American Dryseal Pipe Threads (NPTF and NPSM)

American Dryseal Pipe Threads (NPTF and NPSM)

This commonly used connection incorporates two methods of sealing. The male NPTF (Dryseal) tapered thread will mate with the NPTF tapered female, which is usually a port, and seal when the special threads are crushed together. Male PTF (Short Dryseal) are identical to male NPTF threads except that the thread lengths have been shortened by one full thread from the small end of the taper. Additional sealing aids such as pipe dope and Teflon tape are often used with theses threads. If the male has a 30 seat it will mate with the 30 cone seat in the NPSM straight thread swivel female, usually found on adapters, and is mechanically held together by the threads. NPTF and NPSM are not interchangeable with the British pipe threads.

Click here for a guide on how to properly measure threads.

Click here for printable, actual size pipe fitting profiles. You will need to have Adobe Reader to view and print the file.


American Dryseal Pipe Threads (NPTF and NPSM)
Dash
Size
Inch
Size
Thread Male
Thread
O.D.
mm
Male
Thread
O.D.
inches
Female
Thread
I.D.
mm
Female
Thread
I.D.
inches
2 1/8 1/8 - 27 10.3 .41 9.4 .37
4 1/4 1/4 - 18 13.7 .54 12.4 .49
6 3/8 3/8 - 18 17.3 .68 15.7 .62
8 1/2 1/2 - 14 21.3 .84 19.3 .76
12 3/4 3/4 - 14 26.9 1.06 24.9 .98
16 1 1 11-1/2 33.3 1.31 31.5 1.24
20 1-1/4 1-1/4 11-1/2 42.2 1.66 40.1 1.58
24 1-1/2 1-1/2 11-1/2 48.3 1.90 46.2 1.82
32 2 2 11-1/2 60.4 2.38 57.9 2.29