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1、a Date: 24 September 2008 Origin: National Latest date for receipt of comments: 30 November 2008 Project no.: 2005/01280 Responsible committee: FME/9/1 Material Interested committees: FME/9/1 Title: Draft BS 7371 Coatings on metal fasteners - Part 3: Specification for electroplated zinc and cadmium
2、coatings Supersession information: If this document is published as a standard, the UK implementation of it will supersede BS7371-3 : 1993 and partially supersede. NONE If you are aware of a current national standard which may be affected, please notify the secretary (contact details below). WARNING
3、: THIS IS A DRAFT AND MUST NOT BE REGARDED OR USED AS A BRITISH STANDARD. THIS DRAFT IS NOT CURRENT BEYOND 30 November 2008. This draft is issued to allow comments from interested parties; all comments will be given consideration prior to publication. No acknowledgement will normally be sent. See ov
4、erleaf for information on commenting. No copying is allowed, in any form, without prior written permission from BSI except as permitted under the Copyright, Designs and Patent Act 1988 or for circulation within a nominating organization for briefing purposes. Electronic circulation is limited to dis
5、semination by e-mail within such an organization by committee members. Further copies of this draft may be purchased from BSI Customer Services, Tel: +44(0) 20 8996 9001 or email . British, International and foreign standards are also available from BSI Customer Services. Information on the co-opera
6、ting organizations represented on the committees referenced above may be obtained from the responsible committee secretary. Cross-references The British Standards which implement International or European publications referred to in this draft may be found via the British Standards Online Service on
7、 the BSI web site http:/. Direct tel: 020 8996 7106 Responsible Content Developer: Mr S Wright (BSI) E-mail: S Draft for Public Comment Head Office 389 Chiswick High Road London W4 4AL Telephone: +44(0)20 8996 9000 Fax: +44(0)20 8996 7001 Form 36 Version 8.0 DPC: 08/30133820 DC Licensed CopyChinese
8、University of Hong Kong, 21/10/2008 03:29, Uncontrolled Copy, (c) BSI b Introduction Your comments on this draft are invited and will assist in the preparation of the resulting British Standard. If no comments are received to the contrary, this draft may be implemented unchanged as a British Standar
9、d. Please note that this is a draft and not a typeset document. Editorial comments are welcomed, but you are advised not to comment on detailed matters of typography and layout. Submission of comments The guidance given below is intended to ensure that all comments receive efficient and appropriate
10、attention by the responsible BSI committee. This draft British Standard is available for review and comment online via the BSI British Standards Draft Review system at http:/. Registration is free and takes less than a minute. Once you have registered on the Draft Review system you will be able to r
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13、not be corrected. A link to the BSI British Standards Draft Review system, or to a specific draft hosted on the system, may be distributed to other interested parties so that they may register and submit comments. It is not necessary to purchase a copy of the draft in order to review or comment on i
14、t; however, additional copies of this draft may be purchased from BSI, Tel: +44(0) 20 8996 9001 or email: . Drafts and standards are also available in PDF format for immediate download from the BSI Shop http:/ Licensed CopyChinese University of Hong Kong, 21/10/2008 03:29, Uncontrolled Copy, (c) BSI
15、 WARNING. THIS IS A DRAFT AND MUST NOT BE REGARDED OR USED AS A BRITISH STANDARD. THIS DRAFT IS NOT CURRENT BEYOND 30TH NOVEMBER 2008. BS 7371-3: 2008 BS 7371-3 Coatings on metal fasteners Part 3: Specifications for electroplated zinc coatings Licensed CopyChinese University of Hong Kong, 21/10/2008
16、 03:29, Uncontrolled Copy, (c) BSI WARNING. THIS IS A DRAFT AND MUST NOT BE REGARDED OR USED AS A BRITISH STANDARD. THIS DRAFT IS NOT CURRENT BEYOND 30 NOVEMBER 2008. Contents Foreword 3 Introduction 4 1 Scope 6 2 Normative References 6 3 Terms and Definitions 6 4 Application and type of coating 7 5
17、 Coating 7 Table 1 Nominal coating thicknesses 8 6 Chromate treatment or topcoat 8 7 Suitability of coatings for components with parallel treads 9 8 Information to be documented and supplied to the coater 9 9 Identification 9 Table 2 Coating designation and corrosion resistance 10 Table 3 Designatio
