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Braze copper pipe with brass rod?

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  • psomero
    replied
    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.

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  • wmgeorge
    replied
    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.

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  • cxagent
    replied
    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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  • johansen
    replied
    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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  • Sparky_NY
    replied
    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 ??

    Leave a comment:


  • johansen
    replied
    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..

    Leave a comment:


  • Sparky_NY
    replied
    Originally posted by JoeCB View Post
    Without side tracking the OP too far... have any of you guys in the trade heard of the need ( requirement?) for filling the tubing with inert gas before brazing to prevent the formation of oxides that could flake off and plug/ damage AC components? Seems like over kill to me based on what I have see as common industrial practice. Maybe on the space shuttle !!!

    Joe B
    Yup, standard practice. There are pinhole openings in areas of a system plus its like having sand in your motor oil, very bad for the compressor, definitely not over kill. It can be the difference if a system lasts 5 years or 20 years.

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  • JoeCB
    replied
    Without side tracking the OP too far... have any of you guys in the trade heard of the need ( requirement?) for filling the tubing with inert gas before brazing to prevent the formation of oxides that could flake off and plug/ damage AC components? Seems like over kill to me based on what I have see as common industrial practice. Maybe on the space shuttle !!!

    Joe B

    Leave a comment:


  • cxagent
    replied
    Originally posted by Sparky_NY View Post

    I have used many many pounds of it doing copper to brass on AC units, never with flux and never a problem. I do clean the joints first though. All the ac units have brass valves that the copper pipe attaches to, I never heard of anyone in the trade using any flux.
    No argument here. My experience matches yours. If I were handing this Silphos to the person and maybe demonstrating its use I would have said the same thing (no flux needed). But I have not / will not meet this person much less demonstrate what I do. So I referenced the manufacturer's web site for more information. And I never contradict a more knowledgeable source like the manufacturer even if my personal experience is different.

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  • Fasttrack
    replied
    Originally posted by cxagent View Post

    Fasttrack - nothing to do with CX gas. Most of what I do for work is building commissioning which is abbreviated CX. (I don't know why) I did work in the defense industry for over a decade so I had some experience with NBC design requirements. Everything had to be designed so it could be cleaned after contamination. Never had to deal with during exposure.
    Got it! Looks like you're a fairly new member here so, in case others haven't said it yet, welcome aboard! Glad to have you here.

    Leave a comment:


  • Sparky_NY
    replied
    Originally posted by cxagent View Post
    I would agree with Sparky_NY comments. I have to keep the oxy- acetylene torch moving to keep from melting the copper tube or fittings. I suspect TIG would get plenty hot but you would need to develop some great skills to melt only the braze rod and not the copper.

    I put a note in the box about flux. No flux needed on copper to copper joints. I looked up the manufacturer's recommendations for flux just to be sure. Harris said they did recommend flux when joining copper to brass. I included the link on the note. As always - what you do is up to you.

    Fasttrack - nothing to do with CX gas. Most of what I do for work is building commissioning which is abbreviated CX. (I don't know why) I did work in the defense industry for over a decade so I had some experience with NBC design requirements. Everything had to be designed so it could be cleaned after contamination. Never had to deal with during exposure.
    I have used many many pounds of it doing copper to brass on AC units, never with flux and never a problem. I do clean the joints first though. All the ac units have brass valves that the copper pipe attaches to, I never heard of anyone in the trade using any flux.

    Leave a comment:


  • cxagent
    replied
    I would agree with Sparky_NY comments. I have to keep the oxy- acetylene torch moving to keep from melting the copper tube or fittings. I suspect TIG would get plenty hot but you would need to develop some great skills to melt only the braze rod and not the copper.

    I put a note in the box about flux. No flux needed on copper to copper joints. I looked up the manufacturer's recommendations for flux just to be sure. Harris said they did recommend flux when joining copper to brass. I included the link on the note. As always - what you do is up to you.

    Fasttrack - nothing to do with CX gas. Most of what I do for work is building commissioning which is abbreviated CX. (I don't know why) I did work in the defense industry for over a decade so I had some experience with NBC design requirements. Everything had to be designed so it could be cleaned after contamination. Never had to deal with during exposure.
    Last edited by cxagent; 09-27-2021, 12:33 PM. Reason: spelling error

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  • Sparky_NY
    replied
    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.
    The Silfos rod is a brazing operation, you need a somewhat wide heat area for the rod to flow into the joint, Tig could work but is more of a pinpoint heat so you would have to walk it around a bit and not melt the base metals. I have seen the bare ground wire from Romex used BUT that was a TIG welding operation of copper to copper, not brazing. The difference here is between laying a bead and it wicking into the joint.

    Tig would work but have to keep the heat down and keep it moving so as not to melt the base metal. The oxy-acetylene is a better choice, much wider heat area.

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  • gzig5
    replied
    Originally posted by cxagent View Post
    I will put some in the mail.

    You will need oxy-acetylene torch. Or maybe I should say I can't use anything less to braze with Silphos.
    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.

    Leave a comment:


  • Fasttrack
    replied
    Originally posted by cxagent View Post
    I will put some in the mail.

    You will need oxy-acetylene torch. Or maybe I should say I can't use anything less to braze with Silphos.
    That's generous of you!

    I've got nothing to add to this topic but your name caught my eye... any experience with chemical warfare agents? CX is truly nasty stuff...

    Leave a comment:

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