At 4.39 pm, in a polypropylene production plant, an aluminium alkyl (Al-diethyl chloride) transfer hose burst in a 1,400 l storage area. The alkyl flowed into the ground. This product, which ignites in air, caught fire, causing a fire in the bunker box and a loud noise (explosion on contact with water). An employee who was supervising the operation, alerted by the suspicious noises, took cover. Shocked by the sound wave, he was briefly hospitalised. In accordance with the procedures and equipment provided by the operator, the burning liquid flowed through the gutters towards a remote retention pit allowing the site’s firefighters to suffocate the fire by covering it with the inert sand available next to the tank. The tank was rapidly isolated using an automatic valve closing system in the event of excessive heat. The incident was over 13 min after the hose burst. However, the significant heat flux caused the roof made of plastics to burn, producing dark smoke that could be seen outside of the plant. The amount of alkyl released was estimated at 481 l. Measures were taken such as changing the hoses (dimensioned at 40 bar, conditioned, sealed and tested without water), measuring the absence of humidity in the hoses and using metal hoses with more suitable sizes to reduce unnecessary lengths and low points.

The day before, the hose had been connected to the installations as per the usual procedure (nitrogen flushing with several flushes). The sealing had been checked. After closing the valves, the installation had been ready for use. The nature of the burst indicated significant overpressure. The presence of wastewater and the very rapid oxidation kinematics of alkyl by water explained the bursting of the hose. The water possibly originated from multiple sources, such as, residues from the hydraulic test carried out by the supplier, pollution during the transport, and condensation during storage. The operator considered new preventive and protective measures, such as, installing pipes limiting the length of the hoses to 1 m, and isolation valves to isolate the container, moving the wide range of items to be handled outside of the boxes, installing a remote emergency stop control for the boxes, and studying the sealing of windows between the boxes and tanks.