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NPT - National Pipe Taper

American National Pipe Taper (NPT), Like British Standard Pipe (BSP), is designated by trade size, rather than actual diameter, as shown in the NPT/NPS Table.

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 are casual references.

NPT threads have a 60° included angle and have flat peaks and valleys (this is a Sellers thread form).