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Braze copper pipe with brass rod?

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  • #16
    Originally posted by johansen View Post
    I flow propane through systems when brazing, works just as well as argon or nitrogen. No need to lug a tank around.

    As for using 5 to 15% silphos for copper to brass.. It sort of works. Its not reliable. Still get a brittle joint.


    You dont need oxy acyetalene, i have brazed 3/4" pipe with two propane torches and ceramic fiber insulation. 1/2 pipe can be done with 1 torch..
    Flowing propane through pipes while getting them red hot brazing with a open flame, what could possibly go wrong ??

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    • #17
      Originally posted by Sparky_NY View Post

      Flowing propane through pipes while getting them red hot brazing with a open flame, what could possibly go wrong ??
      Once the propane makes it through the system you just light it on fire wherever it comes out. You dont need more than a standard torch worth of propane so it is not a fire hazard. You can turn the source down to the point its just like that of a cig lighter if you want.

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      • #18
        Originally posted by johansen View Post
        I flow propane through systems when brazing, works just as well as argon or nitrogen. No need to lug a tank around.

        As for using 5 to 15% silphos for copper to brass.. It sort of works. Its not reliable. Still get a brittle joint.


        You dont need oxy acyetalene, i have brazed 3/4" pipe with two propane torches and ceramic fiber insulation. 1/2 pipe can be done with 1 torch..
        If it works for you - keep doing it. I use oyy acetylene torch so I can get on it and off of it quickly. Usually I can complete the braze before there is much oxidation of the bare copper.

        I use 0% siphos becasue it is cheaper and more readily available.You use what works for you.

        I flow nitrogen at about 3 psi and a very low flow rate. I don't want the N2 to blow the silphos out of the joint when I am trying to seal it.

        Brittleness? I have had no known problem with a brittle joint. I'm not sure how I would know if the joint was brittle. There is roughly double the copper at the joint in addition to the silphos braze. I have have never seen a brittle mechanical failure at or near the joint. But then the HVAC joint really don't have a mechanical load on them. The only real load would be hoop stress from the pressure of the refrigerant.

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        • #19
          5% Sil Phos is what I used all the time in my 30 years plus. I have used the Harris flux when brazing old copper or copper to brass. Yes you can Sil Phos with propane or Mapp gas depending on the size of the pipe. I usually used a B tank of acetylene with a Turbo torch cheaper and more portable.
          Retired - Journeyman Refrigeration Pipefitter - Master Electrician - Fine Line Automation CNC 4x4 Router

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          • #20
            Originally posted by gzig5 View Post
            Thanks! I've got fresh oxy-acetylene tanks.

            Would TIG work with these rods as well? I saw a utube where he did it with silicon-bronze rod and one that used copper ground wire from some Romex.
            Given the choice, I'd use gas with the proper solder instead of silly rod on TIG. I tend to make cold welds or blow through low melt temp material much more readily with TIG brazing.
            -paul

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