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  • bad root

    Hey guy's new to this site. I am tig welding ss pipe. 10" and the problem is in the root. It looks as if there is no gas. The pipe is damed with rags (so less argon is needed), i even put the gas up to 80cfm. Would bad alignment on the root face cause this problems? Never had problem on the other end wich is necked down to 2". Any idea's?

  • #2
    Did you let the pipe completely fill with gass before you started?

    I assume you are welding a pipeline?

    the interior of the pipe has to completely fill with gas, for argon you might try just the lower side, If it looks better, just wait before you start. the top

    you might be better off taping over the end with duct tape, and poking a small hole, when gas starts to escape you know the pipe is full, ease the preasure back to 4-6 psi and check that gas is still flowing out of the pipe

    hope that helps some

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    • #3
      root weld

      i agree with ht1 tape the ends, purge the, pipe poke a 3\32 hole in the opposite end as the purge, let it fill with argon and hold a lighter up to the hole the purge should blow out the lighter.let it purge for a few minutes before welding this should help

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      • #4
        Are you wrapping the joint with aluminized tape?
        Two turn tables and a microphone.

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        • #5
          same as other members have said,bung or tape up all the joints.put your purge in the oposite end from were you are welding.tape up the joint removing the tape in quarters as you weld up to it.
          between 10 and 20 lpm should be more than enough purge.

          fnc
          THE IMPOSIBLE I CAN DO,MIRACLES TAKE A LITTLE LONGER

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          • #6
            Originally posted by fillncap View Post
            same as other members have said,bung or tape up all the joints.put your purge in the oposite end from were you are welding.tape up the joint removing the tape in quarters as you weld up to it.
            between 10 and 20 lpm should be more than enough purge.

            fnc
            Correct me if I'm wrong, but if I'm loosing that much gas from the joint that I think I need to tape the joint to keep the purge gas in my thoughts are
            1. My fit up is unsatisfactory
            2. I need a backing ring BADLY
            3. isnt the tape residue going to contaminate my weld???

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            • #7
              Originally posted by HT1 View Post
              Correct me if I'm wrong, but if I'm loosing that much gas from the joint that I think I need to tape the joint to keep the purge gas in my thoughts are
              1. My fit up is unsatisfactory
              2. I need a backing ring BADLY
              3. isnt the tape residue going to contaminate my weld???
              My fit up is unsatisfactory---Wrong. Any gap in the joint can allow ambient air in.

              I need a backing ring BADLY---Nope

              isnt the tape residue going to contaminate my weld???---No, you put the tape on the outer surface of the pipe, not down in the joint. After the root is in, clean the pipe.
              Two turn tables and a microphone.

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              • #8
                Try it with deferent gas

                Mack, from Germany
                We weld root pass gtig welds with 90%Argon 10%Hydrogen(perging gas)
                Preperge 20 seconds per liter volume of pipe with 25 lpm, escape hole about 12mm. After preperge time, reduce gas for welding to 15 lpm.

                PS. Your welding gas can contain 2 or 3% Helium, It really helps constant penetration.
                Last edited by macforce; 02-09-2009, 03:20 PM.

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                • #9
                  root

                  i always rip off 3-4 inches of tape when i first start the weld,as i come up to the tape i'll rip off more but never break my arc until i stop welding.this helps keep the purge on the weld.don't forget to turn your purge down to 4-5 psi when you close the pipe or you"ll get suck back in the root.pangea said it perfectly you shouldn't need a backer on a good fit.

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                  • #10
                    Thanks guy's all good info. great forum. I am thinking it is still bad gas, it was purged for 5 minutes, now the pipe was 11 feet long but still. the joint was taped as well the ends plus i had a dam that was a few inches from the joint to save on argon. Got mad enough plus rush job like alway's finished it by arc.

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                    • #11
                      11'of 10" pipe and you only purged it for 5 minutes? Well, there's your problem.
                      Two turn tables and a microphone.

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                      • #12
                        There must be a calcutation involved for Diam. of pipe by lengh and so much cfm? HMMM! While tacking and welding though i had a dam only 6 inches from joint.

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