Stick welding a copper boiler?
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  1. #1

    Stick welding a copper boiler?

    Hi All,
    This is my first post, and I have limited welding experience. Previously I have done a course in stick welding, but have no TIG or MIG experience.

    I have a copper coffee machine boiler, and wanted to know if it is possible to weld it using a stick welder. I notice that Cigweld has a special electrode (Bronzecraft AC-DC) for welding copper and copper alloys. Has anyone ever tried?

    Also, I am interested in what the weld quality would be like? Strength? The boiler will be run at upto 1.5 Bar pressure. Obviously TIG would be better, but the cost of getting it done for me is similar to a complete boiler.

    If it is possible, I will weld and then get the boiler pressure tested professionally.

    Thanks for any help in advance.

  2. #2
    Join Date
    Jul 2008
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    922

    Re: Stick welding a copper boiler?

    Quote Originally Posted by dane5431 View Post
    The boiler will be run at upto 1.5 Bar pressure.
    That's gonna leave a mark.

    Seriously, I would not attempt this with a stick welder, even if it was possible (which I doubt) and even if I didn't have "limited welding experience."

    On the other hand, do ya feel lucky?

  3. #3
    Join Date
    Aug 2007
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    1,765

    Re: Stick welding a copper boiler?

    Don't even look at it with a stick welder. In fact, get it to a professional with copper TIG experience before you even have another thought. At best, a newbie welding on a thin copper boiler is going to destroy it.
    Have we all gone mad?

  4. #4
    Join Date
    Jun 2010
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    Louisville, KY
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    407

    Re: Stick welding a copper boiler?

    I wouldn't weld it at all. Brazing (or TIG brazing) with Sil Phos would be the best way to fix it. Coffee machine boiler = Small diameter pieces. 1.5 bar is about 23 psi. This isn't going to be thick stuff and it won't take much material at all to hold that pressure with the small diameters involved.

  5. #5
    Join Date
    Jul 2008
    Location
    Long Island
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    2,215

    Re: Stick welding a copper boiler?

    You've heard two good suggestions.
    TIG is the best way, and color match would be the best. Is this polished and on "display"?
    I don't understand why it should be as expensive as a new boiler though.

    Silphos will be plenty strong, and is actually the easiest method, but if the boiler is brass, or if it is overheated when brazed, the silphos may foam a bit. That's not likely to cause a leak, but porosity can fail this if noticed by the health inspector (if that's a concern for you). Sanitary welds cannot have porosity, because nasties live in there, but boiling water at 1.5bar should sterilize anything anyway (that's pressure canner / autoclave territory).

    I've actually used silphos as filler when TIG welding a heavy piece of copper, when I couldn't get my machine hot enough to use copper filler (the thick copper was soaking away too much heat).

    The real concern is busting under pressure. Filled with compressed air, it is a bomb. Filled with boiling water under pressure, it's even worse. As soon as the pressure is released, it will instantly flash into steam. Even if the burst doesn't kill you, the steam can certainly be life threatening.

  6. #6

    Re: Stick welding a copper boiler?

    Why don't you use use O/A and use a copper filler rod. Will hold 1.5 bar no problem with the right joint prep. Make sure you purge with nitrogen though otherwise you will have a mess inside.

  7. #7
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    Re: Stick welding a copper boiler?

    Quote Originally Posted by dane5431 View Post
    Hi All,
    This is my first post, and I have limited welding experience. Previously I have done a course in stick welding, but have no TIG or MIG experience.

    I have a copper coffee machine boiler, and wanted to know if it is possible to weld it using a stick welder. I notice that Cigweld has a special electrode (Bronzecraft AC-DC) for welding copper and copper alloys. Has anyone ever tried?

    Also, I am interested in what the weld quality would be like? Strength? The boiler will be run at upto 1.5 Bar pressure. Obviously TIG would be better, but the cost of getting it done for me is similar to a complete boiler.

    If it is possible, I will weld and then get the boiler pressure tested professionally.

    Thanks for any help in advance.
    Is this a repair, or a modification?
    At least post a picture and a short explanation of what you need to do; such an open-ended question is hard to give any but very general opinions about, even though they've been great so far.

  8. #8
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    Feb 2011
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    Pacific Northwest
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    94

    Re: Stick welding a copper boiler?

    Quote Originally Posted by TIG Fabrication View Post
    Why don't you use use O/A and use a copper filler rod. Will hold 1.5 bar no problem with the right joint prep. Make sure you purge with nitrogen though otherwise you will have a mess inside.
    Sounds good to this newb ...
    I have been there, done that ... I have taken the scars and left the smiles to prove it ... U.S. Marine extraordinaire ...Wars fought, tigers tamed, revolutions started, bars emptied, alligators castrated ...

  9. #9
    Join Date
    Feb 2011
    Location
    Alberta, Canada
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    216

    Re: Stick welding a copper boiler?

    You don't mention what type of repair you are about to attempt. Is it a split seam, cracked fitting, light or heavy gauge, etc. If this isn't repairable by soldering, then leave it alone entirely. If you think that having previously taken a stick welding course qualifies you for making this type of repair, then you will surely get a rude awakening when you take it in to get it pressure tested "professionally.

  10. #10

    Re: Stick welding a copper boiler?

    Thanks all for the advice.
    I had a pretty good idea of what kind of responses I was going to get.

    The boiler is about 10lt, 20cm diamtere, 40cm long. I want to cut the end cap off one end, and reduce the boiler length/volume, and re-attach the boiler end cap.

    I have not cut it yet, so I dont know the guage of the material. but I would say that is weighs around 6kg and measured surface area around 2000cm2. With copper being around 9gm/cm3, and weight of the boiler about 3gm/cm2, i think it should be around 3mm thick.

    A new copper boiler of the size I want to reduce it to is around $250, and the TIG quote I got was $240. I think I might just go this option.

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