文档介绍：BRITISH STANDARD BS 21:1985 Reprinted, incorporating Amendment No. 1 Specification for Pipe threads for tubes and fittings where pressure-tight joints are made on the threads (metric dimensions) –: BS21:1985 This British Standard, having been prepared under the directionof the Piping mittee, was published under the authorityofthe Executive es into effect on 30 September 1985 ? BSI 03-1999 First published April 1905 First revision November 1909 Second revision November 1938 Third revision December 1957 Fourth revision March 1973 Fifth revision September 1985 The following BSI references relate to the work on this standard: Committee reference PSE/9 Draft ment 83/78475 DC ISBN 0 580 14556 mittees responsible for this British Standard The preparation of this British Standard was entrusted by the Piping Systems mittee (PSE/-) to mittee PSE/9, upon which the following bodies were represented: Association of Hydraulic Equipment Manufacturers pressed Air Society British Gas Corporation British Hydromechanics Research Association British bustion Engine Manufacturers’ Association British Malleable Tube Fittings Association British Steel Industry British Valve Manufacturers’ Association Ltd. Department of Trade and Industry (National Engineering Laboratory) Energy Industries Council Engineering Equipment and Materials Users’ Association Gauge and Tool Makers’ Association Institution of Civil Engineers Institution of Gas Engineers Institution of Public Health Engineers Institution of Water Engineers and Scientists Water Authorities Association panies Association Wrought Fitting Makers’ Association Amendments issued since publication Amd. No. Date of ments 6633 December 1990 Indicated by a sideline in the margin BS21:1985 ? BSI 03-1999 i Contents mittees responsible Inside front cover Foreword ii 1 Scope 1 2 Definitions 1 3 Symbols 2 4 Basic forms of pipe threads 2 5 Jointing threads 3 6 Longscrew threads 4 Appendix A mended gau