201140 Explosion with fatalities during cargo tank cleaning

Edited from report from IMO FSI Sub-Committee 12th Sesion

On a product tanker on a short voyage between two busy ports, the crew started tank cleaning operations. They fitted a water-driven fan to ventilate the tank with plastic ducting extending to the lower portion of the tank. After completing the ventilation, two crew members entered the tank to remove oil cargo residues. There was an explosion which tore away bulkheads to adjoining tanks and ignited the aviation fuel and kerosene slops that were stored in them. The explosion breached the hull in these tanks and the engine room and the ship flooded rapidly, developed a starboard list and sank. The crew escaped by jumping into the sea. Out of a total of 16 crew, seven were rescued by passing ships. Three bodies were recovered from the sea, while a further six crew members are missing, presumed dead.

Probable cause/contributory factors
The source of ignition could not be identified. It was probably either a discharge of static electricity from the crew's winter clothing or from the plastic ventilation ducting, or a friction spark created when an ordinary metal can that was used to carry tools impacted with the tank's internal surfaces;
The crew was under pressure to complete the tank cleaning operation due to the short duration of the transit.

Lessons learnt
It is vital to ensure sufficient time for tank cleaning operations to minimise the possibility of missing steps or not paying adequate attention to the operation;
Crews are required to take training in tanker operations. That training must be continually reinforced onboard, and it is important to ensure that it is properly applied.