Gas explosion in the cat cracking and gas plant units of a refinery

N° 3969 -  09/11/1992 -  FRANCE - 13 - CHATEAUNEUF-LES-MARTIGUES
C19.20 - Manufacture of refined petroleum products
Pollution
Humain
Environnement
Economique

An extremely violent explosion occurred at 5:20 am inside a refinery operating normally; this blast, felt up to 30 km away, was followed by several others.

The internal emergency plan was activated at 5:45 and rescue teams called to the scene. The “red plan” was implemented at 6:15; 250 firemen dispatched from neighbouring industrial sites, cities and department were mobilised. The fire re-ignited at 9:50 am and was finally brought under control at 1:30 pm.

A very heavy toll was announced: 6 deaths and 37 injured, including a refinery employee in serious condition and 2 firemen. The site was devastated over a 2-ha area and windows shattered in a 1-km radius outside the refinery boundary (with broken panes observed as far as 8 km away). No adverse environmental impacts were recorded: the extinction water was collected in 2 retention basins encompassing 33,000 m³, and floating booms were installed as a preventive measure.

A judicial investigation was carried out; its conclusions indicated a gas leak arising on an 8-inch gas plant pipeline (10-bar gas treatment tower, associated with the catalytic cracker). The cloud causing the explosion (UVCE-type) was determined to consist of 5 tonnes of a mix of various gases (butane, propane) and light naphtha. Due to a domino effect, the fractioning column in turn exploded (into a fireball) and 6 distinct fire sources could be observed, one of which was located on a tank 200 m away.

To bring the 5,000 m² of fire under control, 150 m³ of emulsifier were introduced. The unit’s control room was destroyed (and 3 technicians killed). A crane being used to build another unit collapsed.

Damages amounted to over €230 million. The refinery resumed activity in 1994.

9 years after the accident, the operator declared having invested €192 million, 25% of which targeted site safety upgrades: the control room replaced by a bunker-type structure, the number of gas detectors expanded, and the pipe inspection programme strengthened.

In a decision issued on 24 April 2002, the criminal court sentenced 7 employees or former employees (including 3 former executives) to suspended prison terms of 4 to 18 months and fines ranging between €1,500 and €4,500.

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