Handling of Soya Cargo
This cargo must be carried in accordance with the requirements of the latest edition of the IMO International Convention for the Safe Carriage of Grain in Bulk (the Grain Code).
Very often, claims arising at the discharge port often involve allegations of deterioration and/or contamination. Condition of the cargo may have been affected by:
- Decomposition, self-heating, mold growth and/or caking due to the beans having an excessive moisture content
- Sweat (i.e. condensation) damage
- Water ingress from non-weather-tight hatch covers, bilge lines and/or leaking ballast tanks
- Heat damage to cargo in the vicinity of the engine room bulkhead and/or tanks containing hot fuel oil
Given the potential for damage and shortage claims, Members may wish to consider appointing a cargo surveyor to attend the vessel during loading and discharge operations to protect their interests.
The moisture content of the cargo is one of the most important factors affecting the carriage of this product. Although soya beans are hygroscopic and will absorb moisture, it is unusual for the average moisture content of the cargo to change appreciably during the voyage unless there has been some specific incidence of wetting such as water ingress or the development of sweat inside the cargo holds. Depending on the circumstances, moisture migration may also occur due to temperature gradients established across the stow as a result of the heating or cooling of steelworks. These scenarios will increase the moisture content of a proportion of the cargo within the affected area. If the soya beans had an inherently high moisture content at the time of loading or are whetted while on board, the oil within the beans may start to decompose during the voyage and cause the cargo to self-heat, promoting the growth of mold which can result in caking. This type of deterioration affects the quality of the product.
The risk of deterioration increases significantly if the moisture content of the beans exceeds 14%. Soya beans with a moisture content of between 13% and 14% may also deteriorate if exposed to warm climatic conditions throughout the voyage. Similarly, deterioration may occur if the moisture content of the beans differs widely. Soya beans with a moisture content below 10% are less likely to deteriorate but are more susceptible to handling damage.
It is generally accepted that the moisture content of soya bean cargoes should not exceed 13% when presented for loading. Cargo interests will usually provide a quality certificate declaring the moisture content of the soya beans to be 13% or slightly less, but this is likely to be an average figure. In practice the actual moisture content of some of the beans may be higher, making them more susceptible to deterioration.
In order to identify any cargo that may have started to self-heat, the OOW should also be instructed to measure the temperature of the beans at regular intervals.
The cargo holds should be prepared to the grain clean/high cleanliness standard.
In all cases the holds should be thoroughly cleaned to remove any residues of previous cargo, loose rust scale, paint flakes, paint blisters, infestation and any other foreign matter. The holds should then be washed, carrying out a final rinse with fresh water to remove all traces of chlorides. Prior to loading the holds should be completely dry and odour free.
Any abnormal coloring should be investigated at the time of loading, particularly if it appears to differ from the color stated in the cargo documentation.
The cargo should be protected from rain at all times and all non-working hatch covers should be kept closed during loading operations. If rain is imminent, cargo work should be suspended and the working hatches should be closed without delay.
If the master or the surveyor has any doubts regarding the condition of the cargo during loading or its fitness for carriage, the Club should be contacted at the earliest opportunity as it may be necessary to obtain expert advice.
Once the cargo has been loaded, and subject to any fumigation requirements, the holds should be ventilated in accordance with the Club’s Loss Prevention Bulletin on Cargo
Ventilation and precautions to minimize sweat
Mechanical rather than natural ventilation of the holds is generally preferable for achieving efficient air circulation. However, as with any agricultural product shipped in bulk, air will fail to penetrate the body of the stow regardless of which method is used.
If it is intended to ventilate the cargo in accordance with the Three Degree Rule during the voyage, then the average temperature of the sub-surface cargo should be established after the completion of loading.
Detailed temperature records, as well as the times of starting and stopping ventilation should be maintained. If it is not possible to ventilate the cargo due to fumigation, heavy weather or any other reason, such details should also be recorded. In addition to taking temperature readings and adjusting the ventilation during the day, the crew should also follow the same routine at night. Again, failure to monitor and record such activities during the hours of darkness may make it difficult to defend any allegations of inadequate ventilation.
Any fuel oil tanks bordering the cargo holds should not be heated excessively as the hot steelworks may induce self-heating and, over time, scorch the beans in that area or trigger moisture migration. The fuel should only be heated to the minimum temperature necessary for use. Similarly, fuel which is overly hot should not be transferred to such tanks. In addition, the temperature of the engine room bulkhead should be considered as this may also result in heat damage and moisture migration.
Soya beans continue to respire after harvesting. The respiration process may result in less oxygen within the cargo holds and elevated levels of carbon dioxide, making the atmosphere unsafe to breathe. Deck houses may also be affected if they contain hold access hatches which are not gas tight. Enclosed space entry procedures should always be followed if it is necessary for anyone to enter such compartments.
All crew members should be briefed about these hazards and the necessary precautionary measures prior to loading, particularly the oxygen depletion risks. Ideally all cargo hold access hatches should be locked shut and suitable warning notices posted.
In common with many dry bulk cargoes, shortage claims may arise. Draft surveys should therefore be carried out by the vessel at all load and discharge ports. However, if the vessel is due to discharge at particular ports where shortage claims are endemic, it may be prudent to delegate this task to reputable independent surveyors. Members may also consider sealing and unsealing holds under survey at the load and discharge ports, inviting cargo interests to attend in each case.
Arrangements should also be made to have empty hold certificates issued upon completion of discharge. It should not be assumed that a fixed trade allowance for cargo shortages will always apply. In some countries the courts may not permit such a defense, and in others the trade allowance may vary depending on the province in which the discharge port is situated.