Npt stands for national pipe tapered threads also known as ansiasme b1201 pipe threads. The outside diameter of each pipe fitting must be measured and compared to the table for size identi fication.

The Difference Between Pipe Threads And Straight Threads
What is npt thread. Threaded pipes can give an effective seal for pipes using hydraulic fluids. National technical standards for screw threads used on threaded pipes and pipe fittings. How to determine npt national pipe thread size male npt is denoted as either mpt or mnpt female npt is either fpt or fnpt pipe thread sizes do not refer to any physical dimension. It may also be reffered to as mpt mnpt or npt m for male external threads and fpt fnpt or npt f for female interal threads. American national standard pipe thread standards often called national pipe thread npt standards for short are us. Because of the pipe wall thickness the actual diameter of the threads is larger than the nps considerably so for small nps.
They include both tapered and straight thread series for various purposes including rigidity pressure tight sealing or both. For example a 1 mpt pipe thread has an outside diameter of 1315 npt size thread diameter od of mpt. A thread sealant must always be used to achieve a leak free seal except for nptf. Npt is defined by ansiasme standard b1201. They were established as a standard by the american national standard pipe thread commonly referred to as the national pipe thread standards. Npt stands for national pipe thread and is an american standard thread.
Pipe standards for tapered threads. It is a us. While this implies a greater degree of precision than is ordinarily achieved these dimensions are the basis of gage dimensions and are so expressed for the purpose of eliminating errors in computations. Standard for tapered threads used to join pipes and fittings. The dimensions of the npt thread are given to four or five decimal places. Npt is the abbreviation for national pipe thread tapered which is the us.
Standard for measuring tapered threads on threaded pipes and fittings. 1the abbreviation of the npt is national american pipe thread belong to the american standard of 60 degrees taper pipe threads it main used in north america. Npt national pipe threads and fpt female pipe threads are terms used regarding us. The national standard for gbt12716. Nominal pipe size is loosely related to the inside diameter of schedule 40 pipe. Npt are common threads used for general purposes while fpt are a type of npt.
American national standard taper pipe thread npt chart note.