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  1. #1
    Join Date
    Nov 2005
    Posts
    1,350

    Unions and pipe dope?

    I was working with an apprentice today and he began to dope the threads on a union. I thought he was joking and I started laughing, and he looked puzzled. He said that he had been taught to dope the threads. Have I missed something? I have been in the trade for 16 years and have never put any kind of thread sealant on union threads.

    Please find me a place where I can find something in print to debunk this notion that you need dope on union threads.
    I STARTED WITH NOTHING, AND I STILL HAVE MOST OF IT!

  2. #2
    Join Date
    Feb 2007
    Location
    Southeast Texas
    Posts
    888

    Thumbs up This works great

    On unions. We spec this out on a regular basis for refinery turnarounds.

  3. #3
    Join Date
    Aug 2006
    Posts
    2,600
    I put sealant on the mating surfaces, way back when, you didn't do this, the unions of today you'd better or expect leaks. Lot of times I just get dia-electrics, just to avoid the problem.

    Today I came across a recently installed compressor, with Blue goop on the roto-locks, just shook my head and walked away.

  4. #4
    Join Date
    Jul 2008
    Location
    Denver, CO
    Posts
    4,229
    Right here is the only time I've doped a union.
    Attached Images Attached Images

  5. #5
    Join Date
    Nov 2009
    Location
    Saskatchewan
    Posts
    492
    A few fridays, at 5 pm, when I had to reuse an old one that leaked. Tape and dope.

  6. #6
    Join Date
    Mar 2007
    Location
    Madison, Wisconsin
    Posts
    2,260
    If you can't find a good enough union from your supplier, it's time to switch suppliers!

    Your just asking to get dope in the gas valve that way!
    I r the king of the world!...or at least I get to stand on the roof and look down on the rest of yall

  7. #7
    Join Date
    Nov 2005
    Posts
    1,350

    Thumbs down

    I've looked all over the web, and the only time I can see it is acceptable is with thread lock for vibration. It just seems so wrong. It's like when a see a DIY dope the threads on gas flex lines on his HWT.
    I STARTED WITH NOTHING, AND I STILL HAVE MOST OF IT!

  8. #8
    Join Date
    May 2007
    Location
    Dry as a bone Tucson
    Posts
    4,344

    dope

    Quote Originally Posted by allstar08 View Post
    I've looked all over the web, and the only time I can see it is acceptable is with thread lock for vibration. It just seems so wrong. It's like when a see a DIY dope the threads on gas flex lines on his HWT.


    SOP here for SW gas-does az and Nev, everything gets a lick-mate surfaces and threads,unions and flare ftgs.
    Some Talk, Some Do
    "keeping condensing pressures low and evaporator pressures high"
    "Some customers are more interested in comfort than energy savings"
    Blog
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  9. #9
    Join Date
    May 2004
    Location
    Rapid City, SD
    Posts
    7,415
    I've doped the threads before, mostly just to help make it able to be torn apart at a later date. Nothing better than needing 2 36" pipe wrenches for a 1/2" union.
    "If you call that hard work, a koala’s life would look heroic."

  10. #10
    Join Date
    May 2000
    Location
    Rochester, NY, USA
    Posts
    14,308
    If you have to put pipe dope on a Union, you ain't doing your job right.

    around here we have to hard pipe furnaces and Hot water tanks, we are not allowed to use appliance hose. except for stoves and dryers. We can't even run CSST to a furnace/HWT.
    The Last four letters


    American = I Can, Republican = I Can, Democrats = Rats


    any questions

  11. #11
    Join Date
    Dec 2004
    Location
    Washington State
    Posts
    217
    I have never seen one in 32 years in the field.

  12. #12
    Join Date
    May 2007
    Location
    Dry as a bone Tucson
    Posts
    4,344

    earthquakes

    Wait till you get some tremors from a quake, there will be a lot of contractors wishing they would have used a flex connector instead of a hard pipe!
    Some Talk, Some Do
    "keeping condensing pressures low and evaporator pressures high"
    "Some customers are more interested in comfort than energy savings"
    Blog
    Web
    Facebook


  13. #13
    Join Date
    May 2000
    Location
    Rochester, NY, USA
    Posts
    14,308
    Quote Originally Posted by ACFIXR View Post
    Wait till you get some tremors from a quake, there will be a lot of contractors wishing they would have used a flex connector instead of a hard pipe!

    In western NY it is against code to use a flex connector.

    Trust me, I would use one in a hart beat if I could. It would save me hours of time
    The Last four letters


    American = I Can, Republican = I Can, Democrats = Rats


    any questions

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