Cooling power loss in a foundry

This near miss occurred at metal smelting unit of a foundry.
At 9:45 a.m., due to a power outage, the cooling pumps of two furnaces containing nickel and chromium stopped. One of the two furnaces was at the end of the smelting cycle. The temperature of the metal was 1300°C.
Due to the stop of the cooling system, water from the public network took over the cooling function, but was not efficient, causing the cooling coil to overheat.
At this point, the risk was a contact between the molten metal and the water contained in the coil, which could have generated hydrogen, its ignition followed by an explosion.
Therefore, the operator triggered the evacuation alarm and alerted the firefighters.
The emergency services provide external cooling with water and perform natural ventilation followed by mechanical ventilation. After approximately two hours, the furnace cooled, the metal froze and the risk of explosion avoided. After additional two hours, the firefighters' intervention was over.

The initiating cause of the event was a malfunction in an electrical cabinet, which caused the shutdown of the 380 V power supply to the plant. Due to the lack of power, the cooling pumps of the melting furnace stopped.
The replacing flow of city water was insufficient to stabilise furnaces temperature because a valve was not fully open. Nobody verified the operation of this valve, because the attention of the personnel was focussed on the electrical failure.

metals furnace, colling coils

The near miss occurred following a power cut.

After the event, the operator adopted the following corrective measures:
• changed the water inlet valve so that its opening could be easily checked;
• revised its check lists in case of an incident;
• implemented training to improve responsiveness and targeted more frequently exercises;
• prioritised cooling above any other action in the event of an incident.