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Thread: Leaky threaded brass fiitting to shower valve

  1. #1

    Default Leaky threaded brass fiitting to shower valve

    Hi;

    I, like many people have leaky fittings. This is a .5" supply line to a threaded brass fitting to the shower/bath valve (also brass.) I have used 2-3 loops of white teflon tape and have pulled fairly hard on a 12" crescent wrench and still get a drop coming out. How hard can I yank on this? I am not super strong, but I know I can still crank it some more without too much effort.

    Is the main seal made be bedding the fittings togeather tightly? If I damage the valve thread, I'll need a new valve...

    Should I use more tape/teflon dope/etc. or just wrench more?

    Thanks for your advice,
    Regards,
    Barry

  2. #2
    Retired Defense Industry Engineer jadnashua's Avatar
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    While it is possible to split a fitting or valve by tightening too much, it is not common unless you are using a really long wrench or it is defective in the first place. Pipe threads are tapered and interference. The tighter you turn, the more it wedges itself into the fitting. The tape or pipe dope seals around the threads to make it waterproof, the tapered function holds it together. Some people use the belt and suspender solution of putting some pipe dope on top of the tape. You might try that. Either one should work on its own, though.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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    In the Trades Gary Swart's Avatar
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    I can't add much to advice already given, just a comment. I am sort of old school I guess, but I prefer pipe dope alone. I know you can get good results with tape alone or tape and dope in combination, but I seems to be all thumbs when trying to use tape. I don't have to worry about wrapping it the right direction or how many wraps to use. I'd venture the opinion that you have not tightening the fitting enough. I agree that you are not likely to split the fitting with a 12" wrench unless you are an Olympic strongman. I'd tighten it until it doesn't turn anymore. If that doesn't work, then disassemble and start over with new tape and/or dope and see if that doesn't do it.

  4. #4

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    Hi all;

    Thanks for the advice; I ended up removing the teflon tape and using pipe dope (white ptfe paste). It did the trick, I did not crank super hard on the joint and it does not leak.

    Next question though... To unscrew the threaded adapter, I had to rotate the opposite end which was a pex fitting. So does rotating the fitting in the pex pipe, say 8x to loosen and 8x to tighten damage the pex crimp seal? It isn't leaking now, but this can't be a good thing. Does the 'pex manual'(sic) have anything to say about rotating crimped fittings?

    Regards,
    Barry

  5. #5
    Retired Defense Industry Engineer jadnashua's Avatar
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    Shouldn't hurt the pex fitting/connection. The crimp is applying pressure to the pipe and compressing it between two ridges on the fitting...it's the ridges that make the seal, the crimp just keeps it in position. At the worst, you may want to use the go/no-go gauge to verify you didn't loosen the crimp. A quality fitting shouldn't gouge the inside of the pipe, leaving the thing waterproof.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  6. #6
    DIY Member topshot's Avatar
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    Quote Originally Posted by Gary Swart View Post
    I can't add much to advice already given, just a comment. I am sort of old school I guess, but I prefer pipe dope alone. I know you can get good results with tape alone or tape and dope in combination, but I seems to be all thumbs when trying to use tape. I don't have to worry about wrapping it the right direction or how many wraps to use. I'd venture the opinion that you have not tightening the fitting enough. I agree that you are not likely to split the fitting with a 12" wrench unless you are an Olympic strongman. I'd tighten it until it doesn't turn anymore. If that doesn't work, then disassemble and start over with new tape and/or dope and see if that doesn't do it.
    Looks like I'll need to do this with my Delta R10000. I put on what I thought was too much paste just to be safe, but it's still leaking. I don't see what tape gives that dope doesn't but maybe I'll try both. I had tried tape alone first but am pretty sure I didn't use enough - normally just 1.5 layers has worked in the past. This is frustrating - I want to get the surround put on so I can keep working and what should be the simplest joints are giving the most trouble!

  7. #7
    Journeyman & Gas Fitter Doherty Plumbing's Avatar
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    Quote Originally Posted by bbortnic View Post
    Next question though... To unscrew the threaded adapter, I had to rotate the opposite end which was a pex fitting. So does rotating the fitting in the pex pipe, say 8x to loosen and 8x to tighten damage the pex crimp seal?
    Yes it sure can. And I would avoid doing it.

    Cut the pex before you unthread what it is you're unthreading and then couple it back together once you're done threading and unthreading stuff on that pex line.

    You can use a regular pex coupling or a compression coupling like a sharkbite.

  8. #8
    Moderator & Master Plumber hj's Avatar
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    Or you could do it the easy way and cut the PEX at the valve and then reattach it to the same fitting afterwards. IF your valve had male threads, which the Delta does, then most plumbers, myself included, would solder the copper tubing directly into the valve without using threaded adapters, thus eliminating any possible leaks. When the valve does require adapters, I solder them to the valve's threads rather than use tape or dope, thus also eliminating potential leaks.

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