An ammonia (NH3) leak at night on the refrigeration installations of a facility that packaged and distributed frozen foods was detected by its smell when employees arrived for their shift.

A maintenance company localised and isolated the leak on an external heat-insulated NH3 pipe. A several metres long corrosion had caused the leak, which was flowing at an estimated 0.5 to 1 litre/h. Investigations revealed, over several metres of pipe length, the absence of a greasy strip to provide efficient protection against corrosion. This negligence during pipe installation 11 years earlier was the source of the incident, whose consequences were indeed limited: the NH3 leak flow rate remained low and dispersion took place without triggering a flash. At the request of Inspection Authorities, the facility operator was given 1 month to: analyse the causes of the malfunction responsible for initiating the incident; order an evaluation of the suspect pipe; inspect all on-site heat-insulated pipelines transporting NH3; adopt all measures necessary to reduce the probability of a similar incident; and build a strategy for using the NH3 refrigerant in on-site installations while simultaneously reducing the risks inherent to the use of this fluid.