1、AWS C4.4/C4.4M:2007An American National StandardRecommendedPractices forHeat Shapingand Straighteningwith Oxyfuel GasHeatingTorches550 N.W. LeJeune Road, Miami, FL 33126AWS C4.4/C4.4M:2007An American National StandardApproved by theAmerican National Standards InstituteSeptember 11, 2007Recommended P
2、racticesfor Heat Shaping and Straighteningwith Oxyfuel Gas Heating Torches2nd EditionSupersedes AWS C4.4/C4.4M:2004Prepared by theAmerican Welding Society (AWS) C4 Committee on Oxyfuel Gas Welding and CuttingUnder the Direction of theAWS Technical Activities CommitteeApproved by theAWS Board of Dire
3、ctorsAbstractThis second edition of Recommended Practices for Heat Shaping and Straightening covers the shaping of metal productsby prudent use of heat to obtain a desired configuration. The text reviews the theory and analytical calculations thatexplain how heat shaping and straightening occurs. Sa
4、mple calculations and tables are presented for typical materials.General heating patterns and heat shaping and straightening techniques are discussed. Specific heating applications areillustrated for various sections.iiAWS C4.4/C4.4M:2007International Standard Book Number: 978-0-87171-079-6American
5、Welding Society550 N.W. LeJeune Road, Miami, FL 33126 2007 by American Welding SocietyAll rights reservedPrinted in the United States of AmericaPhotocopy Rights. No portion of this standard may be reproduced, stored in a retrieval system, or transmitted in anyform, including mechanical, photocopying
6、, recording, or otherwise, without the prior written permission of the copyrightowner.Authorization to photocopy items for internal, personal, or educational classroom use only or the internal, personal, oreducational classroom use only of specific clients is granted by the American Welding Society
7、provided that the appropriatefee is paid to the Copyright Clearance Center, 222 Rosewood Drive, Danvers, MA 01923, tel: (978) 750-8400; Internet:.iiiAWS C4.4/C4.4M:2007Statement on the Use of American Welding Society StandardsAll standards (codes, specifications, recommended practices, methods, clas
8、sifications, and guides) of the AmericanWelding Society (AWS) are voluntary consensus standards that have been developed in accordance with the rules of theAmerican National Standards Institute (ANSI). When AWS American National Standards are either incorporated in, ormade part of, documents that ar
9、e included in federal or state laws and regulations, or the regulations of other govern-mental bodies, their provisions carry the full legal authority of the statute. In such cases, any changes in those AWSstandards must be approved by the governmental body having statutory jurisdiction before they
10、can become a part ofthose laws and regulations. In all cases, these standards carry the full legal authority of the contract or other documentthat invokes the AWS standards. Where this contractual relationship exists, changes in or deviations from requirementsof an AWS standard must be by agreement
11、between the contracting parties.AWS American National Standards are developed through a consensus standards development process that bringstogether volunteers representing varied viewpoints and interests to achieve consensus. While the AWS administers theprocess and establishes rules to promote fair
12、ness in the development of consensus, it does not independently test, evalu-ate, 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
13、special, indirect, consequential, or compensatory, directly or indirectly resulting from the publication, use of, or relianceon this standard. AWS also makes no guarantee or warranty as to the accuracy or completeness of any informationpublished herein.In issuing and making this standard available,
14、AWS is neither undertaking to render professional or other services for oron behalf of any person or entity, nor is AWS undertaking to perform any duty owed by any person or entity to someoneelse. Anyone using these documents should rely on his or her own independent judgment or, as appropriate, see
15、k theadvice of a competent professional in determining the exercise of reasonable care in any given circumstances. It isassumed 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 edi
16、tions. Users should ensure that they have the latest edition.Publication of this standard does not authorize infringement of any patent or trade name. Users of this standard acceptany and all liabilities for infringement of any patent or trade name items. AWS disclaims liability for the infringement
17、 ofany 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 d
18、iscovered, are postedon the AWS web page (www.aws.org).Official interpretations of any of the technical requirements of this standard may only be obtained by sending a request,in writing, to the appropriate technical committee. Such requests should be addressed to the American Welding Society,Attent
19、ion: 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
20、 they do not constitute professionaladvice. Such opinions represent only the personal opinions of the particular individuals giving them. These individualsdo not speak on behalf of AWS, nor do these oral opinions constitute official or unofficial opinions or interpretations ofAWS. In addition, oral
21、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 mustbe reviewed every five years, and if not revised, it must be either reaffirmed or withdrawn.
