PDFWAC 296-301-120
Drying cans.
(1) Pressure reducing valves and pressure gages must conform to the ASME Code for Pressure Vessels, section VIII, 1968, Unfired Pressure Vessels.
(2) Vacuum collapse. If cans are not designed to prevent vacuum collapse, each can must be equipped with one or more vacuum relief valves with openings of such a size as to prevent the collapse of the can if vacuum occurs.