Open top drums are equipped with rubber gaskets attached to the drum lid to create a seal between the drum and the drum lid. Heat from the sun warmed the air inside the drum, which could have caused the pressure build-up. Recommended Action 1. Always assume that any closed drum can be pressurized. If you are not familiar with the drum, you may not have a reference point for this visual exam.
Some drums have a crown to the lid as part of their design.
To test for pressure, press down with your hand on the center of the lid with as much weight as you can. The lid should flex unless significant pressure has built up. Open all drum closure devices slowly in small increments to allow any pressure that has built up, to escape. The above steps are for drums that are not bulged. If a drum is visibly deformed from the pressure build-up, contact your Hazards Control team for assistance.