Serious ammonia incidents are rarely created by one dramatic mistake. They develop when assumptions, incomplete information, weak handovers and uncontrolled work combine around a system that still contains hazardous energy.
The Kamloops warning
In May 2022, workers were disassembling an ammonia refrigeration system at an ice-making facility in Kamloops, British Columbia. A valve holding back pressurised ammonia was opened, causing a major release, multiple exposures and one fatality.
Technical Safety BC found that the ammonia had not been removed before disassembly. Those involved believed the system had previously been emptied. The investigation identified contributing issues including miscommunication, personnel changes and the failure to safely verify the presence of ammonia before work began.
Belief is not verification. An ammonia system must be proven safe at the point where it will be opened.
Assumptions survive longer than plant knowledge
Decommissioning work often happens after the people who operated or maintained the plant have changed. Drawings may be incomplete. Labels may describe an intended condition rather than the actual one. A verbal statement that the system was pumped out can become accepted fact without anyone establishing how it was verified.
This is precisely when procedural discipline matters most. The condition of the system must be established from the plant itself, not reconstructed from confidence, memory or an inherited assumption.
Six controls before line opening
Define the boundary
Identify every component, valve, branch and trapped volume included in the work. If the condition of a section cannot be proven, expand the isolation and pump-out boundary.
Prove refrigerant removal
Do not rely on a handover, label, historic assumption or the absence of obvious pressure. Use suitable service points and verified methods to establish the actual condition.
Verify zero energy
Confirm isolation, pressure condition and the potential for liquid or vapour to remain trapped. Treat every opening as hazardous until the zero-energy state has been demonstrated.
Control the line opening
Use a task-specific plan covering authorisation, competent personnel, PPE, ventilation, gas detection, controlled loosening, escape and emergency arrangements.
Keep plant status visible
Drawings, tags, permits and shift handovers must agree. Changes in personnel or ownership cannot be allowed to erase the true condition of the system.
Stop when reality disagrees
Unexpected pressure, odour, liquid, frost, noise or valve behaviour is not something to work around. Stop, withdraw and reassess the system boundary.
Pressure and odour visibility
Before line opening, workers need a deliberate means of establishing pressure and refrigerant condition. Where a suitable service point is not available, that is not permission to proceed blind. The correct response is to step back and expand the pump-out or isolation boundary until the condition can be safely demonstrated.
Checking one convenient point is not enough where closed valves, check valves, elevation changes or liquid pockets can leave sections isolated. The verification method must match the actual system configuration and the precise location of the work.
The procedure must survive contact with the job
A safe work procedure is not useful merely because it exists. It must reflect the plant, define the hazardous boundary and give competent workers clear stop points when conditions differ from the plan.
Toolbox discussions should test the work team’s shared understanding: what is being opened, what can remain trapped, how the condition will be proven, who controls the task, what PPE and detection are required, where people will withdraw and what will trigger an emergency response.
Learn immediately after the task
Post-task reflection should not be reserved for incidents. If access was difficult, a valve did not behave as expected, the drawings were wrong or the pump-out took longer than planned, that information needs to be captured while it is still fresh.
These observations improve procedures, drawings, training and future planning. Without that feedback loop, the organisation is free to repeat the same uncertainty on the next shift, the next shutdown or the next generation of the plant.
The line in the sand
No proof. No opening.
Competence is not demonstrated by pressing on through uncertainty. It is demonstrated by recognising when the system’s condition has not been proven and stopping the job before that uncertainty becomes a release.
Discuss ammonia critical controlsAdapted and expanded from Pádraic Durham’s original LinkedIn article. Read the original on LinkedIn ↗