How to Join CPVC Pipe to Metal Pipe
Plumbing your house with CPVC pipe can be quicker and easier than using copper. In many applications though, you will need to make the final connection to a sink or appliance with metal. Making this transition may leave you scratching your head for a solution if you've never done it before.
It's actually easy if you keep a few basics in mind. Use a male plastic fitting to join CPVC to metal whenever possible. A metal female fitting will compress the plastic male end, slightly increasing its strength. If over-tightened, a metal male fitting will crack or even split a plastic female fitting.
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Things You'll Need
- CPVC pipe cutting tool
- CPVC cleaning solvent and glue
- CPVC slip/male thread fitting
- Plumbing tape
- Metal female fitting
Instructions
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1
Cut the CPVC stub to the proper length.
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2
Clean and prime the last two inches of the stub with CPVC cleaning solvent.
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3
Clean and prime the inside of the CPVC slip fitting with cleaning solvent. Do not use solvent or glue on the threaded side of the fitting.
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4
Apply CPVC glue to the outside of the stub and the inside of the slip fitting.
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5
Insert stub end into slip fitting. Twist and press firmly to seat stub in fitting. Allow the glue time to cure before stressing the joint.
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6
Wrap the male end of the CPVC fitting with plumber's tape. Two to three wraps of tape should suffice.
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7
Screw female fitting onto CPVC male end.
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8
After making final connection to appliance or outlet, check for leaks.
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Tips & Warnings
Special CPVC to metal transition joints and fittings are available and should be used whenever possible.
When joining plastic to metal piping, consider a union fitting. The cost is slightly more than a standard fitting but will make any future repair or remodeling job significantly easier.
When wrapping threaded fittings with plumber's tape, be sure to wrap the tape in the direction of the thread. Wrapping in the opposite direction will allow the tape to simply roll off while threading the connection.
CPVC pipe can be cut with a fine-tooth hacksaw but it will leave small plastic shavings on the ends of the pipe. These shavings can cause problems with the valves in washing machines and icemakers. If you use a hacksaw, be sure to scrub the inside and outside of the pipe to remove these small burrs before cleaning the joint with solvent.
Be sure you have adequate ventilation when using plastic solvents and glue.
Failure to use solvent to clean a joint before gluing can result in leaks or failure when pressurizing the system.
Never connect plastic piping or fittings directly to a water heater.
