Pressure test using air instead of water causes horrific injury

Filtration Service Engineering Ltd, a Worcestershire engineering firm has been fined £45,325 (inc. costs) on 20 February 2014 after a worker lost both his legs in a factory blast.

The circumstances were:

• On 8 December 2011 the company was testing a 335-litre vessel as there were concerns about the quality of the welding. 
• However, instead of simply filling it with water (which has low stored energy) , the firm decided to use compressed air (which has high stored energy).
• The factory’s compressed air supply was directly connected to one of the vessel’s openings. 
• A valve, which could be manually opened and closed, and a pressure gauge were installed, and the vessel filled with compressed air. 
• The pressure built up to such an extent that eventually the vessel exploded.
• Clive Dainty was hit by part of the vessel, forcing him into a cabinet against a wall.
• He was hospitalised for several months and had to have both legs amputated. He also suffered head injuries and has severely restricted movement in his arms, which have been repaired with metal plates.
• The force of the blast also threw a fire extinguisher through a nearby wooden staircase.

The HSE inspector said:

“The injuries sustained in this incident were more akin to those sustained on a battlefield. The vessel exploded like a bomb during the course of a normal working day, and everyone in the factory was at risk from the operation because no measures were put in place to protect them. Pneumatic testing is a dangerous activity and significant planning is required to ensure the risks are managed. The management of health and safety in this factory was woefully inadequate and simple measures could have been implemented to prevent the incident from happening. An assessment of the risks involved in pneumatic pressure testing should have identified that air was not a suitable testing medium. The test could have been carried out by simply filling the vessel with water. It is a miracle that more people were not injured and that nobody lost their life.”