Nominal Diameter

Written by Matt Milbury on . Posted in Pipe

The nominal diameter or nominal pipe size (NPS) is the external size diameter designated of pipe or threads.

Nominal pipe size is a dimensionless number representing pipe sizes in inches. NPS 1/8 to NPS 12 is a approximate represented number, not exactly the inside or outside dimension. NPS 14 and larger is equal to the  outside diameter.