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Features of ISO Refrigerated Containers & Safe Handling in Port

ISO Reefer containers require special care after they are loaded onboard ship. These containers need to be supplied with power, monitored closely for proper function, and repaired as required in case of malfunction. The article here is about procedures and guidelines on Reefer cargo handling in Port

Unlike permanent cold stores or refrigerated ships, where robust equipment is under constant care by qualified personnel, the ISO refrigerated container may travel by several different modes and be in the care of many and varied people. Before being despatched to load refrigerated cargo (usually at shippers' premises), the container and its machinery should be subjected to a rigorous examination. External damage received during the previous handling must be noted. If necessary, repaired ­and in cases where the external sheathing is pierced, insulation must be examined with particular reference to the ingress of water. Internally the successful carriage of refrigerated cargo depends on air circulation.



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All airways and battens should be inspected for damage (particularly floor extrusions where fitted) and fans tested. Cleanliness is of paramount importance and should be dealt with as previously outlined. Doors and their fastenings (including hinges and seals) should receive special attention so that an airtight seal is ensured when the door is closed.

Stowage position onboard the vessel will be governed by the commodity carried, its temperature and other carrying requirements and the type of container (port-hole, air or water-cooled integral, or clip-on unit).

Insulated or port-hole containers have now been phased out for refrigerated use although it is not impossible that units may be utilised for general cargo. Port-hole containers were usually 20ft units of 8ft or 8ft 6 ins in height. The major problems with using them for general cargo are the risk of damage to their relatively lightly constructed walls and the possibility of water ingress though ill-fitting vent closures if stowed on deck.

Reefer container side view
Image credite: CMA CGM

Integral containers with air-cooled machinery and containers fitted with clip-on units are usually stowed on deck. However, vehicle decks of Ro-Ro vessels, with appropriate ventilation facilities, may be suitable and acceptable. Water-cooled integral containers must be stowed so that the hose connections are facing the correct way, and the comments (above) regarding 8ft and 8ft 6in container problems also apply.

Inspecting and testing should be carried out by qualified personnel and a certificate issued. Containers may require to be pre-cooled before loading (depending on the type of cargo and local regulations).

When a clip-on unit is fitted, or in the case of integral unit containers, the correct temperature for the cargo to be carried must be set, and the recording chart fitted. The information recorded on the chart should include: When appropriate (e.g., for live fruit cargoes), the air intake/outlet vents should be set open to allow carbon dioxide and other gases to exhaust from the container. When loaded, sealed, and delivered to the ship (as in the case of a port-hole unit), there is little that can be done other than an external examination and inspection of the accompanying documents. If a clip-on unit is fitted, thermometers and thermostat settings should be inspected along with its general condition. It is usual for the temperature recording chart to be changed when the container is received on board with the original being retained for future reference.

An integral unit should be similarly checked and stowed so that the machinery is readily accessible. Power supply cables and connectors must be tested. Although largely standardized, differences are sometimes found, and converting links should be available. The voltages and transformer settings should be carefully checked before connecting up. Thermostat settings should be checked correctly for the contents and the plant operating smoothly. Though major machinery breakdowns are a specialist's concern and unlikely, regular checks for the temperature must be made and variations investigated. The causes may be simple and easily rectified; a blown fuse, a slipping or broken fan belt, thermostat settings altered by vibration. Spares should be carried as attention to minor defects may well save a valuable cargo.

The majority of reefer containers are now constructed with smooth or flat internal walls. Such containers have been found to have a high incidence of cargo damage traced to packaged break-bulk cargo being stowed hard against the smooth walls and thus impeding the flow of air around the block of cargo. Airflow beneath, above, and at the door end of the stow is not a problem but is impeded along the sidewalls and the solid end wall. Therefore, it is necessary to either stow cartons in a staggered way at the sides or places vertical 10mm wood or polystyrene battens, thus providing a gap through which air can circulate. The problem does not arise with palletized cargo as the pallets themselves hold the cargo away from the walls.

Modern container ships and reefer ships can carry huge numbers of integral containers. While systems allow them to be monitored remotely, it may be necessary to access the stack to carry out maintenance. The photograph below shows a permanent structure to provide access to refrigerated containers carried on the deck of a reefer ship.

It shall be confirmed beforehand from the terminal foreman/superintendent or local agent whether reefer container plugging / unplugging operation will be performed by ships crew or shore hands.

Reefer handling in port

Reefer containers shall be plugged in and supplied with ship's power as soon as practicable after loading. In case it is to be done by shore hands, ships crew shall still closely monitor the operation and confirm that all reefer containers are supplied with power earliest after loading.

Where applicable, cooling water shall be connected, and valves opened. This is usually in case of water-cooled reefer container units loaded under deck.

Reefer remote monitoring cables shall also be connected whenever equipped and compatible.
Once power supply to the reefer container is confirmed, its condition shall be checked for the following: In case of any discrepancy in temperature or ventilator settings, the local agent/booking line shall be informed and clarifications sought.

Clarification will be given by the booking line (directly or via the agent), and only upon written instruction from them will the vessel adjust any settings of temperature or ventilation. No temperature or ventilation settings may have tampered within the absence of such written instructions.

