What happened at Port Silo, Stavanger?

In June 1970, an industrial dust explosion accident occurred at Port Silo, Norway’s largest built silo of its day. On the day of the incident the temperatures were hot and dry.

The main explosion lasted for around 25 to 30 seconds with secondary multiple explosions occurring every 10-second interval. Flame propagated quickly up to 1,500 metres through conveyor and bucket systems, ductwork and pipes, setting off explosions in six of the silos holding a total volume of 2000m3 of product.

The internal pressures of the silos vented through manhole covers, blowing the roof off one. Almost all of the windows in the office block were also blown out.

What caused the Port Silo explosion/fire?

Investigation into the incident could not confirm the source of the ignition, but a number of hypotheses were explored.

Firstly, it is possible that the product of dust deposits in the boot of the elevator self-ignited due to thermal organic heating.

Secondly, heated deposits within the bucket could have ignited via repeated impact from the buckets collecting and depositing products. This heated product could have eventually loosened and fell into the silo.