Treads and Connector Identification NPT & NPS Threads


NPT is National Pipe Taper (American)

Thred from per ANSI/ASIH/ASME B1.20.1

NPT is National Pipe Straight (Parallel)

Thred from per ANSI/ASIH/ASME B1.20.1

NPT is National Pipe Taper for Fuel

Thred from per Sae J476

NPT is National Pipe Straight Mechanical

Thred from per ANSI/ASIH/ASME B1.20.1

National Pipe threads are similar in function to BSP threads, but are not generally interchangeable.


NPTF threads (also know as Dryseal) are an improvement to NPT.


Controlled truncation of threads mean the metal-to-metal thread seal is at root and crest of threads, in addition to flanks of threads.


Use of thread sealant is recommended for NPT male and NPT female connection.

Measure NPT male thread OD and NPT female thread ID at first thread near end of fitting.

NPT Thread Dimensions

NPSM Thread Dimensions

Thread size refers to the nominal bore of the pipe.


Subtract approximately 1/4"()6 mm from thread meas ure ment for nominal pipe size.


Pitch is Thread Per Inch (TPI).