American Dryseal Pipe Thread (NPTF & 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 NPTF (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 these 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.