ANSI AWS C4.3 C4.3M-2007 Recommended Practices for Safe Oxyfuel Gas Heating Torch Operation (Third Edition).pdf

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1、AWS C4.3/C4.3M:2007An American National StandardRecommendedPractices forSafe Oxyfuel GasHeatingTorchOperation550 N.W. LeJeune Road, Miami, FL 33126AWS C4.3M/C4.3M:2007An American National StandardApproved by theAmerican National Standards InstituteApril 30, 2007Recommended Practicesfor Safe Oxyfuel

2、GasHeating Torch Operation3rd EditionSupersedes AWS C4.3/C4.3M: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 DirectorsAbstractThe newly revised manual for oxyfue

3、l gas heating torch operation includes the latest procedures to be used in conjunc-tion with oxyfuel gas heating equipment. The manual also includes the latest safety requirements. Complete lists ofequipment are available from individual manufacturers.iiAWS C4.3/C4.3M:2007International Standard Book

4、 Number: 978-0-87171-070-3American 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,

5、 including mechanical, photocopying, recording, or otherwise, without the prior written permission of the copyrightowner.Authorization to photocopy items for internal, personal, or educational classroom use only or the internal, personal, oreducational classroom use only of specific clients is grant

6、ed by the American Welding Society provided that the appropriatefee is paid to the Copyright Clearance Center, 222 Rosewood Drive, Danvers, MA 01923, tel: (978) 750-8400; Internet:.iiiAWS C4.3/C4.3M:2007Statement on the Use of American Welding Society StandardsAll standards (codes, specifications, r

7、ecommended practices, methods, classifications, and guides) of the AmericanWelding Society (AWS) are voluntary consensus standards that have been developed in accordance with the rules of theAmerican National Standards Institute (ANSI). When AWS American National Standards are either incorporated in

8、, ormade part of, documents that are included in federal or state laws and regulations, or the regulations of other govern-mental bodies, their provisions carry the full legal authority of the statute. In such cases, any changes in those AWSstandards must be approved by the governmental body having

9、statutory jurisdiction before they can become a part ofthose laws and regulations. In all cases, these standards carry the full legal authority of the contract or other documentthat invokes the AWS standards. Where this contractual relationship exists, changes in or deviations from requirementsof an

10、 AWS standard must be by agreement between the contracting parties.AWS American National Standards are developed through a consensus standards development process that bringstogether volunteers representing varied viewpoints and interests to achieve consensus. While AWS administers the processand es

11、tablishes rules to promote fairness in the development of consensus, it does not independently test, evaluate, orverify the accuracy of any information or the soundness of any judgments contained in its standards.AWS disclaims liability for any injury to persons or to property, or other damages of a

12、ny nature whatsoever, whetherspecial, indirect, consequential or compensatory, directly or indirectly resulting from the publication, use of, or relianceon this standard. AWS also makes no guaranty or warranty as to the accuracy or completeness of any informationpublished herein.In issuing and makin

13、g this standard available, 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 judgm

14、ent or, as appropriate, seek theadvice of a competent professional in determining the exercise of reasonable care in any given circumstances.This standard may be superseded by the issuance of new editions. Users should ensure that they have the latest edition.Publication of this standard does not au

15、thorize infringement of any patent or trade name. Users of this standard acceptany and all liabilities for infringement of any patent or trade name items. AWS disclaims liability for the infringement ofany patent or product trade name resulting from the use of this standard.Finally, AWS does not mon

16、itor, police, or enforce compliance with this standard, nor does it have the power to do so.On occasion, text, tables, or figures are printed incorrectly, constituting errata. Such errata, when discovered, are postedon the AWS web page (www.aws.org).Official interpretations of any of the technical r

17、equirements 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 D)

18、.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 professionaladvice. Such opinions represent only the personal opinions of the par

19、ticular 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 opinions are informal and should not be used as a substitute for an official interpretation.This standard

20、 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. Comments (recommendations,additions, or deletions) and any pertinent data that may be of use in improvin

