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1、| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS 7570:2000 ICS 25.160.3
2、0 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Code of practice for validation of arc welding equipment Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:48:29 GMT+00:00 2006, Uncontrolled Copy, (c) BSI This British Standard, having be
3、en prepared under the direction of the Engineering Sector Committee, was published under the authority of the Standards Committee and comes into effect on 15 May 2000 BSI 05-2000 First published July 1992 Second edition May 2000 The following BSI references relate to the work on this standard: Commi
4、ttee reference WEE/6 Draft for comment 99/708518 DC ISBN 0 580 33149 0 BS 7570:2000 Amendments issued since publication Amd. No.DateComments Committees responsible for this British Standard This British Standard has been prepared by Technical Committee WEE/6, Arc welding equipment, upon which the fo
5、llowing bodies were represented: Association of Welding Distributors British Cable Makers Confederation British Cables Association Cranfield University Institute of Electrical Engineers National Association of Arc Welding Equipment Offshore Contractors Association Welding Institute Welding Manufactu
6、rers Association Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:48:29 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7570:2000 BSI 05-2000i Contents Page Committees responsibleInside front cover Forewordii Introduction1 1Scope2 2Normative references2 3Terms a
7、nd definitions2 4Validation accuracies3 5Consistency3 6Frequency of validation and calibration3 7Validators of welding equipment3 8Validation3 8.1General3 8.2MMA4 8.3TIG4 8.4MIG/MAG and FCW4 8.5Auxiliary components5 9Validation techniques5 9.1General5 9.2Safety precautions5 9.3Instrumentation5 9.4Po
8、wer source loads5 9.5Method6 10Validation labels and certificates7 10.1 Valiation labels7 10.2 Validation certificate7 Annex A (informative) Proposed accuracies for precision grade power sources8 Annex B (informative) Wire feed equipment8 Annex C (informative) Slope, pulse and synergic controls9 Ann
9、ex D (informative) Precautions to be taken with TIG welding equipment10 Annex E (informative) The validation of ancillary components in a welding system10 Annex F (informative) Voltage drops in the welding circuit11 Figure F.1 Example of a welding circuit11 Table 1 Validation accuracies for standard
10、 grade power sources3 Table A.1 Validation accuracies for precision grade power sources8 Table B.1 Validation accuracies for wire feed equipment8 Table F.1 Voltage drop in copper and aluminium welding cables at normal and elevated temperatures12 Licensed Copy: London South Bank University, London So
11、uth Bank University, Fri Dec 08 11:48:29 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ii BSI 05-2000 BS 7570:2000 Foreword This British Standard is published under the authority of committee WEE/6, Arc welding equipment. It supersedes BS 7570:1992, which is withdrawn. Welding is considered to be a spe
12、cial process because the final result may not always be capable of being verified by testing, hence it requires continuous control and/or adherence to documented procedures. The standard series BS EN 729, Quality requirements for welding Fusion welding of metallic materials, has been published to id
13、entify the controls and procedures required. BS EN 729 requires the use of calibrated welding equipment, then the quality/consistency of the weld depends upon accurate and repeatable setting of parameters such as current, voltage, speed, gas flow, etc. This new edition of BS 7570 has been written ba
14、sed on the experience gained in using BS 7570:1992 over the last few years. This edition has been simplified and concentrates on validating equipment built to the constructional standard BS EN 60974-1. The accuracy of this equipment is designated as standard grade. A higher level of accuracy (precis
15、ion grade) was introduced in BS 7570:1992, but this has not gained wide acceptance so is now included in annex A for information. Annexes A to F are all informative. As a code of practice, this British Standard takes the form of guidance and recommendations. It should not be quoted as if it were a s
16、pecification and particular care should be taken to ensure that claims of compliance are not misleading. A British Standard does not purport to include all necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard
17、 does not of itself confer immunity from legal obligations Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 12, an inside back cover, and a back cover. The BSI copyright notice displayed in this document indicates when the document was last is
18、sued. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:48:29 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BSI 05-20001 BS 7570:2000 Introduction The quality and consistency of a weld depends on the welder, the materials and the welding equipment. Variability in
19、the output of the welding equipment will affect the quality of the weld. In some arc welding processes, e.g. MMA, the welder controls the process through his experience, and measurement of run out length is used to monitor the heat input. However, in other arc welding processes, the quality of the w
20、eld depends upon accurate and repeatable setting of parameters such as current, voltage, speed, gas flow, pulse characteristics etc. The relevant construction standard for arc welding equipment is BS EN 60974-1. This standard sets the reference level for the accuracy and consistency of the welding o
21、utput. BS EN 60974-1 derives its specification for performance accuracy from the requirements of manual welding. In manual welding the welder plays a key role in adapting and adjusting the output of the equipment to meet the requirements of the weld. This adaptability allows equipment to be construc
22、ted with a relaxed specification for calibration of output. Mechanized welding methods lack the skilled adaptability of the manual welder and require precise control of all aspects of the welding process. The control of the output of the welding equipment is of particular importance. Manufacturers h
23、ave responded to this need by producing equipment with an accuracy of output control and calibration which far exceed the requirements of BS EN 60974-1. In addition to the demands of mechanized welding, manual welding methods have become more refined and welding procedures often call for the precise
24、 control of power source outputs to limit the freedom of the manual welder in order to produce particular results. The improvement in equipment construction, the adoption of mechanized welding, the introduction of quality assurance programmes and the increased understanding of the factors which cont
25、rol weld quality have led to the demand for more rigorous calibration and validation of welding equipment performance. The term calibration has been used in the foregoing text to introduce the general subject of checking that the welding equipment output meets the manufacturers specification and is
26、fit for the purpose of making welds. This is a commonly accepted term for this checking operation but it does not meet the strict definition of the word calibration. Clause 3 of this document gives the definition of calibration. The operation of calibration can be applied only to determining and adj
