Acc Code UG-100 a pneumatic testing of vessels are allowed, if it "canot supported safely be filled with water". Does it mean, that I have to do first everything to do so, or is a pneumatic test allowed but not recommended?
In the case the TP is 13bar, but the volume 5000m³, code U2 and the vessel site fabricated. Could we avoid a hydro test? I know it is a safety problem...

Thorium,

Pneumatic test is allowed but not recommended since a pressurized air tank/ vessel is a safety hazard.

Code allow pneumatic pressure test at a lower pressure (1.1 x MAWP) as compare to hydrotest at 1.3 x MAWP probably to lower down the risk/ hazard involved in pneumatic pressure test.

Finally there is no escape from a pressure test, either hydro or pneumatic test has to be carried out in order to get the equipment stamped.

Regards