bs21-1985英制螺紋標準

1、BRITISH STANDARD BS 21:1985Reprinted, incorporating Amendment No. 1Specification forPipe threads for tubes and fittings where pressure-tight joints are made on the threads (metric dimensions)621.643.414 – 762.4:621

2、.882.082.22Licensed copy:PONTYPRIDD COLLEGE, 25/09/2006, Uncontrolled Copy, © BSIBS 21:1985© BSI 03-1999 iContentsPageCommittees responsibleInside front coverForeword ii1 Scope 12 Definitions 13 Symbols 24 Basi

3、c forms of pipe threads 25 Jointing threads 36 Longscrew threads 4Appendix A Recommended gauging systems for jointing threads 10Appendix B Methods of verification of jointing thread dimensions and form using recommended

4、 gauging systems described in Appendix A 15Appendix C Special parallel external threads for gas appliances where pressure-tight seals are made on machined faces 15Figure 1 — Terms relating to pipe threads 1Figure 2 — Ba

5、sic Whitworth form 3Figure 3 — Basic form of taper pipe thread 4Figure 4 — Typical designs illustrating internal taper or parallel pipe threads complying with 5.1 5Figure 5 — System A screw gauges assembled respective

6、ly with threads of maximum and minimum sizes 7Figure 6 — System B screw gauges assembled respectively with threads of maximum and minimum sizes 8Figure 7 — Taper full-form screw plug gauge (system A) 10Figure 8 — Taper

7、 full-form screw ring gauge (system A) 10Figure 9 — Taper full-form screw plug gauge (system B) 12Figure 10 — Taper full-form screw ring gauge (system B)12Figure 11 — Taper plain plug gauge (system B) 12Figure 12 — Taper

8、 plain ring gauge (system B) 12Table 1 — Lengths for dimension A in Figure 4 6Table 2 — Basic dimensions and limits of size9Table 3 — Dimensions of taper full-form screw plug and ring gauges for system A 11Table 4 — Dim

9、ensions of taper full-form screw and taper plain plug and ring gauges for system B 13Table 5 — Manufacturing tolerances for gauges for systems A and B 14Table 6 — Special parallel external threads for gas appliances whe