Expert advice needed for stainless tig
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  1. #1
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    Expert advice needed for stainless tig

    Hi,
    I have to make a stainless steel tank with 1/8 stainless, what is your suggestion on the amps I should be running . Tried a practice weld on junk pieces and welds were good but they seem dark, no regular stainless shine.....too much amps?

    250 dx with 3/32 316 filler.... What's your take? Thanks GH

  2. #2
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    Re: Expert advice needed for stainless tig

    Let's see a pic of the weld u layed down? What joint Configuration? What's the tank for?

  3. #3
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    Re: Expert advice needed for stainless tig

    I'd start by using 1/16" filler. It will consume faster meaning you can move quickly. I'd say 75 amps would be plenty and likely to hot if you don't move with fluidity. Perfect fit up is your friend on thin stainless. If your smooth and travel well with tig then you could perhaps turn the amps up a hair.

  4. #4
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    Re: Expert advice needed for stainless tig

    Welcome to the wonderful world of stainless tig.
    Weld like a "WELDOR", not a wel-"DERR"
    Miller Dynasty700DX, Dynasty350DX 2ea., Dynasty200DX, ThermalArc 400 GTSW, LincolnSW200 2ea., MillerMatic350P, MillerMatic200 with spoolgun, MKCobraMig260, Lincoln SP-170T,PlasmaCam/Hypertherm 1250

  5. #5
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    Re: Expert advice needed for stainless tig

    Quote Originally Posted by Showdog75 View Post
    I'd start by using 1/16" filler. It will consume faster meaning you can move quickly. I'd say 75 amps would be plenty and likely to hot if you don't move with fluidity. Perfect fit up is your friend on thin stainless. If your smooth and travel well with tig then you could perhaps turn the amps up a hair.
    He said the base metal is 1/8" that's not that thin. And I dout 75 amps for a fillet when using filler is enough

  6. #6
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    Re: Expert advice needed for stainless tig

    Corner weld, was using 3/32 filler.......5' x 2' x 20" fuel tank for a boat, install 2 baffles in tank, plus fittings.What's got me puzzled is you check out YouTube and their welds are nice and shiny like when we stick weld stainless.Man there's some good welders(tig) out there!!!

    Thanks for reading and your input!!! GH

  7. #7
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    Re: Expert advice needed for stainless tig

    You want the amps high enough that you don't have to wait around for the puddle to form but not so hot that you can't control it. I like to use a #8 cup on stainless for better coverage. Good shielding and moving keeping the heat low(moving fast) is the trick for decent looking stainless welds. For small parts I like to use a heat sink backing up the weld. Make things a little more forgiving. Also if you welding a tank I'd set up a back purge to shield the inside.

  8. #8
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    Re: Expert advice needed for stainless tig

    are you backing the weld with an aluminum bar? you should be. your getting dark color because the material hasn't cooled down enough by the time its out of the shielding gas coverage, pretty typical with thicker SS. you can find a way to keep it shielded with gas or you can surround the weld area as best as possible with aluminum to help it cool faster. side bonus it will also help to keep things from warping, and if the bar is held tight enough on the back side it will prevent cantamination on the back side of the weld.

    when i weld stainless i use 1/2" x 3" aluminum bar clamped tightly to the back and either side of weld as close *** possible with out interfering with torch movement.
    Last edited by tracymobilecnc; 01-10-2017 at 06:52 PM.

  9. #9
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    Re: Expert advice needed for stainless tig

    Hit it with a wire brush. It's a gas tank, what difference does it make what color it is? Just make sure it doesn't leak.
    Last edited by TimmyTIG; 01-10-2017 at 07:29 PM.

  10. #10
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    Re: Expert advice needed for stainless tig

    Quote Originally Posted by TimmyTIG View Post
    Hit it with a wire brush. It's a gas tank, what difference does it make what color it is? Just make sure it doesn't leak.
    Timmy,first thanks for the reply. Built tank today and pressure checked it ( 14lbs) and no leaks......but will take suggestions from all you guys and will keep in mind for shure. But can't get those beautiful welds out of my mind!!!!! lol

    GH

  11. #11
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    Re: Expert advice needed for stainless tig

    Quote Originally Posted by goose hunter View Post
    Timmy,first thanks for the reply. Built tank today and pressure checked it ( 14lbs) and no leaks......but will take suggestions from all you guys and will keep in mind for shure. But can't get those beautiful welds out of my mind!!!!! lolGH
    Hey, goose hunter,

    May I suggest that you grab a few more of those practice pieces, and try running a bit faster than what you usually do on mild steel. I've found that stainless requires "hotter and faster," much the same as aluminum (but not quite) in order to achieve a nice, shinny bead. When you aren't running fast enough, you get the dull bead, due to "cooking" the metal.

