National Pipe Thread - Terminology

Terminology

Sometimes these terms may be used:

• MIP: stands for Male Iron Pipe, or Male International Pipe, or MPT Male Pipe Thread. It is a term for pipe fittings.
• FIP: stands for Female Iron Pipe, or Female International Pipe, or FPT. It is a term for pipe fittings that MIP fittings fit into.

The difference between FIP, MIP and Compression fittings is in the tapering of the thread. FIP has taper of 1:16 (6.25% slope), compression has taper of 13:96(13.5% slope).

A female iron connection has a tapered thread, which thins out to the end of the pipe. As the fitting is tightened, the ever-decreasing thread depth means that the connection becomes watertight. To properly seal the fitting, paste thread sealant or PTFE (polytetrafluoroethylene) tape more commonly called Teflon tape, wrapped around the thread is required.

MIP fittings are usually found in thicker copper pipe, iron pipe, steel pipe, gas pipe, gas stove, gas oven, gas heater, and gas water heater connections.