipped. Tests on such material may, or may not, have been conducted. The basis for the “certification” required by the specification is the classification test of “representative material” cited above, and the “Manufacturer’s Quality Assurance Program” in AWS A5.01M/A5.01 (ISO 14344 MOD). Electrodes sold as a standard size must also meet the dimensional, surface finish, and identification requirements established in this specification.

B5. Ventilation During Welding B5.1 Five major factors govern the quantity of fumes in the atmosphere to which welders and welding operators are exposed during welding: (1) Dimensions of the space in which welding is done (with special regard to the height of the ceiling) (2) Number of welders and welding operators working in that space ` ` ` , ` , ` , ` ` , ` ` , ` , , ` ` ` ` ` , ` , ` , , , ` ` , , ` , , ` , ` , , ` -

(3) Rate of evolution of fumes, gases, or dust, according to the materials and processes involved

(4) The proximity of the welders or welding operators to the fumes, as the fumes issue from the welding zone, and to the gases and dusts in the space in which they are working (5) The ventilation provided to the space in which the welding is done

B5.2 American National Standard ANSI Z49.1, Safety in Welding, Cutting, and Allied Processes (published by the American Welding Society), discusses the ventilation that is required during welding and should be referred to for details. Attention is drawn particularly to the section of that document on Health Protection and Ventilation.

B6. Operation Characteristics B6.1 The choice of an electrode classification, size, and welding current is influenced by the type and thickness of the base metals being welded. The capacity of tungsten electrodes to carry current is dependent upon numerous factors in addition to the classification and size, including type and polarity of the current, the shielding gas used, the type of equipment (air or water cooled), the extension of the electrode beyond the collet (sleeve or tube that holds the electrode), and the welding position. An electrode of a given size will have its greatest current-carrying capacity with direct current, electrode negative (straight polarity), less with alternating current, and still less with direct current, electrode positive (reverse polarity). Table A.1 lists some typical current values that may be used with argon shielding gas. However, the other factors mentioned above should be carefully considered before selecting an electrode for a specific application. B6.2 Tungsten has an electrical conductivity that is about 30% that of copper and a thermal conductivity that is 40% that of copper. Therefore, there will be more heating as current is passed through the tungsten electrode. When welding with tungsten electrodes, the arc tip should be the only hot part of the electrode; the remainder should be kept as cool as possible. B6.3 One method of preventing electrode overheating is to keep the extension of the electrode from the collet short. If the extension is too long, even a relatively low current can cause the electrode to overheat and melt above the terminus of the arc. Conversely, if the current density is too low, the arc will be erratic and unstable.



AWS A5.12M/A5.12:2009 (ISO 6848:2004 MOD)

B6.4 Many electrode classifications contain emissive oxide additions. These additions lower the temperature at which the electrode emits electrons, to a temperature below the melting point of tungsten. Such an electrode operates cooler, or it can operate at higher currents, as can be noted from Table A.1. Benefits of these additions include easier starting, particularly when using superimposed high frequency, more stable operation, and reduced contamination. These benefits are noted in the description listed for the various classifications containing oxide additives. B6.5 All tungsten electrodes may be used in a similar manner. However, electrodes of each classification have distinct advantages with respect to other classifications. The following section discusses the specific electrode classifications with regard to their operating characteristics and usability.

