Although this Coast Gaurd Bulletin is specific to maritime vessels, it can and should be applied to relief valves on land as well. There are some really good practices in this bulletin, such as when to perform the test in-situ vs. bench testing. The incident happened when a relief valve on the associated compressor was removed because it had a lower set-point than the relief valve on the air receiver being tested. Unfortunately, the isolation valve between the compressor and the air receiver was mistakenly left CLOSED during the test, resulting in a dead-head situation, causing the compressor to rupture, and sending shrapnel throughout the space.