cpvc to brass ok?

sniffdogOctober 13, 2012

I need to fix a leak in my geothermal loop manifold. I would like to connect a 2" CPVC slip x MIP adaptor

directly to a 2" brass ball valve? Can I do this?

They make a CPVC adaptor with a brass MIP fitting but the cost of that part is almost $100. I could save myself a lot of money if I could use a pure cpvc adaptor instead.

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The thread adaptor is fibne,,just don't forget to apply pipe joint compound on the male thread before making up the threaded joint.

    Bookmark   October 13, 2012 at 10:23AM
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Not to disagree, but I have to share this:

I just completed a walk-in shower with extra functions and used cpvc. I had a heck of time wrenching those all-cpvc adaptors tight enough to not leak without stripping the "nut" first. I was using teflon tape. I ended up having to replace a couple of them with the brass-cpvc ones because I couldn't get 'em tight enough.

A few weeks later I mentioned this problem to a couple plumbers at the plumbing supply (they were buying a bag of the brass-cpvc ones). One guys says, "oh yeah, we just drove one of our best plumbers nuts on a job using those things! He was going crazy and he's good, too...". They said that if you have to use all-cpvc adaptors at all, use pipe dope AND teflon tape on the threads.

    Bookmark   October 13, 2012 at 10:51AM
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Correction: I believe I first tried using Rectorseal 5 pipe dope. Out of 8 fittings, I had couldn't tighten 3 of them enough and got drips. Then, to be safe, I replaced them all with brass-cpvc since I had too much thread exposed in the joints anyhow.

    Bookmark   October 13, 2012 at 11:03AM
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ASTM specifications prohibit using both PTFE tape & pipe dope.

I always use non hardening Rectorseal and I have never had a problem tightening the joints.

    Bookmark   October 13, 2012 at 11:25AM
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Use the correct pliers and you should not have any problems.

Slip joints with hex cutout on the toothed jaws.

At least a12 inch pair.

And put enough dope on the threads.

There should be enough it squeezes out as the joint comes to final tightness in a ring around the fitting.

The female threads need to be pushing extra dope out of the way as the joint is tightened.

Except for special 'dry-seal' thread, the dope IS the final seal.

Dry-seal threads are also almost always 'one time' threads.
They have an interference fit to make the seal.

One reason they are expensive (VERY tight tolerances) and rarely used in routine plumbing.

I use them regularly in plumbing for specialized gases and liquids that can have NO contamination.

    Bookmark   October 13, 2012 at 12:00PM
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Thanks for all the reply's. I will try the pure cpvc adaptor and put plenty of dope on the threads.

    Bookmark   October 13, 2012 at 6:13PM
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