18、n of chromate treatments 11 Table 4 Designation of tri-valent based treatments 11 Annex A (normative) Coating thickness for threaded parts 12 Table A.1 Upper limits of nominal coating thickness 12 Annex B (normative) Measurement of coating thickness 13 Figure B.1 Measuring area for local coating thi
19、ckness measurement on fasteners 14 Annex C (informative) Guidance on procedures that may be adopted to accommodate thick coatings 15 Bibliography 17 Licensed CopyChinese University of Hong Kong, 21/10/2008 03:29, Uncontrolled Copy, (c) BSI WARNING. THIS IS A DRAFT AND MUST NOT BE REGARDED OR USED AS
20、 A BRITISH STANDARD. THIS DRAFT IS NOT CURRENT BEYOND 30TH NOVEMBER 2008. Foreword Publishing information This part of BS 7371 is published by BSI and came into effect on XX Month 200X. It was prepared by Technical Committee FME/9/1, Material. A list of organizations represented on this committee ca
21、n be obtained on request to its secretary. Supersession This part of BS 7371 supersedes BS 7371-3:1993, which is withdrawn. Relationship with other publications Other published Parts of BS 7371 are as follows: BS7371-1, Coatings on metal fasteners - Specification for general requirements and selecti
22、on guidelines BS 7371-2, Coatings on metal fasteners Part 2: Specification for torque/clamping force relationship BS 7371-4, Coating on metal fasteners Part 4: Specification for electroplated nickel, nickel/chromium and copper/nickel/chromium coatings BS 7371-6, Coatings on metal fasteners Part 6: S
23、pecification for hot dipped galvanized coatings BS 7371-7, Coatings on metal fasteners Part 7: Specification for mechanically applied zinc and zinc based coatings BS 7371-8, Coatings on metal fasteners Part 8: Specification for sherardized coatings BS 7371-9, Coatings on metal fasteners Part 9: Spec
24、ification for phosphate or phosphate and oil coatings BS 7371-10, Coatings on metal fastenings Part 10: Specification for phosphate or phosphate and oil coatings. BS 7371-11, Coatings on metal fasteners Part 11: Specification for zinc flake non-electrolytically applied cured coatings 1) BS 7371-12,
25、Coatings on metal fasteners Part 12: Requirements for imperial fasteners Information about this document This is a full revision of the standard, and introduces the following principal changes: The option of specifying non hexavalent chromium containing conversion coatings. Details concerning cadmiu
26、m have been deleted from this Standard due to the restrictions below. 1) Obsolete, replaced by BS EN ISO 10683:2000 but remains current. Licensed CopyChinese University of Hong Kong, 21/10/2008 03:29, Uncontrolled Copy, (c) BSI WARNING. THIS IS A DRAFT AND MUST NOT BE REGARDED OR USED AS A BRITISH S
27、TANDARD. THIS DRAFT IS NOT CURRENT BEYOND 30 NOVEMBER 2008. The attention of the user of this Part of BS 7371 is drawn to the restrictions placed on the marketing and use of cadmium and its compounds contained in the Environmental Protection (Controls on Injurious Substances) (No 4) Regulations 1992
28、 1. Assessed capability. Users of this British Standard are advised to consider the desirability of quality system assessment and registration against the appropriate standard in the BS EN ISO 9000 series by an accredited third-party certification body. Hazard warnings WARNING. This British Standard
29、 calls for the use of substances and/or procedures that can be injurious to health if adequate precautions are not taken. It refers only to technical suitability and does not absolve the user from legal obligations relating to health and safety at any stage. The attention of the user of this Part of
30、 BS 7371 is drawn to the restrictions placed on the use and supply of hexavalent chromium containing substances by ECC Directive 2000/53/EC of 18th September of 27th 2000 on End of Life Vehicles and amendment of Annex II by Commission Decision June 2002 (Document No. C(2002) 2238) 2, and non- use on
31、 Motor Vehicles marketed after July 2007. The Waste Electrical and Electronic Equipment (WEEE) Directive (2002/96/EC) 3 is also noted and which came into force on 31st December 2006. Presentational conventions The provisions of this standard are presented in roman (i.e. upright) type. Its requiremen
32、ts are expressed in sentences in which the principal auxiliary verb is “shall”. Commentary, explanation and general informative material is presented in smaller italic type, and does not constitute a normative element. Contractual and legal considerations This publication does not purport to include
33、 all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard cannot confer immunity from legal obligations. Introduction The BS 7371 series deals with the performance and selection of coatings on metal fasteners and accessories. T