B7. Description and Intended Use of Electrodes (ISO designations are given in parentheses) B7.1 EWP (WP) Electrode Classification (Green). The EWP electrodes are commercially pure tungsten electrodes (99.5 percent tungsten minimum). Their current-carrying capacity is lower than that of other electrodes. They provide good stability when used with alternating current, either balanced wave or continuously high frequency stabilized. They may be used with direct current and also with either argon or helium, or a combination of both, as a shielding gas. They maintain a clean, balled end, which is preferred for aluminum and magnesium welding. These electrodes have reasonably good resistance to contamination of the weld metal by the electrode, although the oxide containing electrodes are superior in this respect. EWP electrodes are generally used on less critical applications, except for welding aluminum and magnesium. The lower cost EWP electrodes can be used for less critical applications where some tungsten contamination of welds is acceptable. B7.2 EWCe-2 (WCe 20) Electrode Classification (Grey). The EWCe-2 electrodes are tungsten electrodes containing about two percent cerium oxide (CeO 2), referred to as ceria. The EWCe-2 electrodes were first introduced into the United States market in 1987. Several other grades of this type electrode are commercially practical, including electrodes containing one percent CeO, but only one grade, EWCe-2, has been incorporated in this specification as having commercial significance. The advantages of tungsten electrodes containing ceria, compared to pure tungsten, include increased ease of starting, improved arc stability, and reduced rate of vaporization or burn-off. Unlike thoria, ceria is not a radioactive material. These advantages increase with increased ceria content. These electrodes operate successfully with alternating current or direct current, either polarity. B7.3 EWLa-X Electrode Classifications. The EWLa-X electrodes are tungsten electrodes containing lanthanum oxide, referred to as lanthana. The advantages and operating characteristics of these electrodes are similar to that of the EWCe2 electrodes. Unlike thoria, lanthana is not a radioactive material. B7.3.1 EWLa-1 (WLa 10) Electrode Classification (Black). The EWLa-1 electrodes are tungsten electrodes which contain nominally 0.8-1.2 weight-percent (wt.-%) lanthanum oxide, referred to as lanthana. The advantages and operating characteristics of this electrode type are very similar to those of EWCe-2 electrodes.

B7.3.2 EWLa-1.5 (WLa 15) Electrode Classification (Gold) . EWLa-1.5 designates a tungsten electrode containing 1.3–1.7 wt.-% of dispersed lanthanum oxide (La 2O3) for enhanced arc starting and stability, reduced tip erosion rate, and extended operating current range. These electrodes can be used as nonradioactive substitutes for 2% thoriated tungsten, as the operating characteristics are very similar. Lanthanated tungsten can be used for both DCEN and ac applications. B7.3.3 EWLa-2 (WLa 20) Electrode Classification (Blue) . EWLa-2 designates a tungsten electrode containing 1.8– 2.2 wt.-% of dispersed lanthanum oxide (La 2O3). The EWLa-2 electrode has the highest volume of oxides of any of the specific single-additive AWS-specified electrodes types, which serves to enhance arc starting and stability, reduce tip erosion rate, and extend operating current range. Lanthanated tungsten electrodes can be used for both dcen and ac applications. B7.4 EWTh-X Electrode Classifications. The EWTh-X electrodes are tungsten electrodes containing thorium oxide, referred to as thoria. The thoria in all classes is responsible for increasing the usable life of these electrodes over the EWP electrodes because of their higher electron emission, better arc starting and arc stability. They generally have longer life and provide greater resistance to tungsten contamination of the weld.



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AWS A5.12M/A5.12:2009 (ISO 6848:2004 MOD)

