Dieter Ackermann, Thomas Lange
Serious miscalculation – Fire in a refinery
At a refinery to the north of Casablanca, Morocco, a petroleum tank burnt out in a fire that lasted over 30 hours.
The blaze consumed the 7,000 m3 of fuel contained in the tank and destroyed the tank itself. The loss amount of €1.75m is carried by the fire insurer.
On the evening of 18 September 2003, a tank containing 7,000 m3 of unleaded super caught fire at Morocco’s largest refinery to the north of Casablanca. The tank was not only used to store refinery products but also served as a vessel in which additives were mixed in with the fuel to improve engines’ anti-knock performance.
A batch process is used in the refinery for this purpose. In contrast to the inline process, in which an additive is continuously fed into the product stream, which is mixed by the turbulent current, the batch process involves feeding the additives, consisting of reformat, naphtha, and butane, at one and the same time. Subsequent stirring mixes them with the crude petroleum.
The fire
The fire in the tank was first noticed by the shift foreman. Using his walkie-talkie, he immediately ordered that the pumps be switched off and the connected lines closed. Just as he was informing the works fire brigade, a guard sounded the alarm. The guard was putting the equipment and materials stored near the fuel tank in a safe place for the night. He suffered second-degree burns to his hands and face.
A few minutes after the alarm was given, the works fire brigade arrived on the scene with three fire companies. Fire-brigade units from Mohammedia and Casablanca as well as from the country’s second largest refinery at Sidi Kacem supported the local fire brigade. Altogether 56 fire brigade units were in action. In the meantime, the fire had spread over the entire tank.
Grass and bushes in the surrounding area were burnt by the radiant heat that usually develops in this sort of tank fire. The flames threatened to spread to the lubricating oil tanks on the other side of the road. An air compressor used for sandblasting the product pipes caught fire, as did diesel and paint canisters. These smaller fires were extinguished without delay using portable fire extinguishers.
The fire teams used water curtains to protect the fuel tanks in the surrounding area from the extreme heat. As a precaution, propane gas tanks standing near the seat of the fire were also cooled using the same method. These measures were so successful that the fire was restricted to the one tank.
The fire-fighting operations
The fire-fighting operations focused on the blazing fuel tank. The tank was cooled on the outside with water and at the same time an attempt was made to smother the fire inside the tank with foam. The fire brigade connected foam production systems to the pipes intended to supply the fuel tank with extinguishing agent. It turned out that not enough foam was produced to bring the fire in the tank under control. The firefighters made three further attempts to extinguish the fire within the next 24 hours, but each time they thought they had overcome the fire, the flames flared up again seconds later.
It was not until the early morning of 20 September that the fire brigade commander gave the all-clear. After more than 30 hours the fire was extinguished as the contents of the tank had been completely consumed. All the supply and discharge lines were disconnected from the tank and sealed with blind flanges. Two fire companies stayed on the scene for a few days to make sure that there was no longer any danger.
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