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  • nitrogen purge

    Nitrogen gas suggested as a purge for welding a stainless nozzle to heat exchanger. So I thought I would use nitrogen in my torch too. Doesn't work with torch at all. I got nervous and switched the purge to argon before I buggered the job. Rumor is if I keep the gap small and the arc doesn't get near the purge, I would have been ok? Can anybody give me the straight goods with regards to using nitrogen as a welding and/or purging gas for stainless welding?

  • #2
    Originally posted by Azphiks View Post
    Nitrogen gas suggested as a purge for welding a stainless nozzle to heat exchanger. So I thought I would use nitrogen in my torch too. Doesn't work with torch at all. I got nervous and switched the purge to argon before I buggered the job. Rumor is if I keep the gap small and the arc doesn't get near the purge, I would have been ok? Can anybody give me the straight goods with regards to using nitrogen as a welding and/or purging gas for stainless welding?
    Bad Idea as a Torch gas... it does not work.... stick to Argon

    Becoming more popular as a SS backpurge...
    .

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    • #3
      Much cheaper than argon for purging!!
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      • #4
        Use to use nitrogen as a purge gas, butt the PEI dept. stopped it, said it caused cracking,,,, never used on the torch, it won't work. The shops use to use the nitrogen because of price, but you have to use more to accomplish the same purge as argon, so it works out in the wash to just use argon, IMHO. Plus you can't use out for nickel base alloys, it won't do the trick.
        pull-do

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        • #5
          Re: N2...

          I don't believe nitrogen is an inert gas...

          John
          sigpic...John

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          • #6
            Originally posted by blazehaze69 View Post
            I don't believe nitrogen is an inert gas...

            John
            It does displace oxygen though...

            Here is an AWS article worth reading on the subject

            https://app.aws.org/wj/supplement/WJ_1975_01_s12.pdf



            Here is a very good overview of backpurging gasses and techniques

            http://www.boc-gas.com.au/internet.l...e351_68116.pdf

            .
            Last edited by H80N; 09-07-2015, 03:34 PM.
            .

            *******************************************
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            • #7
              Re: N2...

              Very interesting...thanks!
              sigpic...John

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              • #8
                If I'm correct, the main issue with using Nitrogen as a purging gas is the possibility of the diatomic Nitrogen molecule (N2) coming in contact with the electric arc, presumably if there is a slight gap in the joint. N2 is not soluble in the molten weld pool, but if it comes in contact with the electric arc it dissociates (separates) into monoatomic nitrogen atoms, which are soluble, and diffuse into the weld pool causing nitrogen embrittlement. That's only from what I've read researching the subject.
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                • #9
                  Originally posted by OscarJr View Post
                  If I'm correct, the main issue with using Nitrogen as a purging gas is the possibility of the diatomic Nitrogen molecule (N2) coming in contact with the electric arc, presumably if there is a slight gap in the joint. N2 is not soluble in the molten weld pool, but if it comes in contact with the electric arc it dissociates (separates) into monoatomic nitrogen atoms, which are soluble, and diffuse into the weld pool causing nitrogen embrittlement. That's only from what I've read researching the subject.
                  Oscar

                  did you get a chance to read the "White Papers" that I linked...??
                  Last edited by H80N; 09-07-2015, 07:06 PM.
                  .

                  *******************************************
                  The more you know, The better you know, How little you know

                  “The bitterness of poor quality remains long after the sweetness of low price is forgotten”

                  Buy the best tools you can afford.. Learn to use them to the best of your ability.. and take care of them...

                  My Blue Stuff:
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                  • #10
                    Not yet, been up-n-down all day today, lol. I'll have a good sit-down tomorrow and read them in their entirety.
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                    • #11
                      Talking about Argon...

                      I thought I'd put this in for the heck of it...

                      I bought a tank of Argon from a neighbor. The label was sort of crappy looking, so I thought I'd do a little checking. I ruled out that it was C25 buy bubbling some of the gas into a beaker of distilled water. I checked the pH with a meter my wife had- she's a retired chemist- and the pH remained around 7.0...
                      I did the same test with a tank of C25, and the pH went down to around 4.5...
                      sigpic...John

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                      • #12
                        Originally posted by blazehaze69 View Post
                        I thought I'd put this in for the heck of it...

                        I bought a tank of Argon from a neighbor. The label was sort of crappy looking, so I thought I'd do a little checking. I ruled out that it was C25 buy bubbling some of the gas into a beaker of distilled water. I checked the pH with a meter my wife had- she's a retired chemist- and the pH remained around 7.0...
                        I did the same test with a tank of C25, and the pH went down to around 4.5...
                        Why not try to TIG with it and see if it is OK or if it eats Tungsten....??
                        .

                        *******************************************
                        The more you know, The better you know, How little you know

                        “The bitterness of poor quality remains long after the sweetness of low price is forgotten”

                        Buy the best tools you can afford.. Learn to use them to the best of your ability.. and take care of them...

                        My Blue Stuff:
                        Dynasty 350DX Tigrunner
                        Dynasty 200DX
                        Millermatic 350P w/25ft Alumapro & 30A
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                        • #13
                          Originally posted by H80N View Post
                          Why not try to TIG with it and see if it is OK or if it eats Tungsten....??
                          Less time consuming and a bit more scientific...
                          sigpic...John

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                          • #14
                            Originally posted by blazehaze69 View Post
                            Less time consuming and a bit more scientific...
                            Maybe simplistic but effective... reading that tungsten could tell you lot

                            ALSO... what color is the bottle..?? and whose name is on the collar..??
                            Last edited by H80N; 09-11-2015, 10:29 AM.
                            .

                            *******************************************
                            The more you know, The better you know, How little you know

                            “The bitterness of poor quality remains long after the sweetness of low price is forgotten”

                            Buy the best tools you can afford.. Learn to use them to the best of your ability.. and take care of them...

                            My Blue Stuff:
                            Dynasty 350DX Tigrunner
                            Dynasty 200DX
                            Millermatic 350P w/25ft Alumapro & 30A
                            Millermatic 200

                            TONS of Non-Blue Equip, plus CNC Mill, Lathes & a Plasmacam w/ PowerMax-1000

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                            • #15
                              Originally posted by H80N View Post
                              Maybe simplistic but effective... reading that tungsten could tell you lot

                              ALSO... what color is the bottle..?? and whose name is on the collar..??
                              The neck ring is blank (customer owned), and the bottle is grey- which sometimes doesn't mean a lot...
                              sigpic...John

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