Schedule 40 PVC unions join two pieces of PVC pipe together. Unlike a coupling, however, unions are able to be disassembled for quick access to the pipe itself. Unions are commonly used to allow quick access to a piece of pipe allowing users to quickly add and remove components or clean out the line. Unions are composed of three parts: a female end, a male end, and a nut. The female and male ends attach to the pipe and the nut is tightened to prevent leakage.