Gard Club informed about an incident where a manual cleaning operation in a cargo tank aboard a vessel resulted in the death of four seafarers.
According to Gard, in the incident the crew members were required to enter a cargo tank to squeegee the residual cargo towards the bell mouth during discharging. While the crew were able to carry out the necessary operation, the fatalities occurred as they were exiting the cargo tank.
Furthermore, the investigation by the port authorities revealed high levels of carbon monoxide when the cargo was continuously heated over a period of time. Carbon Monoxide is a by-product of incomplete combustion and can be emitted when certain cargoes are heated above their flow point.
In this incident, gas testing revealed that the CO content in the cargo tank top sides reached dangerous levels. This was not expected given that the MSDS of the cargo does not state any hazards of CO emissions due to heating.
Cargo tanks often contain residual gases and vapours that can be toxic or flammable. Without adequate ventilation, these gases can accumulate to dangerous levels, posing a risk of asphyxiation, poisoning, or explosion.
In this incident, the continuous heating of Coconut Fatty Acid Distillate resulted in the emission of a harmful level of Carbon Monoxide (CO), a colourless and odourless gas that can be lethal even at low concentrations.
Safety recommendations:
- The hazards of the unknown
Seemingly unharmful cargoes like vegetable oils are very likely to emit CO when heated. Always monitor CO concentration before and during tank entry, especially at the tank bottom.
- Enclosed space entry permits
Before entering any cargo tank, conduct a thorough risk assessment to identify potential hazards, including the presence of toxic gases at all levels. Ensure that all crew members are aware of the risks and are trained in safe entry procedures.
- Ensure proper ventilation
Always ensure that cargo tanks are adequately ventilated before entry and throughout the period of work activity in the space.
- Monitor cargo temperature
Regularly monitor the temperature of the cargo, especially when heating is required. Be aware of the flow point of the cargo and the potential for CO emissions when heated.
- Continuous monitoring
The atmosphere should be tested frequently whilst the space is occupied, and persons should be instructed to leave the space should there be any sign of deterioration in the conditions.
- Use personal protective equipment (PPE)
Ensure that all crew members entering cargo tanks are equipped with PPE, including gas detectors, respirators, and protective clothing.
- Implement emergency response plans
Develop and implement emergency response plans for incidents involving toxic gas exposure. In addition, ensure that all crew members are familiar with these plans and know how to respond in an emergency. Moreover, conduct regular drills to test the effectiveness of the emergency response plans and identify areas for improvement.
Gard points out that most investigations related to enclosed space entries reveal basic lapses in following safe procedures which are preventable.
This incident serves as a stark reminder of the risks associated with entering cargo tanks without proper ventilation and the potential for Carbon Monoxide emission from heated cargo.
