At a flammable liquids depot, fire broke out in an empty home heating oil tank, which had been degassed and cleaned in preparation of its 10-year hydraulic test. Three maintenance subcontractors were performing welding to repair the lifting device on this tank’s internal screen (a hot work permit had been issued) when they noticed thick black smoke. They immediately left their post to sound the alarm. The director activated the internal emergency plan, ordered employees to evacuate the depot and moved a cistern being unloaded onto an adjacent tank. The first response vehicle arrived 18 min after the fire was detected: other vehicles (3 lorries and 2 cars) joined them less than 15 min later. The accident quickly extinguished by itself given the lack of fuel, even without fire-fighter assistance. Less than 1 hour after detection, fire-fighters entered into the tank equipped with a thermal camera: an incandescent 80-cm-in-diameter surface was identified, along with the absence of any product inside. The consequences of this blaze were very limited.

According to the depot operator’s initial conclusions, a rubber part falling onto the internal screen could have ignited following welding work. Upon analysis, the operator decided to upgrade the site’s prevention and protection resources by: installing a spark cover; assigning 1 or 2 employees equipped with hoses or water cannons to quickly intervene during workss involving tanks; and improving the quality of preliminary risk analyses.