SAFETY NOTE Thoria is a low-level radioactive material. However, if welding is to be performed in confined spaces for prolonged periods of time, or if electrode grinding dust might be ingested, special precautions relative to ventilation should be considered. The user should consult appropriate safety personnel. The following statement was developed by the International Institute of Welding (IIW) Commission VIII on Health and Safety: STATEMENT OF COMMISSION VIII ON HEALTH ASPECTS IN THE USE OF THORIATED TUNGSTEN ELECTRODES “Thorium oxides are found in Thoriated Tungsten Electrodes {up to 4.2% (ISO 6848-WT 40 Electrode)} 6. Thorium is radioactive and may present hazards by external and internal exposure. If alternatives are technically feasible, they should be used. “Several studies carried out on Thoriated Electrodes have shown that due to the type of radiation generated, external radiation risks—during storage, welding, or disposal of residues—are negligible under normal conditions of use. “On the contrary, during the grinding of electrode tips there is generation of radioactive dust, with the risk of internal exposure. Consequently, it is necessary to use local exhaust ventilation to control the dust at the source, complemented if necessary by respiratory protective equipment. The risk of internal exposure during welding is considered negligible since the electrode is consumed at a very slow rate. “Precautions must be taken in order to control any risks of exposure during the disposal of dust from grinding devices. “The above statement is based on a considered view of the available reports. Commission VIII will continue to keep these aspects under review.” B7.4.1 EWTh-1 (WTh 10) Electrode Classification (Yellow). These electrodes were designed for direct current applications. They have 0.8–1.2 percent of thoria content dispersed throughout their entire length. They maintain a sharpened point well, which is desirable for welding steel. They can be used on alternating current work, but a satisfactory balled end, which is desirable for the welding of nonferrous materials, is difficult to maintain. B7.4.2 EWTh-2 (WTh 20) Electrode Classification (Red) . The higher thoria content (1.7–2.2 percent) in the EWTh-2 electrode causes the operating characteristic improvements to be more pronounced than in the lower thoria content EWTh-1. Should it be desired to use these electrodes for alternating current welding, then balling can be accomplished by briefly, and carefully, welding with direct current electrode positive prior to welding with alternating current. Du ring alternating current welding, the balled end does not melt and so emission is not as good as from a liquid ball on an EWP electrode. B7.4.3 (WTh 30) Electrode Classification (Violet). This 3% thoriated electrode has no commercial significance in the United States. B7.4 EWZr-X Electrode Classifications B7.5.1 EWZr-1 (WZr 3) Electrode Classification (Brown). The EWZr-1 electrode is a tungsten electrode containing about 0.3% zirconium oxide, referred to as zirconia. This electrode is preferred for applications where tungsten contamination of the weld must be minimized. This electrode performs well when used with alternating current, as it retains a balled end during welding and has a high resistance to contamination. B7.5.2 EWZr-8 (WZr 8) Electrode Classification (White). This 0.8% zirconiated electrode has no commercial significance in the United States. B7.6 EWG Electrode Classification (manufacturer may select any color not already in use). The EWG electrode is a tungsten electrode containing an additive not specified by an existing classification. The purpose of the addition is to affect the nature or characteristics of the arc, as defined by the manufacturer. Although no additive is specified, the manufacturer must identify any specific additions and the nominal quantities added.

6

“Up to 4.2% (ISO 6848-WT 40 Electrode)” was deleted from ISO 6848 at the time of publishing 2004 edition, and it was never in AWS A5.12/A5.12M.



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B8. General Recommendations These recommendations, when followed, should maintain high weld quality and promote welding economy in any specific application. B8.1 The appropriate current (type and magnitude) should be selected for the electrode size to be used. Too great a current will cause excessive melting, dripping, or volatilization of the electrode. A welding current which is too low to properly heat the electrode tip may cause instability of the welding arc or inability to maintain a welding arc. B8.2 The electrode should b e properly cut and ground tapered by following the supplier's suggested procedures. Breaking or severing an electrode is not recommended since it may cause a jagged end or a bent electrode, which usually results in a poorly shaped arc and excessive electrode heating. B8.3 The electrodes should be handled carefully and kept as clean as possible. To obtain maximum cleanliness, they should be stored in their original package until used. B8.4 The shielding gas flow should be maintained until the electrode has cooled. When the electrodes are properly cooled, the arc end will appear bright and polished. When improperly cooled, the end may oxidize and appear to have a colored film which can, unless removed, adversely affect the weld quality on subsequent welds. All connections, both gas and water, should be checked for tightness. Oxidized, discolored, or otherwise contaminated electrodes will cause difficult arc starting and may prevent starting depending upon conditions and the arc starting method used. B8.5 The electrode extension within the gas shielding pattern should be kept to a minimum, generally dictated by the application and equipment. This is to ensure protection of the electrode by the gas even at low gas flow rates. B8.6 The equipment and, in particular, the shielding gas nozzle should be kept clean and free of weld spatter. A dirty nozzle adversely influences the gas shielding. This contributes to improper gas flow patterns and arc wandering, which can result in poor weld quality. It may also contribute to excessive electrode consumption.

B9. Discontinued Classifications The EWTh-3 classification was discontinued in the AWS A5.12-92 revision of this specification, as having no commercial significance. For information about this classification, the user is referred to the AWS A5.12-80 revision.

B10. General Safety Considerations ` ` ` , ` , ` , ` ` , ` ` , ` , , ` ` ` ` ` , ` , ` , , , ` ` , , ` , , ` , ` , , ` -

B10.1 Safety and health issues and concerns are beyond the scope of this standard and, therefore, are not fully addressed herein. Some safety and health information can be found in Annex B5. Safety and health information is available from other sources, including but not limited to Safety and Health Fact Sheets listed in B10.3, ANSI Z49.l, and applicable federal and state regulations. B10.2 Safety and Health Fact Sheets. The Safety and Health Fact Sheets listed below are published by the American Welding Society (AWS). They may be downloaded and printed directly from the AWS website at http://www.aws.org. The Safety and Health Fact Sheets are revised and additional sheets added periodically. B10.3 AWS Safety and Health Fact Sheets Index (SHF) 7 No.

