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1、BRITISH STANDARD BS 7570:1992 Code of practice for Validation of arc welding equipment Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:42:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7570:1992 This British Standard, having been prepared under the directio
2、n of the Welding Standards Policy Committee, was published under the authority of the Standards Board and comes into effect on 15 July 1992 BSI 02-1999 The following BSI references relate to the work on the Standard: Committee reference WEE 6 Draft for comment 91/70593 DC ISBN 0 580 20713 7 Committe
3、es responsible for this British Standard The preparation of this British Standard was entrusted by the Welding Standards Policy Committee (WEE/-) to Technical Committee WEE/6, upon which the following bodies were represented: British Cable Makers Confederation Electricity Association Health and Safe
4、ty Executive Institution of Incorporated Executive Engineers National Association of Arc Welding Equipment Repairers Power Generation Contractors Association (BEAMA Ltd.) Welding Institute Welding Manufacturers Association (BEAMA Ltd.) Coopted members Amendments issued since publication Amd. No.Date
5、Comments Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:42:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7570:1992 BSI 02-1999i Contents Page Committees responsible Inside front cover Forewordiii 0 Introduction1 1Scope3 2References3 3Definitions4 4Validat
6、ion accuracies for the equipment classified as grade 1 (standard grade)4 5Validation accuracies for the equipment classified as grade 2 (precision grade)5 5.1Repeatability5 5.2Welding power sources5 5.3Wire feed equipment5 5.4Instrumentation5 6Frequency of validation and calibration6 7Authorized val
7、idators of the welding equipment6 8Validation techniques6 8.1General6 8.2The validation of current controls and current meters6 8.3 The validation of voltage controls and voltage meters9 8.4Validation of wire feed speed controllers and wire feed speed meters11 8.5The validation of welding power sour
8、ce special current control functions12 9Validation labels and certificates13 9.1Validation label13 9.2Invalidity label13 9.3Validation certificate13 Annex A (normative) Practical details for the application of this standard14 Annex B (informative) The validation of ancillary components in a welding
9、system14 Annex C (normative) The validation of tungsten inert-gas welding equipment15 Annex D (normative) The use and construction of loading devices for welding power sources15 Annex E (normative) The validation of welding power source current controls and current meters17 Annex F (normative) The v
10、alidation of voltage controls and voltage meters on welding power sources18 Annex G (normative) The validation of wire feeders19 Annex H (normative) The validation of special current controls19 Figure 1 Welding equipment validation aid chart 120 Figure 2 Welding equipment validation aid chart 221 Fi
11、gure 3 Welding equipment validation aid chart 322 Figure 4 Illustration of waveform terminology23 Figure 5 Validation connections for current controls and current meters24 Figure 6 Validation connections for voltage controls and voltage meters25 Licensed Copy: London South Bank University, London So
12、uth Bank University, Fri Dec 08 11:42:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7570:1992 ii BSI 02-1999 Page Figure 7 Validation methods for wire feeders26 Figure 8 Validation connections for special current controls27 Table 1 Validation accuracies for grade 1 power sources5 Table 2 Validati
13、on accuracies for grade 1 instruments5 Table 3 Validation accuracies for grade 2 power sources5 Table 4 Validation accuracies for grade 2 wire feeders5 Table 5 Validation accuracies for grade 2 instrumentation6 Table 6 Frequency of validation6 Table 7 Loading devices for welding power sources7 Table
14、 8 Current measuring transducers8 Table 9 Current measuring instruments8 Table 10 Voltage measuring instruments10 Table 11 Wire feed speed measuring instruments11 Table 12 Waveform measuring devices12 Table 13 Waveform measuring device instrument types19 List of referencesInside back cover Licensed
15、Copy: London South Bank University, London South Bank University, Fri Dec 08 11:42:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7570:1992 BSI 02-1999iii Foreword This standard was prepared under the direction of the Welding Standards Policy Committee. The need for an improved specification for t
16、he calibration, validation and accuracy of welding equipment was foreseen by the committee and this voluntary code of practice has been written to fulfil that need. It is well known that the maintenance of the required accuracy of outputs of power sources and other equipment is vital in the producti
17、on of satisfactory welds particularly with those processes where the welder does not manually control the application of the arc. The urgent need for guidance and standardization having been recognized, this standard was produced after detailed consultations with users and manufacturers of arc weldi
18、ng equipment. (It was considered that all other aspects required to ensure the production of satisfactory welds were already covered by compliance with existing process and procedure standards, codes of practice, etc.) Many manufacturers of arc welding equipment realize the vital role of the equipme
19、nt and hence the need to test and maintain the performance of their products. In the absence of any other guidance, they operate their own quality control and maintenance schedules. In addition they build equipment with accuracies of performance superior to those required by national and internation
20、al standards at present in general use. This standard sets out to regularize the equipment calibration and validation requirements for all arc welding processes ranging from the least demanding to the most sophisticated. It is intended to serve all areas of the arc welding industry and to simplify t
21、he preparation of quality assurance documentation. Summarizing the functions of the code, it: a) states the required accuracy of operation for a particular task; b) shows how the equipment can be validated or checked to that accuracy; c) shows how to record and label the equipment to prove it has be
22、en validated or checked; d) contains information about practical and economic means of achieving good welding instrumentation. BS 7570 is intended to serve all areas of industry that manufacture or use welding equipment. It is expected to play a key part in quality assurance of electric arc welding.
