A petrol distillates spill and subsequent pool fire occurred at 3 pm. in a refinery during maintenance works. The accident occurred on a 750 mm diameter elevated flare line around which a scaffold platform had been erected to assist in the removal of a gate valve. The ambient temperature was near freezing and this allowed significant liquid to condense out in the flare pipelines. The flare line in the vicinity of the valve was supposed isolated from other working parts of the flare system, drained and tested.

Four workers were involved with the removal of the valve. When the majority of the bolts were undone, the joint opened slightly and liquid dripped from a small gap between the flanges. The workers sought advice. The valve was checked and it was concluded that it was safe to carry on. Non ferrous hammers were provided before continuing with the removal. All the bolts were removed and the crane took the weight of a spacer and started to remove it, at which point gallons of liquid poured from the valve. A flammable vapour cloud formed from the rapidly spreading pool. The cloud reached the nearby air compressor (used to supply air for the breathing apparatuses of the maintenance crew), ignited and flashed back around the working area.

Two workers managed to escape the fire but a fitter and a rigger were engulfed by the flames and killed. The fire was allowed to burn in a controlled manner for almost two days while the rest of the refinery was shut down and the flare system purged with nitrogen. The costs of the material damages (pipelines, electrical cables/equipments, crane, breathing air compressor etc.) has been estimated at 0.28 M euros.

The investigation into the accident revealed a number of technical and organisational failures. After the accident, the following measures were established:

• any work on the refinery flare system will have to be authorised at senior management level. Work methods and safety precautions must be detailed in writing and agreed by representatives from a number of refinery departments who in turn will closely monitor work as it progresses;
• each valve should have an indication of its position and at the base of critical isolation valves have been added orifices to which steam can be injected to dissolve blockages;
• the performance of flare drainage will be verified;
• the lines will be purged with inert nitrogen gas to clear residual flammable gases and to prevent air from reaching any pyrophoric scale inside the pipes;
• the flanges will be moved apart gradually with bolts still in position until the contents of the line can be positively identified;
• trays will be used under the flanges as they are moved apart to collect liquids in a safe way;
• diesel-engine operated compressors will be avoided nearby; at locations to which the refinery air system does not extend, mobile air storage tanks should be provided for breathing apparatuses.
• alternative escape routes from scaffold platforms or any work area must always be available;
• provide a refinery fire tender on stand-by at the work scene.

This accident will be followed by 2 others within a 3-month period, respectively on the 22/03 (ARIA 6189) and 11/06.