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  1. #1
    Join Date
    Dec 2003
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    Brazing 3 1/8 pipe

    Does anybody have any advice or suggestions on brazing big large copper pipes such as as 3 1/8 and 2 5/8 ? It's for an air conditioning system I will be installing in the next few weeks. Also any advice for brazing in sight glass's "

    Thanks in advance

  2. #2
    Join Date
    Apr 2003
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    Maple Grove, MN
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    Full sized oxy acetylene rig with a rosebud and lots of patience and lots of silfoss. It takes a long time to heat up and braze pipe that big. A second set of hands and another torch would also be helpful.

    Keep the torch(es) slowly moving between the pipe and the fitting and when the silfoss starts to melt try to draw it into the fitting as much as you can.
    If at First You Don't Succeed, Skydiving Is Not for You.

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  4. #3
    Join Date
    Jun 2014
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    Dover, DE
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    Oxy rig.
    An air rig will do it with a 32 tip but you’ll be draining bottles fast not to mention you’ll need ear protection for that tip-it’s loud when lit.
    I havent failed. Ive just found 10,000 ways that wont work. - Thomas Edison

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  5. #4
    Join Date
    Jul 2012
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    WA
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    I use 1/8” X 1/8” silphos rods.

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  7. #5
    Join Date
    Jul 2012
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    WA
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    For sight glasses...wet rag and point the flame away from the sight glass. They can be copper plated steel, so don’t burn the copper plating off. On Sporlans you can remove the moisture indicator so you don’t burn it up.

  8. #6
    Join Date
    Aug 2002
    Location
    Southold, NY
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    27,233
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    Thats some big suction line. What refrigerant?

  9. #7
    Join Date
    Jan 2015
    Location
    Iowa
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    Make sure joint area material is really clean. Use full size Oxy rig, I would use a little flux, get a dual head torch. I don't like the ring torches. Have a helper tap the tube as you are adding filler metal it will help break any surface tension in the filler metal and capillary action will work better. From having worked on a lot of 3" copper for air systems it takes lots of patients and it's hard to get the filler metal to flow evenly into the whole joint. I've cut several apart to see how well my technique allows the filler metal to penetrate and fill the joint. I suggest you try that too.

  10. #8
    Join Date
    Nov 2014
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    Northern Idaho
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    Only tip in particular other than of course using the proper sized tip is what Redman said, the square beefier rod is much nicer to use on large pipe.

  11. Likes Red Man liked this post.
  12. #9
    Join Date
    Aug 2016
    Location
    San Diego
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    When we brazed a section of 8inch we had one guy holding two large B tank tips and the other feeding the rod. It took forever to heat it up to where it would flow.

  13. #10
    Join Date
    Mar 2008
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    kansas
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    I’ve used a cutting tip just don’t hit the air
    Honeywell you can buy better but you cant pay more

    I told my wife when i die to sell my fishing stuff for what its worth not what i told her i paid for it

  14. #11
    Join Date
    Sep 2007
    Location
    State College, PA
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    Just a question...

    Would it not be better to use stay-brite 8? That would limit how much heat you would need for that size pipe.

    The biggest I have brazed was 1-7/8" and that took a lot of heat. Even with nitro I was afraid of the damage I was doing to the inside of the copper.

    Seems like it would be better for the sight glass for sure.
    Can someone please explain to me -
    Why is there never enough time to do it right the first time, but plenty of time to do it twice?


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  15. #12
    Join Date
    Nov 2014
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    Northern Idaho
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    Quote Originally Posted by joemach View Post
    Just a question...

    Would it not be better to use stay-brite 8? That would limit how much heat you would need for that size pipe.

    The biggest I have brazed was 1-7/8" and that took a lot of heat. Even with nitro I was afraid of the damage I was doing to the inside of the copper.

    Seems like it would be better for the sight glass for sure.
    I would definitely go with silphos brazing, even for that size pipe that is fine. At that pipe size I'm pretty sure the sightglass is typically removable.

  16. #13
    Join Date
    Jul 2012
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    WA
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    Quote Originally Posted by joemach View Post
    Just a question...

    Would it not be better to use stay-brite 8? That would limit how much heat you would need for that size pipe.

    The biggest I have brazed was 1-7/8" and that took a lot of heat. Even with nitro I was afraid of the damage I was doing to the inside of the copper.

    Seems like it would be better for the sight glass for sure.
    1 7/8”...I don’t think that’s a pipe size. Larger pipe takes more heat, but the pipe temp isn’t any different. Just need a larger tip so you can heat it up fast enough.

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