Pollution
Humain
Environnement
Economique

The utility production facilities (electricity, water, air, and steam) at a refinery were isolated from the power grid and switched to two turbine generators in anticipation of a storm. At 9:50 p.m., both turbine generators shut down at the same time. Deprived of the necessary water and air, the boilers and all the production units transitioned to a safe state. The effluent drained from the units that shut down was sent to detention ponds. Gas was directed to the flare stack. A leak of burning hydrogen and petrol occurred in one production unit. The inspection authorities for classified facilities, the local residents, and the media were informed. The facilities were restarted over the course of several days, but efforts were plagued by incidents due in particular to thermal fluctuations (pump breakage, water leak, steam leak, clogs, boiler with a punctured heating source). The burning leak, which was quickly brought under control, may have been caused by differential thermal stresses applied to the tightening bolts of the two companion flanges and significant pressure fluctuations that occurred when the units transitioned to a safe state. The temperature difference caused by the cooling inertia of the connected facilities and the thickness of the ring joint facilitated the loss of hydrogen. The cascade shutdown of the turbine generators was due to the control system, which failed because of an improperly connected electronic circuit board and a lack of pressure in the hydraulic circuit.