Pollution
Humain
Environnement
Economique

Two successive fires broke out in an interval of few minutes in 4 cells (1 isolated + 3 successive) in the electrolysis room of a chlorine production plant. The technicians brought the fire under control using the fire-fighting equipment located nearby. The presence of hydrogen (H2) and a spark resulting from a short circuit was responsible for the two accidents. In the first case, the H2 leaked when a rubber-plastic pipe was manually disconnected from a H2 trap. The preceding operation that is subject to a procedure was performed when H2 quality was not good enough to be collected. During the 2nd fire, a sleeve pierced by corrosion was responsible for the H2 leak. Several causes were identified to explain the short circuit: defective or inappropriate insulators (their properties were not studied), absence of anode / cathode tightness, closeness of anode and the H2 flange following a modification of the H2 outlet and deviation in the alignment of cells. The analysis of the accident and the corrective actions retained were presented in the company CHSCT (committee on hygiene, safety and working conditions) before operations could resume. These included deciding on a better suited insulting material, improving process orifice to reduce the presence of chlorine in the hydrogen and avoid disconnection of the pipe from the trap, improving quality control and supervision by team leader, planing H2 flanges to space them out from the anode, communicating the lessons learnt from the accident to the staff, improving procedures and guidelines, taking stock of all insulation malfunctions of all cells, etc.