May 24 2007 Explosion

GexCon identifies the cause of the devastating 2007 tank explosion in Norway

The tanks that exploded in Sløvåg on 24 May 2007 transformed the industrial area at the far end of the Sognefjord into a war zone. GexCon was contacted to determine the cause of the explosion. "Sheet iron flew over my watchman's head," says Norvald Hauge, captain of M/T Karen Knudsen, which was docked in Sløvåg when the explosions occurred. The 26 people aboard Karen Knudsen had their guardian angels with them that day.

Vest Tank's facility is across the fjord from Mongstad, and is the largest independent tank facility in Norway. The explosion and subsequent fire caused damage to the facility amounting to NOK 20 million, while 10 people needed medical care, and a fire-fighter was sent  to hospital. "It is a miracle that no lives were lost," said Bergen's fire chief Helge Eidsnes, who led the rescue and extinguishing work after the accident.

On 24 May 2007, three waste tanks exploded in Sløvåg, Gulen municipality. GexCon's Øystein Larsen (from left), Ronan Abiven, Kees van Wingerden and Trygve Skjold were put on the case. The background photograph is taken by Lasse Fossedal, Norwegian Air Ambulance.

Searching for the cause of the explosion
The accident investigation began immediately after the fire was extinguished. GexCon has a total of 300 years of experience with fire and explosion safety. It was no surprise that the company was contacted when the police wanted to learn why the tanks in Sløvåg exploded. There were many questions: what type of material had exploded, and what was the ignition source? 

GexCon put a team on the job: Trygve Skjold, Kees van Wingerden, Ronan Abiven and Øystein Larsen. Their mandate was to find possible direct causes for the accident, and to assess plausible chains of events, including using simulations with the FLACS CFD code. Their job included drawing up a bibliography and a final report. The team was engaged by the Hordaland police district, the National Criminal Investigation Service and the Directorate for Civil Protection and Emergency Planning. 

At first the team visited the site, studied the literature, performed laboratory work, and reviewed the case documents. It was then time for analyses and assessment of different chains of event. In the meanwhile, the press kept a strong focus on the case. After the explosion, there were rumours that toxic gases had been emitted. There was great media coverage, with interviews of people who lived close to the tank facility in Sløvåg. Many people believed that they had become ill as a result of emissions of toxic substances after the explosion.

GexCon Managing Director Øystein Larsen presented the findings at a press conference at the Bergen police station on 31 October 2007:

"It probably started with a smoulder fire in the charcoal filter at the top of tank T3. The fire then ignited an explosive gas compound at the bottom of the filter, and the explosion then propagated back to the tank through a flexible pipe. Witnesses observed white smoke from the charcoal filter, indicating that the smoulder fire probably began between 06:00–08:00. The explosion in T3 occurred at about 10 in the morning on May 24, 2007."

FLACS & LNG Model Evaluation Protocol
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