27、usting the errors of a measuring instrument. An item of welding equipment is not a measuring instrument though the meters fitted to the welding equipment are and can be calibrated. The difficulty of terminology and the checking task is further compounded as many pieces of welding equipment do not ha
28、ve calibrated outputs but are scaled in arbitrary units. Again this is a function of the manual welding usage in which the skill of the manual welder is used to adjust and set the welding variables. It is necessary to use an alternative term to describe the operation of verifying that the welding eq
29、uipment is fit for the intended purpose. The term selected is validation. Validation is the operation which verifies that the welding equipment conforms to the operating specification for that equipment. If the equipment fails to conform to the specification then the correction of the errors within
30、the equipment is outside the scope of this standard. That operation is the province of the manufacturers or equipment specialists. It is implicit in the introduction of a more rigorous standard for accuracy of control of output for welding equipment that the scope of application of that standard sho
31、uld be defined. This standard defines two levels of accuracy. One is derived directly from BS EN 60974-1 and is called standard grade. A higher level of accuracy for more exacting welding applications is defined, called precision grade, and this is given in annex A for information. The use of precis
32、ion grade is dependent upon the welding application. The welding equipment covered by this standard will be fitted with controls intended to regulate the output of the welding equipment. The controls may be scaled in absolute units (amperes, volts, metres per minute) or in arbitrary units (numbers,
33、letters, geometrical marks). Controls scaled in absolute units may be validated and the consistency of those controls scaled in arbitrary units may be assessed. The welding equipment may be fitted with meters that measure the output of the equipment and these meters should normally be validated agai
34、nst the appropriate standard, unless a different method is used to control the welding process. The use of meters and measuring instrument packages with welding equipment that is required to produce welds of integrity and reliability is strongly recommended. This code of practice recommends the use
35、of resistive loads to validate the power source and associated meters. Alternatively, independent instrumentation may be used to monitor the welding process, rather than validating the power source itself. The method of control and type of instrumentation should be detailed on the welding procedure
36、sheet. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:48:29 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 2 BSI 05-2000 BS 7570:2000 1 Scope This British Standard gives recommendations for validation methods for welding equipment constructed and used to the acc
37、uracy specified in BS EN 60974-1 or other equivalent standards. The accuracy of this equipment is designated as standard grade. The welding equipment covered by this standard includes: 1) welding power sources; 2) wire feeders; 3) welding instrumentation. Guidance is also given on the calibration an
38、d validation of ancillary equipment which may affect the quality of the weld, e.g. flow gauges, thermocouples, robots and manipulators. 2 Normative references The following normative documents contain provisions which, through reference to this text, constitute provisions of this British Standard. F
39、or dated references, subsequent amendments to, or revisions of, any of these publications do not apply. For undated references, the latest edition of the publication referred to applies. BS 89-2:1990, Direct acting indicating analogue electrical measuring instruments and their accessories Part 2: Sp
40、ecification for special requirements for ammeters and voltmeters. BS 90:1975, Specification for direct-acting electrical recording instruments and their accessories. BS 499-1:1991, Welding terms and symbols Glossary for welding, brazing and thermal cutting. BS 638-4:1996, Arc welding power sources,
41、equipment and accessories Part 4: Specification for welding cables. BS 638-7:1984, Arc welding power sources, equipment and accessories Part 7: Specification for safety requirements for installation and use. BS 638-10:1990, Arc welding power sources, equipment and accessories Part 10: Specification
42、for safety requirements for arc welding equipment: welding power sources (withdrawn, see clause 4). BS EN 729:1995 (all parts), Quality requirements for welding Fusion welding of metallic materials. BS EN 60051-1:1999, Direct acting indicating analogue electrical measuring instruments and their acce
43、ssories Part 1: Definitions and general requirements common to all parts. BS EN 60974-1:1998, Arc welding equipment Part 1: Welding power sources. 3 Terms and definitions For the purposes of this British Standard, the terms and definitions given in BS 499-1 and the following apply. 3.1 calibration o
44、perations for the purpose of determining the magnitude of the errors of a measuring instrument and if necessary to determine other metrological properties 3.2 validation operations for the purpose of demonstrating that an item of welding equipment or a welding system conforms to the operating specif
45、ication for that welding equipment or system 3.3 accuracy closeness of an observed quantity to the defined or true value 3.4 consistency test test to determine the consistency of the equipment output over a period of time NOTEThe results obtained from the present validation are compared to the resul
46、ts of the previous validation. The repeatability/consistency is the difference between these readings. 3.5 class designation according to the accuracy of a measuring instrument conforming to BS EN 60051-1:1999, BS 89-2:1990 or BS 90:1975 NOTEFor example, class 2.5 refers to2.5 % full scale deflectio
47、n. 3.6 portable welding monitor (brief case monitor) assembly of measuring instruments packaged in a portable case used to measure, record and/or analyse the welding equipment output 3.7 expert (competent, skilled person) person who can judge the work assigned to him and recognize possible dangers o
48、n the basis of his professional training, knowledge and experience and his knowledge of the relevant requirements 3.8 standard grade grade of validating equipment built to the constructional standard BSEN60974-1or BSEN638-10:1990 NOTEBS 638-10:1990 was withdrawn in 1998 and superseded by BS EN 60941
49、-1:1998. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:48:29 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BSI 05-20003 BS 7570:2000 3.9 precision grade grade of validating equipment built to the constructional standard BS EN 60974-1 or BS 638-10:1990 but with a higher level of accuracy for more exacting welding applications NOTESee annex A for power sources and annex B for wire feeders. 4 Validation accuracies When tested in accordance with clause 9, the validation accuracies for standard grade power source con
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