Due to a mishap from improper testing of a vapor safety relief valve on a compressed air system, the Coast Guard Office of Commercial Vessel Compliance (CG-CVC) issued a Marine Safety Information Bulletin to remind all those concern of the risks and best practices in conducting or witnessing the testing of relief valves.
In particular, USCG informs that, while preparing for a test, the 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. Fortunately, no one was injured.
USCG notes that, although this information is based on testing compressed air systems using vapor relief valves, the guidance is also relevant to safety valves in other pressure systems, except boilers.
USCG highlights that Marine Inspectors should be aware of the following: A section of CFR requires checking the settings of safety or relief valves periodically based on Certificate of Inspection (COI) issuance. The most common way to meet this requirement is witnessing the valve operate under pressure by bench testing (that is, with the valve removed, witnessing a pneumatic pressure test using a test rig in a controlled manner) or in-situ testing (that is, witnessing an operational test of the valve under pressure as installed). However, if not operationally pressure testing the valve, the Marine Inspector should verify the following: Further information may be found in the following report:
Source: USCG
