In April 2011, an OSHA State Plan investigated a 3,600-pound ammonia release at a large warehouse where anhydrous ammonia is used in the refrigeration system in a cold storage building. In this incident, one worker was burned on the arm from the escaping gaseous ammonia. As part of the planned mechanical integrity schedule, two (2) employees were changing out the two (2) pressure relief valves that protected an ammonia compressor.
This incident contains CRITICAL INFORMATION for those who OPEN chemical processes, even for “routine maintenance”! Had these employees NOT donned their Full-Face APRs BEFORE unscrewing the PRV, this incident could have easily been a double fatality! Here is OSHA’s accident report of how these workers INCORRECTLY used the 3-way valve below the PRV and how their FF APR’s saved their lives.