This article has been written by Capt. Jatinder Singh Chada (Jatin) MIIMS as a brief introductory guide to loss prevention, specifically for carriage of electrically powered refrigerated containers inside cargo holds (under deck). With the increase in transportation of refrigerated commodities and containerization, container vessels are being designed to accommodate more and more refrigerated containers under deck, in addition to the customary practice of loading reefer containers on deck, as operators want to cash in the extra freight.
Based on statistics of incidents handled by the author, it has been noted that most of the incidents involving high temperatures (and related malfunctions) on containers loaded under deck have generally been associated with cooled/chilled cargoes {those maintained between (-)30C and (+)160C}.
Meticulous planning can however minimize and avoid the chances of such incidents. It needs to be mentioned that the cooled/chilled cargoes (generally consisting of fresh fruits) have lesser range of tolerance for temperature variation and demand more attention, as compared to frozen cargoes.
Systematic planning and additional care from carrier(s) are required prior designating the containers for carrying cooled/chilled cargoes. The containers should be carefully inspected, PTI carried out and precooling undertaken prior to releasing the container to the shipper. As a loss prevention measure, the carrier may consider advising the shipper to arrange proper pre-cooling of the cargo, prior to vanning into a container.
These are normal practices and do not relate to the location of container carried on board. The concerns are however raised when the high temperatures and related malfunctions are noted during carriage, particularly in under deck spaces. These are hence directed towards the design of vessel and/or carriage/care on board. Effective planning to avoid carriage of containers with cooled/chilled cargoes in under deck spaces and preferably loading these on exposed decks may result in minimizing these unwanted occurrences. Due to various constraints, at times, the planners are however pressed, and the containers need to be stowed in under deck spaces.
An understanding of the design and structure of the vessel, in general, and cargo holds in particular, plays an important role in preventing such losses. During the stage of designing and classification of vessel, the number of reefer receptacles and the ventilation system of cargo holds are taken into consideration along with calculations of capacities. Hence, the vessels may not be able to carry refrigerated containers in excess of certified/allowed capacity. The hold ventilation system has to be in working order prior to shipment. But still, there have been incidents, which have led to malfunction of refrigerated containers and/or incapacity to reach the desired temperatures.
Bear in mind that the refrigerated containers give out hot exhaust air and require copious supply of colder fresh air. Also, it has to be kept in mind, that in addition to normal refrigerated cargoes, the fresh fruits themselves give out heat, which requires continuous replacement. Some of the fruits (such as Durian) are known for giving out extensive heat. The other perishable cargoes, for instance poultry and dairy products and other frozen commodities, however, do not give out that much heat. The point to note here is that a refrigerated container can properly cool the cargo and contents only if the air supplied is of lower temperature than the exhaust air. If the air supplied is at a higher temperature, the cooling system may be adversely affected and shall lead to losses.
In view of the above scenarios, proper planning involving stowage of containers according to the vessel’s ventilation system/plan is paramount, especially when reefer containers are being loaded under deck. It needs mindful planning so that the hot exhaust gases, which are vented out from ship’s hold ventilators are not re-circulated back through the inlets of hold ventilators. The vessels may have fixed ventilation ducts or, there may be a changeable/adjustable system. There may be times when both the exhaust(s) and the inlet(s) are positioned along the same cross deck. This arrangement needs to be borne in mind by the ship’s staff to assure proper ventilation of cargo holds. The refrigerated containers, carrying cooled/chilled cargoes should be positioned closer to the ventilation ducts to enable effective air exchange. Also, the subject containers should avoid being stowed closer to hot areas, like the engine room, heated bunker or tanks as heat from these sources shall adversely affect the air temperature around the inlets of containers.
The ambient temperature also plays a part in this story. When a vessel is trading in summertime and carrying cooled / chilled cargoes, extra caution needs to be taken. If necessary, arrangements for additional cooling of the air inside holds may be considered to ensure effective recirculation and exchange of air.
As a good practice, the ship’s staff may consider monitoring the container temperatures and readings more frequently, especially if automated continuous monitoring is not a feature on the vessel. If an abnormal rise or variation in temperature is observed, the contingency planning should be immediately initiated.
To conclude, loss prevention is feasible only if the planning and implementation are effectively done keeping in mind various factors. In regard to the subject matter of claims about high temperatures and related malfunctions with reefer containers carried under decks, the ventilation of cargo holds and proper exhaust and inlet planning is of vital importance.
It is hoped that in addition to guiding the concerned parties, this paper shall act as a reminder to recall various issues, which might have become dormant over time because of various regular operations.
The writer of this article is a Master Mariner, with extensive experience as a Senior Surveyor/Consultant and Manager. He has extensively dealt with numerous cargo claim cases and carried out plentiful investigations. He is also a member of the prestigious organization, the International Institute of Marine Surveying (IIMS), which has been extensively supporting the marine surveying industry.
This article taken from The Report, Edition 102
The writer of this article is a Master Mariner, with extensive experience as a Senior Surveyor/Consultant and Manager. He has extensively dealt with numerous cargo claim cases and carried out plentiful investigations.
