Grooved pipe fittings are also called clamp connections, which can be either exposed or buried, that is, steel joints and flexible joints. Grooved pipe fittings include two categories: one is the pipe fittings that play the role of connection and sealing, including rigid joints, flexible joints, mechanical tee and grooved flanges; the other is that the pipe fittings that play the role of connection transition include elbows, three pass, cross, reducer, blind plate, etc.