The extent of the loss

The fire destroyed the fuel tank completely. Owing to the extreme heat that built up, the tank wall collapsed inwards and the tank crashed to the ground. The external fire protection, consisting of a ring line and a distributor for the extinguishing agent, was completely inoperable.

Suspected causes of the fire

On the day of the fire, the process engineer established the composition of additives needed to produce the required product quality (octane number) of the fuel. In the late afternoon, the primary control unit turned on the pumps that feed the specified volume of butane from the spherical gas container into the fuel tank. When the process engineer’s calculation was examined, it was found that he had requested almost three times the necessary volume of butane.

The solubility of the butane in the crude petroleum was not high enough for the additional amount to be absorbed as well. A bubble of gas must therefore have formed beneath the floating roof of the tank. The butane, which is heavier than air, must have escaped through the seal of the floating roof and ran down the tank wall to the surrounding area. Although it remains fluid given a slight positive pressure, it easily evaporates at atmospheric pressure, and forms an explosive gas mixture on contact with the air.

This meant that two components of the fire triangle were present: combustible gas and atmospheric oxygen. This bubble of explosive gases pervaded the air near the ground in the area around the tank until it reached an ignition source.

As to the third component – ignition source – several possibilities were examined and the following hypotheses may be considered:

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  It is possible that the floating roof of the tank suddenly dropped because of a very rapid release of gas. When the roof made contact with the tank’s metal inner wall, a spark was generated which then ignited the gas.
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  It is also conceivable that, although smoking was prohibited, the watchman was having a cigarette or that he was cooking himself something for supper on a little stove, which was also forbidden.

The watchman denies having violated any of the safety regulations at the refinery. The cause of the fire was not identified.

The loss is covered by fire insurance regardless of the cause. Under the terms of the policy, the policyholder was entitled to reimbursement of the following costs:

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  Removal of the destroyed fuel tank and cleaning of the premises
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  Delivery and assembly of a replacement tank (replacement value)
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  Indemnification for the burnt fuel
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  Fire brigade costs

The loss for the fire insurer is put at €1.75m.

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