The atmosphere was found to be 20.6% oxygen, with hydrocarbon at 26% LEL. The Master approved the risk assessment and work plan for two crew members to enter the space with emergency escape breathing devices. When they reached the tank bottom, the men felt dizzy; one exited but the other collapsed. Despite being warned not to, the Master entered the tank and was overcome. Although both men were brought out by crew wearing breathing apparatus, the Master could not be revived.

While discharging an oil cargo from a tanker, an oil sampler was lost to the bottom of tank 3P. It was decided that once the discharge was finished and crude oil washing completed, the sampler would be retrieved before loading the next cargo into 3P to avoid any potential damage to the ship’s equipment from the sample bucket or tape.

Once empty, the tank was ventilated. Over several days the tank atmosphere of tank 3P was measured using an explosimeter and sample hose. Although oxygen was near normal levels, HC was at 57% of LEL on day one of ventilation and 38% of LEL on day two. After discussion, it was agreed that entry into 3P tank would start the next morning (day three) if the gas levels were ‘less’.

The next morning, the tank atmosphere of 3P tank was found to be 20.6% oxygen, with HC at 26% of LEL. Tank entry equipment was prepared and placed near the tank access hatch; breathing apparatus (BA) sets, emergency escape breathing devices (EEBDs), stretcher and heaving lines. The Master was shown the risk assessment and work permit for enclosed space entry and although the HC LEL was indicated at 26% he stated that the oxygen content was good. It was decided that two crew should go in, each wearing an EEBD.

Two crew members entered the cargo oil tank via the tank access hatch each with an EEBD worn over the shoulder, a torch and a personal gas meter. Several other crew members and the Master were in attendance at the tank access hatch. The lead crew member proceeded down to the first platform and checked the atmosphere across the platform with his gas meter. The second crew member then proceeded down the stairs to meet him.

This was repeated for the remaining platforms until they reached the tank bottom almost 20 metres below the main deck. The lead crew member then reported feeling dizzy and heard his personal gas meter alarming. The second crew member reached the tank bottom and instantly felt the effects of the gas inhalation; he also heard his personal gas meter alarming. The lead crew member shouted and gestured to the second to wear his EEBD and leave the tank. The lead crew member felt dizzy and immediately proceeded to exit the tank. The second attempted to don his EEBD and activate it but collapsed soon afterward. Meanwhile, on deck, the Master entered the tank with an EEBD worn over his shoulder.

Although another crew member warned the Master not to enter the tank the Master nonetheless proceeded into the tank. Two crew members on deck donned the BA sets already available at the entrance.

Source: Mars Reports/ Nautical Institute