Tragedy on a par with the disaster 11 years ago in which 167 people died was only averted because the cable hoisting a 10.5tonne liquid nitrogen tank snapped just 3cm from the ground.

The two companies involved in the incident were fined a total of �21,000 for breaches of health and safety regulations at Aberdeen Sheriff Court.

The tank was being lifted from a vessel

The court heard part of the lifting gear, known as a pennant, bore a certificate confirming it had been tested to carry loads of up to 15 tonnes. However, the tests had not been carried out.

Commenting on the case a spokesman for the Health and Safety Executive said in the worst case scenario the accident could have resulted in a massive hydrocarbon explosion.

The accident happened in January when a crane on the Britannia installation used the pennant to help lift the tank of liquid nitrogen from the supply vessel Oil Trader.

Procurator Fiscal Andrew Grant told Sheriff Alexander Jessop, said: "The pennant was hooked onto the crane and put into use.

"The tank cleared the deck by only 300mms before the pennant broke and the tank dropped back onto the deck of the vessel.

'Structural damage'

"It was lucky the pennant failed almost immediately. On both the supply vessel and the installation serious structural damage could have resulted.

"The consequences would have been disastrous for anyone in the immediate vicinity."

Mr Grant said that had the tank of liquid nitrogen ruptured it would have formed a cloud of poisonous gas which would have suffocated anyone nearby and have corroded any metal it came into contact with.

If it had fallen on the supply vessel it could have caused the boat to sink and put the lives of its 11-man crew at risk.

European Management and Marine Corporation Ltd was fined 16,000 when it admitted, under health and safety legislation, failing to ensure that the equipment it had made was safe to use.

Maximum penalty

And Aberdeen Certification and Lifting was given the maximum penalty of �5,000 under the Offshore Installations Act for entering information on a certificate when it knew no examination and testing had been carried out and knew that the information was false.

The Britannia installation was in the process of being commissioned at the time of the incident but there were 390 people aboard it and the accommodation platform to which it was linked.

Had the tank fallen on the Britannia once it was in production, HSE inspector Joe Boswell said: "The consequences could have been a major failure of processing and plant and a massive hydrocarbon release with explosion and fire."