Following recent tragic incidents involving coconut oil and its derivatives, NorthStandard P&I Club draws attention to a critical but often underestimated risk in the maritime industry: toxic gas generation in cargo tanks carrying vegetable oils.
As explained by Manish Nayyar, Senior Loss Prevention Executive at NorthStandard, contrary to common perception, vegetable oils—particularly coconut oil and its derivatives, pose significant atmospheric hazards in enclosed spaces. Understanding these risks are crucial for safe operations. In particular:
- Carbon Monoxide (CO) Generation: CCNO contains higher levels of impurities and has lower stability compared to refined products. When heated or agitated, it can release carbon monoxide—a colorless, odorless, and deadly gas.
- Volatile Organic Compounds (VOCs): CFAD contains medium-chain fatty acids (capric acid C10, lauric acid C12) that vaporize when heated or agitated, creating flammable atmospheres and displacing oxygen.
- Oxygen Displacement: Vaporization and chemical reactions can rapidly deplete oxygen levels, creating asphyxiation hazards—even when initial readings appear safe.
- Dynamic Atmospheric Changes: Safe pre-entry readings do not guarantee continued safety. Cargo movement (circulation, heating, stripping) can release trapped gases, transforming a “safe” atmosphere into a lethal one.
Key safety measures
#1. Absolute prohibition
NO cargo movement (circulation, stripping, heating, or line clearing) shall occur while personnel are inside cargo tanks—unless specifically authorized by a dedicated, documented risk assessment with stringent controls. This is the single most important rule.
- Enhanced atmospheric testing
Before entry:
- Conduct multi-point testing (top, middle, bottom of tank)
- Test from multiple access points (manholes, butterworth openings)
- Allow adequate ventilation time (minimum 4 hours for vegetable oils)
- Verify oxygen levels ≥ 20.9% and toxic gases at 0 ppm
During entry:
- Maintain continuous atmospheric monitoring
- Use extended sampling tubes to check multiple levels
- Set alarm thresholds conservatively (O₂ < 20.5%, CO > 25 ppm)
- Monitor at minimally 15-minute intervals
- Ventilation requirements
For large cargo tanks carrying coconut oil products, multiple ventilation points (not single portable blower) must be used. Calculate air exchange based on tank volume and maintain positive ventilation throughout the entry period. Consider tank configuration and potential dead spaces.
- Communication protocols
Implement closed-loop communication, Cargo Control Room (CCR) must receive “all personnel clear” confirmation before starting ANY cargo operations. Radio checks with people inside the cargo tanks must be done at regular intervals (every 10-15 minutes). Documented log of communications must be maintained by the officer in charge inside CCR. Emergency code words for immediate evacuation must be agreed upon.
Special considerations for coconut oil products
- Crude Coconut Oil (CCNO): Contains higher impurity content which increases CO generation risk due to lower thermal stability. It requires lower heating temperatures and is more prone to vapor release during agitation
- Coconut Oil Fatty Acid Distillate (CFAD): Contains volatile medium-chain fatty acids and has higher vaporization risk when heated. It can generate flammable atmospheres and can be particularly dangerous in confined spaces.
- Refined Coconut Oil: It has lower risk but not entirely risk-free. It is still capable of generating toxic vapors and requires same precautionary measures.
Coconut oil cargo operations demand strict adherence to safety protocols, continuous monitoring, and cargo-specific awareness. These measures are not optional but lifesaving.
Heating temperatures should be maintained at minimum necessary levels. Monitoring of temperature gradients within tanks should be conducted. Rapid temperature changes should be avoided.
Tank cleaning and squeezing operations present elevated risks for Coconut Oil Products as residues are often heated to aid removal. Agitation of such residues can release trapped gases. Bottom residues may contain concentrated impurities as well.