Pressure in blocked vent causes explosion destroying boiler house… A UK dairy company has been prosecuted as a result of an explosion at one of its cheese factories in Cumbria.
The boiler house at the Aspatria Creamery bore the brunt of the explosion on 29 July 2010 and was almost completely destroyed as debris was thrown more than 100 metres across the site. As it turned out there were no injuries caused by the explosion despite the fact that it was of such force that it lifted the roof off the boiler building and blew out two of the walls on the ground floor.
However despite the fact that there were no fatalities, the dairy company was prosecuted by the Health and Safety Executive after an investigation revealed that a blocked vent on a calorifier water heating system had led to the accident.
Carlisle Magistrates’ Court heard that this vent had the capacity to hold up to 9000 litres of water and was typically used to generate hot water for washing down the dairy machinery and equipment. The court was also told that engineers at the site had been manually controlling the supply from the calorifier in recent times after an automatic control system had malfunctioned.
The HSE investigation revealed that the vent which should have been used to allow water to escape when it went above a certain temperature, had gradually become more and more blocked with calcium carbonate until it was almost impossible for the water to escape. This meant that the pressure inside the tank continued to rise and rise to unstable temperatures that would eventually cause the explosion.
The dairy company pleaded guilty to a breach of the Pressure Systems Safety Regulations 2000 by failing to ensure the vent pipe on the calorifier was functioning correctly. The company was fined £20,000 and ordered to pay £36,064 in prosecution costs.
HSE Inspector Michael Griffiths spoke after the hearing:
“The tank could not cope with the increase in pressure when the temperature of the water reached almost 150 degree Celsius.
“I hope this prosecution will act as a warning to any other company that uses hot water and steam systems to make sure they are properly maintained so that incidents like this don’t happen in the future.”