22、 Comments (recommendations,additions, or deletions) and any pertinent data that may be of use in improving this standard are required and should beaddressed to AWS Headquarters. Such comments will receive careful consideration by the AWS C4 Committee on OxyfuelGas Welding and Cutting and the author
23、of the comments will be informed of the Committees response to thecomments. Guests are invited to attend all meetings of the AWS C4 Committee on Oxyfuel Gas Welding and Cutting toexpress their comments verbally. Procedures for appeal of an adverse decision concerning all such comments areprovided in
24、 the Rules of Operation of the Technical Activities Committee. A copy of these Rules can be obtained fromthe American Welding Society, 550 N.W. LeJeune Road, Miami, FL 33126.This page is intentionally blank.ivAWS C4.4/C4.4M:2007vAWS C4.4/C4.4M:2007PersonnelAWS C4 Committee on Oxyfuel Gas Welding and
25、 CuttingA. T. Sheppard, Chair The DuRoss GroupM. J. Hogan, 1st Vice Chair The Harris Products Group, A Lincoln Electric CompanyD. B. Overvaag, 2nd Vice Chair Smith Equipment Company, Division of ITWA. M. Alonso, Secretary American Welding SocietyJ. D. Compton JD therefore, each system must be used i
26、ndependently.Safety and health issues may not be fully addressed bythis standard. Users of this standard should consult ANSIZ49.1, Safety in Welding, Cutting, and Allied Processes,applicable federal, state, and local regulations and otherrelevant documents concerning safety and health issuesnot addr
27、essed herein.2. Normative ReferencesThe 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
28、, or revi-sions of, any of these publications do not apply.AWS documents:1AWS A3.0, Standard Welding Terms and Definitions,Including Terms for Adhesive Bonding, Brazing, Solder-ing, Thermal Cutting, and Thermal Spraying; andAWS F4.1, Recommended Safe Practices for Prepara-tion for Welding and Cuttin
29、g of Containers and Piping.Other documents:ANSI Z49.1, Safety in Welding, Cutting, and AlliedProcesses;21AWS standards are published by the American Welding Society,550 N.W. LeJeune Road, Miami, FL 33126.2ANSI Z49.1 is published by the American Welding Society,550 N.W. LeJeune Road, Miami, FL 33126.
30、Recommended Practices for Heat Shaping andStraightening with Oxyfuel Gas Heating TorchesAWS C4.4/C4.4M:2007 2CGA E-5, Torch standard for welding and cutting;3andISO 5175, Equipment used in gas welding, cuttingand allied processes Safety devices for fuel gases andoxygen or compressed air General spec
31、ifications,requirements and tests.43. Terms and DefinitionsAll the terms in this section are used in various parts ofthis document and require definition for correct interpre-tation of the instructions. AWS A3.0, Standard WeldingTerms and Definitions, Including Terms for AdhesiveBonding, Brazing, So
32、ldering, Thermal Cutting, andThermal Spraying, provides the basis for terminologyused in this document. Some of the terms are listed inAWS A3.0, but their definitions have been enhanced toclarify their use in this document, as noted below.For the purposes of this document, the following termsand def
33、initions apply:apex. The narrow or pointed end of a V heat shapepattern (see Clause 10).backfire. The momentary return of the flame into thetorch that is usually signaled by a popping sound. Theflame may either extinguish or reignite at the end ofthe tip.block heat. A heating pattern that moves in a
34、 linear fash-ion, weaving back and forth in a marked area main-taining the same width.coefficient of thermal expansion. An alloy-specificnumerical value (with units of in/in/F mm/mm/C)which can be used to calculate the change in unitlength or the change in volume of a solid when itstemperature is ch
35、anged.cold restraining material. The material, or portionthereof, preventing movement (expansion) of theheated area, thus causing the heated portion to upset.flashback. The return of the flame through the torch andinto the hose and/or regulator. It may also reach thecylinder. This event is caused by
36、 the oxygen and fuelmixing in one side of the oxyfuel system and subse-quently being ignited at the tip. This condition is gen-erally caused by the reverse flow of one gas into theother side of the system. Flashback can be hazardous,3CGA standards are published by the Compressed Gas Associ-ation, 42
