Five Tips for Large-Diameter Solvent Welding

Many factors go into the solvent welding process, but the three most important considerations would be the pipe material, pipe size, and job conditions. For large-diameter pipe, the process demands more planning, prep and labor.

Note: Oatey considers pipes to be large-diameter if they are 150mm (six inches) or greater.

Let’s take a look at five tips to keep in mind while solvent-welding large-diameter PVC, ABS, or CPVC plumbing systems.

1. Use the proper tools and practices when preparing the pipe. 

Proper preparation of the pipe before a solvent weld reduces the chance of any pipe-connection failures. Prepping a large pipe comes down to how you cut, deburr, chamfer, and clean it.

Cutting: We recommend using a pipe wrap to produce an accurate line to follow when cutting. This will create a pipe-end that is “squarely” cut, which ensures maximum surface area to create fusion, joint strength and the strongest bond.

Deburring: After cutting the pipe, a rough area of burr may form around the inside edge. Using a deburring tool will remove the burr and polish the edges of the pipe for a smooth finish. If you skip this step, pieces of plastic can break free and move through the system, leading to blockages.

Chamfering: The next step would be to chamfer the outside ends of the pipe. Chamfering is the removal of the sharp outside edge of the pipe at a minimum of 3/32 inches which is equal to a 10 to 15-degree angle. Chamfering the outside is important to streamline assembly and ensure leak-free joints.

You can use a portable or stationary chamfering machine, a hand grinder, or a router bit. We recommend assessing all the potential safety hazards on-site before choosing the best pipe chamfering method for your job.

Cleaning: The final step would be to clean off any dirt or grease that may have gotten on the pipe edge. This is important before applying the primer and cement, so that nothing interferes with the application. You can use Oatey Clear Cleaner on all ABS, PVC and CPVC pipe and fittings.

2. Use the right primer and cement for the job.

For large diameter PVC and CPVC piping systems, primers should be used. Oatey Industrial Grade Primer removes contaminants as well as softens the pipe surface to allow for a fast, secure solvent weld.

When choosing a solvent cement, base your selection on the three keys cited above: pipe material, size, and job conditions.

If you use the wrong cement, you won’t create the proper weld you need.

The larger the pipe, the thicker the viscosity of the cement you will need. We recommend using medium-body cement if your pipe is up to six inches in diameter; and a heavy-body cement if your pipe is over eight inches.

Oatey offers heavy-duty cement (PVC) that covers up to 12-inch pressure pipe and 18-inch non-pressure; and heavy-duty cement (CPVC) that covers up to 12-inch pressure and 14-inch non-pressure. Oatey also offers extra heavy-duty cement (only for PVC) that covers up to 24-inch pressure and 30-inch non-pressure.

You will also need to consider the cure time once the assembly is in place. You can view our complete instructions on solvent weld using Oatey cement types. You can also find our recommended cure time chart below, based on pipe diameter and temperature during assembly.

Contact Oatey Technical Services for cure times for pipe diameters larger than an eight inches. Contact Info: 800-321-9532

3. Use the proper tool for cement application.

Before opening any cement containers, be sure to give them a good shake. The solids can separate in some of the thicker cement types if the container sits for too long.

Once you have a good uniform mixture to work with, you can begin applying it onto the pipe, using a swab or roller.

You’ll want to use the correct tool for the pipe size to apply the cement evenly. According to the ASTM standard, your swab/roller should be half the size of the diameter of the pipe.

  • When handling pipes up to six inches, we recommend using a swab. So, for a six-inch pipe, you should be using a three-inch swab.
  • For anything larger than six inches, use a roller. Oatey offers rollers and swabs up to 12 inches so that you can be sure to have a proper application.

4. Use more than one person or a specialized tool to help the connection.

Since you will be working with heavier pipes, be sure to have additional help when it comes time to align and create the connection. If the pipe is not properly connected, you could have a failure, leaks, or an off-measurement.

Multiple people and a mechanical joining tool should be used to get an accurate and secure solvent weld. You’ll want to position yourself, the pipe and fittings to assure proper joint alignment during installation. Using a mechanical pipe puller will safely and cleanly join the large diameter pipes together and be seated completely for a true connection. The finished joint must not be disturbed for the recommended set up time.

Oatey does not recommend using heavy equipment, like a backhoe, which could result in severe damage to the pipe and fittings.

5. Prefabricate as much as you can.

Having multiple people prepping and working on the pipe will help cut down on time, so that you can get the connection together as quickly as possible. We recommend assembling any joints beforehand to make your job easier.

Take, for example, an underground job: Here, you can assemble the pipe out of the trench ahead of time and then lower it down into the trench to reduce the number of connections you’ll need to make in the smaller space.

Similarly, if you are going through multiple floors, assemble as many pieces as possible before feeding them up. That way, you will not have to work in a cramped space. 

Working with a large-diameter pipe for solvent-welding need not be complicated. It all comes down to using the right tools for the welding material. Following the correct procedures will ensure a secure connection.

To get our best tips for creating the perfect solvent weld, watch our video here.

Related Resources


How to Solvent Weld with Oatey Products

Oatey Blue Lava Hot PVC Cement