In a refinery, at around 3.35 a.m., an alarm in the control room informed the operators of a fire in the distilling unit. At around 4.00 a.m., the flames had reached a height of 50 m and had engulfed an area of 2,500 m². The fire was located in an area that contained crude oil feed pumps, distillate pumps, air coolers, an analyser shelter and associated piping. At 3.39 a.m., the unit’s emergency shutdown procedure was initiated from the control room. The feed line was shut down, the unit was isolated and the stationary protective resources in the zone were put into operation. Between 300 and 600 m³ of flammable substances were involved in the zone on fire. The internal fire-fighting resources were initiated at 3.44 a.m. to extinguish the fire and cool down certain installations in addition to the fixed installations at the site. The site’s internal operations plan (IOP) was initiated at 4 a.m. A safety perimeter was also established and the road leading to the site was blocked off. The fire brigade was called in to take atmospheric samples around the site (H2S, SO2, NO2 and VOC). At around 08.00 a.m.: the prefecture recommended that the local population and employees of neighbouring businesses remain indoors. The water used to fight the fire was directed to dedicated containment facilities on the site. Floating booms and absorbent socks were deployed in the location where the water was released into the canal. The fire was eventually brought under control slightly after 8.00 a.m. At around 10.25 a.m.: given the absence of detection by the atmospheric measurement system installed around the site, the confinement recommendations were lifted. At 11.30: main fire was extinguished.; however, a gas leak continued to burn at around 4:30 p.m. At around 6 p.m.: the last secondary fire was extinguished. Cooling continued overnight. The IOP was then deactivated at 2.25 p.m. the following day.

No injuries were reported on or off the site. A diffuse plume of smoke was visible and an odour of hydrocarbons could be smelt in neighbouring towns, up to a distance of 8km away. No soot was observed in the surrounding area. A light sheen was observed in the canal. Aqueous effluents were pumped and processed by the site’s installations. The distillation unit was partially destroyed over an area measuring 50 m x 50 m, and flaring episodes were required.

A petrol leak was discovered on a 3” diameter pressure testing pipe of a flowmeter on a hollow tubular support. The operator had visually noted corrosion on the support already 3 years earlier. Replacement of the support was planned to take place during the regulatory shut-down period in late 2019 but was not performed. As far as the fire is concerned, the ignition source was not precisely identified. Before the fire started, an alarm corresponding to the 20% lower explosive limit had been triggered 6 times, without the operators noticing. As some of the units had still been shut down, the alarms dedicated to the unit in operation were filtered. This filtering arrangement masked the display of the fire and gas alarms and only displayed those pertaining to the unit’s processes that had been restarted. The flashing light visible in the control room was considered a “process” alarm, knowing that such signals are not explicitly dedicated to fire and gas alarms.

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