An explosion occurred on Sunday at around 5:00 p.m. in a water-filled pit while two bars of a copper and zinc alloy were being parallel cast on the vertical semi-continuous line of a bronze foundry. Three workers were seriously injured by the steam, molten metal and metal parts of the facility projected by the blast and were taken to hospital. In the bars fabrication process, molten metal flows from a spout and into two moulds at the same time. The moulds are cooled with water to solidify the skin of the bars. The bars are immersed in a water-filled casting pit to accelerate the cooling of their core temperature. The firefighters extinguished the beginnings of several graphite-dust fires in the workshop. After using a thermographic camera to check for remaining hot spots, they left at around 8:15 p.m. The premises were nevertheless monitored over night. The damaged facility was repaired and re-opened one week later.

Piercing of the skin of one of the bars following insufficient solidification caused the water in the pit to come into contact with the molten metal and vaporise violently. Typically, three casting operators are required for this job (one per bar to regulate the flow rate in the cooling mould and one to open the casting spout). On the day of the accident, the spout operator temporarily left to check the melting furnaces. The other operators probably were required to resupply one of the moulds (the needle valve controlling the flow rate of the metal was completely open for one mould and closed for the other). This resulted in a short cooling time and the formation of an insufficient layer of skin on the bar.

The site operator plans to implement new technical and organisational procedures for casting operations. These include fitting out and securing certain type of work-station equipment, redefining some casting parameters, creating a start-up checklist and a fitting system to measure the temperature of bars upon exiting the ingot mould, reducing the number of castings involving the use of water-filled pits and revising casting-industry procedures. It also plans to look into laying out the work station so that operators are at the appropriate safety distance. It will also bring in an outside body to check the facility’s technical equipment and whether they meet labour-code requirements. The inspection authorities for classified facilities reminded the operator of its obligations regarding the reporting of accidents.