    Please post pics when you get there.

    BTW... did you hear about the thousands of migrating snow geese that were killed last November when they stopped by the old Berkeley pit in Butte, and drank the poisoned water? Since I am still awed at the many thousands of pounds of biomass, moving back and forth over Montana each year, I was standing in my front yard at 3 AM, watching the snows traverse back and forth over town, while trying to get their bearings, during a storm. They, eventually, headed west instead of south, and found themselves in the pit.
    Last edited by Weldordie; 01-12-2017 at 11:42 PM.

  12. #12
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    Re: Expert advice needed for stainless tig

    Sorry but stainless deffently does not take more "heat" then mild steel. Mild steel dissapate heat faster then stainless meaning it will not take as many amps to get a puddle. U got it backwards. U run to fast and u will loose gas shielding over the red area on the weld and it will look grey. There's a fine line on speed and getting shielding still

  13. #13
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    Re: Expert advice needed for stainless tig

    Quote Originally Posted by motolife313 View Post
    Sorry but stainless deffently does not take more "heat" then mild steel. Mild steel dissapate heat faster then stainless meaning it will not take as many amps to get a puddle. U got it backwards. U run to fast and u will loose gas shielding over the red area on the weld and it will look grey. There's a fine line on speed and getting shielding still
    I think you misread my suggestion. Nowhere did I say that stainless takes more heat than mild steel. I, also, did not recommend running, "...to(sic) fast..," Of course there is a fine line between speed and shielding, but that "fine line" of nice looking, shiny beads is, also, achieved by not dwelling too long and "cooking" the puddle before dipping the rod. Upping the heat a bit, and moving a bit faster helps eliminate that grey bead appearance. I would, also, recommend practicing by joining two pieces of stainless by autogenous welding in order to get the desired appearance.

    (It makes little sense to compare heat requirements for dissimilar metals, due to the variables involved. Each metal/job sets the requirements for the parameters needed to provide the optimum end result, i.e., type of metal and gas, thickness of materials, preparation, etc.)
    Last edited by Weldordie; 01-13-2017 at 06:44 PM.

  14. #14
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    Re: Expert advice needed for stainless tig

    Quote Originally Posted by Weldordie View Post
    Hey, goose hunter,

    May I suggest that you grab a few more of those practice pieces, and try running a bit faster than what you usually do on mild steel. I've found that stainless requires "hotter and faster," much the same as aluminum (but not quite) in order to achieve a nice, shinny bead. When you aren't running fast enough, you get the dull bead, due to "cooking" the metal.

    Please post pics when you get there.

    BTW... did you hear about the thousands of migrating snow geese that were killed last November when they stopped by the old Berkeley pit in Butte, and drank the poisoned water? Since I am still awed at the many thousands of pounds of biomass, moving back and forth over Montana each year, I was standing in my front yard at 3 AM, watching the snows traverse back and forth over town, while trying to get their bearings, during a storm. They, eventually, headed west instead of south, and found themselves in the pit.

    Regarding your snows, I never heard about that mishap......I live all the way in eastern Canada.But very sad to hear news like that!!!!Darn!

  15. #15
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    Re: Expert advice needed for stainless tig

    Thanks for the input guys, will use it in practice runs for shure.Useally hold my own on aluminium....for an amateur that is!

    Thanks GH

  16. #16
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    Re: Expert advice needed for stainless tig

    The air movement in your weld area needs to be dead calm. Make sure you have enough post flow on your timer. If you want to see what shielding gas does at the end of the weld be sure to hold the torch right where you stop welding. Raise your helmet, even if you have an autodark, so you can see the colors clearly without any shade. If you held your torch in position and still have post flow you should see shiny weld under the cup. If your weld is hot enough and you still have post flow you can move your torch away and see the weld change colors as soon as you lose shielding gas.

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