In a chemical plant, subcontractors had been dismantling a styrene storage tank for 1 week when a fire broke out at 4:50 p.m. The fire spread to all of the polymerised styrene in the tank, releasing thick black smoke visible from around the site. A crisis unit was set up immediately. The internal fire brigade, present during the dismantling operations, set up a water hose. The 40 men from the emergency services, alerted by the operator, were able to bring the fire under control in 40 minutes after having deployed a layer of foam. The site manager spoke with journalists in front of the site to explain the intervention. The alarm was lifted at 6:25 p.m. and the 500 m³ of extinguishing water was directed to an emergency collection basin, then conveyed to the site’s treatment facility.
Product involved: styrene is an aromatic organic compound (C8H8). It is colourless, oily, toxic and flammable and used in the production of synthetic plastics and rubbers. The storage conditions in the tanks (temperature, inhibitor) must prevent its highly exothermic polymerisation with an increase in pressure. Here, the tank had to be dismantled because it had become unusable due to the polymerisation of a large quantity of styrene on its dome.
The analysis of the accident indicated that the subcontractor was cutting the last shell of the tank to discharge the water remaining in the bottom. The intervention authorisation and the fire permit were not respected as a cutting torch was used instead of the hydraulic shear/clamp stipulated in the works document. A thin layer of polymerised styrene on the wall of the tank ignited upon contact with the cutting torch, all the more easily since it was in summer.
Non-compliance on several levels: an organisational change within the subcontractor’s crew. The subcontractor had several tools in his truck, some of which were not adapted to the risks inherent in this type of dismantling operation. The operator’s fire permit did not specify that the use of tools generating hotspots, flames or sparks was prohibited.
The operator increased the awareness of the personnel and the subcontractor regarding the risks of organic waste and the importance of using the appropriate tools. The prohibited tools are quarantined. From an organisational point of view, each internal firefighter in charge of monitoring job sites must now also sign the fire permits.
