Brass to Copper Replacement

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by dlipter, May 15, 2013.

  1. dlipter

    dlipter New Member

    May 5, 2013
    I'm replacing a section of threaded brass water pipe with copper to install a "point of entry" bypass for a whole house water filter. I have limited space between opposing brass threaded fittings to work with.

    If I sweat the new copper solid using a sweated slip coupling as the last joint, and find that one or both of the threaded copper NPT adapters leaks, I won't be able to tighten them up. I don't want to use unions due to space limitations. Maybe if I "loosen" one of the fittings with a torch and torque the leaking threaded adapter, that might work.

    This is all new to me and I am trying to anticipate potential problems. How would you experienced plumbers handle this?


    Last edited: May 15, 2013
  2. Gary Swart

    Gary Swart In the Trades

    Sep 1, 2004
    Yakima WA
    You must be a novice with sweating copper. First of all, a sweat joint done properly should never leak. Secondly, if for some reason, lack of flux, dirty joint, improper heating for example, it does leak, you can not just reheat, twist, and add solder. Once water hits a bad solder joint, it must be completely disassembled, the pipe(s) and fitting(s) cleaned, fluxed, assembled, and re soldered.
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  4. dlipter

    dlipter New Member

    May 5, 2013
    I'm not concerned about the sweated joints leaking.

    My concern is the NPT threaded coupling leaking at the thread junction. I can't pressure test the threads until I solder everything up. Once everything is soldered, the threads can't be tightened.
  5. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    Heat might degrade the sealant (pipe dope or tape) in the threaded connections depending on how close they are, your technique, and skill level. A picture of what you're dealing with may offer some suggestions.
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