AWS C4.4/C4.4M:2007

An American National Standard

Recommended Practices for Heat Shaping

and Straightening with Oxyfuel Gas Heating Torches

AWS C4.4/C4.4M:2007

An American National Standard

Approved by the American National Standards Institute

September 11, 2007

Recommended Practices for Heat Shaping and Straightening with Oxyfuel Gas Heating Torches

2nd Edition

Supersedes AWS C4.4/C4.4M:2004

Prepared by the American Welding Society (AWS) C4 Committee on Oxyfuel Gas Welding and Cutting

Under the Direction of the AWS Technical Activities Committee

Approved by the AWS Board of Directors

Abstract

This second edition of Recommended Practices for Heat Shaping and Straightening covers the shaping of metal products by prudent use of heat to obtain a desired configuration. The text reviews the theory and analytical calculations that explain how heat shaping and straightening occurs. Sample calculations and tables are presented for typical materials. General heating patterns and heat shaping and straightening techniques are discussed. Specific heating applications are illustrated for various sections.

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International Standard Book Number: 978-0-87171-079-6

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© 2007 by American Welding Society

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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 govern- mental 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.

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This standard may be superseded by the issuance of new editions.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

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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).

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 C4 Committee on Oxyfuel Gas Welding and Cutting. 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 C4 Committee on Oxyfuel Gas Welding and Cutting 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 C4 Committee on Oxyfuel Gas Welding and Cutting 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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Personnel

AWS C4 Committee on Oxyfuel Gas Welding and Cutting

A. T. Sheppard, Chair The DuRoss Group

M. J. Hogan, 1st Vice Chair The Harris Products Group, A Lincoln Electric Company

1. B. Overvaag, 2nd Vice Chair Smith Equipment Company, Division of ITW

   1. M. Alonso, Secretary American Welding Society

J. D. Compton JD & Associates

J. D. Karow American General Corporation

L. L. Liston, Jr. Consultant

1. R. McGowan McGowan Technical Services

2. Mirgliotta Forest City Erectors, Incorporated

D. A. Pryor Thermadyne Industries, Incorporated

R. A. Smith Compressed Gas Association

Advisors to the AWS C4 Committee on Oxyfuel Gas Welding and Cutting

J. G. Dawson, Jr. Consultant

D. Hambleton Smith Equipment Company, Division of ITW

C. M. Hightower BMS, Incorporated

R. E. Holt Retired

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Foreword

This foreword is not part of AWS C4.4/C4.4M:2007, Recommended Practices for Heat Shaping and Straightening with Oxyfuel Gas Heating Torches, but is included for informational purposes only.

The shaping of metals by the use of heat has a long history of successful applications. This shaping has been used to curve, camber, or otherwise shape a product as well as to correct members that have become distorted or damaged by accident or fire.

This second edition of Recommended Practices for Heat Shaping and Straightening with Oxyfuel Gas Heating Torches presents methods and techniques used by engineers and technicians to shape and straighten metal parts by careful appli- cation of heat.

All revisions to the 2004 edition are identified by a vertical line in the margin next to the text.

Comments and suggestions for the improvement of this standard are welcome. They should be sent to the Secretary, AWS C4 Committee on Oxyfuel Gas Welding and Cutting, American Welding Society, 550 N.W. LeJeune Road, Miami, FL 33126.

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Table of Contents

Page No.

Personnel v

Foreword vii

List of Tables xi

List of Figures xi

1. Scope 1

2. Normative References 1

3. Terms and Definitions 2

4. Theory of Heat Shaping 2

5. Distortion 6

6. Fundamentals and Precautions 7

7. Equipment and Supplies 8

   1. Standard Equipment. 8

   2. Special Equipment 8

   3. Oxygen Supply 8

   4. Fuel Supply 8

   5. Maximum Acetylene Pressure 9

   6. Pressure Regulators 9

   7. Hoses and Fittings 11

   8. Heating Torches 12

   9. Heating Tip/Head. 12

   10. Maintenance of Heating Tips or Heads 12

   11. Personal Protective Equipment (PPE) 13

   12. Safe Use, Handling, and Storage of Gas Cylinders 14

8. Startup and Shutdown Procedure 15

   1. Setting Up Equipment 15

   2. Lighting the Torch 16

   3. Equipment Shutdown 17

   4. Equipment Not in Use 17

   5. Reuse of Equipment Already Connected 17

9. Flame Adjustment 17

   1. Types of Flames 17

   2. Flashback Arrestors and Check Valves 18

10. General Technique 19

11. Procedures for General Applications 20

    1. Mechanically Restrained Structures 20

    2. Freestanding Unrestrained Members 21

    3. Shaping of Plate 23

    4. Flattening Plates 23

    5. Plate Tightening 23

       Page No.

12. Procedures for Specific Applications 23

    1. Bending of Flat Bar, V Heat 23

    2. Bending of Channel, V Heat 26

    3. Bending of Beams. 26

    4. Bending of Angle 27

    5. Bending of T Sections 27

    6. Bending of Plate 30

    7. Pipe 30

13. Line Heating and Flame Bending in Shipyards 30

    1. Background 30

    2. Basic Concepts. 32

    3. Planning and Methods 32

    4. Recommended Practices 33

    5. Code Compliance. 33

    6. Conclusions 33

14. Safety and Health 33

Annex A (Informative)—Informative References 35

Annex B (Informative)—Fuel Gas Withdrawal Rates 39

Annex C (Informative)—Guidelines for the Preparation of Technical Inquiries 41

List of AWS Documents on Oxyfuel Gas Welding and Cutting 43

List of Tables

Table Page No.

