If you’re plumbing in a new drain or vent and have to join two different kinds of plastic pipe, black ABS and white PVC, don’t assume that you can simply glue them together. Most plumbing codes don’t allow ABS pipe to be solvent-welded (glued) to PVC. Check with your local plumbing inspector. The proper way is to use a transition coupling (Photo 2), a neoprene rubber sleeve that fits over each pipe. It’s then held tight with a stainless steel metal jacket and integral clamps. The coupling will be labeled as to which type of pipe (plastic ABS and PVC, steel, cast iron, copper) each end can be fastened to. Look for a plastic-to-plastic designation on the coupling.
When inserting a pipe between two fixed ends, cut the new piece to leave an 1/8-in. gap at both joints. Loosen and slide the metal jacket and clamps off the rubber sleeves and slide the jackets onto the fixed pipes. Push one end of the rubber sleeve onto the fixed pipe and then roll back the other end (Photo 1) to make room for the new piece of pipe. Hold the new piece of pipe between the two fixed pipe ends and unroll the rubber sleeves over the ends of the new pipe. Next, slide the metal jackets over the rubber sleeves and tighten the clamps. Snug them up with a socket wrench.