34、his Part of BS 7371 specifies the requirements for zinc electroplated coatings. Other published Parts of BS 7371 are as follows: BS 7371-1, Specification for general requirements and selection guidelines2) BS 7371-2, Coatings on metal fasteners Part 2: Specification for torque/clamping force relatio
35、nship BS 7371-6, Coatings on metal fasteners Part 6: Specification for hot dipped galvanized coatings BS 7371-7, Coatings on metal fasteners Part 7: Specification for mechanically applied zinc and zinc based coatings 2) This is supplementary to all other Parts of BS 7371. Licensed CopyChinese Univer
36、sity of Hong Kong, 21/10/2008 03:29, Uncontrolled Copy, (c) BSI WARNING. THIS IS A DRAFT AND MUST NOT BE REGARDED OR USED AS A BRITISH STANDARD. THIS DRAFT IS NOT CURRENT BEYOND 30TH NOVEMBER 2008. BS 7371-8, Coatings on metal fasteners Part 8. Specification for sherardized coatings BS 7371-9, Coati
37、ngs on metal fasteners Part 9. Specification for phosphate or phosphate and oil coatings BS 7371-11, Coatings on metal fasteners Part 11: Specification for zinc flake non-electrolytically applied cured coatings 3) BS 7371-12, Coatings on metal fasteners Part 12: Requirements for imperial fasteners Z
38、inc electroplated coatings covered by this Part of BS 7371 are for use on fasteners and accessories where the following apply: a) a coating giving galvanic protection is required for ferrous fasteners; b) a substrate is required to improve the corrosion resistance of subsequent coatings on ferrous f
39、asteners, e.g. organic; c) the risk of hydrogen embrittlement of high tensile steel fasteners is acceptable; The coating has a silver appearance which can be modified to yellow, olive green or black by a hexavalent chromium containing conversion (passivation) treatment applied to improve corrosion r
40、esistance. Trivalent chromium containing top coatings can be applied which will give a transparent to bluish iridescence or pale green iridescence. Additional coatings are available to further modify colour but these may influence coating performance, e.g. lubricity or electrical conductivity. The s
41、hape of certain parts may create difficulties in the application of a coating of uniform thickness and reference to the coater is recommended to enquire if a difficulty exists or if it can be overcome by the use of specialized processing methods. Typical difficulties as outlined in BS 4479-1 and BS
42、4479-2 arise when bulk processing: 1) long thin parts; 2) parts with flat surfaces that can stick together during processing, e.g. flat washers; 3) parts with recesses which do not receive the full coating; 4) parts with shapes that induce nesting and interlocking; 5) the internal surfaces of hollow
43、 parts. The coatings are suitable for application to metal components such as the following: i) parallel threaded fasteners and accessories; ii) screws that cut or form their own threads, e.g. self tapping screws (see for example BS 4174); iii) woodscrews (see for example BS 1210); iv) springs and s
44、pring components; v) pipe nuts and connectors with parallel or tapered threads. When these coatings are applied to non-ferrous fasteners, the only part of the specification that will apply will be the coating thickness requirement. These coatings should not be 3) Obsolete, replaced by BS EN ISO 1068
45、3:2000 but remains current. Licensed CopyChinese University of Hong Kong, 21/10/2008 03:29, Uncontrolled Copy, (c) BSI WARNING. THIS IS A DRAFT AND MUST NOT BE REGARDED OR USED AS A BRITISH STANDARD. THIS DRAFT IS NOT CURRENT BEYOND 30 NOVEMBER 2008. specified for application to copper or copper all
46、oys unless an undercoat is also specified, e.g. nickel. NOTE The coating processes covered by this standard may induce hydrogen embrittlement in certain ferrous fasteners. Attention is drawn to the appropriate requirements in BS 7371-1. 1 Scope This Part of BS 7371 specifies requirements for coating
47、s applied by the electrolysis of solutions of zinc. The coatings consist principally of zinc and can be lubricated to give controlled torque/clamping force properties when required (see for example, BS 7371-2). In addition to the requirements in this Part of BS 7371, the requirements in Part 1 of th
48、e standard which are applicable to zinc electroplated coatings apply. This Part of BS 7371 also specifies requirements for the following: a) the coating thickness; b) the type of conversion treatment or topcoat to be applied; c) quality assessment of the corrosion resistance of unused coated parts w
49、hen subjected to neutral salt spray testing (for example BS EN ISO 9227); d) adhesion test. Annexes include tables indicating suitable coating grades for standard screw threads and methods of determination of coating thickness. 2 Normative References The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. F