Fatality inside chemical cargo tank

The chief officer on board a chemical tanker died after entering a cargo tank which contained hydrocarbon vapours and was deficient in oxygen. When the ship sailed at night after the cargo had been discharged, the two tanks (5P and 7S) that had carried hexene-1 were still inerted with nitrogen gas. As the tanks were to be loaded at the next port within two days, the crew began day/night tank cleaning operations soon after sailing. The chief mate was a non watchkeeper, so was able to direct the tank cleaning crew continuously. Early the next morning, during post-cleaning ventilation, the chief mate, who was preparing t o conduct pre-loading inspection of the empty tanks, was informed that a “petrol-like” odour was still coming from 5P tank. He had filled out the enclosed space entry checklists for the tanks he intended to enter that morning, but significantly, no enclosed space entry checklist was filled out for 5P tank.

Later that morning, when the master received an email from the ship's agent requesting pre - arrival information, he was unable to locate the chief mate. Eventually, his lifeless body was located slumped at the bottom of 5P tank. A rescue team donned BA sets and after carrying out tank entry checks, pulled out the officer and moved him to the upper deck. It was noted that the oxygen content of the atmosphere inside the tank varied between 12 per cent and 16 per cent.

Continuous resuscitation efforts were made until the arrival of a helicopter with shore medical personnel, who soon declared that the chief mate was dead. The next day, the vessel arrived at her destination and the chief mate's body was landed.

Root cause/contributory factors

1. Lack of compliance: the chief mate did not follow established industry standards and company specific safety procedures prior to tank entry and the checklist prepared for that day contained many improper entries;

2.The chief mate did not tell anyone that he was entering the tank;

3.An autopsy determined that the chief mate did not fall and that he died as a result of asphyxiation (oxygen deficiency) caused by inhaled hexene-1 vapours.

4.It is possible that, due to complacency or time related pressures, he may have mistakenly entered the wrong tank. In any case, despite his considerable tanker experience, competence and diligence, he inexplicably entered the tank without implementing common safety procedures.

Recommendations/corrective/preventative actions

The managers introduced/implemented the following measures:

1.Enclosed space drills to increase awareness of the danger associated with enclosed space entry and rescue;

2.A fleet advisory notice circulated regarding the accident;

3.Formal training for fleet superintendents, focusing on the permit to enter system at the checks they should carry out during their audits;

4.Enhanced warning signage at tank entrances, stating that the tank may be deficient in oxygen;

5.Development of a one-day training session on enclosed space entry for all officers and ratings joining the company's tankers.