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Tube welding

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  • Tube welding

    Hey guys,

    I am new to the board and have a question about tube welding with my tig. I just purchased a 330 A/BP ( CIRCA mid 60's) and I was cuting up some of my T-joints I was welding with square tubing, when I looked at the inside of the tube that was in the vertical position during welding I noticed that my penetration actually created a crater along the length of the weld actually making the tube seem thinner in that area. Is this a bad thing and if so how do I correct this.

    Thanks for any of your help

  • #2
    Welcome aboard and we'll need some more info, tubing thickness,amperage, used direction of travel, gas used and pressure, ACor DC with or without Hi-frequency, filler. These are all variables and do play a part in the proper response we will give for advise.



    • #3
      pics of some cross sections would be even more helpfull.
      Trailblazer 302g
      super s-32p
      you can never know enough


      • #4

        A PJ and Dyn88 mentioned there is not a lot of info and a picture can be worth many words. However, I'll take a guess: It sounds like you are traveling up hill too slowly on the vertical runs. Uphill travel will put more heat into your welds than will downhill travel. You do want uphill travel for structural work. You can travel faster or turn down the amperage a bit and cut another coupon to see if this corrects the issue. Is it a problem? Probably.

        Now when we get some pictures we may see my answers are all wrong.


        • #5
          I am using 100% argon, 2% thorium 3/16", 15cfh pressure and approximately 67 to 68 amps. I took a rough measurement on the tube steel it was around 0.090". I am starting the weld on the t-joint at the farthest point away from me and traveling towards me. I will get some pics this weekend or sooner and post them. If I use higher amps I burn through the material to fast, so I think I am at the peak amps to be used.

          Thanks guys


          • #6
            I would say 3/16" tungsten way too large 3/32 would be better. I prefer ceriated or lanthanated, but thoriated will work. I would run the gas a little higher 18-22 cfh. Reducing the tungsten size will raise the amperage required as will increasing the gas because the gas will cause the electrode to run cooler, these changes should bring your amperage requirement to 75-85 amp range.

            Hope this helps,


            • #7
              Sorry, I said I was using 3/16 but actually it is 3/32" tungsten. I tried to take some close up pics but they all suck and won't show you the story. On my amperage dial it is marked in percentages and I am at 27% of the range of 80-250 amps. I don't know if this is off alittle bit because my outlet for the power is putting out 242 volts and my only setting hookup on the machine is 230 volts Miller said that was ok and would not hurt my machine. When I really study my weld it looks like the tube that is standing vertical in the t-joint is getting penetrated so hard the the metal is actually flowing outwards towards the face of the bead. I wish I could explain it better or get some pics that are worth a ****.

              Thanks guys