At around 4:00 p.m., a burning gas leak occurred on a gas line under maintenance at a steel plant. The pressure was 65 mbar. The contractor overseeing this maintenance was taken to hospital for burns. The fire was brought under control by implementing the plant’s internal procedures: the facilities were cooled and protected using fire hoses, the coking plant’s gas-powered facilities (hot-rolling mill and external customers) were shut down, the coking gas recovery system was shut down and gas was diverted to the stacks, nitrogen was injected into the line to deplete the gas and extinguish the flame. The coke plant extractors were shut down at 7:00 p.m., the pressure in the line dropped to 3 mbar at 9:30 p.m. and the flame was extinguished at 10:00 p.m. 

The accident occurred whilst bolts were being replaced on a flange of the pipeline. The possibility of gas being present during this work had not been identified despite the fact that gas was indeed present nearby. Gas leaking out of a corroded nozzle located near the work area on the pipe was ignited by an electric torque screwdriver. The risks analysed prior to the work had not been properly identified, with the result being that unsuitable equipment was used.

Following the event, the operator supplemented the safe operating procedures to include systematic checking of the thickness of the metal sheet near jobsites and the implementation of preventive and/or protective means suited to each situation. The inspection authorities for classified facilities required the operator to provide information on the training levels of authors of its safe operating procedures. It also required the operator to provide the list of nozzles along with their uses and, where necessary, plan their removal.