BS 21:1985

Superseded

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Specification for pipe threads for tubes and fittings where pressure-tight joints are made on the threads (metric dimensions)

Available format(s)

Hardcopy , PDF

Superseded date

04-30-2016

Language(s)

English

Published date

09-30-1985

Publisher

British Standards Institution

Foreword
Committees responsible
Specification
1 Scope
2 Definitions
3 Symbols
4 Basic forms of pipe threads
5 Jointing threads
6 Longscrew threads
Appendices
A Recommended gauging systems for jointing threads
B Methods of verification of jointing thread dimensions
    and form using recommended gauging systems described
    in appendix A
C Special parallel external threads for gas appliances
    where pressure-tight seals are made on machined faces
Tables
1 Lengths for dimension A in figure 4
2 Basic dimensions and limits of size
3 Dimensions of taper full-form screw plug and ring
    gauges for system A
4 Dimensions of taper full-form screw and taper plain
    plug and ring gauges for system B
5 Manufacturing tolerances for gauges for systems A and
    B
6 Special parallel external threads for gas appliances
    where pressure-tight seals are made on machined faces
Figures
1 Terms relating to pipe threads
2 Basic Whitworth form
3 Basic form of taper pipe thread
4 Typical designs illustrating internal taper or
    parallel pipe threads complying with 5.1
5 System A screw gauges assembled respectively with
    threads of maximum and minimum sizes
6 System B screw gauges assembled respectively with
    threads of maximum and minimum sizes
7 Taper full-form screw plug gauge (system A)
8 Taper full-form screw ring gauge (system A)
9 Taper full-form screw plug gauge (system B)
10 Taper full-form screw ring gauge (system B)
11 Taper plain plug gauge (system B)
12 Taper plain ring gauge (system B)

Range of threads from $9A to 6, together with thread forms, dimensions and tolerances, designations; includes appendices for recommended gauging systems and methods of use of gauges. Requirements for jointing threads for taper external threads, for assembly with either tapes or parallel internal threads and for longscrew threads for longscrews specified in BS 1387.

Committee	ISE/110
DevelopmentNote	Supersedes 83/78475 DC and BS 21(1973). (07/2002) Supersedes DEFSTAN 47-4/1(1985) (08/2003) Reviewed and confirmed by BSI, March 2013. (03/2013)
DocumentType	Standard
Pages	22
PublisherName	British Standards Institution
Status	Superseded
SupersededBy	BS EN 10226-2:2005 BS EN 10226-1:2004 BS EN 10226-3:2005
Supersedes	BS 21:1973

BS 1387:1985

Specification for screwed and socketed steel tubes and tubulars and for plain end steel tubes suitable for welding or for screwing to BS 21 pipe threads