Straight Pipe Taps
Internally threaded straight pipe fittings are mated with taper pipe external threaded parts to produce a properly sealed assembly when length restrictions are considered. Straight pipe taps are less common than taper pipe but fit a specific need.
Assemblies of internally threaded NPS, NPSC or NPSM parts conform to ANSI (American National Standards Institute) but do not provide a seal unless an O ring is used.
NPSF (American National Standard Fuel) taps produce a straight internal thread intended for assembly with NPTF external taper pipe.
PTF-SAE Short internal threads are used in couplings/fittings when a shorter length of engagement is desired. Dryseal SAE taps produce a thread that is one pitch (thread) shorter at the large end of the coupling.
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.