7

Title

1

Fumes and Gases

2

Radiation

3

Noise

4

Chromium and Nickel in Welding Fume

AWS standards are published by the American Welding Society, 550 N.W. LeJeune Road, Miami, FL 33126.



AWS A5.12M/A5.12:2009 (ISO 6848:2004 MOD)

No.

Title

5

Electrical Hazards

6

Fire and Explosion Prevention

7

Burn Protection

8

Mechanical Hazards

9

Tripping and Falling

10

Falling Objects

11

Confined Spaces

12

Contact Lens Wear

13

Ergonomics in the Welding Environment

14

Graphic Symbols for Precautionary Labels

15

Style Guidelines for Safety and Health Documents

16

Pacemakers and Welding

17

Electric and Magnetic Fields (EMF)

18

Lockout/Tagout

19

Laser Welding and Cutting Safety

20

Thermal Spraying Safety

21

Resistance Spot Welding

22

Cadmium Exposure from Welding & Allied Processes

23

California Proposition 65

24

Fluxes for Arc Welding and Brazing: Safe Handling and Use

25

Metal Fume Fever

26

Arc Viewing Distance

27

Thoriated Tungsten Electrodes

28

Oxyfuel Safety: Check Valves and Flashback Arrestors

29

Grounding of Portable and Vehicle Mounted Welding Generators

30

Cylinders: Safe Storage, Handling, and Use

31

Eye and Face Protection for Welding and Cutting Operations

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AWS A5.12M/A5.12:2009 (ISO 6848:2004 MOD)

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AWS A5.12M/A5.12:2009 (ISO 6848:2004 MOD)

Annex C (Informative) Guidelines for the Preparation of Technical Inquiries This annex is not part of AWS A5.12M/A5.12:2009 (ISO 6848:2004), Specification for Tungsten and Oxide Dispersed Tungsten Electrodes for Arc Welding and Cutting, but is included for informational purposes only.

C1. Introduction

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The American Welding Society (AWS) Board of Directors has adopted a policy whereby all official interpretations of AWS standards are handled in a formal manner. Under this policy, all interpretations are made by the committee that is responsible for the standard. Official communication concerning an interpretation is directed through the AWS staff member who works with that committee. The policy requires that all requests for an interpretation be submitted in writing. Such requests will be handled as expeditiously as possible, but due to the complexity of the work and the procedures that must be followed, some interpretations may require considerable time.

C2. Procedure All inquiries shall be directed to: Managing Director Technical Services Division American Welding Society 550 N.W. LeJeune Road Miami, FL 33126 All inquiries shall contain the name, address, and affiliation of the inquirer, and they shall provide enough information for the committee to understand the point of concern in the inquiry. When the point is not clearly defined, the inquiry will be returned for clarification. For efficient handling, all inquiries should be typewritten and in the format specified below. C2.1 Scope. Each inquiry shall address one single provision of the standard unless the point of the inquiry involves two or more interrelated provisions. The provision(s) shall be identified in the scope of the inquiry along with the edition of the standard that contains the provision(s) the inquirer is addressing. C2.2 Purpose of the Inquiry. The purpose of the inquiry shall be stated in this portion of the inquiry. The purpose can be to obtain an interpretation of a standard’s requirement or to request the revision of a particular provision in the standard. C2.3 Content of the Inquiry. The inquiry should be concise, yet complete, to enable the committee to understand the point of the inquiry. Sketches should be used whenever appropriate, and all paragraphs, figures, and tables (or annex) that bear on the inquiry shall be cited. If the point of the inquiry is to obtain a revision of the standard, the inquiry shall provide technical justification for that revision. C2.4 Proposed Reply. The inquirer should, as a proposed reply, state an interpretation of the provision that is the point of the inquiry or provide the wording for a proposed revision, if this is what the inquirer seeks.



