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Some days ago I assembled the following joint using pipe dope (it is solvent based that semi hardens to a rubber like stuff).

PVC to metal

I waited 2 days to pressurise the system and after a few days it started leaking.

How can I fix that?

Edit: this is how it looks after disassembly:

disassembled joint

Luiz Borges
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3 Answers3

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You should try TFE pipe thread joint tape. This tape is a thin white film that you wind several times around the externally threaded part before screwing the parts together.

I would suggest cleaning away as much of that dope material as possible before re-assembling with the the TFE tape. Also it may be well to look at the possibility of using a new PVC part. That particular one looks a little bit low quality as the molding marks show that the two halves of the mold did not line up perfectly which leads to the slight misalignment of the threads at the mold line plus the mold line itself. This may be contributing to the leak problem.

Michael Karas
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You'll probably never get a good joint between metal and PVC, no matter what type of dope you use. Instead, you'll want to use an adapter. Something with metal threads on one end, and a PVC hub on the other.

enter image description here

Tester101
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You can fix this by removing any residue from this dope and re-joining with Whitlam's Industrial Grade 'Blue Magic' Pipe Thread Compound. I frequently make joints just like you have on hot or cold water pipe with pressures up to 100 psi and have never had a leak at the joint. This is quite expensive, 15-18$ for a 200 gm tin, but well worth it.

nomind
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