When using PVC drain pipes, considering the different house structures, it is necessary to use some PVC drainage joints with different structures to change the direction of the pipes for easy construction. Different joints have different functions, such as the downstream pipe fittings, the waste pipe fittings and the corrugated pipe fittings. The drain pipe bending connection and change the direction of the pipes. The PVC pipe fittings coupled from one component to another can connect PVC pipes for drainage to pipes, pipes to fittings, and even connectors, permanently. In addition, there are many types of the PVC drain pipe joints. This article will introduce the different kinds of the drainage pipe coupling.