21、g this standard are required and should beaddressed to AWS Headquarters. Such comments will receive careful consideration by the AWS C4 Committee onOxyfuel Gas Welding and Cutting and the author of the comments will be informed of the Committees response to thecomments. Guests are invited to attend

22、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 the Rules of Operation of the Technical Activities Committee. A copy of these Rules can be obtained from

23、the American Welding Society, 550 N.W. LeJeune Road, Miami, FL 33126.This page is intentionally blank.ivAWS C4.3/C4.3M:2007vAWS C4.3/C4.3M:2007PersonnelAWS C4 Committee on Oxyfuel Gas Welding and CuttingA. T. Sheppard, Chair The DuRoss GroupM. J. Hogan, 1st Vice Chair The Harris Products Group, A Li

24、ncoln 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 independently.Although many references are made to safe practicesthroughout this standard, it is strongly

25、recommended thatall operators become thoroughly familiar with all aspectsof a safe oxyfuel heating operation. Safety and Healthinformation is available from various sources, including,but not limited to, ANSI Z49.1, Safety in Welding, Cutting,and Allied Processes, and applicable federal, state, andl

26、ocal regulations.2. Normative ReferencesThe following standards contain 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 amendment

27、s to, 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 Prepa-ration for Welding and Cu

28、tting of Containers and Piping.Other documents:ANSI Z49.1, Safety in Welding, Cutting and AlliedProcesses;2ISO 3821, Gas Welding Equipment Rubber Hosesfor welding, cutting, and allied processes;31AWS standards are published by the American WeldingSociety, 550 N.W. LeJeune Road, Miami, FL 33126.2ANSI

29、 Z49.1 is published by the American Welding Society,550 N.W. LeJeune Road, Miami, FL 33126.3ISO standards are published by the International Organizationfor Standardization, 1 rue de Varemb, Case postale 56, CH-1211Geneva 20, Switzerland.Recommended Practices for Safe OxyfuelGas Heating Torch Operat

30、ionAWS C4.3/C4.3M:20072NFPA-51, Standard for the Design and Installation ofOxygen-Fuel Gas Systems for Welding, Cutting, andAllied Processes;4andOSHA 29CFR1910, Occupational Safety and HealthStandards.53. Terms and DefinitionsThe terms listed are used in various sections of this docu-ment and requir

31、e definition for correct interpretation.Most of these terms are not contained in AWS A3.0,Standard Welding Terms and Definitions, IncludingTerms for Adhesive Bonding, Brazing, Soldering, Ther-mal Cutting, and Thermal Spraying, or if they are listedin AWS A3.0, their definitions have been enhanced to

32、clarify their use in this document.For the purposes of this document, the following defini-tions apply: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.flashback. The return of the f

33、lame through the torch andinto the hose and/or regulator. It may also reach thecylinder. This event is caused by the oxygen and fuelmixing in one side of the oxyfuel system due to thepressure differential and subsequently being ignited atthe tip. This condition is generally caused by thereverse flow

34、 of one gas into the other side of the sys-tem. Flashback is considered a hazardous conditionthat could lead to an explosion.sustained backfire. The return of the flame into thetorch with continued burning inside the torch. Thisevent can be identified by an initial popping soundfollowed by a squeali

35、ng or hissing sound caused bythe continued burning inside the torch.These terms describe potentially hazardous events thatcan occur when using oxyfuel equipment. It is importantfor the operator to understand these events and the termsthat are associated with them.4NFPA standards are published by the

36、 National Fire ProtectionAssociation,1 Batterymarch Park, Quincy, MA 02169.5OSHA standards are published by the Occupational Safetyand Health Administration, U.S. Government Printing Office,Washington, DC 20402.4. Equipment and SuppliesTo perform oxyfuel heating operations, some or all of thefollowi

37、ng are needed:6(1) Oxygen(2) Fuel gas(3) Cylinder or line pressure regulators(4) Check valves or flashback arrestors (see Clause10 for additional selection information).(5) Oxyfuel hoses(6) Heating or welding torches(7) Torch extensions (straight or curved)(8) Heating tips or heating heads(9) Spark

