Lessons from Incidents
Each entry below illustrates a representative incident pattern seen across the process industries — not a specific named company or disclosed client. The sequence diagram, root causes, and lessons are written to be directly useful in your own HAZOP, MOC, and PSSR reviews.
A level instrument failure went undetected during a routine transfer, leading to tank overfill, vapour release, and a delayed-ignition vapour cloud explosion.
A batch process scale-up without updated thermal hazard testing led to a cooling failure triggering a runaway exothermic reaction and emergency relief discharge.
A temporary maintenance bypass of a pressure relief valve was never formally tracked, and the line was returned to service with the bypass still in place.
A single-valve isolation believed sufficient for line-breaking work allowed residual toxic gas to migrate back into a line during maintenance, resulting in a localized release.
