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.