38、lighters(10) Tip cleaners(11) Safety equipment and personal protective equip-ment (PPE)(12) Temperature indicating devicesCAUTION: Check valves or flashback arrestors canbe used. However, before using these devices, the usermust determine that they will allow adequate flowcapacity for the equipment

39、being used.Note: These devices restrict flow which could result in abackfire or sustained backfire.4.1 Oxygen Supply. Oxygen of high purity can be sup-plied in individual cylinders (see Figure 1), manifoldedcylinders, or bulk liquid oxygen systems. Oxygen fromon-site generators, while of a lesser pu

40、rity, may be usedfor flame heating. However, for optimum heating resultscommercially pure oxygen should be considered. Whenproperly mixed with a fuel gas, high purity oxygen willproduce the most effective flame. Always refer to oxy-gen by its proper name, “OXYGEN.” It should never becalled “AIR.” At

41、mospheric air (the air that we breathe)contains approximately 21% oxygen by volume. Usingair instead of oxygen will dramatically reduce flametemperature resulting in lower heating. Regardless of thesource, one must be sure that sufficient pressure and flowcapabilities are available for the work to b

42、e done. The lit-erature supplied by the heating apparatus manufacturershould be consulted for volume requirements since eachmanufacturers operating data apply only to their equip-ment. To avoid the possibility of contaminating an oxygencylinder, the cylinder should never be completely emptied,6To me

43、et Federal OSHA requirements, all gas apparatus mustbe listed in or comply with CFR 1910, subparagraph 251.AWS C4.3/C4.3M:20073nor the valve left open when the cylinder is depleted ornot in use.CAUTION: OXYGEN VIGOROUSLY ACCELER-ATES COMBUSTION. Never use oxygen in pneu-matic tools, to clean equipme

44、nt, dust off clothing,provide ventilation, or any other application notintended for pure oxygen. Improper use of oxygenmay result in fire or explosion.4.2 Fuel Supply. Many different fuel gases are utilizedin the oxyfuel gas heating process. They include acety-lene, propane, natural gas, methylacety

45、lene-propadienestabilized (MPS), propylene, hydrogen, and severalpropane-based mixtures. The different fuel gases varyin flame characteristics. The oxyfuel operator shouldbecome familiar with the proper flame adjustments forthe fuel gas being used. The gas supplier should be con-tacted for the prope

46、r fuel-gas parameters.Fuel gases are supplied in individual cylinders (see Fig-ure 2) or distributed by pipeline from manifolded cylin-ders or bulk sources. Every fuel-gas cylinder has a limitas to its maximum safe withdrawal rate capabilities (seeTables B.1 through B.4). Contact the gas supplier or

47、equipment manufacturer to determine the number ofcylinders to be manifolded for proper operation.4.3 Maximum Acetylene Pressure. Acetylene shall notbe generated, piped (except in approved cylinder mani-folds), or utilized at a pressure in excess of 15 psig103 kPa (gauge pressure), or 30 psia 207 kPa

48、 (abso-lute pressure). Use at higher pressures is hazardous,resulting in the possibility of acetylene decomposition(explosion) from sudden shock or heat.The 30 psia 207 kPa limit is intended to prevent unsafeuse of acetylene in pressurized chambers such as caissons,underground excavations, or tunnel

49、 construction. Abso-lute pressure is equal to gauge pressure plus atmosphericpressure, which at sea level is approximately 15 psia103 kPa. Thus, at sea level, a gauge reading of 15 psig103 kPa is equal to an absolute pressure of 30 psia207 kPa. If higher operating pressures are required, oneFigure 1Oxygen CylinderREMOVABLE METAL CAPOUTLET VALVEPRESSURE RELIEF DEVICEPRESSED STEEL NECK RINGHIGH-PRESSURE OXYGENCYLINDER. PRESSURE INEXCESS OF 2000 psi 14 MPaFigure 2Typical Fuel Gas CylindersREMOVABLEMETAL CAPPOROUSFILLERPLUSLIQUIDACETONEBRASS ORSTEEL VALVESAFETY FUSEPLUGPRESSU