Coconut oil is not immediately associated with risk, but its carriage can release toxic vapours and cause oxygen depletion in enclosed spaces. Manish Nayyar, Senior Loss Prevention Executive, NorthStandard, explains why crew working inside cargo tanks must be fully informed

Transporting coconut oil and its derivatives, viz. Crude Coconut Oil (CCNO), Coconut Oil Fatty Acid Distillate (CFAD) and Refined Coconut Oil, by sea comes with a critical but underestimated risk: the generation of toxic gas inside the vessel’s cargo tanks.

Contrary to common belief, vegetable oils, and particularly crude coconut oil (CCNO), pose substantial atmospheric hazards in enclosed spaces. Due to its higher impurity levels and lower thermal stability compared to refined coconut oil, CCNO can release carbon monoxide (CO) – a colourless, odourless and potentially lethal gas – when heated or agitated.

Similarly, coconut fatty acid distillate (CFAD) contains medium-chain fatty acids such as capric acid (C10) and lauric acid (C12), which can vaporise when heated or agitated, potentially creating flammable vapour-air mixtures, displacing oxygen and causing skin and eye irritation.

Both hazards can cause asphyxiation and are difficult to detect without sensors. Even when sensors or gas detectors are used, only conducting safe pre-entry readings do not guarantee continuous safety throughout the operation. When the cargo is moved —either during circulation, heating or stripping—it can release trapped gases, quickly turning a ‘safe’ tank atmosphere into a hazardous one.

The risk is real

Two recent case studies have provided a wake-up call to the tanker industry. In the first, two crew members entered a cargo oil tank to perform squeezing operations during a routine CCNO discharge at Rotterdam.

Although pre-entry test readings indicated the tank was safe (recording oxygen levels of 20.9% and virtually zero CO or hydrogen sulphide), cargo circulation resulted in visible vapours forming near the bell mouth. The pumpman’s gas detector alarm got activated, but he lost consciousness before he could evacuate the tank and both crew members were hospitalised. Subsequent testing of the tank atmosphere revealed alarming CO levels of 400ppm.

In the second incident, recorded during a CFAD discharge operation at Lianyungang, China, five crew members entered a cargo tank without conducting proper atmospheric testing nor following enclosed space entry procedures. All five of them collapsed due to toxic gas exposure, four of whom died.

Incident analysis

In hindsight, these accidents were foreseeable due to repeated procedural failures. The ship staff failed to identify the release of hazardous vapours during cargo circulation, while pre-entry risk evaluations proved inadequate. Both incidents were further compounded by breakdowns in communication; for instance, the Cargo Control Room (CCR) was not informed that personnel were still inside the tank.

The incidents also exposed inadequate crew knowledge and awareness. The affected personnel had limited understanding of the specific toxic vapour hazards of coconut oil products, the impact of cargo movement on enclosed space atmospheres and the fact that initial ‘safe’ readings do not ensure continued safety.

In addition, it is worth considering that personal gas detectors can only go so far in warning their users, and often only when the danger is at an advanced stage. In the first case of CCNO discharge at Rotterdam, a single portable ventilation unit proved inadequate for effective use in a large cargo tank.

Tank entry preparation

Building on this knowledge, it is important for the tanker industry to put measures in place to prevent similar incidents.

One crucial safety measure is prohibition of any cargo movement while personnel are inside the cargo tanks, unless it is authorised through a dedicated, documented risk assessment. This rule was violated in the first incident at Rotterdam, which directly contributed to the tragedy.

Other important checks and measures are necessary. Before entry, crew must conduct enhanced, multi-point testing at the top, middle and bottom of the tank, and from multiple access points, such as manholes and butterworth openings. Where vegetable oils are involved, at least four hours should be allocated to ventilation, and then oxygen levels should be verified to be at/above 20.9% as well as toxic gases (including CO) at 0ppm.

After entry, personnel inside the tank must maintain atmospheric monitoring at intervals of no more than 15 minutes, using extended sampling tubes to check atmosphere at multiple levels and set conservative alarm thresholds (for example, oxygen dropping below 20.5% or CO rising above 25ppm).

Ventilation and communication

Large cargo tanks carrying coconut oil products require multiple ventilation points; a single portable blower is not adequate to make the required changes. Crew must ensure that the tank remains well-ventilated throughout the entire entry period, with any areas of poor air circulation identified and safeguarded.

Communication protocols must be strengthened. The CCR should use closed-loop communication and obtain explicit “all personnel clear” confirmation before starting any cargo operations. While personnel are working inside the tank, radio checks should be conducted every 10-15 minutes using pre-agreed codewords for immediate evacuation, with all communications logged by the officer responsible for the CCR.

Significant defences

Finally, temperature management is crucial to safe operations when handling coconut oil products. HeatingTemperatures in cargo tanks should be kept at the minimum necessary levels to maintain cargo fluidity while avoiding hazards, with a special focus on avoiding rapid temperature changes.

Risks are elevated for coconut oil product residues during tank cleaning and squeezing operations because the process of heating these residues to facilitate their removal can release trapped gases, and bottom residues may contain concentrated impurities that increase the likelihood of hazardous atmospheric changes.

Combined, these measures should not be seen as optional tasks, but as significant defences against crew illness, injury and death.