37、21 Walney Road, 5th Floor, Chantilly, VA 20151.4ISO standards are published by the International Organizationfor Standardization, 1, rue de Varemb, Case Postale 56, CH-1211 Geneva 20, Switzerland.whereby; it can potentially cause an explosion at anypoint in the system.line heat. Heat applied in a li
38、near manner.modulus of elasticity (or Youngs Modulus). A physi-cal constant, usually represented by the letter E, thatexpresses the ratio of stress and strain below theproportional limit in pounds per square inch.patterns. See V heat, line heat, spot heat, and blockheat.plastic flow. Slip or atomic
39、movement within a materialwhen stressed beyond its elastic limit into a plastic (orpermanent) deformation mode.quenched and tempered. A heat treatment of steel per-formed by heating steel to not less than 1650F899C, quenching in water or oil, then tempering atnot usually less than 1100F 593C.shape.
40、To camber, curve, straighten, or produce sweep ina member.spot heat. A flame bending pattern at a given point (seeClause 10).strain. Deformation in inches per inch mm/mm.sustained backfire. The return of the flame into thetorch with continued burning inside the torch. Thisevent can be identified by
41、an initial popping soundfollowed by a squealing or hissing sound caused bythe continued burning inside the torch.thermal stress. Stress in metal resulting from nonuni-form temperature distributions.upset. The localized material thickening resulting fromthe application of heat.V heat. Heat applied fo
42、r flame bending in a V-shapedpattern (see Clause 10).yield strength. Stress level at which permanent dimen-sional changes begin to take place in a material.4. Theory of Heat ShapingMuch has been written about heat curving/straightening(see Annex A), and most of the literature delves intoengineering
43、theory. This document will do that to someextent in the paragraphs below, but first there will be apractical example of the phenomenon so that the user canbetter understand what happens to the steel member thatneeds to have a change in geometry.AWS C4.4/C4.4M:2007 3Take a steel bar of 1 in 1 in 6 in
44、 25 mm 25 mm 150 mm and heat it to 1100F 593C. The bar willattain a dull red color. The bar will expand three dimen-sionally; length, width, and depth. When it cools it goesback to its original shape.If the bar is put in a vise (see Figure 1) and is similarlyheated, it will try to expand in all dire
45、ctions. It will not beable to expand lengthwise; however, it will becomethicker (it expands in the width and depth directions).When the heat source is removed, the material will cooland contract in all three dimensions. What was thethicker portion, width and depth, contracts and the barshortens.In p
46、ractice, the surrounding unheated steel will act likethe vise to restrain movement. In a beam, girder, or othershape, the unheated portion of the flange or web restrainsthe movement of the heated zone. The material getsthicker in the heated zone and shortening follows duringcooling. This shortening
47、causes movement of the mate-rial. Thus by the application of heating patterns in properlocations, the curvature wanted or unwanted is counter-balanced by the movement (shortening) of the steel.As a result, bent portions of beams and girders can bestraightened, dimples in webs can be removed, camberc
48、an be added or removed, and all kinds of heat shapingcan be performed. The use of heat to straighten or curvea steel member has been called “black magic”; however,if the logic described above is followed, the mysterydisappears.The engineering theory follows.Metal expands as it is heated. The restrai
49、nt of this expan-sion by adjacent cooler metal causes plastic strain, andcooling causes deformation which can change the shapeof a member. If there is no restraint, or if the attempt toexpand does not cause stresses to exceed the yieldstrength of the metal, there will be no permanent defor-mation. However, restraint of the expansion of a metal,as it is heated, can stress a portion of the member beyondits yield point and cause permanent deformation (plasticstrain). The basic equations for expansion and contrac-tion are as shown below.At or below the elastic li
