What does NPT stand for in pipe fittings?

• A. National Pipe Thread
• B. Normal Pipe Thread
• C. National Pressure Thread
• D. New Pipe Thread

Answer: (A)

National Pipe Thread is the North American standard for threaded pipe fittings. It defines the shape, angle, and taper of the threads so fittings from different manufacturers will screw together and seal properly. The taper means the threads get tighter as you tighten, which helps create a seal with or without thread sealant. This standard is what you rely on when selecting fittings for plumbing and piping in the U.S. and Canada. Some reference sources call it National Pipe Taper, but in practice the common label used in charts and testing is National Pipe Thread, the same family of standards.