Specificationfor
Electroplated coatings on threaded ponents
Part1:Cadmium onSteelComponents-
Part2:ZinconSteel Components
Co-operatingorganizations
The Mechanical Engineering Industry Standards Committee under whosesupervision this British Standard was prepared consists of representatives from the following Government departments and scientific and industrialorganizations:
Gas Council High Commission of IndiaInstitute of Marine Engineers Institute of PetroleumInatitution of Civil Engineers Institution of Gas EngineersInstitution of Heating and Ventilating EngineersInstitution of Mechanical Bngineers* Institution of MechanicalInstitution of Production Engineers* Engineers (Automobile Division)Lootive and Allied Manufacturers Association of Great Britain*Machine Tool Trades AssociationMinistry of Labour (Factory Inspectorate) Ministry of PowerNational Coal Board Ministry of Transport Ministry of WorksNational Physical Laboratory (D.S.LR.)*Radio Industry Council* War Office*
Admiralty* Air Ministry*Associated Offioes′ Technical Committee Association of Consulting EngineersBritish Chemical Plant Manufacturers (Incorporated)British Compresed Air Society AssociationBritish Electrical and Allied Manufacturers’ Association*British Engineers’ Association* British Gear Manufacturers’ AssociationBritish Internal Combustion Engine Manufacturers AssociationBritish Iron and Steel FederationCrown Agente for Oversea Governments and British Railways The British Transport Commission*AdministrationsD.S.LR. National Engineering Laboratory* Electricity Council The Generating BoardEngineering Bquipment Users’ Association* and the Area Boards in England and Wales
The Government departments and scientific and industrial organizationsdirectly represented on the Committee entrusted with the preparation of this marked with an asterisk in the above list together with the following werestandard:
Radio and Electronic Component Manufacturers FederationScientific Instrument Manufacturers’ Associationsmn po m AssociationSociety of British Aireraft Constructors Society of Motor Manufacturers and TradersTelemunication Engineering and Ltd.Manufacturing AsociationIndividual Manufacturers
Agricultural Engineers Association British Bolt Nut Serew and RivetBritish Non-ferrous Metals Research FederationCouncil of British Manufacturers of AssociationElectronic Bngineering Association Petroleum Equipment Gauge and Tool Makers' Association Institute of Metal FinishingMinistry of AviationNational Association of Marine Enginebuilders
This British Standard havingMechanical Engineering Industry Standards been approved by theCommittee and endorsed by the Chairman of tbeEngineering Divisional Council was published underthe authority of the General Councilon12 May 1961
Amendments issued since publication
Amd. No. Date of issue Comments6279 November 1967Committee reference MEE/1 and 926 March November Indicated by a sideline in the margin1994
BSI 03-2000
Contents
PageCo-operating organizations Foreword Inside front cover iIntroductory notes 11 Scope Definitions 32 3 Inspection 3 34 Screw thread dimensions 4Part 1: Cadmium plating (bright or dull) on steel ponents 5 Resistance to corrosion 46 Purity 47 8 Adhesion Porosity 4 49 Reduction of hydrogen embrittlement 410 11 Finish and appearance of plated surfaces Plating thickness 5 512 Passivation 6Part 2: Zinc plating (bright or dull) for steel ponents 913 14 Resistance to corrosion Purity 915 Reduction of hydrogen embrittlement Finish and appearance of plated surfaces 616 17 Plating thickness 6 619 Passivation 7Appendix B “Strip and weigh” method for the determination of Appendix A Passivation treatment 8group and sample average plating thicknesses 6Appendix C Determination of the thickness of cadmium plating by the Clarke “time of gassing” test 9Appendix D Notes on surface areas of bolts serews and nuts 10Appendix E Examples of calculations of deposit thicknesses on plated threaded shanks 12Figure 1 - Probable frequeney distribution of thickness in a barrel load 2Figure 2 - Curve of determination of average thickness ofcadmium coatings Figure 3 - Constituent surface areas of a screw or bolt 10 11Table 1 - Plating thickness 5Table 1A - Plating thickness (millimetre dimensions) Table 2 - Screws and bolts - B.S.W. and B.S.F. threads 13 5Table 3 - Screws and bolts - UNC and UNF threads 14Table 4- Serews and bolts - B.A. threads Table 5 Screws and bolts B.S.C. and B.S.P. threads 15 15Table 6- Table deletedTable 7- Table 8 Nuts - B.S.W. and B.S.F. threads Nuts -- B.A. threads 16 16Table 9 - Nuts -UNC and UNF threads 17Table 10-Table deleted
Foreword
This standards makes reference to the following British Standards:BS 57 B.A. screus bolts nuts and plain washers. BS 84 Parallel screw threads of Whitworth form.BS 93 British Association (B.A.) screto threads with tolerances for sizes 0 B.A.to 16 B.A. BS 450 Machine screws and machine screw nuts (B.S.W. and B.S.F. threads).BS 811 Cycle threads.BS 919 Screw gauge limits and tolerances.BS 1083 Precision hexagon bolts screws nuts and plain uashers. BS 1210 Wood screus.BS 1580 Unified screuw threads.BS 1706 Electroplated coatings of cadmium and zinc on iron and steel.BS 1768 Unified precision hexagon bolts screws nuts (UNC and UNF threads) and piain washers - normal series.BS 1981 Unified machine screics and machine screw nut8.electronic equipment. BS 2011 Basic climatic and durability tests for ponents for radio and alliedBS 2779 Fastening threads of BSP sizes.BS 3155 American machine screws and nuts in sizes belou / inch diameter.
This British Standard has been prepared under the authority of the Mechanical Engineering Industry Standards Committee. It deals with the plating of smallthreaded ponents such as bolts screws and nuts in various materials platedwith the moner protective finishes.
The pleted standard will refer to:
-Part I: Cadmium on steel ponents;-Part 2: Zinc on steel ponents; -Part 3: Nickel and nickellchromium on steel ponents;Part 4: Nichel and nickel/chromium on brass ponents;Part 5: Tin on copper and copper alloys (including brass) ponents; Part 6: Siluer on copper and copper alloys (including brass) ponents; Part 7: Thicher platings on threaded ponents (which will deal with thosespecial cases where greater protection than that provided by Parts I and 2 isrequired).
Parts 1 and 2 deal with thicknesses of plating which without preventing theassembly of threaded ponents will ensure the best possible protection against corrosion on threads conforming to tolerances and allowances laid down inrelevant screw thread standards. These will be adequate for most purposes.Greater thicknesses cannot be acmodated on standard threads without undue risk of interference. In each of Parts 1 and 2 guidance is given as to the degree ofprotection which will be afforded by each coating.
Under severe conditions or for particular duties for which a threaded ponent
is required greater protection than that provided in Parts 1 and 2 may beneeded. In such cases reference should be made to Part 7 of this standard.
The zinc and cadmium electroplating of ISO metric fasteners is specified inBS 7371-3:1993.
A British Standard does not purport to include all 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 prises a front cover an inside front cover pages i to iv pages 1 to 17 and a back cover.
This standard has been updated (see copyright date) and may have hadamendments incorporated. This will be indicated in the amendment table on the inside front cover.
