At 10.20 pm in a pentane storage of a foam production plant, 14 m3 of pentane leaked from a pump after the rupture of a feeding pipe. The leak occurred during normal operation of the installation in a corrugated hose connecting a pump to the fixed piping. The gas detection system (poorly positioned ?) was immediately saturated and the pump did not switch off automatically when reaching 40% LEL of pentane gas. Due to the failure of the safety systems, pentane was released without being detected in the pump manhole, then diffused into the inspection manholes of the underground tanks connected to the pump manhole.

When the damage was detected, the pump manhole and the manholes of the underground tanks were already filled and pentane had reached the pavement of courtyard and evaporated. Out of the 14 m3 that leaked, about 1 m3 penetrated into the ground. The soil pollution will be investigated through test boring and cleaned. The remedial costs are estimated at 75 000 euros.

An excessive load on the corrugated hose is the most probable cause of this accident. The damaged corrugated hose was exactly fitted (exact length) between the transfer pump and the fixed piping. The lifting movement of the pump exposed the corrugated hose to a continuous mechanical strain. The substitution of the corrugated hose was scheduled once a year and the hose concerned had been operating for 8 months ; the substitution cycles of the corrugated hoses will be redefined with an expert. The length of corrugated hoses will not be longer an exact fit. A redundant safety system including a leakage probe (5 cm above the pump manhole bottom) and a gas-sensor (10 cm above the pump manhole bottom) will be installed in the manhole of the pump. The whole installation will be checked by an expert, including the integrity of the corrosion protection of the underground tanks.