In an alkene manufacturing unit at a refinery, a separator exploded, causing the release of ethane, ethylene, methane and hydrogen, at the time of restarting the deep freeze installation. Other pressurised containers, pipelines, process command and control instruments and metal structures were all damaged. The emergency shutdown system was activated, and the air conditioning device at the recording station was depressurized, drained, disconnected, cleaned and drained once again. Total property damage was estimated at 3 million marks (i.e. €1.5 million).

The explosion resulted from an internal crack (1,600 mm) of the equipment along the weld seam (the base metal was ferritic, while the weld was made using austenitic metal). The corrosion induced by hydrogen also stemmed from start/stop cycles imposed by the production routine. Moreover, a maintenance deficiency could have been the cause as well.