A hex plug NPT‑M is a precision-engineered pipe fitting designed to seal or close the end of a female NPT-threaded port or pipe. It features male National Pipe Taper (NPT‑M) threads and a hexagonal head for easy tightening or removal with a wrench. This fitting provides a reliable, leak-resistant seal in piping and instrumentation systems, preventing fluid or gas leakage at unused ports.
Hex plugs are widely used in hydraulic, pneumatic, instrumentation, and fluid systems across industries such as oil and gas, chemical processing, power generation, and industrial manufacturing. When installed with appropriate thread sealant or PTFE tape, the NPT threads create a secure seal suitable for high-pressure and demanding applications.

