Court hears explosion was result of gas leak

Separated joint was to blame for blast, experts concluded

An explosion that completely destroyed an elderly couple’s bungalow came from a gas leak from a pipe leading to a recently-fitted central heating boiler, a court heard yesterday.

The boiler, installed by plumber Craig Hall, was found in the ruins of Marion and Robin Cunningham’s home after the 2013 blast in Callander, Perthshire, Stirling Sheriff Court was told.

Explosions expert Steven Critchlow said he found the gable wall of the utility room where the boiler was situated had been “moved outwards by a metre” by the force of the explosion, and the boiler had fallen to the floor.

He said water pipes leading to the boiler were damaged and bent but still connected, while the gas supply pipe was separated but still straight.

Mr Critchlow, 44, the Health and Safety Executive’s specialist gas incidents investigator, said the difference between the state of the water pipes and the gas supply pipe in the aftermath of the blast was “an obvious and interesting contrast”.

He said: “The only scenario by which I can imagine that the gas pipe remained in that position was that it was separated from the boiler before the wall moved with the force of the explosion.”

Mr Critchlow concluded that the leak source that led to the explosion was the separated joint under the boiler.

Prosecutor Shona McJannett asked: “In your experience, do gas pipes that have been fitted properly normally separate in this manner?”

He replied: “No.

“It was my opinion, from looking at the pipe on site, that it had never been soldered.

“When I went back to our laboratory I asked our metallurgists to examine the pipe, and they reinforced that opinion.”

Principal metallurgist at the Health and Safety Executive William Geary said he examined the vertical pipe and an associated 15mm elbow piece.

Dr Geary said the fitting “had clearly not been fully soldered”, adding: “It was clear that although some heat had been applied, it wasn’t sufficient to melt the solder and form a joint.”

Hall, 35, of Tullibody, Clackmannanshire, is accused of failing to ensure that the gas supply pipe was adequately joined and properly supported when he fitted the new boiler at Mr and Mrs Cunningham’s home in Murdiston Avenue, Callander, on August 2 2012.

As a consequence, it is alleged, the supply pipe to the equipment separated from an inlet pipe, allowing gas to escape – and on March 28 the next year (2013) to ignite, resulting in an explosion that caused extensive damage to the Cunninghams’ home and injuries to them both.

Hall denies causing the blast by carrying out the installation of the boiler dangerously and otherwise than in accordance with appropriate standards, contrary to the Gas Safety (Installations and Use) Regulations 1988.

He also denies an alternative charge, under the Health and Safety at Work Act, of failing to take reasonable care for Mr and Mrs Cunningham’s safety as a result of his “acts or omissions”.

The trial, before Sheriff William Gilchrist, continues.

The only scenario by which I can imagine that the gas pipe remained in that position was that itwas separated from the boiler before the wall moved with the force of the explosion. STEVEN CRITCHLOW EXPLOSIONS EXPERT

Marion and Robin Cunningham’s home was ripped apart by the blast.