wrote

These tanks are welded, to begin with, they are made to be welded.
Yes, they are made to be welded - and then X-Rayed and
hydrostatically tested. Brazing, unlike welding, does not run the risk
of undercutting or "burning" the steel - it adds a ductile material
which bonds TO the surface, not menting the substrate. A GOOD welder
can weld it and pretty well guarantee the repair is as strong as, or
stronger than the base metal. Most , even on this list, can not.
With brazing, you can.

A lot has to do with what is wrong with the tank. If it is leaking because
the mount has been bent, and the wall compromised, then yes, it can be fixed
easily. But, if it is due to corrosion, then it is more difficult because
of thinner wall thicknesses, and the probability that there is more than one
site of compromise.

Steve