Npt Fitting Dimensions

Each thread size has a defined number of threads per inch tpi or pitch.

Npt fitting dimensions. American national standard pipe thread standards often called national pipe thread npt standards for short are u s. Npt pipe fittings are a family of threaded fittings which used in conjunction with ansi pipe and are available in the same size range. The various types are each named with a symbol and a full. Female npt is either fpt or fnpt pipe thread sizes do not refer to any physical dimension.

Customer should limit the number of times an npt fitting is pp60 3 8 npt 15 000 0 75 1 12 assembled and disassembled because thread deformation during assembly will result in deteriorating seal quality over time. Pipe fittings 1 pipe fittings pipe fittings 1 16 to 1 in. Sizes smaller than 1 8 inch are occasionally used for compressed air while sizes larger than 2 inches are uncommon due to the use of alternative methods of joining that are used with these larger sizes. The outside diameter of each pipe fitting must be measured and compared to the table for size identi fication.

The pipe thread size as shown in column 3 of the table below is measured and based on the inside of the pipe. Pipe sizes do not refer to any physical dimensions. Npt is defined by ansi asme standard b1 20 1. Due to the tapered threads wider diameter at the base of the threads similar to a trapezoid the male fitting will tighten the further it is threaded into.

Nominal pipe size is loosely related to the inside diameter of schedule 40 pipe. For example a 3 4 npt pipe thread has an outside diameter of 1 050 inches. The confusion comes from the fact that the outside diameter od of an npt fitting does not match the name of the fitting. Pick the right npt national pipe taper fittings with this chart of npt and npsm thread dimensions and pipe sizes both internal and outer measurements.

But to actually determine the size of a pipe the outside diameter of each pipe or fitting must be measured and compared to the table for size identification. For example a 1 mpt pipe thread has an outside diameter of 1 315. National technical standards for screw threads used on threaded pipes and pipe fittings they include both tapered and straight thread series for various purposes including rigidity pressure tight sealing or both. When using only ptfe tape consider using thread lubrication to prevent galling of mating parts.

A 3 4 npt pipe thread has an outside diameter od of 1 050 inches. The outside diameter of a pipe or fitting must be measured and compared to a table for size identification.