Another reply from someone not understanding my post. The "Cratering" that I was talking about has nothing to do with inept welders, but rust. As I said previously, they might be pinholes on the outside, but the inside of the tank will look like a moonscape. There's nothing wrong with TIG/MIG welding, brazing etc on good metal of consistent thickness, but if you're going to attempt to weld a cratered tank from the outside with any sort of welder, you're going to have problems........