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TT Club, COA and CINS jointly unveil guidelines for shipping of cargo by non-operating reefer containers

Guidelines for the carriage of cargo in non-operating reefer containers were launched by TT Club, Container Owner Association (COA), and Cargo Incident Notification System (CINS) on 15th August.  Refrigerated containers (known as reefers) are designed to be used to transport temperature controlled cargo. Since there may be insufficient temperature controlled cargo for a ‘return’ leg, reefers would normally be positioned empty to a demand location.

 In order to minimise empty repositioning costs, container operators may use reefer containers in a non-operating mode to carry approved dry cargo on a return leg. Such cargo is described as non-operating reefer cargo (NOR cargo). NOR cargo is defined as a cargo that is approved for packing into a refrigerated container to be transported without operating the refrigeration machinery. Transporting NOR cargo enables the carriage of additional cargo in busy trade lanes where reefers need to be positioned for their next cargo move, but are competing for slot space with revenue earning dry cargo.

Reefer containers differ from General Purpose (GP) containers in both design and materials. This must be taken into account in relation to the approval of and packing requirements for NOR cargo. These guidelines are intended to help container operators and shippers in making decisions that appropriately protect both cargo and containers. The design of reefer containers enables cargo that is sensitive to temperature to be transported in an insulated container with its own refrigeration machine that circulates air, controlled at a set temperature.

 The characteristics of a reefer container are:

The provision of accurate control of temperature and air flow, within specified technical parameters. Satisfying hygiene and similar standards, for example related to food cargo, pharmaceuticals or flowers.  The design is complex and reefers are seven times more costly than GP containers to purchase. The internal construction materials used are susceptible to damage if cargo packing techniques are not adjusted. Repairs to reefers are more difficult and costs are seven times higher than for GP containers.

 Dry Cargo in Reefers: Issues to Consider

There are a number of issues to be considered concerning the characteristics of a reefer container before approving it to carry a NOR cargo or commencing packing cargo.

Reefer Interior

  Smaller internal dimensions than a GP container require increased awareness and attention when preparing the packing plan.  Front-heavy weight distribution from refrigeration machinery should be taking into account in planning cargo distribution. In planning appropriate cargo distribution, the packer should take account of front-heavy weight distribution in the container from the refrigeration machinery.  Materials used for construction are less robust and particularly susceptible to piercing or stress.  Unpainted metal surfaces are susceptible to corrosion from cargo and improper cleaning processes.

Interior damage

There are various causes for the type of corrosion that are presented in reefer container. Although the most common cause is the cargo itself, including treatments (e.g. residues of fumigation) that might be applied to the cargo, cleaning with caustic materials will also cause corrosion or oxidation to the interior of the unit.

Say no to fumigation

Note that fumigation is not allowed in operating reefers; shippers should ensure fumigated cargo is adequately ventilated before packing the container. It is difficult to treat and permanently repair this corrosion as the surface of the aluminium has had its protective oxide layer contaminated. In addition to corrosion, the aluminium T Floor sections are susceptible to mechanical damage, such as caused by fork or pallet truck wheels. Most reefer interior sidewalls are protected by aluminium scuff liners. Aluminium is a softer material than the steel used in GP containers, so can be more easily cut by forklifts used during the packing/unpacking process or by the sharp edges of packaging, such as pallets. Some reefers use Fibre Reinforced Plastic (FRP) as lining material, which is more resistant to damage. Cuts in the scuff liner or sidewall, as shown in Picture 6, allow moisture into the insulating foam that needs to be repaired before the insulation deteriorates. The thin panel aluminium ceilings are significantly easier to damage than the Corten steel used in the roofs of GP containers. Such damage  exposes the insulation foam and must be repaired to prevent moisture absorption. It is not operating, the refrigeration machine is exposed to the atmosphere inside the container.

Corrosion by leaked gases

 Gases released from cargo can corrode and 1 50% of a reefer container’s new value is the complex refrigeration machinery at the front of the unit. Half of this machinery is located inside the container.  Corrosion to the coil can result in the coil area reducing, air resistance increasing or refrigerant pipes being corroded through. Such damage will affect the cooling performance of the machinery and its ability to maintain temperature settings for future temperature controlled cargoes. In some cases, corrosion and corrosion products may also compromise the quality of certain cargo types, although not generally NOR cargo. There are detailed maintenance guidelines for machinery that need to be followed in order to prolong optimal performance and avoid damage to future temperature controlled cargoes, adds TT Club advisory.

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