American Dryseal Pipe Threads (NPTF and NPSM Stainless) 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 degree seat it will mate with the 30 degree 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.
Dash Size
Inch Size
Thread Size
Male Thread (O.D.)
Female Thread (I.D.)
2
1/8"
1/8-27
.41
.37
4
1/4"
1/4-18
.54
.49
6
3/8"
3/8-18
.68
..62
8
1/2"
1/2-14
.84
.76
12
3/4"
3/4-14
1.06
.98
16
1"
1-11.5
1.31
1.24
20
1 1/4"
1 1/4-11.5
1.66
1.58
24
1 1/2"
1 1/2-11.5
1.90
1.82
32
2"
2-11.5
2.38
2.29
(866) 620-7320 M-F: 8am-5pm MST
My account
Blog
