Can I Coat a Leaking Aluminum Water Tank with Epoxy ?

[nknowland]

Our alum water tank has developed several pin hole links over the years. Can I cover the entire tank with epoxy to seal the leaks and continue using the tank? Or does it need to be replaced?

[CSY Man]

Yup.

West System Epoxy is "food grade" and inert after it cures.

I did the same with my water tank. Bad smell and taste disappeared.
Consulted with a chemist for the water company here in town before I started coating the tank, he said go ahead and he said the US Navy is using epoxy for their water tanks.

[Ram]

I wonder how well it will stick to Aluminum, will it corrode under the epoxy? I have a small hole in my Diesel tank would it work there as well?

[barnakiel]

Can be done but possible issues getting epoxy adhere to alloy. Abrade, degrease and then epoxy immediately (at least the leak region) for a long lasting water-tightness.

b.

[Jim Cate]

FWIW,

We successfully cured a small leak in a "corner" weld in an aluminum diesel tank by getting a bit of soft alu sheet metal, bending it to fit over the leak area and epoxying it in place. Cleaned up the area, sanded with coarse paper, wiped with acetone and stuck it on... pretty easy! Was good for the ten years before we sold the boat, and I think it's still in service 6 years on from that.

Cheers,

Jim and Ann s/v Insatiable II lying Towlers Bay, NSW, Oz

[Bergovoy]

after you figure out the preperation requirements, i would try to coat the inside of the the tank, and outside... but if you can create an 'envelope' inside the tank, then yea, it will keep the tank for leaking and create a barrier so there wont be any funny/metalic tastes...

they are using that technology to coat the inside of copper pipes in housing when the pipes start leaking all over...they also appyl a coating inside the aluminum water bottles..

[witzgall]

If coating the outside, you should:
1. Sand aluminum
2. clean
3. brush on epoxy
4. While the epoxy is STILL WET, sand again, which removes the oxidation, but does not allow new oxidation to form in it's place, as the epoxy keeps the air out.

I would do one coat this way, and then simply sand lightly and do another coat on the outside, but without the wet sanding

You can do the same with stainless steel.

Chris

[s/v Jedi]

Originally Posted by witzgall

If coating the outside, you should:
1. Sand aluminum
2. clean
3. brush on epoxy
4. While the epoxy is STILL WET, sand again, which removes the oxidation, but does not allow new oxidation to form in it's place, as the epoxy keeps the air out.

Exactly! it will get messy of course but this is the only way to do it without etching with acid. I use a stainless steel brush to brush the epoxy into the aluminium which is a bit less messy. This also works well on lead (think keel).

cheers,
Nick.

[Henk Koornstra]

My aluminum water tank hole had a hole of about 1/16 of an inch. When I performed my research, I checked various fixes, including 5200 (not tested for food safety) and West System epoxy (not tested for food safety). I finally settled on Sikaflex 291 as this product is food safe, which is noted in their specifications. The recommended process by Sika staff in an e-mail, included cleaning the tank area of the leak thoroughly, applying an activator, called Sika Aktivator, applying a primer and subsequently Sikaflex 291. The primer is not food safe, therefore taping the area is required. Because my hole was not that large, the salesperson of Sika mentioned verbally that the primer could be deleted.
My process therefore only included a thorough cleaning, applying the activator and pasting the Sikaflex 291. I applied it on the inside and the outside of the tank. After waiting for a thorough drying period of one week, I added water to the tank and it worked as promised: No more leaks.
While doing the work, I made a test piece on a piece of aluminum and copied the same process I used for the tank. I tried to pry the Sikaflex 291 off the test piece without success, as it has a very strong bond with the aluminum. If future holes need to be patched in my water tank on the boat, I would use this process again.

I could perform the above process, as I had made a hand hole in the top of the watertank several years ago. The hole was covered with an aluminum plate that was about one inch wider than the hole, with a rubber seal between the tank and the cover plate. I used machine screws every inch around the edge of the plate to insure a good water tight fit.