The HSE reported that in the January 2002 accident, a mobile crane was lifting a concrete beam into place in a new multi-storey car park. Sam Ball, an employee of UK Erection, working on the expansion of Merck Sharpe and Dohme’s UK headquarters in Broxbourne, Hertfordshire, was approaching a grab line attached to the lifting frame when he was struck by the falling beam.

The pin was purchased by a UK importer direct from a ‘reputable’ South African-based supplier, the HSE said. Forensic tests carried out by the Health and Safety Laboratory revealed that the pin had broken because of ‘low temperature temper embrittlement’, associated with tempering the pin between 225°C-250°C (437°F-482°F).

The South African supplier, whose manufacturing process deficiencies were the “fundamental cause” of the accident, was found to have gone out of business. As a result, the HSE determined that legal proceedings would not be possible.

Although the lifting frame had been inspected by a competent person, the equipment’s design made it impossible to see and examine the pin without dismantling the equipment. This was not done in the examination before the accident.

“HSE experts advised that whilst it may be desirable to dismantle the link during thorough examination, the examination process could not normally be expected to include dismantling unless the link (containing the pin) was visually defective,” the HSE said. “The pin failed because it had received heat treatment at an inappropriate temperature and this would not have necessarily been apparent during a routine thorough examination.”

“There is one point that arises from this investigation, which needs to be considered by others. Where components of lifting tackle are not visible, the competent person undertaking the routine examination should give careful consideration to the circumstances in which such components should be removed for examination or routinely replaced. The suppliers and manufacturers should provide information on this subject to their customers.”