At work I won't allow any air compressor tank in the building that we buy as a stand alone, unless it is ASME certified with inspection ports, the exception is a small hand held tank only for filling tires or blowing air in say a small machine, as the one we have will slowly bleed of air and not stay pressurized after a week. I don't have a choice if a machine we use has a tank that is built into it by the manufacture, we allow those. Not that the cert will make a difference, but at least it has passed some sort of certification it was welded correctly and looked at from the inside after the welding process. I assume our insurance company would push for this form of pressure vessel.