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Thread: Welding Stainless with TIG

  1. #1
    Join Date
    May 2005
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    Milwaukee
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    Default Welding Stainless with TIG

    I've got one of the cheap Harbor Fright DC TIG welders and need to fix a couple cracks in the stainless exhaust system on my car. I can't find the manual, not that that would help any, but do I use the same configuration of the leads as I would for carbon steel? For some reason I thought that I would reverse + and -.

  2. #2
    Join Date
    Sep 2009
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    NW Illinois USA
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    Default

    Same polarity as carbon steel.

  3. #3
    Join Date
    Jul 2009
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    Waukesha, WI
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    548

    Default SS Tig polarity

    SS tig will have the electrode negative. DCEN.

    If your are asking about carbon steel and tig it would be the same.

    I'm old school enough that I still use stick for a lot of steel process's, most likely 'cause I obtained hundreds of pounds of stick rod free, and commonly for the stick process the electrode will be positive, DCEP.

    see here for more info:
    http://www.thefabricator.com/article...ten-electrodes

    If you haven't done much tig I would practice on a salvage yard pipe before I would attack my car's system.
    Don't know if it is practical to remove the exhaust system before welding, but some things that are a snap flat can be a real trial when welded in position.
    Good luck
    Paul

  4. #4
    Join Date
    Jul 2002
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    3,862

    Default

    I concur with ironmonger on practicing first. Thin SS is more easily holed than carbon steel. At least it is for me.

  5. #5
    Join Date
    May 2005
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    Milwaukee
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    Default

    Thanks guys, I definitely plan on practicing first, and hopefully I can find some free scraps at a muffler shop or cheap from a junk yard. I hope I can do it in place without removing the exhaust. This car is a 2000 BMW M5 and the dual exhaust is one piece from the headers to the tailpipes, weighs a couple hundred pounds and is a real bear to get out and in.

  6. #6
    Join Date
    Oct 2005
    Location
    Colorado
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    Default

    I'm no welding expert but, most muffler and exaust in stainless is type 409 SS.
    Most info says you should use 309L filler rather that the standard 308L.
    FWIW

  7. #7
    gnm109 Guest

    Default

    With welding on the outside only, you stand a chance of getting oxidatoin (sugaring) inside of your weld. It's OK if you don't burn through but if that happens, you will have a mess.

    Ordinarily, welding SS pipes should be done with an argon purge inside of the pipe to prevent this.

    Without the possibiity of back purge since the exhaust wil be on the car, just go slow and don't use max. heat.

  8. #8
    Join Date
    Jun 2005
    Location
    Alberta
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    1,079

    Default

    And get it as clean as possible in prep.......
    Opportunity knocks once, temptation leans on the doorbell.....

  9. #9
    Join Date
    Oct 2002
    Location
    Russellville, AR
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    719

    Default

    Do it with the engine running to purge, preheat, and post heat all-in-one.

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