In a textile factory, a propane leak was detected at 2 pm on a 3-tonne tank used to supply foam production machines (gas manifolds used in the fusible printing process). The alarm was transferred to the guardhouse. The accident occurred on a bank holiday and the alarm caught the attention of the guard, who alerted the fire department and on-call manager. The emergency services crew cooled the tank and set up a safety perimeter. The on-call manager requested the intervention of the on-call maintenance team. At 4 pm, the tank was cooled to 21°C, but the valve remained in the exhaust. The fire department stopped the leak at around 5:30 pm. The maintenance team experienced difficulty (especially on a bank holiday) finding a subcontractor to perform the necessary repairs (three valves changed plus the removal of a pressure reducing valve, with a second remaining as a backup). The intervention ended at around midnight. On Sunday at 8 am, the maintenance team checked for the conformity of works performed and approved the start-up of activities for the following Monday. According to the operator and the service supplier, the incident was due to a rise in external temperature, which increased the tank temperature and therefore its pressure. The valve released some gas to reduce pressure on the tank, thus fulfilling its safety role. The escaped gas was detected by cells provided for this purpose. However, only a detailed examination of the safety devices would confirm or reject this preliminary analysis. The tank was filled to 85% on 12th July at 7 am. The Classified Facilities Inspectorate was not notified of the incident, as required by regulation, despite clear indications to do so in the safety procedure. Moreover, it was found that the operator had not been receiving the installation intervention reports from the service provider and therefore exercised no effective control over the installations, hence affecting the safety of its various sites. Following this incident, the operator was made fully aware of the on-call manager’s noncompliance with the warning procedure and made plans to offer training sessions for its staff. Furthermore, the operator would ensure that the service provider could be reached quickly at all times and that the intervention reports would be available for consultation at the site. It was also agreed that the equipment responsible for this incident, i.e. the valves (specifically the pressure-reducing valve), would be analysed on the service provider’s premises in the presence of a third party expert and give rise to a report to be submitted to the Inspectorate.