Ignoramus25760 fired this volley in
:
Would I be correct in concluding that the tank is no longer usable for
compressed air, even if it passes a hydraulic pressure test?

When I first saw your post, I assumed you were asking about how to weld
feet to a tank, and I was going to suggest "saddle straps" instead --
basically large band clamps around the tank, with the feet welded to the
clamps.

But what you have is potentially a bomb. No. Don't use it. Certified
(or certifiable) tanks are not that expensive. Soft tissues are. Hard
body parts more so.

LLoyd