Ignoramus25760 wrote:
I saw something strange on Monday. A big horizontal compressor tank,
with nice old blue paint on it. It is a 25 HP reciprocating Dresser
LeRoi compressor written off by Fermilab, surplused as "scrap". It is
not even a compressor, it is a head separate from the tank as a pile
of garbage.

It is probably rather broken, though I have no way of knowing. It is
also huge.

Here's my question.

The horizontal 120 gallon tank has feet welded to it, looks like stick
welded out of position. The welds are not painted at all, and clearly
have this blue paint burned around the welds. So they welded the feet
on themselves, not too long ago.

I thought that you are not allowed to weld stuff to tanks like this?
That welding stuff to air tanks could lead to some bad failures,
stresses, etc?

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

take it home and use it.