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.

Street Elbows are a type of pipe fitting intended to join a pieces of pipe or another pipe fitting at a 90 degree angle. The difference between a Street Elbow and a regular elbow is the Street Elbow features male pipe thread on one end and female pipe thread on the other.