Calor Gas has been fined for safety failings after two workers suffered severe burns when they were caught in a flashover explosion triggered by a gas leak near Bristol.

Kevin Bates, from Oxfordshire, and Graham Crouch, from Hampshire, were inspecting LPG gas tanks at Stancombe Quarry when the explosion occurred in June 2010.

Crouch suffered 22% burns to his hands, face and chest and was hospitalised for nine weeks. Bates suffered lesser burns to his face and hands, but also required emergency treatment.

Calor Gas, who employed Crouch and contracted Bates for the job, appeared before North Somerset Magistrates on 21 March in proceedings brought by the Health & Safety Executive (HSE), which investigated the explosion.

The court heard the men were carrying out a routine inspection of a large industrial gas tank at the quarry.

As part of the job, they used specialised equipment on the back of a converted lorry to remove residual gas from the tank. The gas was piped into a slops tank on the back of the vehicle and a pressure relief valve was fitted to allow excess gas to escape harmlessly into the atmosphere.

However, the men had not fully removed a tarpaulin that covered the valve, which allowed gas to build-up under the cover on the back of the truck.

Bates and Crouch were in a special cab attached to the back of the truck when they heard a whistling noise. As they exited the cab to inspect what was happening, the gas ignited and they were caught in the explosion.

Calor Gas Ltd, was fined a total of £30,000 and ordered to pay £105,983 in costs after pleading guilty to breaching Sections 2(1) and 3(1) of the Health and Safety at Work Act 1974.

HSE Inspector Ian Whittles said: "This was a very serious incident that could easily have resulted in both Mr Crouch and Mr Bates being killed. In the event, they suffered severe burns and a great deal of pain, which could have been avoided.

"Calor Gas' instructions about use of the tarpaulin were not clear or adequate and they should have provided more detailed training for their staff. Gas pressure relief valves must never be covered when they might be operating. Any build-up of gas, such as LPG, is potentially lethal."

Bates has made a civil claim which is in the process of being settled by Calor and Crouch has already been rehabilitated back into full-time work with the company.

“Everyone at Calor deeply regrets the serious injuries sustained as a result of the incident at Stancombe Quarry, Flax Bourton in 2010. Calor is fully committed to the health, safety and welfare of all our staff, contractors, customers and the general public,” said Stephen Rennie, managing director of Calor Gas Ltd.

“Calor has co-operated fully with the authorities throughout their investigation and entered guilty pleas at the earliest opportunity. Calor has undertaken to amend existing operating procedures and redesign the unit with a view to avoid any future incidents of this kind. All of this is being done with the involvement of the HSE.”

Further information on safety in the LPG industry can be found on the HSE website.