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Joining copper to stainless steel

Discussion in 'Expedition Builds' started by TheJackRabbit, Aug 4, 2009.

  1. what are some good leak proof ways of joining copper pipe to a stainless steel tank? Not much pressure other than gravity feed and temperature around 170-190 degrees. Hot water feed for camping. I have a ss tank and would like to use copper tubing as I have a roll of it (1/2 inch).

    I have read that ss will reject the silver solder used for sweating copper pipes. Alternatively, the welding rod for stainless steel requires so much heat it will likely melt the copper tube. So, what are some good ways of making leak resistent joints?

    Thanks in advance.
  2. askeyey

    askeyey New Member

    Watertown, NY
    You might try a "shark bite" style fitting for the copper pipe...it presses on to the end of the pipe and provides a water tight seal. ( no leaks in my bathroom in 3 years)..the other end of the shark bite can be pretty much any fitting the manufacturer has, but I would go with a threaded one that your could mate to a stainless steel or perhaps PVC fitting to affix to the tank...the pvc would be like the style you see on farm water tanks that have a gasket and ring for the inside of the tank and a gasket and fitting on the outside...should work well..

    you can find the shark bites at home depot or lowes...

    SharkBite Connection System
  3. I checked the website and it is interesting although I am not sure itwill work for my set up. We have nothing like Home Depot or Lowes for 130 miles, so will have to see what are local stores can come up with.

  4. doug720

    doug720 SILVER Star

    El Segundo
    Can you weld stainless? If yes, why not buy a SS flare fitting and weld it to the tank? Then use a flare fitting to connect the copper line? You can also get a o-ring sealed "Bulkhead" fitting and just drill a hole in the tank to mount. But, I think welding is the best.

  5. Mace

    Mace rock scientist.. Staff Member s-Moderator

    Las Vegas
  6. Bogo

    Bogo New Member

    On the farm
    I second this.

    If you feel you need for galvanic isolation, have a stainless steel FPT fitting welded to the tank. Then use a short nipple of high temp handling PVC pipe. Then use a brass compression fitting to adapt to the copper tube.
  7. Walton

    Walton New Member

    The Evergreen State
    There is absolutely nothing wrong with soldering copper tube to stainless.
  8. rusty_tlc

    rusty_tlc Dain Bramaged Member Moderator

    Reno, NV
    It's all about the flux, you need a highly active flux in order to wet the stainless.
  9. Dirtsquirt

    Dirtsquirt New Member

    Spokane Wa.
    x2 on the brazing

    silver bearing solder and a good flux will the job nicely.

    did it all the time in the military with Wexler fittings (300 series Stainless) to Schedual L copper tube.

    Saftey-silv 50% silver is what we always used. I actually considered brazing at the temps of this product.

    Staybrite 8 can be done with map gas and should do a fair job
  10. JohnR

    JohnR Regular Member

    Laredo, Texas
    Brazing (silver or sil-phos) would probably be the best bet.

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