A merchant coupling is a fitting used to join pipes, of similar size, together in a straight-line run. Merchant steel fittings are designed with Dryseal Taper Threads (NPTF) for more critical applications. NPTF Dryseal threads produce a mechanical seal by the mating and slight crushing of the threads when a wrench is applied to tighten the fittings. Half Merchant Couplings are about half the length of Full Merchant Couplings.

Pipe Elbows are used in a piping system to change the flow direction. It is used to connect two pipes with the same nominal diameter to make the pipe, and thus the fluid direction, turn 90 degrees.