British Pipe Thread - BSP (BSPT & BSPP)
The British 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.) 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.