AWS A5.12M/A5.12:2009 (ISO 6848:2004 MOD)

C3. Interpretation of Provisions of the Standard Interpretations of provisions of the standard are made by the relevant AWS technical committee. The secretary of the committee refers all inquiries to the chair of the particular subcommittee that has jurisdiction over the portion of the standard addressed by the inquiry. The subcommittee reviews the inquiry and the proposed reply to determine what the response to the inquiry should be. Following the subcommittee’s development of the response, the inquiry and the response are presented to the entire committee for review and approval. Upon approval by the committee, the interpretation is an official interpretation of the Society, and the secretary transmits the response to the inquirer and to the Welding Journal for publication.

C4. Publication of Interpretations All official interpretations will appear in the Welding Journal and will be posted on the AWS web site.

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C5. Telephone Inquiries Telephone inquiries to AWS Headquarters concerning AWS standards should be limited to questions of a general nature or to matters directly related to the use of the standard. The AWS Board of Directors’ policy requires that all AWS staff members respond to a telephone request for an official interpretation of any AWS standard with the information that such an interpretation can be obtained only through a written request. Headquarters staff cannot provide consulting services. However, the staff can refer a caller to any of those consultants whose names are on file at AWS Headquarters.

C6. AWS Technical Committees The activities of AWS technical committees regarding interpretations are limited strictly to the interpretation of provisions of standards prepared by the committees or to consideration of revisions to existing provisions on the basis of new data or technology. Neither AWS staff nor the committees are in a position to offer interpretive or consulting services on (1) specific engineering problems, (2) requirements of standards applied to fabrications outside the scope of the document, or (3) points not specifically covered by the standard. In such cases, the inquirer should seek assistance from a competent engineer experienced in the particular field of interest.



AWS A5.12M/A5.12:2009 (ISO 6848:2004 MOD)

Annex D (Informative) List of Deviations from ISO 6848:2004 This annex is not part of AWS A5.12M/A5.12:2009 (ISO 6848:2004), Specification for Tungsten and Oxide Dispersed Tungsten Electrodes for Arc Welding and Cutting, but is included for informational purposes only.

Changed title to “ Specification for Tungsten and Oxide Dispersed Tungsten Electrodes for Arc Welding and Cutting” globally Changed “International Standard” to “Standard” at several places 1. Scope: Added separate paragraph saying, “This specification makes use of both International System of Units (SI) and the U.S. Customary Units. The measurements are not exact equivalent; therefore, each system must be used i ndependently of the other without combining in any way when referring to material properties. The specification designated A5.12M uses SI Units; and the specification designated A5.12 uses U.S. Customary Units. The later units are shown within brackets [ ] or in appropriate columns in tables and figures. Standard dimensions based on either system may be used for sizing of filler metal or packaging or both under A5.12M or A5.12 specification.” 2. Normative references: Added additional normative references as below: AWS A5.01M:A5.01 (ISO 14344 MOD), Procurement Guidelines for Consumables—Welding and Allied Process— Flux and Gas Shielded Electrical Welding Process8 ASTM F 288, Specification for Tungsten Wire for Electron Devices and Lamps9 ` ` ` , ` , ` , ` ` , ` ` , ` , , ` ` ` ` ` , ` , ` , , , ` ` , , ` , , ` , ` , , ` -

ASTM E 29, Standard Practice for using Significant Digits in Test Data to Determine Conformance with Specifications ANSI Z49.1, Safety in Welding, Cutting, and Allied Processes10 ISO 31-0:1992, Annex B, Rule A11 3. Classification: Numbered first sentence as 3.3; and added subclauses 3.2, 3.3, 3.4, and 3.5 4. Changed Clause 4: Was: “4 Symbols and requirements

Symbol for the product/process The symbol for gas shielded tungsten arc processes is the letter W.

