Gas release at the Bulk Terminals complex, Chicago, Illinois. April 26, 1974

 
Accident summary

Bulk Terminals was a storage tank farm with 78 tanks ranging in size up to 4900 m³. At about 12:30 hours on Friday 26 April 1974 a dull thud was heard and fumes were seen rising from the bund surrounding a 3300 m³ tank of silicon tetrachloride. It was discovered that a pressure relief valve on a 6-inch line leading to the tank had been inadvertently closed. The pressure in the system was sufficient to burst a flexible coupling in the line, shifting the piping system and cracking a 3-inch line on the tank wall. Liquid silicon tetrachloride escaped forming an irritant cloud containing hydrogen chloride gas.

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