PVC pipe glueing

To ensure that the pipe will be fully seated in its fittings, measure the distance between the shoulders on the fittings at each end of the pipe.  Spread cement primer over the outside of the pipe and the inside of the fitting where they'll overlap. The primer softens and cleans the plastic. Assemble everything to make sure the pipe is the correct length. On fittings such as elbows, position is critical, so make a reference mark from the pipe onto the fitting. Apply the cement to the primed areas on the inside of the fitting and to the outside of the pipe.  Slide the pipe into the fitting until it bottoms out against the fitting's shoulder, then give it a ¼-inch turn to spread the glue and speed its cure. If you're attaching a fitting, push it in with the reference marks slightly out of register, and turn the fitting to align the marks. Hold for 30 seconds, then wipe up any excess cement with a dry rag.