BSP

BSP stands for British Standard Pipe. It is a family of technical standards for screw threads for interconnecting and sealing pipes and fittings by mating an external (male) thread with an internal (female) thread. The BSP connections include two types of threads, BSPP which are straight (or parallel) and BSPT which are tapered. The BSPT tapered male will mate with a BSPT tapered female (usually a port) and seals on the threads. The BSPP parallel male has a 30° chamfered seat which seals with a BSPP swivel female on its 30° cone seat. (Similar to the American NPSM-NPTF connection, however the BSPP swivel female end is commonly found on couplings.)

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The BSP threads are similar to, but not interchangeable with American NPTF pipe threads. The thread pitch is different in most sizes, and the thread angle is 55° instead of 60° angle found on NPTF and NPSM threads.

The thread form follows the British Standard Whitworth standard:

• Symmetrical V-thread in which the angle between the flanks is 55° (measured in an axial plane)
• One-sixth of this sharp V is truncated at the top and the bottom
• The threads are rounded equally at crests and roots by circular arcs ending tangentially with the flanks where r=0.1373P
• The theoretical depth of the thread is therefore 0.6403 times the nominal pitch

References

1. ISO 228 standard (formerly BS-2779)
2. http://www.bspt.co.uk/
3. http://fittingsandadapters.com/britstanpipb.html
4. http://www.engineeringtoolbox.com/british-pipe-threads-d_754.html
5. http://www.spgspg.com/library/Pipe%20Thread%20NPT%20and%20BSPT%20fittings%20compatibility.pdf
6. http://fittingsandadapters.com/britstanpipb.html