1. Acetylene Withdrawal 39

2. Methylacetylene-Propadiene Stabilized (MPS) Withdrawal 39

3. Propylene Withdrawal 40

4. Propane Withdrawal 40

List of Figures

Figure Page No.

1. Shortening of Bar from Application of Heat 3

2. Variation in Yield Strength and Modulus of Elasticity with Respect to Temperature for

   ASTM A 36 Steel 4

3. Imperceptible Welding Distortion of a Thick Steel Plate 5

4. Welding Distortion of a Thin Steel Plate 7

5. Oxygen Cylinder 9

6. Typical Fuel Gas Cylinders 9

7. Pressure Regulators 10

8. Hoses and Fittings 11

9. Manual Heating Torch 12

10. Multi-Flame Heating Heads 13

11. Water-Cooled Flame Hardening Head 13

12. Carburizing Flame 18

13. Neutral Flame 18

14. Oxidizing Flame 18

15. Basic Heating Patterns 20

16. Externally Restrained Plate 21

17. Externally Restrained Beam 21

18. V Shape Heat Pattern for Straightening or Shaping a Flat Bar 22

19. Dimensions for Calculating Upset 23

20. Behavior of ASTM A 36 Steel Perfectly Confined in One Axis as a Function of Temperature 24

21. Heat Patterns in Rolled Shapes 25

22. Spot Heat Repair of Dent in Plate 25

23. Spot Heat Repair (Tightening) on Irregular Plate 26

24. Application of V Shape Heat Pattern and Direction of Movement 26

25. Bending of Channel Toward Flange 27

26. Bending of Channel Toward Web 27

27. Bending of Channel Toward Open Side 27

28. Bending of Beam Toward Open Side 28

29. Bending of Beam Toward Flange 28

30. Bending of Angle Toward Face of Leg 28

31. Bending of Angle Toward Edge of Leg 29

32. Bending of T Section Toward Web 29

    Figure Page No.

33. Bending of T Section Toward Flange 29

34. Bending of Plate 29

35. Bending of Plate (More Movement) 30

36. Decreasing Diameter of Heavy Wall Pipe 31

37. Straightening of Pipe or Round 31

38. Straightening Pipe or Round Stock—V Shape Heating with Serpentine Path 31

39. Straightening Pipe or Round Stock—V Shape Heating with Line Heating Pattern 32

Recommended Practices for Heat Shaping and Straightening with Oxyfuel Gas Heating Torches

1. Scope

   This publication describes some causes of distortion and corrective actions through the use of heat. It also describes some heat shaping techniques and the direction of movement expected in the heated metal. Equations are provided to aid in estimating the amount of movement for a given heating technique. The methods discussed are specifically applicable to ferrous metals, but many of the methods can be applied to nonferrous metals as well. For a more comprehensive description of specific applica- tions, see Annex A, Informative References.

   Heat has been used to shape and straighten structural ele- ments in bridges, buildings, and marine constructions for over a hundred years. Since the late 1930s, the use of oxyfuel gas torches to do this work has become more prevalent. This publication is a recommended practice for using the torch process for work on bridges and buildings, and to some extent, shipbuilding.

   Mechanical forces in fabrication and erection, forces occurring in service, accidental impacts from external forces, fire, and explosion, all cause stress in a structural member or a part of a member. If that stress exceeds the elastic limit of the material, distortion will occur, and the member will not conform to its desired shape. Heat shap- ing and straightening is an economical method to pro- duce the desired movement to bring the member into conformance.

   The shipbuilding industry throughout the world has taken heat shaping to new heights in shaping technology. Particularly, the use of line heating to shape complex curves in hull structures has become an integral part of a group technology in shipbuilding which also includes product work packages and accuracy control.

   Basically, straightening and shaping involves controlled thermal expansion and contraction of a structural ele- ment. The method, location, and shape of the heat appli- cation are covered briefly in this publication. This

   
   

   recommended practice is limited to fundamentals and sim- ple applications (see Annex A for additional information).

   This standard makes use of both U.S. Customary Units and the International System of Units (SI). The latter are shown within brackets [ ] or in appropriate columns in tables and figures. The measurements may not be exact equiva- lents; therefore, each system must be used independently.

   Safety and health issues may not be fully addressed by this standard. Users of this standard should consult ANSI Z49.1, Safety in Welding, Cutting, and Allied Processes, applicable federal, state, and local regulations and other relevant documents concerning safety and health issues not addressed herein.

   
   

2. Normative References

The following standard contains provisions, which, through reference in this text, constitute mandatory pro- visions of this AWS standard. For undated references, the latest edition of the referenced standard shall apply. For dated references, subsequent amendments to, or revi- sions of, any of these publications do not apply.

AWS documents:1

AWS A3.0, Standard Welding Terms and Definitions, Including Terms for Adhesive Bonding, Brazing, Solder- ing, Thermal Cutting, and Thermal Spraying; and

AWS F4.1, Recommended Safe Practices for Prepara- tion for Welding and Cutting of Containers and Piping.

Other documents:

ANSI Z49.1, Safety in Welding, Cutting, and Allied Processes;2

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

2 ANSI Z49.1 is published by the American Welding Society, 550 N.W. LeJeune Road, Miami, FL 33126.