23、 It is not intended to supersede the requirements of BS 638, IEC 974-1 or any other relevant construction or safety standard for welding equipment. The selection of the grade of validation and the implementation of validation methods should always be entrusted to appropriately qualified and experien
24、ced staff. 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 specification and particular care should be taken to ensure that claims of compliance are not misleading. A British Standard does not purport to include all
25、 the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i to i
26、v, pages 1 to 28, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Licensed Copy: London South Bank University, London South Bank University, F
27、ri Dec 08 11:42:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI iv blank Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:42:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7570:1992 BSI 02-19991 0 Introduction 0.1 The integrity and reliability of a weld is a f
28、unction of the materials and the equipment used to make the weld. It can be demonstrated that the variability in the output of the welding equipment will directly affect the quality of the weld. The maintenance of the accuracy and the consistency of the performance of the welding equipment is a key
29、component in the final quality of the weld. 0.2 The primary standard for the production of accurate and reliable welding equipment is the appropriate national, European or international standard. The relevant standard for the construction of welding equipment referred to in this standard is BS 638-1
30、0. It sets the reference level for the accuracy and consistency of the output of welding equipment in the United Kingdom. 0.3 The construction standard BS 638-10 derives its specification for performance accuracy from the requirements of manual welding. In manual welding the welder1) plays a key rol
31、e in adapting and adjusting the output of the equipment to meet the requirements of the weld. This adaptability allows equipment to be constructed with a relaxed specification for calibration of output. 0.4 Machine welding methods lack the skilled adaptability of the manual welder and requires preci
32、se control of all aspects of the welding process. The control of the output of the welding equipment is of particular importance. Manufacturers have responded to this need by producing equipment with an accuracy of output control and calibration which far exceed the requirements of BS 638-10, etc. 0
33、.5 In addition to the demands of machine welding, manual welding methods have become more refined and welding procedures often call for the precise control of machine outputs to limit the freedom of the manual welder in order to produce particular results. 0.6 The improvement in equipment constructi
34、on, the adoption of machine welding, the introduction of quality assurance programmes and the increased understanding of the factors which control weld quality have led to the demand for more rigorous calibration and validation of welding machine performance. 0.7 This standard seeks to address this
35、need by considering the following: a) the accuracy of calibration or validation for each category of welding equipment (see clauses 4 and 5); b) the frequency of calibration or validation necessary to maintain the standard of operation of the equipment (see clause 6); c) the authorities competent to
36、 calibrate and validate welding equipment (see clause 7); d) the calibrating and validating tests necessary to maintain the standard of operation of the equipment (see clause 8); e) the documentation necessary to prove that the recommended standard has been achieved (see clause 9); f) the practical
37、means whereby the foregoing recommendations can be realized (see Annex A to Annex H); g) provision for the calibrator or validator with the means to determine the optimum route, relevant to the available resources, to achieve the recommended standard (see Annex A to Annex H). 0.8 The term calibratio
38、n 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 fit for the purpose of making welds. This is a commonly accepted term for this checking operation but it does not meet the strict definiti
39、on 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 adjusting the errors of a measuring instrument. A piece of welding equipment is not a measuring instrument though the meters fitted to the we
40、lding 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 have calibrated outputs but are scaled in arbitrary units. Again this is a function of the manual welding usage in which the skill of the ma
41、nual 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 equipment is fit for the intended purpose. The term selected is validation. 1) The term “welder” is used in this context to distinguish the
42、operator of manual welding equipment from the “welding operator” of mechanized welding equipment. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 11:42:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7570:1992 2 BSI 02-1999 0.9 Validation is the operation which
43、 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 the equipment is outside the scope of this standard. That operation is the province of the manufacturers or
44、 equipment specialists. 0.10 It is implicit in the introduction of a more rigorous standard of accuracy of control of output for welding equipment that the scope of application of that standard should be defined. This standard defines two levels of accuracy, one derived directly from BS 638-10 and t
45、his is called grade 1 or standard grade. A higher level of accuracy for more exacting welding applications is defined and called grade 2 or precision grade; this is dependent upon the welding application. The use of grade 2 (precision grade) is determined by one of the following: a) the maker of the
46、 welding equipment; b) the welding procedure requirements; c) the weld quality standard or code; d) the quality assurance programme. Pre-eminent among these is the developer of the welding procedure. 0.11 If the grade 2 accuracy is specified in a welding procedure or a quality control document it wi
47、ll be necessary for the user of the equipment first to determine that the equipment can operate to the required standard and then to validate the operation of the equipment. 0.12 The items of welding equipment covered in this standard have been selected as those with the most significant effect on t
48、he quality of the weld. Other items of equipment considered for inclusion were weld head tractors, orbital welding heads, robotic manipulators, arc length control devices, rotators and gas flow controls. The production of a weld, whether by manual welding or a complex welding machine, should be rega
49、rded as a complete operational system and care should be exercised with maintenance and calibration of all parts. To assist in this operation some guidance on the preparation and maintenance of equipment outside the scope of this standard is given in Annex B. 0.13 It is intended that the use of the calibration and validation methods given in this standard should follow a simple route. a) Select the validation grade, using clause 1 and Figure 1, aided by the relevant notes in this introduction. b) Select the validation accuracy value, us
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