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  1. #1
    Join Date
    May 2009
    Posts
    4

    Default 1" threaded copper union leaking

    I'm wondering what the proper way is to install a "ELKHART 33584 UNION C TO C 1" COPPER" (or similar) fitting to keep it from leaking

    I had to replace the house water shut-off valve, and I had lots of trouble soldering due to the bending stresses of the existing pipes, so I cut the line downsteam and used a 1" copper threaded union to allow me to solder the joints in free air, then screw the last joint together.

    The union uses a simple rounded seat and mating rounded head on the two pieces, and when I first assembled the joint and turned the water on, the joint leaked profusely through the threads. I took it apart used some teflon tape wrapped partly around the thread, and partly lapping into the seat of the joint.

    After turning on the water, I got only a little slow drip, and with time it seems to be stopping.

    Is there some other trick I should have used?

    Thanks
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  2. #2
    Join Date
    Aug 2007
    Posts
    612

    Default Re: 1" threaded copper union leaking

    I prefer to use pipe dope rather than teflon tape. And the teflon tape should not be on the seat of the connection. I am assuming you used two good size wrenches to to really tighten the fitting.

    However, it may not have been your fault at all. The cheaper fittings bought from a big box store supplied from China have become known for "hit or miss" threading. I have read on many forums frustrated users reporting that the threading on some parts are not machined well enough to allow a tight, leak free fit. It's probably a case of 90% good, 10% bad, but it's the 10% that people take the time to post about.
    Last edited by bp21901; 05-04-2009 at 08:54 AM.

  3. #3
    Join Date
    May 2008
    Location
    Pacific Northwet
    Posts
    1,418

    Default Re: 1" threaded copper union leaking

    Only the seat of the union is intended to provide a seal. The threads are not meant to seal; they are only there to provide a mechanically strong connection. The seats should provide a good seal with just metal-to-metal contact; no compound or tape necessary.

    If the union is not sealing, then the seats are not mating properly. As bp21901 says, it may be a poor-quality union.
    The "Senior Member" designation under my name doesn't mean I know a lot, it just means I talk a lot.I've been a DIYer since I was 12 (thanks, Dad!). I have read several books on various home improvement topics. I do not have any current code books I can refer to. I was an apprentice plumber for two years.

  4. #4
    Join Date
    May 2009
    Posts
    4

    Default Re: 1" threaded copper union leaking

    I did not use pipe dope - the way I wrapped the teflon tape, it overlapped into the seating area by just a small amount.

    After the joint sat a while, the dripping has stopped, now it's just a "cold sweat" of moisture. For now, I'm going to leave it as-is and monitor. Fortunately, as you can see in my pic, I'm not lying on my back under the house to work on it, it's waist-high in an alcove under the stairwell, so it's easy to check on.

    Maybe next weekend I'll give the joint another crank with wrenches - I admit I just used channel-locks on the nut. With a bit of re-tourqing it should be OK. I may even open it up and put some pipe dope in there.

    Thanks for the advice.

  5. #5
    Join Date
    May 2009
    Posts
    4

    Default Re: 1" threaded copper union leaking

    By the way...

    The Union I got from Home Depot is identified with the logo:
    Streamline Mueller Industries, Made In USA, Fulton MS

  6. #6
    Join Date
    Aug 2007
    Posts
    612

    Default Re: 1" threaded copper union leaking

    ***, you got one made in USA, that may be a museum piece!

    I would get a couple pipe wrenches and very firmly, by pushing one and pulling the other, try to get a leeeettle extra snugness out of the union fitting. I would bet that will take care of the drip.

    You just have to "persuade" that drip to leave town!

  7. #7
    Join Date
    Jun 2007
    Location
    Fayette County, Ohio
    Posts
    5,622

    Default Re: 1" threaded copper union leaking

    A little pipe dope on the seat may help and a little more torque.
    Jack
    Be sure you live your life, because you are a long time dead.-Scottish Proverb

  8. #8
    Join Date
    May 2009
    Posts
    4

    Default Re: 1" threaded copper union leaking

    Well actually what remaining drip there was has gone away. If I wipe my hand across the bottom of the fitting it comes back a little damp, but there isn't enough moisture to even create a drip.

    I'll torque it up a little next weekend, if it will budge

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