NPT - pipe thread

The most common types of pipe thread are:

• NPT - American Taper Pipe Thread = National Pipe Taper
• NPTF - American Taper Pipe Thread for dryseal joint without sealant compound = National Pipe Taper Fue

NPT gas thread

NPT and NPTF appear to be identical. Both have the same pitch diameter at the top of the hole of the internal thread or end of the pipe on external threads and both have the same thread lengths or depths. However, there is a subtle difference in the root and crest diameters of the threads.

NPT threads are also sometimes referred to as:

• MIP (Male Iron Pipe)
• FIP (Female Iron Pipe)
• IPT (Iron Pipe Thread)
• FPT (Female Pipe Thread)
• MPT (Male Pipe Thread)

Note that these references are somewhat casual, and might possibly be used in reference to NPS instead of NPT thread. NPS thread (National Pipe Straight) is not interchangeable with NPT thread.

Flank angle is 60 °.
Female and male thread are both tapered at equal angles