8

AWS standards are published by the American Welding Society, 550 N.W. LeJeune Road, Miami, FL 33126. ASTM standards are published by the American Society for Testing and Materials, 100 Barr Harbor Drive, West Conshohocken, PA 19428. 10 This standard is published by the American Welding Society, 550 N.W. LeJeune Road, Miami, FL 33126. 11 ISO standards are published by the International Organization for standardization, 1 rue de Varembé, Case postale 56, CH-1211 Geneva 20, Switzerland. 9



AWS A5.12M/A5.12:2009 (ISO 6848:2004 MOD)

Symbol for the chemical composition

The symbol for the chemical composition of the tungsten electrode is the chemical symbol for the principal oxide additive followed by digits indicating the nominal mass percent of the oxide additive multiplied by 10. If there is no additive, the symbol is the letter P. Table 1 lists the composition requirements.” 4. Symbols and requirements: Replaced Clause 4 explaining ISO 6848 classification designation scheme with a clause on acceptance based on ANSI/AWS A5.12/A5.12M-98. 5. Chemical analysis: Added “The referee method shall be ASTM F 288 Specification for Tungsten Wire for Electron Devices and Lamps. The results of the analysis shall meet the requirements of Table 1 for the classification of electrode under test.” 7. Marking: Added conversion of “3 mm” to [1/8 in]. Added “Such color coding shall have no adverse effect on the operation or use of the electrode.” Table 1: Put ISO symbols in parentheses and added AWS designations. Added EWG classification. Corrected web address. Added “Note: 1. Intentional additions of “doping oxides” other than indicated for a particular electrode classification is prohibited” in Table 1. 8. Standard sizes and tolerances: Combined subclause 8.1 Electrode diameters and subclause 8.2 Electrode lengths into subclause 8.1 Electrode diameters, lengths, and tolerances. Combined Tables 2 and 3 into one Table 2 and added sizes in US Customary Units. Changed tolerance for 2.4 mm diameter size and 2.5 mm diameter size from ± 0.1 mm to ± 0.08 mm. Added subclause 8.2 Finish. Replaced ambiguous 8.3 Electrode straightness text with language and illustration from ANSI/AWS A5.12/A5.12M-98. It was “Electrodes shall not deviate straight by more than 0.5 mm over any 100 mm of length or less.” Added subclause 8.4 Electrode Roundness. 9. Rounding-off procedure: Added reference to ASTM E 29, Standard Practice for using Significant Digits in Test Data to Determine Conformance With Specifications. 11.1 Marking of packages: Changed item a) to read number of this Standard, i.e., AWS A5.12 (ISO 6848):2008; Added subclauses 11.3 Marking of overpacking and 11.4 Warning label. Table A.1: Added “[3/32 in] after 2.5 mm in first and second rows. Changed “Non-alloy steels” to “Non-alloy (carbon) steels” Table A.2: Added note a.

Added Additional Informative National Annexes B, C, and D.



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AWS A5.12M/A5.12:2009 (ISO 6848:2004 MOD)

AWS Filler Metal Specifications by Material and Welding Process

OFW

SMAW

GTAW GMAW PAW

Carbon Steel

A5.20

A5.10

A5.18

A5.20

A5.17

A5.25

A5.26

A5.8, A5.31

Low-Alloy Steel

A5.20

A5.50

A5.28

A5.29

A5.23

A5.25

A5.26

A5.8, A5.31

A5.40

A5.9, A5.22

A5.22

A5.90

A5.90

A5.90

A5.8, A5.31

A5.15

A5.15

A5.15

Nickel Alloys

A5.11

A5.14

A5.34

Aluminum Alloys

A5.30

A5.10

A5.8, A5.31

Copper Alloys

A5.60

A5.70

A5.8, A5.31

Titanium Alloys

A5.16

A5.8, A5.31

Zirconium Alloys

A5.24

A5.8, A5.31

Magnesium Alloys

A5.19

A5.8, A5.31

Tungsten Electrodes

A5.12

Stainless Steel Cast Iron

A5.15

FCAW

SAW

ESW

EGW

Brazing

A5.8, A5.31 A5.14

A5.14

A5.8, A5.31

Brazing Alloys and Fluxes Surfacing Alloys

A5.8, A5.31 A5.21

A5.13

A5.21

Consumable Inserts

A5.30

Shielding Gases

A5.32

A5.21

A5.21

A5.32

A5.32

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AWS A5.12M/A5.12:2009 (ISO 6848:2004 MOD)


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AWS A5.12M/A5.12:2009 (ISO 6848:2004 MOD)

AWS Filler Metal Specifications and Related Documents Designation

Title

FMC

Filler Metal Comparison Charts

IFS

International Index of Welding Filler Metal Classifications

UGFM

User’s Guide to Filler Metals

A4.2M (ISO 8249: 2000 MOD)

