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Metallco explosion 2017 (Photo: B. Lunde, NRK).

CEO, Chairman of the Board, and Company convicted after explosion

In 2017 two workers lost their lives in an explosion caused by water containing metal dropped into molten aluminium. In a district court verdict in Gjøvik Tingrett last week, the CEO was sentenced to 10 months in prison, while both the Chairman of the Board and the company were fined. The CEO was found guilty of violating the Working Environment’s Act, specifically for not ensuring a safe workplace. According to the verdict, the firm’s work practices were unsafe and risk assessments related to the melting of scrap aluminium were deficient. In addition, the firm had failed in documenting routines for the hazardous work processes and in providing adequate training of employees.

HYEX Safety strives to help our customers understand hazards and risks. In several fields we have developed advanced modelling approaches related to explosion physics. A volume of water trapped inside molten metal can expand 5-10,000 times generating damaging blast waves and dangerous projectiles. From literature we are not aware of any detailed 3D modelling approach for blast and projectiles from water explosions in molten metal, only simplified TNT-equivalence approaches. At the 2019 Loss Prevention Symposium June 2019, Olav R. Hansen presented an article (co-authored by Ane Kristiansen) describing a 3D CFD modelling approach to predict blast waves and projectiles for water explosions from molten metal furnaces. The study was motivated by incidents like the aluminium furnace accident mentioned above (and that case is mentioned in the article’s introduction). The case study presented in the article is a risk assessment for a copper melting facility where the owners wanted to properly understand the potential risks to workers and building. While the detailed physics is challenging, parametric studies helped find a consistent way of defining a blast source for the explosions. This way the scenarios could be assessed with reasonable accuracy, e.g. to understand how much water can be dropped into a furnace before severe damage to the building and risk to workers would be feared, and also, to quantify the effect of a metal hood around the furnace limiting the explosion consequences. The increased understanding will hopefully help them take proper measures to prevent dangerous accidents.

The recent verdict underscores corporate management’s responsibility for a safe workplace and highlights board members’ risk of personal liability in case there is insufficient corporate dedication to understand and minimise explosion risk. Nevertheless, in view of the fate of the two workers that lost their lives the verdict may well be considered mild.

Link to article

Maximum blast pattern onto surfaces from explosion of 0.6 kg water trapped in molten copper with protective metal hood above furnace.