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  1. #1
    Join Date
    Aug 2011
    Posts
    2

    Question Millermatic 175 230V porosity problem after changing gas tank

    I have had this Miller 175 230V wire welder for about 4 years. Recently I changed out the gas tank. The old gas tank was C25 as usual. The new tank given me was Nitrogen. I didn't think this would make a difference since both lack oxygen.
    Now after 4 hours of disassembling & cleaning everything no matter what settings I use for wire and amperage the welds look terrible and are very porous. Gas is flowing freely and everything seems right. Is it just the gas or am I missing something?

  2. #2
    Join Date
    Oct 2010
    Location
    Lake View,NY (Buffalo)
    Posts
    18

    Default

    Take it back & get another tank of c25, your problems will go away. Nitrogen is a inert gas but doesn't have the same properties of argon, or 25/75. If you do any plastic welding you can use theNitrogen for that, makes for nicer welds than compressed air, not going to do anything for you hooked up to the mm175 though.

  3. #3
    Join Date
    Feb 2006
    Location
    Northern CA, Shasta CO.
    Posts
    152

    Default

    ""As an example, nitrogen in solidified steel reduces the ductility and impact strength of the weld and can cause cracking. In large amounts, nitrogen can also cause weld porosity.""

    http://www.esabna.com/EUWeb/MIG_handbook/592mig4_1.htm

  4. #4
    Join Date
    Jul 2011
    Posts
    162

    Default

    The middle of the Industrial Revolution was driven by the spread of the Bessemer Process to make steel from blast furnace iron, air was bubbled through the molten iron to burn out the carbon (4%+) but because air is mostly nitrogen, the steel was relatively weak. Yes, iron combines with nitrogen in the weld. And most Bessemer steel is nearly not weldable, most BS was riveted.

    Using nitrogen to shield will result in many problems. You would have better luck with straight carbon dioxide if C25 is not available.

    Never compromise with shielding gas, use the right stuff. And if your process variables are all on, yet welds look poor, suspect the gas. Sometimes people make mistakes.

    Last cylinder of argon I bought, I was given C25. Didn't pull the bonnet.

  5. #5
    Join Date
    Aug 2011
    Posts
    2

    Default

    Thanks to everyone. I thought I was going nuts. I am returning the Nitrogen today.

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