Standard Procedures for Calibrating Magnetic Instruments to Measure the Delta Ferrite Content of Austenitic and Duplex Ferritic-Austenitic Stainless Steel Weld Metal

A4.3

Standard Methods for Determination of the Diffusible Hydrogen Content of Martensitic, Bainitic, and Ferritic Steel Weld Metal Produced by Arc Welding

A4.4M

Standard Procedures for Determination of Moisture Content of Welding Fluxes and Welding Electrode Flux Coverings

A5.01M/A5.01 (ISO Procurement Guidelines for Consumables —Welding and Allied Processes — Flux and Gas Shielded Electrical 14344:2002 MOD) Welding Processes A5.02/A5.02M

Specification for Filler Metal Standard Sizes, Packaging, and Physical Attributes

A5.1/A5.1M

Specification for Carbon Steel Electrodes for Shielded Metal Arc Welding

A5.2/A5.2M

Specification for Carbon and Low-Alloy Steel Rods for Oxyfuel Gas Welding

A5.3/A5.3M

Specification for Aluminum and Aluminum-Alloy Electrodes for Shielded Metal Arc Welding

A5.4/A5.4M

Specification for Stainless Steel Electrodes for Shielded Metal Arc Welding

A5.5/A5.5M

Specification for Low-Alloy Steel Electrodes for Shielded Metal Arc Welding

A5.6/A5.6M

Specification for Copper and Copper-Alloy Electrodes for Shielded Metal Arc Welding

A5.7/A5.7M

Specification for Copper and Copper-Alloy Bare Welding Rods and Electrodes

A5.8/A5.8M

Specification for Filler Metals for Brazing and Braze Welding

A5.9/A5.9M

Specification for Bare Stainless Steel Welding Electrodes and Rods

A5.10/A5.10M

Specification for Bare Aluminum and Aluminum-Alloy Welding Electrodes and Rods

A5.11/A5.11M

Specification for Nickel and Nickel-Alloy Welding Electrodes for Shielded Metal Arc Welding

A5.12M/A5.12 (ISO Specification for Tungsten and Oxide Dispersed Tungsten Electrodes for Arc Welding and Cutting 6848:2004 MOD) A5.13

Specification for Surfacing Electrodes for Shielded Metal Arc Welding

A5.14/A5.14M

Specification for Nickel and Nickel-Alloy Bare Welding Electrodes and Rods

A5.15

Specification for Welding Electrodes and Rods for Cast Iron

A5.16/A5.16M

Specification for Titanium and Titanium Alloy Welding Electrodes and Rods

A5.17/A5.17M

Specification for Carbon Steel Electrodes and Fluxes for Submerged Arc Welding

A5.18/A5.18M

Specification for Carbon Steel Electrodes and Rods for Gas Shielded Arc Welding

A5.19

Specification for Magnesium Alloy Welding Electrodes and Rods

A5.20/A5.20M

Specification for Carbon Steel Electrodes for Flux Cored Arc Welding

A5.21

Specification for Bare Electrodes and Rods for Surfacing

A5.22

Specification for Stainless Steel Electrodes for Flux Cored Arc Welding and Stainless Steel Flux Cored Rods for Gas Tungsten Arc Welding

A5.23/A5.23M

Specification for Low-Alloy Steel Electrodes and Fluxes for Submerged Arc Welding

A5.24/A5.24M

Specification for Zirconium and Zirconium Alloy Welding Electrodes and Rods

A5.25/A5.25M

Specification for Carbon and Low-Alloy Steel Electrodes and Fluxes for Electroslag Welding

A5.26/A5.26M

Specification for Carbon and Low-Alloy Steel Electrodes for Electrogas Welding

A5.28/A5.28M

Specification for Low-Alloy Steel Electrodes and Rods for Gas Shielded Arc Welding

A5.29/A5.29M

Specification for Low-Alloy Steel Electrodes for Flux Cored Arc Welding

A5.30/A5.30M

Specification for Consumable Inserts

A5.31

Specification for Fluxes for Brazing and Braze Welding

A5.32/A5.32M

Specification for Welding Shielding Gases

A5.34/A5.34M

Specification for Nickel-Alloy Electrodes for Flux Cored Arc Welding

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AWS A5.12M/A5.12:2009 (ISO 6848:2004 MOD)


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AWS A5.12.pdf

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