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Thread: Welding fuel tanks?

  1. #1
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    Default Welding fuel tanks?

    I am a TIG welder and have been since the 80's (god I am getting old). I remember welding alot of small plane tanks back then that would fracture, I think the mechanics said they were stored with not enough fuel...??? I can't remember the exact reason. Anyway I was wondering if you guys have ever had this problem with cracks in fuel tanks? And if you have is it even legal or ethical to weld a tank? The reason I am asking is I am renewing my certifications, and shopping for a portable tig rig. I am not a pilot or an airplane mechanic, so I thought you guys would be able to give me advise. I work in the Fairbanks area.

  2. #2
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    I TIG welded the tanks for the plane I'm building...0.040, 5052 and they should work fine. I did have a problem with my 170 tanks that are 68 years old...seam cracked but I'm pretty sure that was age and vibration, not how much fuel I kept in the tanks.

    Not sure about Fairbanks but a good tank welder is a real find around here. Most won't touch them...A&P or not.
    Somewhere along the way I have lost the ability to act politically correct. If you should find it, please feel free to keep it.

  3. #3

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    Someone welded the tank to build it so what is wrong with welding to repair it?
    DENNY

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    Could be like welding the muffler on my old Chief . . . seemed a bit thin, but it still took the very careful weld.

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    Quote Originally Posted by boneguy View Post
    Someone welded the tank to build it so what is wrong with welding to repair it?
    DENNY
    The gasoline inside it?

  6. #6
    Member Gerberman's Avatar
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    We weld on fuel tanks all the time, even with diesel and gas in them, just have to know how to not blow your self up. It takes a lot of Carbon Dioxide gas to make sure it does not explode. It is very spooky to weld them, I have only had one tank, a small one I did not purge correctly, explode on me. What a rush. There were a lot of fittings open, so no metal shards flew, I thought the world was ending.

  7. #7

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    z987k
    I would drain it, clean it, purge it/check for other leaks, than weld it. The question was if it was legal or ethical to weld a tank not how to do it. How do you think filler neck cracks cracked drains, or leaking site tubes are repaired?
    DENNY

  8. #8
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    Having just gone through this on my boat tank, here how I tackled it.
    Rinse with cold water a few times (filled, soak, drain). Then I put in some Simple Green cleaner, filled with hot water from the hot water tank, let sit, drain. Did that twice. Came out really clean and fume free. Then filled with water to just below the top (where I was welding) and purged at 5 CFH of Ar/CO2. Kept the purge on while welding. No issues.
    Never wrestle with a pig.
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  9. #9
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    I do truck tanks every week but diesel is much less prone to blow than high octane fuel. I was just trying to insure that there were no special requirments to weld on airplane parts. Thanks for all the responses!

  10. #10
    Member AKDoug's Avatar
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    Don't think that because liquid diesel is harder to light that it is less prone to blow with welding temps. When it does go, it has a much higher energy than gasoline.
    Bunny Boots and Bearcats: Utility Sled Mayhem

  11. #11
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    I guess that you all understand that it is the fumes, not the liquid, that supports combustion . . .

  12. #12

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    Diesel has a flash point of 70 degrees celcius,gasoline is minus 20,Very different beasts. You can wash a gas tank meticulously and they can still go bang when welded.Run a hose from the tailpipe of your truck into it and weld it while truck is running,or use another inert gas to fill tank.Filling with water works but is difficult. Better safe than sorry.

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