How to Glue and Join PVC Plastic Pipe (page 2 of 2)

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Tips and Techniques

CAUTION:
The solvent vapors from the primer and cement can make you dizzy and are dangerous to your health.

Make sure you have plenty of ventilation or wear an approved organic vapor respirator when working with primer and solvent cement.

It’s always a bummer to make a mistake. But at least with plastic pipe it’s easy to fix. Simply saw out the messed up section, whether it’s too long, too short or crooked. Correct the mistake and reassemble the joint with a coupling. In some cases, you can reuse the old section of pipe and fitting. Otherwise, set it aside and cut new parts. You may be able to use the bad section later.

TIP
Buy extra fittings. Having extra on hand will save you a trip to the store. And you can return the extras when you’re done.

Allow for Shrinkage If You Dry-Fit the Pipes

Most novice pipe fitters find it reassuring to cut and assemble a group of pipes and fittings before gluing them together. It’s OK to do this as long as you’re aware of the pitfalls.

Don’t jam the pipe and fitting together too tight. They’ll get stuck and can be difficult to get apart. If a fitting does get stuck, just set a block of wood against the lip and pound the fitting loose with a hammer.

Leaving the fittings loose keeps them from getting stuck, but it creates another problem. You can’t assume that the final assembly will be the same size as the dry-fit parts. When you apply solvent cement to the pipe and fitting and press them together, you’ll lose a little length at each joint. On 1-1/2 in. pipes, this could be as much as 3/8 in. per joint. So keep this in mind if you dry-fit, and allow extra length where fit is crucial.

Another tip is to limit dry fitting to a small group of pipes and fittings. Join this group with solvent cement before moving to the next section.

Use the Proper Solvent for Each Type of Plastic

There are three common types of plastic plumbing pipe: PVC, CPVC and ABS. Each requires a different kind of solvent cement. The white or beige pipes (PVC and CPVC) also require a primer. You don’t need a primer with black ABS pipe. Read the label to match the solvent cement to the type of pipe you’re using. Avoid universal solvent cements.

Use Special Transition Couplings to Connect Different Types of Pipes

Transition couplings have a flexible rubber sleeve surrounded by a metal sleeve and band clamps. They’re handy for connecting plastic pipe to cast iron, copper or steel, especially if you can’t thread on an adapter. Each coupling is labeled with all the different types and sizes of pipes it can join. Home centers and hardware stores keep a few common types on hand. Read the label on the transition coupling to find out which pipe it joins. For less-common connections, contact a local plumbing supplier or ask about ordering a special transition coupling. Rubber couplings without the metal sleeve often aren’t code approved. Ask your local inspector if you’re not sure.

Editor’s Note: My Own Great Goof

I love working with plastic pipe. Mistakes are so easy and cheap to fix that I don’t have to worry much. But I learned the hard way that there’s one mistake you can’t fix. And that’s purple primer on a white sheet vinyl floor. Primer— and to a lesser extent the solvent cement—is impossible to remove from most surfaces, including your skin. So if you’re working around finished surfaces, cover them with plastic dropcloths and set the primer and solvent cement cans in a dishpan or other plastic container to guard against drips and spills. To prevent spills and contain the fumes, keep the caps on when you’re not using the primer and solvent cement.