Dripping Copper Union; O-Ring & Grease?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by speede541, Mar 18, 2021.

  1. speede541

    speede541 Member

    Joined:
    May 1, 2010
    Location:
    Oakland
    I have a 1-1/4" copper union outside that was leaking, just a minor drip.

    Searching the fine upstanding plumbing forums, some recommendations I saw were (1) apply plumbing grease to the threads & shoulder, (2) use pipe dope on the union face, or (3) insert what somebody referred to as a "cheater" gasket.

    I didn't want to introduce any break-away clumps of dope to the system, so I applied the grease, and as for the gasket, I found a 1-11/16 OD x 1/8" rubber O-ring that fit the diameter. Seemed too fat, but It worked! Although I should have tried the plumbers grease alone before installing the O-ring.

    But that's not my question. I feel like the O-ring doesn't belong there. My question is what would a preferred gasket consist of? Short of cutting my own from a sheet, I didn't really see any other viable candidates of this size in the plumbing or hardware areas.
     
  2. Jeff H Young

    Jeff H Young In the Trades

    Joined:
    Feb 27, 2020
    Location:
    92346
    no gasket or o ring on the union
     
    PlumbNuts likes this.
  3. Sponsor

    Sponsor Paid Advertisement

     
    PlumbNuts likes this.
  4. speede541

    speede541 Member

    Joined:
    May 1, 2010
    Location:
    Oakland
    Alas, Jeff, I am in 100% agreement with you. I'm going to try it just with the grease, but if it still leaks, I'll settle for the O-ring over the drip.
     
  5. Jeff H Young

    Jeff H Young In the Trades

    Joined:
    Feb 27, 2020
    Location:
    92346
    ok take a chance just like wrapping with ptfe shouldn't do that and it might not last but in desperation and or temporary measures sometimes things are done that shouldn't . just saying it could be a risk btw outside above ground might not be as critical but keep an eye on it.
     
  6. speede541

    speede541 Member

    Joined:
    May 1, 2010
    Location:
    Oakland
    But would you suggest I try a different — perhaps more suitable — material for the gasket? The O ring seems to be holding, but I wish it were thinner and flatter.
     
  7. Reach4

    Reach4 Well-Known Member

    Joined:
    Sep 25, 2013
    Location:
    IL
    Some tank tee unions use a PTFE ring instead of an o-ring.
    https://www.rcworst.com/Shared/content/mfr/boshart_industries_inc_bii/docs/biitankteeinfo.pdf

    BUNA-N and EPDM are probably a perfectly suitable material,. Compressible sounds like a good thing for a space that was not intended to have an o-ring.
    https://www.theoringstore.com/store/index.php?main_page=page_4
     
    Last edited: Mar 19, 2021
  8. PlumbNuts

    PlumbNuts SC Licensed Plumbing Contractor

    Joined:
    Feb 11, 2021
    Occupation:
    Owner, Plumbing Repair Service
    Location:
    Fort Mill,SC
    If it is an all copper union then it should seal itself without the addition of anything. If you are having issues with it sealing it is most likely caused by mild corrosion. Try cleaning the shoulder and the seat of the union with flux and rinse thoroughly before reconnecting. That should clean the mating surfaces and allow a proper connection.
    However, that does not always work and at that time I would try a very light coating of the grease only. No o-ring!
     
    Jeff H Young likes this.
  9. speede541

    speede541 Member

    Joined:
    May 1, 2010
    Location:
    Oakland
    Thank you everyone for you suggestions. As I mentioned earlier, I should have tried the plumbers grease alone before sandwiching in the O-ring. Today I cracked it open, extracted the O-ring, smeared on another blob of grease, and snugged it back together. The union appears to be holding drip-free at 105 PSI.
     
  10. Jeff H Young

    Jeff H Young In the Trades

    Joined:
    Feb 27, 2020
    Location:
    92346
    glad it worked out ! much better than a gasket
     
    speede541 likes this.
  11. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Joined:
    Sep 2, 2004
    Occupation:
    Retired Systems engineer for defense industry.
    Location:
    New England
    A touch of pipe dope on the mating surfaces can help. An O-ring where one is not intended may not last, especially if you use an oil-based grease that could end up degrading the rubber.

    If you overtighten a union, you can cause a deformation of the mating surfaces, and unless you get it exactly in the same place, can leave a ridge, and let things leak.
     
Similar Threads: Dripping Copper
Forum Title Date
Plumbing Forum, Professional & DIY Advice Soldering copper with dripping water. Jan 28, 2005
Plumbing Forum, Professional & DIY Advice Dripping main sewer stack- from upper floor rehab Apr 5, 2021
Plumbing Forum, Professional & DIY Advice Resin Tank Dripping Noise Oct 28, 2020
Plumbing Forum, Professional & DIY Advice Wet bar faucet dripping Oct 8, 2020
Plumbing Forum, Professional & DIY Advice Dripping Delta faucet Sep 3, 2020

Share This Page