Fatal Welwyn Garden City gas blast costs firms £685,000

Argonite store after the explosion (Image: Archant)

Plumber Adam Johnston died and six other workers were seriously injured by a barrage of flying gas cylinders, which were said to have been “like torpedoes” at Mundells in 2008.

Argonite store before the blast, showing protective cylinder caps removed (Image: Archant)

Mr Johnston, 38, from Sutton, Surrey, was struck by one of 66 heavy cylinders as they rocketed at speeds of up to 170 mph after one toppled over, discharged high-pressure gas, collided with others and set off a “terrifying” chain reaction.

An adjacent corridor showing cylinder above corridor in cable tray after the blast (Image: Archant)

Mr Johnston, who was working on a construction project at the site, was walking with a colleague when he was struck by one of the argonite gas cylinders as they were propelled around the building.

Emergency services at the Mundells explosion site (Image: Archant)

He suffered multiple injuries and died at the scene.

Workers gather outside the Mundells explosion site (Image: Archant)

Several other workers, including electricians working in the argonite store room, suffered injuries and long term effects including recurring nightmares resulting from the trauma of what happened on November 5, 2008.

In a prosecution brought by the Health and Safety Executive, St Albans Crown Court heard on Friday, that 80 cylinders, nearly two metres high and each weighing 142kg, were stored without their safety caps and left without being properly secured in racks.

Crown House Technologies Ltd pleaded guilty at an earlier hearing and was fined £117,000 and ordered to pay costs of £119,393.65

The two Kidde companies (Kidde Fire Protection Ltd and Kidde Products) also pleaded guilty at an earlier hearing and were fined a total of £330,000 plus costs of £119,393.66.

Judge Stephen Gullick said the firms had “failed to have sufficient regard for the safety of all employees on the site”.

And he described the events that led to the explosion as “a domino effect”.

The judge did not read out a witness impact statement by widow Michelle Johnston, but said he could feel her “pain and raw emotion” from the eight-page submission.

After the case, HSE principal inspector Norman Macritchie, said: “Mr Johnston had no control over the chain of events which led to his tragic death. He died while going about his business as a result of the shortcomings of others.

“It is only by chance that this incident did not cause further fatalities.”

In mitigation the Kidde companies’ barrister Oliver Campbell pointed to their early guilty plea and said the firms had no previous convictions and a good accident record.

He also said “steps have been taken to learn lessons”, in the wake of the fatal explosion.

And Prashant Popat, for Crown House Technologies, said the firm had instigated a remedial programme and ‘mission zero policy’ to eliminate all accidents by 2020.