Health and safety

MAIB highlights dangers of working in RSW tanks after fatal enclosed space accident

25 October 2018

An investigation into the death of a second engineer after a suspected gas leak in a refrigerated salt water (RSW) tank on board a trawler, has highlighted the dangers of working in poorly ventilated enclosed spaces and the pressing need for improved safety measures and training.

The UK Marine Accident Investigation Branch (MAIB) report recommended that all of a crew's 'work activities should be subject to risk assessment' and that 'safe systems of work should be put in place'.

The report also said that safety procedures for entering and working in enclosed spaces should be 'robust and understood' by the crew, as should rescue plans in the event of an accident.

The report looked into the fatality on board the fishing vessel Sunbeam in the Scottish port of Fraserburgh on 14 August while it was being prepared for a planned refit.

The second engineer died after he was found unconscious in one of the vessel’s nine RSWs. Crew members who initially went to rescue their colleague became dizzy and short of breath. They recovered after being rescued by two other crew members in breathing apparatus.

The report said that tests of the atmosphere in the RSW tank after the accident showed that the level of oxygen at the bottom was less than 6%, when the normal level should be 20.9%.

Further tests revealed the presence of Freon R22, the refrigerant gas used in the RSW tank's refrigeration plant, which looked 'likely' to have leaked into the tank. The gas is four times heavier than air, toxic, tasteless and mostly odourless. If deeply inhaled, it can cut off oxygen to blood cells and lungs.

The MAIB recommended added safety controls for working in enclosed spaces such as atmosphere testing, provision of positive ventilation and a safety sentry at entry points, as well as breathing apparatus and safety harnesses for rescue teams.

'It is also the responsibility of crew members to behave in a safe manner', particularly 'when working alone', the report said.