In the case of a malfunctioning unit, the local agent must be informed, and reefer technician arranged for inspection and repair. If the unit cannot be satisfactorily repaired within the duration of port stay, it must be offloaded.

In case of Warm or Hot cargo in a reefer is loaded onboard the vessel, it must be first confirmed that the reefer container itself is working well. The shipment may then be accepted after obtaining a letter of guarantee from the shipper through the agent and from an agent on behalf of the booking line relieving vessel owner/operator from cargo claims arising out of damage to cargo from this fact. This hot cargo statement shall be signed by the terminal and local agent.

If a letter of guarantee is impossible to obtain, an exception list may be prepared on board and signatures of the terminal, local agent, and/or any third parties obtained on the same to confirm the condition of the reefer at the time of loading.

Discrepancy report for warm or hot cargo reefer containers must be made out and sent to vessel operators, booking line, local agent and other concerned parties.
In case any reefer container is rejected for loading owing to Temperature / Ventilation discrepancy without clarification, warm/hot cargo without statement, malfunction or any such valid reason, the fact shall be reported to vessel operator and any other parties concerned.

Reefer containers being discharged shall be unplugged from power source only just prior discharge. They shall not be unplugged and left on board awaiting discharge for a long time. The power cables and monitoring cables shall be neatly secured to avoid any damage during cargo operations.

Particular care must be taken in operations involving re-stow of reefer containers in Port. When placed back on board and plugged in, their parameters must be rechecked.

All reefer containers on board shall be monitored by checking physically at least twice daily (am & pm) during vessels stay in Port.

The probability of a reefer container being inadvertently switched off or unplugged while a vessel is in Port does exist. Also, a reefer remote monitor alarm may go unnoticed while the ship is in Port


Reefer Container Shipment

Procedures and guidelines for stowage of reefer containers shall be adhered to. A reefer container list or manifest must accompany every reefer container proposed for shipment. Additionally read our article on:
  1. Reefer cargo Handling In Port
    Reefer containers shall be plugged in and supplied with ships power as soon as practicable after loading. In case it is to be done by shore hands, ships crew shall still closely monitor the operation and confirm that all reefer containers are supplied with power earliest after loading....

  2. Reefer cargo care at sea
    At sea, all reefer containers shall be monitored by checking physically at least twice daily (weather permitting). All monitored data for each reefer container on board shall be entered in a reefer monitoring log and retained for three years. Some reefer containers with special cargo (e.g., VIP cargo) come with instructions for more frequent monitoring and reporting. Such instructions shall be strictly followed. ....

  3. Commodities Shipped In Reefer Containers
    Some cargoes may require controlled humidity (e.g. flower bulbs). In such cases, many refrigeration units are only capable of reducing humidity within the cargo space, and the settings should be applied accordingly. ....

  4. Reefer Cargo Temperature Recording
    A Partlow recorder registers temperature on a pressure-sensitive circular chart over 31 day period. If the voyage transit is expected to exceed 31 days, care must be taken to ensure charts are replaced before expiry. The first chart should be placed underneath the new chart to build up a complete temperature record for the entire voyage up until arrival at the final destination. .....

  5. Reefer Cargo Maintaining Records
    Monitoring the digital & chart temperatures of all reefer containers at least twice a day. Daily reefer container temperature checklists should be maintained, and printouts from monitoring unit should be preserved.....

  6. Reefer Cargo Care During Sea Transit
    Reefer containers usually have their own refrigeration unit, with an air or water-cooled heat exchanger. They have a data logger to record the temperature. The logger may be in the form of a Partlow chart or a digital logger. They usually contain high-value cargo, and any damage to cargo would likely result in substantial claims......

  7. Reefer Cargo Defrosting
    During the operation of a refrigeration unit, a layer of ice will form on the evaporator coils depending on the temperature set, the temperature of the cargo, the amount of fresh air ventilation and the cargo humidity. The unit periodically enters a phase where heat is produced by a series of electrical bars, allowing defrosting to occur. At such times, all fans are turned off automatically to prevent heat from entering the cargo compartment. ....

  8. Basic check item prior stowing Reefer Cargo
    Stowage location of reefers must be checked against vessels reefer receptacle locations. In case reefer containers must be loaded in random locations, it must be confirmed that monitoring and repair will be possible during the voyage, and that vessel has sufficient extension cables for providing power. ....



Container handling additional guideline:

Containership cargo stowage and planning

Stacking Weights Restrictions

Lashing strength calculation

Dangerous goods stowage and segregation

Reefer Container Stowage

Out of Gauge Container Stowage

Special Container Stowage

20 or 40 or 45 feet Compulsory Stowage Locations

Irregular Stowage of Containers

Over-stow of Containers

Hatch Cover Clearance (High cube containers Under Deck )

Other matters regarding cargo stowage as necessary

How to load maximum number 20 feet container on deck ?

What are the extra precaution should be taken prior loading a 45 feet container on deck ?

Container damage in ''2 in 1'' cargo Operation

Modern containership & loading of various container types

How to load containers coming in different forms/sizes



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