Stainless fuel tank repair

Discussion in 'Materials' started by trayle, Jan 19, 2010.

  1. El Sea
    Joined: Aug 2006
    Posts: 55
    Likes: 1, Points: 0, Legacy Rep: 36
    Location: St Petersburg, Florida

    El Sea Junior Member

    When you have a compromised fuel tank you tend not to sleep well at night.
    I would try to sort out what has caused the problem. The boating environment is very unfriendly to the different metals that are used. The DOE warns of the storage of bio-diesel, the EPA warns of the storage of Ethanol.
    I see tanks that have been encased with the foam, this almost aways leads to failure and I see tanks with holes that have been spiked by stray electrical current.

    From a cost and safety point of view, off-load the fuel, pull the tank, clean up the mess that is currently hidden and replace the tank.

    Good Luck,

    Luther Carrier
    Absolute Tank Cleaning
  2. NTGeorge
    Joined: Jan 2010
    Posts: 15
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    Location: Darwin

    NTGeorge Junior Member

    You can get some goop called "Pro-seal" I think that is it's official name. Quite expensive, but is one of the few sealants out there that is Avtur proof so it'll hold back diesel, the avo fellas out there will know it better. They use it to seal the inside of the fuel cells in helicopters and such. I get it to seal fuel gauge units and inspection ports on new tanks that I make for customers.
    I would suggest even somthing as simple as cleaning the affected area really well and then pumping a tube of ordinary commercial silicone into the area, to stop water ingress. Then put a fuel bladder in.
  3. dcapn8
    Joined: Apr 2017
    Posts: 2
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    Location: United States

    dcapn8 New Member

    My plan for sealing my tank.

    I have the same problem on my '86 Ericson 38-200. The leaking diesel is causing black goo in the bilge. I am going to empty the tank (about 40 gallons) and give the fuel away, then cut an inspection/access hole in the top of the foremost (largest/deepest) part of the tank and then try to clean & scour the bottom weld(s) of the tank. Then I will pour/coat the welds with epoxy, (or fiberglass resin?). Before buying/installing an expensive inspection plate cover I will test the seal with a couple gallons of diesel. If the tank still leaks, I will empty it then cut the top off most of the tank, remove the baffles, and then install a 20 gallon bladder-tank. I will post results here. Wish me luck!:cool:
  4. Ike
    Joined: Apr 2006
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    Location: Washington

    Ike Senior Member

    Your idea of a test is not a good one. Only a pressure test will tell whether it leaks or not. You need to pressure test it at 3 PSI (no more) Frankly if it is leaking due to corrosion it should be replaced. Trying to repair a leaking tank is an exercise in futility.
  5. dcapn8
    Joined: Apr 2017
    Posts: 2
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    Location: United States

    dcapn8 New Member


    Thanks Ike,
    you are probably right to forget trying to repair the tank, but it will be a beast of a job to try to remove it (or just cut the top off of it). So I'll give it a shot at a fix first, (then probably admit that I should have listened to Ike...):)
  6. Larrythedove
    Joined: Jan 2019
    Posts: 1
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    Location: Antigua

    Larrythedove New Member

    I had the same problem of leaking stainless steel fuel tanks, each holding 150 to 200 gallons, so they are big and impossible to get them out without destroying the boat. I found a guy to cut a large area in the cabin sole then cut a large inspection hole in the top of the stainless steel tank. We thoroughly cleaned out the tanks cutting large holes in the baffles to allow him to climb into each compartment, then he epoxied all the corners then fiber glassed the inside of the tanks and refit the baffles in place with rivets. The large cut out we riveted and sealed the joints with 5200. It has held for nearly 20 years now. We did the same with both my water tanks but one has now started to leak again.

  7. Barry
    Joined: Mar 2002
    Posts: 1,334
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    Barry Senior Member

    3MTM Marine Adhesive/Sealant 5200 is not recommended for use as a teak deck seam sealer. Extended exposure to chemicals (teak cleaners, oxalic acid, gasoline, strong solvents and other harsh chemicals) may cause permanent softening of the sealant.

    The above excerpt pulled from 3M's technical sheet for 5200 polyurethane adhesive.
    It appears that 5200 can/will soften over time in environments that contain volatile hydrocarbons, gasoline noted in their specs. Perhaps because Larrys inspection plates were on the top of the tank and not in contact with the diesel, he did not have any issues. But I'd be uncomfortable relying on it to permanently seal a fuel tank.

    I realize that this is a very old thread but Larry has opened it up. 5200 is an extremely good product but in in this application, the interface between the inspection plate and a diesel
    tank might not be the best alternative. Better to use an approved rubber gasket.
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