Pipe fitting is the occupation of installing or repairing piping or tubing systems that convey liquid, gas, and occasionally solid materials. This work involves selecting and preparing pipe or tubing, joining it together by various means, and the location and repair of leaks.
Steel pipe is sometimes joined using threaded connections, where tapered threads are cut into the end of the tubing segment, sealant is applied in the form of thread sealing compound or thread seal tape, and it is then threaded into a corresponding threaded fitting using two pipe wrenches. Beyond domestic or light commercial settings, steel pipe is often joined by welding, or by use of mechanical couplings into the ends of the pipes. Other variations of steel pipe include various stainless steel and chrome alloys.