British Standard Pipe is one of the most popular non American threads in the world. There are two type of BSP threads: BSPP and BSPT. The flank angle for both threads is the same. As the name suggests, BSPP is a parallel thread while BSPT is tapered. BSPT (tapered) looks very similar to NPTF thread and one should be careful not to mistake the two. The thread flank angle for all BSP thread is 55 degrees, while the NPTF flank angle is 60 degrees.
