Nipple (plumbing)

A close nipple can only be unscrewed by gripping one threaded end with a pipe wrench which will damage the threads and necessitate replacing the nipple, or by using a specialty tool known as a nipple wrench (or known as an internal pipe wrench) which grips the inside of the pipe, leaving the threads undamaged.

When the ends are of two different sizes it is called a reducer or unequal nipple.

Threads used on nipples are BSP, BSPT, NPT, NPSM and Metric.

A chase nipple is a short pipe fitting, which creates a path for wires between two electrical boxes.

The chase nipple passes through the knockouts of two boxes, and is secured by an internally threaded ring called a lock nut.