Q. Ron do you have any suggestions for TIG welding aluminum gas tanks to make sure they don’t leak? I made an aluminum tank for a guy last year, and I had a lot of trouble getting it to seal in some areas.

Jim Hull
Via the Internet

A. When welding aluminum tanks, you have to be especially careful with each step—the fit up, the cleaning, and especially, you have to be sure you’re getting full penetration. Aluminum is always more problematic to weld than steel. When you end a weld bead on aluminum, you need to taper off on the heat slowly, otherwise a “shrink crater” will occur, forming tiny cracks.

After welding, you should pressure test the tank with air, and brush a little soapy water solution over all the welds. The tiniest leak will show up as a stream of bubbles through the soapy water. If you find any leaks, you can go back and re-weld those areas. It only takes 2 or 3 psi of air pressure to find leaks, and too much pressure can distort the tank badly, especially if it has large flat areas! CT