Without an effective #PSM program, you rely only on memories of your people. With unprecedented #ammonia #refrigeration operators and #management turnover rates, sad stories like this are only the beginning. We must rise and lead to sustain #R717 as the safest refrigerant known to man. However it is not PSM that keeps us safe, it is the people whom we put around the process. It’s a catchy motto, gotta keep it in the pipes, but only will happen with competent and qualified people.
On May 26, 2022, a crew was in the process of cutting up and disassembling two ammonia refrigeration systems (referred to as P24 and P34 in this report) at an Arctic Glacier Inc. ice distribution facility located in the Mount Paul Industrial Park located on Tḱemlúps te Secwépemc reserve in Kamloops, British Columbia. Those present understood that ammonia had been previously removed from both systems. During the removal of a section of the P34 system containing the receiver and compressor, it was identified that a valve handle protruded past the frame and could cause issues with the rigging process. Options to deal with the protruding part, such as turning it, were being discussed and one of the individuals turned the valve handle, resulting in a large release of ammonia.
The individual who turned the handle was sprayed by the ammonia and moved further into the building. The remaining members of the crew evacuated through a nearby open bay door. The individual who opened the valve was extracted from the building and pronounced dead following the incident. In addition to the fatality, there were multiple ammonia exposures, a local evacuation, an extended business shutdown, and an environmental response to the release. Technical Safety’s full report is at this link.
The safe dismantling of an ammonia system requires that the system be assessed, and ammonia and oil be removed prior to any disassembly work. Removal of ammonia and oil from a refrigeration system is regulated work that requires the knowledge and skills that a licensed contractor brings with qualified refrigeration mechanics.
The investigation found that the failure to remove ammonia from the refrigeration system, prior to, or during disassembly was the primary cause of the incident.
The contributing factors to the ammonia not being removed were:
1) An incorrect understanding that ammonia had been removed during the shut-down of the system. This understanding was influenced by:
a. Changes in personnel and their assigned responsibilities.
b. Misunderstood communications regarding the work completed.
2) Ineffective assessments to identify hazardous quantities of ammonia in the receivers. These assessments were affected by:
a. The exclusion of a qualified refrigeration mechanic from a dedicated role
during the disassembly.
b. An irregular configuration of the equipment, which created the appearance.
the P34 system was empty.
The investigation found that there was no physical failure of any ammonia system or component.
In addition, the investigation sought to understand aspects of the equipment that increased the risk of an incident as the system was disassembled. Two aspects of the equipment that increased the risk during disassembly were:
1. At some point, the P34 system was altered by Refrigeration Mechanic A to include a quarter turn ball valve that operates in a binary manner (on-off). When that same valve was opened, the ammonia release was rapid and uncontrolled.
2. The P34 receiver’s dedicated pressure relief valve was likely removed during an earlier modification to the system. When the ammonia was later isolated within the receiver (pumped down), the receiver was in a hazardous state which could have resulted in an over pressurization failure at any point after the ammonia was isolated in the receiver in 2016.