Prep an aluminum gas tank for TIG welding
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  1. #1
    Join Date
    Jul 2013
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    280

    Prep an aluminum gas tank for TIG welding

    How do you prep a gas tank that's had fuel in it for welding? The tank I have to repair is 5052 0.060 inch thick aluminum and about 2 gallons capacity. Buying a new one is not an option. Building a new one is but I'd rather not. The leak is right on an outside corner so it's not a high stress area, I think I must have just missed it in my leak test when I made it. I've reliably fixed plenty of pinholes before so I'm not worried about that I just have not done it on a tank that's had gas in it before.

    I don't want to use epoxy.

  2. #2
    Join Date
    Jul 2019
    Location
    Hartford CT
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    7

    Re: Prep an aluminum gas tank for TIG welding

    Fill it with 90-95% with water and put the leak at the high point. Dry the weld area and have at it.

  3. #3
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    Jul 2013
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    280

    Re: Prep an aluminum gas tank for TIG welding

    Quote Originally Posted by manac View Post
    Fill it with 90-95% with water and put the leak at the high point. Dry the weld area and have at it.
    Have you done this before?

  4. #4
    Join Date
    May 2014
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    Central Wa. state
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    2,634

    Re: Prep an aluminum gas tank for TIG welding

    Do you have access to a high temperature pressure washer? A good one that will do steam too?
    Boil the tank for an hour and all the gasoline remnants will be long gone. Gasoline evaporates pretty fast with high temp water/steam. Follow that with an argon purge and you should be fine.

    Let the flames begin...

  5. #5
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    Nov 2012
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    Groves, Texas
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    Re: Prep an aluminum gas tank for TIG welding

    Purge it with argon or nitrogen? Stuff can't explode without the presence of oxygen.

  6. #6
    Join Date
    Jun 2012
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    Bemidji MN
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    14,074

    Re: Prep an aluminum gas tank for TIG welding

    I've washed out motorcycle tanks, then pressure purged with co2.

    Pressure purging involves creating a slight pressure, then releasing it.
    I did about 10-15 lbs.
    It forces the gas vapors to mix with the purge gas, then exit with it.

    3 to 4 times is pretty normal.

    This is how we worked with new propane tanks too. Only in that case we were purging the inert gas to replace with propane before filling them.

    Also, small tanks can go to the radiator shop to be tank cooked there if desired.
    Dave J.

    Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~

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  7. #7
    Join Date
    May 2019
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    45

    Re: Prep an aluminum gas tank for TIG welding

    I have never done it, but have watched an expert. He just rinsed the tank with water (don't remember how many times -- it has been several years ago), then before welding, he turned the tank so the filler neck was the high point and lit a lighter to be sure all the fumes were gone. They were, and he welded the tank up. OSHA probably wouldn't approve this, but this guy could weld anything. He passed away a few years ago.

  8. #8
    Join Date
    Jul 2019
    Location
    Hartford CT
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    7

    Re: Prep an aluminum gas tank for TIG welding

    Yes, the advantage of water is that you know there is no oxygen present. Disadvantage is that you contaminate the water.
    I’ve done a few car gas tanks as well as a 3000 gal fuel oil tank a long time ago. Don’t think it would be legal to do a large tank with water today. (Was cutting up the large tank)
    Last edited by manac; 09-20-2019 at 11:00 PM.

  9. #9
    Join Date
    Dec 2010
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    SoCal-LA
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    9,262

    Re: Prep an aluminum gas tank for TIG welding

    When need be I wash the inside with hot Dawn dishwashing soap/water and let it soak for a few hours. Then rinse and let dry. Baking in the hot sun to further dry and remove vapors is another step. Then purge with 8 times volume argon and keep a steady flow while welding. At least if it blows it will not knock you across the floor like the first mishap I did without purge. Eventually one will get you, just keep it to a minimum.
    Weld like a "WELDOR", not a wel-"DERR"
    MillerDynasty700DX,Dynasty350DX3ea,Dynasty200DX,Th ermalArc400GTSW,LincolnSW2002ea., MillerMatic350P,MillerMatic200w/spoolgun,MKCobraMig260,Lincoln SP-170T,PlasmaCam/Hypertherm1250,HFProTig4ea,MigMax1ea.

  10. #10
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    Jul 2013
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    280

    Re: Prep an aluminum gas tank for TIG welding

    So for what it's worth here's what I did. I had to chemically strip the tank to repaint so partly because there was debris that got in the tank from stripping and partly to get rid of the gas I washed it out with dawn detergent and hot water followed by multiple hot water rinses until all the soap foam was gone and then a couple more. The gas smell was mostly gone so to be sure I also purged with argon for what I figure was 10x the volume of the tank and turned the argon down but kept it on during welding.

  11. #11
    Join Date
    May 2011
    Location
    Dallas, TX
    Posts
    319

    Re: Prep an aluminum gas tank for TIG welding

    I need to weld a new fitting on a used aluminum surge tank so this thread was timely. Based on the replies I think I'll order a new one and work on that.

  12. #12
    Join Date
    Mar 2014
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    738

    Re: Prep an aluminum gas tank for TIG welding

    Groundhog day, AGAIN!

    I wonder why people are so averse to using the search engine 'round here?

  13. #13
    Join Date
    Jul 2013
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    280

    Re: Prep an aluminum gas tank for TIG welding

    Quote Originally Posted by shovelon View Post
    When need be I wash the inside with hot Dawn dishwashing soap/water and let it soak for a few hours. Then rinse and let dry. Baking in the hot sun to further dry and remove vapors is another step. Then purge with 8 times volume argon and keep a steady flow while welding. At least if it blows it will not knock you across the floor like the first mishap I did without purge. Eventually one will get you, just keep it to a minimum.
    Thanks!

  14. #14
    Join Date
    Dec 2010
    Location
    SoCal-LA
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    9,262

    Re: Prep an aluminum gas tank for TIG welding

    Quote Originally Posted by sand_man_red View Post
    Thanks!
    Glad it worked out.
    Weld like a "WELDOR", not a wel-"DERR"
    MillerDynasty700DX,Dynasty350DX3ea,Dynasty200DX,Th ermalArc400GTSW,LincolnSW2002ea., MillerMatic350P,MillerMatic200w/spoolgun,MKCobraMig260,Lincoln SP-170T,PlasmaCam/Hypertherm1250,HFProTig4ea,MigMax1ea.

  15. #15
    Join Date
    Apr 2006
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    Outside of Raleigh, NC
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    866

    Re: Prep an aluminum gas tank for TIG welding

    Quote Originally Posted by shovelon View Post
    When need be I wash the inside with hot Dawn dishwashing soap/water and let it soak for a few hours. Then rinse and let dry. Baking in the hot sun to further dry and remove vapors is another step. Then purge with 8 times volume argon and keep a steady flow while welding. At least if it blows it will not knock you across the floor like the first mishap I did without purge. Eventually one will get you, just keep it to a minimum.
    I have personally welded fuel tanks before and followed Shovelon’s process above. I’m a strong believer in keeping a low, steady flow of argon thru the tank while welding.
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