As a bend in the water cooler had corroded, toxic/flammable/explosive substances (flammable gases, hydrogen sulphide and hydrogen) could escape to the open air. The hydrogen sulphide emission caused bad bodour in the surroundings of the plant area. The population was alerted. The accident occurred during normal operation in the gasoil hydrogenation plant (operating under vacuum conditions) of a petrochemical industry. The system involved was the reaction products cooler (the cooling medium was water).

– Flammable Gases: amount involved = 145 kg (0.145 tonnes).
– Hydrogen Sulphide (C.A.S. CODE: 7783-06-4, E.E.C. CODE:016-001-00-4): amount involved = 55 kg (0.055 tonnes).
– Hydrogen (C.A.S. CODE: 1333-74-0, E.E.C. CODE: 001-001-00-9): amount involved = 100 kg (0.1 tonnes).

The heat-exhanger of the cooling system was corroded by the action of the hydrogen sulphide contained in the reaction products.

The accesses to the installation were blocked and the reactor contents was sent to the flare system. Hydrogen sulphide concentration measurements were carried out. The population was warned.