Safe, sturdy and cheap, PVC (Polyvinyl Chloride) is a standard for water service lines and the DWV (drain‐waste‐vent) system. PVC and its plastic cousins CPVC (Chlorinated PVC) and ABS (Acrylonitrile Butadiene Styrene) are typically joined together using chemical solvents. If that sounds a little scary, don't worry: it's safe and easy! If you're about to embark on your own PVC project, we have a few tips to help guarantee your success.
Before You Begin
- Unless you need to remove a stuck fitting or deal with some other random problem, you'll likely only need the basics to get to work with PVC: cutters/shears for plastic pipe, PVC primer and PVC solvent cement ("glue"). And don't forget your towel!
- In the event of a not‐so‐clean cut, you might also need a deburring tool made for plastic (you can also use a file, sandpaper/cloth, or a utility knife). Large diameter pipes are often better cut with a hacksaw, in which case deburring is an absolute must.
- Provided you have a stable surface to set the containers on, you can save time by twisting off the lids for the primer and cement. The lids should have an applicator or "dauber" attached, which you can leave inside the container: instead of having to turn and open the container each use, you can just quickly pull the dauber out. Just remember to close everything up once you're finished!
- You need to work quick when joining plastics, but you also need to be safe. Though you shouldn't actually have to come into direct skin contact with primer or cement (thanks to the dauber), it's a good idea to wear nitrile or other chemically‐resistant gloves. Make sure that the work area is well‐ventilated, and don't work near high heat or open flame.
Watch out! There are many different solvent cements ("glues") out there, so be sure to carefully read the label of what you're getting. PVC, CPVC and ABS each require different cements; they are not interchangeable. There are also transitional cements available for joining different materials, and some cements are specially formulated for cold weather, quick drying times, etc.
Why "Dry‐Fitting" Won't Help
Seems like a great idea, right? Fit everything together for your sprinkler system or other PVC project so you know exactly how much to cut, make the cuts, then glue everything back together permanently. Unfortunately, it doesn't work that way: if you dry fit PVC plumbing connections, you'll wind up with bad measurements.
Dry pipe will only go part of the way into the fitting — solvent cement (and some twisting) is needed to make the pipe go all the way in, where it butts up against a ridge or lip called the "hub". Take a look inside a PVC fitting and you'll see the hub a little over halfway from the opening. This distance is referred to as the socket depth.
- PVC fittings are designed to connect to PVC pipe by interference fit, also known as a press fit or friction fit. What this means is that the fitting is designed so that it does not exactly match the pipe – the hub of the fitting is actually tapered a bit to make an extremely snug fit so there are no gaps for PVC glue/cement to fill in.
- Despite the name, PVC glue is not glue at all. It's actually a solvent that kind of liquefies the PVC, so the pipe and the fitting will essentially melt together. Think of it like welding metal — same idea, but with chemicals instead of a torch. Once the connection has cured, the pipe and fitting are no longer separate pieces, which is what makes a properly cemented PVC connection virtually leak‐proof.
- If you need to know exactly what lengths of pipe you'll need to cut for your project, simply measure from the hub of the fitting to the outer edge to determine the exact socket depth.
Pro Tip: Different manufacturers might have slightly different socket depths, so if you're sourcing your fittings from multiple vendors and need a high degree of precision, you might want to measure each fitting. If you're sourcing all fittings from the same manufacturer, you shouldn't need to check every fitting but we would recommend checking at least one from each different size and type.
Solvent Welding Tips
The actual process by which you join PVC pipe and fittings is called "solvent welding". It's a fairly simple procedure — you just need to move quickly, and try not to make a mess!
- Step 1: Always make sure that your cuts are square and free of burrs before you start applying primer and cement, even when using a PVC cutter. Uneven cuts and stray bits of plastic make for weak welds and can lead to issues at the joint down the road. Pipe should be dry and free of dirt and debris, as well.
- Step 2: Start by applying primer to both the inside of the fitting and on the pipe exterior. You'll want to coat each to the socket depth. Don't be stingy, but don't use so much that it puddles or runs excessively. Hold the fitting or pipe so that should the primer drip, it drips down and out of the fitting/pipe, not further inward.
- Step 3: When you're done putting the primer on, move quickly to apply the cement to the fitting and pipe. Spread a generous, even layer of cement directly over the primered areas.
- Step 4: Insert the pipe into the fitting while slowly twisting it a quarter‐turn. This will spread the cement and create a stronger weld. A bead of cement should form around the entirety of the new joint, with excess cement being pushed out.
- Pro Tip: If the orientation of the fitting matters — like with an elbow or tee — insert the pipe with the fitting a quarter‐turn away from its final position. This way the fitting will align perfectly when you turn it to spread the cement.
- Step 5: Firmly hold the new connection together for 30 seconds to keep everything in place as the solvent does its thing. After 30 seconds, the two pieces of plastic will have "melted" together sufficiently to be left alone to fully cure. Gently wipe off any excess cement and primer immediately after the 30 seconds; leaving it on could damage the pipe.
- Step 6: Consult the cement manufacturer's instructions for curing times. Most will require at least two hours before the connection can be put into operation.
How to Glue Plastic Pipe (Video Tutorial)
Learn how to quickly and correctly prime and glue plastic pipe (PVC, CPVC, ABS, etc.) for strong, leak-free joints.