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.

Flanges connect with pipe and fittings to form a piping system for a variety of construction and manufacturing applications. Threaded flanges, also called screwed flanges, include threads inside the flange bore that connect to the external threads on a pipe without welding.