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compressed air lines - copper unions

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  • #16
    Originally posted by Bob Engelhardt View Post

    You'd probably need to cut a grove in one of the faces to constrain it.
    For low pressure (<200 psi) the nut should constrain it radially and the seal will happen on the faces. He could also turn up some plastic washers out of LDPE.
    I just need one more tool,just one!


    • #17
      Originally posted by gmax137 View Post
      I was expecting something more like this.


      • #18
        Originally posted by gmax137 View Post
        I am installing a compressed air system in my small shop, using 1/2 inch copper. In the past I have used the copper unions in the piping around the filter regulator on the compressor outlet. Thinking I would be able to disassemble if needed to repair or change out the regulator. I haven't been able to get the unions leak tight. Is there a trick? They should make-up without any dope or tape on the big nut, right?
        Sounds like a nice setup. I didnt put enough unions. I have had great service with pipe dope rather than tape (scourge of the World).

        No need to get more than the landings. I smear it along the entire male copper or brass fitting to not really leave anything left but whats in the lands.

        It is going to take some friction on the joint to make it gas tight. And take pics before you make the joints. I have screwd up and put a union in backwards, facing the wrong way.

        Oh well, learning is the Key. JR

        My old yahoo group. Bridgeport Mill Group


        • #19
          You could try unscrewing the joints (with the pressure off) and applying a little Loctite 290. It is like penetrating oil and will enter any gaps by capillary action. Re pressurising a couple of hours later would give it time to cure. It is designed as a thread lock to be applied to threads that are already done up.