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Help with tig root pass!!!!!

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  • Help with tig root pass!!!!!

    Hello there welders. I am currently working on getting into the local plumber/pipefitters union. I have a test this Saturday. My issue is the root pass. I am welding 2 inch carbon steel pipe and using a stainless filler. I just have problems running consistent. I am putting the root in at 78 amps. Then i was bumping my amps by 10 or so but was getting alot of suckback. So i backed it down to what I am putting the root in at. I tend to panic thinking i am gonna blow keyholes. Would you folks possibly walk me through it or even give me some pointers? Thank you for your time, have a great day.

  • #2
    Help with tig root pass!!!!!

    well what kind of gap r u runnin and what size wire I prefer a loose 1/8 on small pipe with 1/8 wire where the bevel barely catches the wire stainless on stainless I'd prob run about 70 but stainless on carbon maybe a little hotter I keep my wire layed in bevel but ready to feed if it ever keyholes keep tungsten pointed straight in and walk it tight. but it's all personal preference whatever feels good

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    • #3
      thanks waymack

      I am tacking up with an 1/8 th inch spacer. It typically shrinks down a bit. I keep a knife edge on the pipe. I am using a number 4 cup so i can get down into the bevel. If i go to slow will it take all of my reinforcement out of the bead on the inside? I may bump the amps down a little so i dont have to move so fast.

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      • #4
        I am using 1/8 th inch wire with the laywire technique.

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        • #5
          Help with tig root pass!!!!!

          u may wanna turn amps down and go slower and c how it turns out i push just a little wire on the bottom 1/4s so I won't have any suck back and wash a little wider on top so I don't get to heavy it's just little things that seem to work for me

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          • #6
            Thank you for your input. I will give it a shot!

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            • #7
              Help with tig root pass!!!!!

              I would run about 68 amps and just lay the filler in the gap and keep it pressed in if u can and just run the torch over it with very little side to side it should go in nice and pretty. Just did a 2" tig test a little while ago in 6g went nice and smooth. Just get more arc time and you'll get it

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              • #8
                Thank you pressurewelder. I will be back at it tomorrow and i will give it a shot. Thanks again

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                • #9
                  Per API 1104, suckback on your root is acceptable provided there is complete fusion at the root opening and the cap height is sufficient so that the thickness at the weld joint meets or exceeds the material thickness.

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