BSPP Straight Pipe Taps
BSPP ( British Standard Pipe Parallel) taps produce a straight whitworth (55 degree) female thread in standard sizes from 1/16 to 6 somewhat related to the inside diameter of pipe.
The common joining of a tapered male thread to a parallel internal thread achieves a pressure tight joint when sealed or compressed in soft material such as an O-ring. The BSPP internal thread has been adopted internationally as a standard for plumbing and hydraulic fittings except in the U.S.A. where NPT (American National Standard Taper Pipe) is the standard.