At 12.30 pm, a fire broke out on a flange of the kerosene desulphurisation unit (KHF) of a refinery. Following activation of the Fluid Catalytic Cracking unit (FCC) at around 11.40 am following loss of the instrument air system (ARIA 32493), shutdown of the boilers related to the drop in production of 2 steam generators led to loss of the steam system, and subsequently the placing in slops of all of the desulphurisation units. When combined with the high level of liquid in the slop tank, simultaneously placing several units in slops generated high pressure in the corresponding system. The fluttering of the valves that ensued on the kerosene hydrofining unit (KHF) slops by-pass line caused vibrations and a leak on a flange joint upstream of the valves. At 12.30 pm, a fire broke out by spontaneous ignition on this leaking joint located approximately 17 m from the ground. The plant’s emergency resources (two trucks, four mobile guns and three monitor nozzles) contained the fire within approximately 50 minutes without having recourse to the external emergency services present on the site. The internal emergency plan was activated between 12.35 pm and 1.45 pm. The affected system was isolated and depressurised. Material damage and operating losses were estimated at 20,000 euros and 270,000 euros respectively. The cause analysis carried out by the operator for both events highlighted several organisational/human (following guidelines, guidelines for timing of placing in slops) and technical (design of the systems and equipment, reliability of the devices) anomalies.