Two workers suffered minor injuries following the blast, which happened during the operation of the hydrochloric acid (HCl) burner in September 2013; one suffered a grazed knee from a breeze block dislodged from the wall of the control room and the other a minor caustic burn caused by a drip from the plant in the minutes following the explosion.
A newly installed HCl burner being used by Industrial Chemicals Limited had only been used a handful of times when the explosion occurred. The plant site had been under construction for several months and was undergoing commissioning. The explosion effectively destroyed a tank and displaced a scrubber column upwards and at an angle.
An investigation by the HSE, acting as part of the COMAH competent authority, found that in an attempt to the address risks from chlorine, the company routed the vent gas containing mostly hydrogen through to the plant emergency scrubber where it was able to come into contact with oxygen or chlorine. This explosive mixture found an ignition source and then exploded.
Industrial Chemicals Limited of West Thurrrock pleaded guilty to breaching Regulation 4 of the Control Of Major Accident Hazards Regulations 1999. They were fined £1.2 million and ordered to pay costs of £35,854.
Speaking after the hearing the HSE inspector said, “The investigation has shown that the potential for an explosive atmosphere had not been identified during the design, construction or commissioning of the plant. This incident could have been avoided if simple checks had been carried out. Duty holders should be aware that HSE will not hesitate to take appropriate enforcement action against those that fall below the require standard.”
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