Reefer – IMDG Code Compliance Centre

Dangerous Goods in Reefers

IMDG Code requires certain substances to be transported under temperature control due to the properties of these substances to undergo a self-accelerating decomposition, possibly of explosive violence, when the temperature exceeds a certain value.

Self-accelerating decomposition temperature (SADT) means the lowest temperature at which a self-accelerating decomposition may occur for a substance in the packaging as used in transport.

When a Self-reactive substance or an Organic Peroxide require temperature control during transport the compulsory requirement of usage of reefer container is indicated by words “Shall be transported under temperature control” in column 16 of DGL and Stowage Code SW3 in Column 16a of DGL in 36^th and 37^th amendment of IMDG Code respectively.

The Control Temperature and Emergency Temperature is determined basis the SADT in which the size of package plays a crucial role. For single packagings and IBCs if SADT is 20°C or less the Control Temperature and Emergency Temperature is 20°C and 10°C below SADT respectively.

Actual transport temperature can be lower than Control Temperature however it shall not be so low to form dangerous separation of phases.

Prior stuffing the reefer must be thoroughly inspected, tested and Master must be provided with operating instructions and spare parts. If the Control Temperature is less than +25°C, the reefer must be fitted with audio visual alarm independent from the power supply of the reefer.

Redundant Reefers: Certain Self-reactive substances and Organic Peroxides require dual mechanism reefer which has two independent refrigerating units with separate power supplies and able to start automatically when the running unit fails.

While packing the reefer with packages requiring temperature control and packages not requiring temperature control the packages which require temperature control must be stowed closer to the door for access in an emergency. Similarly if there are different packages with differing control and emergency temperatures the packages having lowest Emergency Temperature should be packed near the door.

Ship staff will monitor the temperature at regular intervals and if due to malfunction if the temperature rise above Control Temperature they will initiate control measures such as repairing the equipment or providing additional coolants when available. If this fails and the temperature reaches the Emergency Temperature ship staff will initiate Emergency Response Measures which may be jettisoning the cargo or rigging fire hoses and pumping copious quantity of water on to the packages inside the reefer to prevent fire or explosion when the temperature reaches SADT.

Quality Control Reefer Shipments: Some dangerous goods which do not require temperature control for safety reasons may be offered by shippers’ in reefers for commercial reasons. These goods may be flammable liquids, flammable gases, flammable solids or corrosive substances. Example: Perfumes, Safety Matches, Paint, Lithium Batteries, Phosphoric Acid, Acetic Acid etc…

When flammable liquids or gases with flashpoint less than 23°C c.c. are loaded in reefers the substance shall be precooled and transported at a temperature at least 10 Deg C below its flashpoint or a reefer with explosion proof electrical fittings is required.

During transport if the reefer fails the Master must disconnect the reefer from power supply and must not reconnect again if the temperature has risen to less than 10°C below the flashpoint. The reefer can continue its journey and discharged at destination as non-operating reefer.

Carriers’ policy: Carriers may have their own policy with respect to set temperature and humidity for dangerous goods in reefers which do not require temperature control for safety reasons as per IMDG Code. One of these is the infamous Calcium Hypochlorite. Some lines insist that they will carry calcium hypochlorite in reefers with +10 or +20 Deg C only. This is to prevent the exposure of cargo to higher temperature which may result in a thermal runaway explosion.

Carrying Calcium Hypochlorite in reefer is a good proactive step to ensure safety. However, since the reefer is a thermally insulated box the probability of equipment failure and resulting trapped heat generated by cargo inside the reefer must be borne in mind while loading on board ships. If the reefer fails the vessel should discharge the reefer at the next port or during long passages open the doors and provide ventilation. It all depends on the Masters’ decision considering the ambient temperature and distance to go to the next port.

Repositioning Empty Reefers: Reefer is a good business for carriers same time repositioning them is a bad business too. In reefer trade lanes carriers may offer non-operating reefers for general goods and dangerous goods so as to earn freight while repositioning. Most carriers do not accept flammable gases in non-operating reefers to avoid the possibility of someone switching on the reefer en route which may result in explosion if there is gas leakage. Some carriers do accept flammable gases in non-operating reefers provided the power cables are secured and blanked.

Primary function of reefer is to carry food grade products. The reefer operator takes care of the equipment avoiding possibility of contamination by not releasing the reefers for carrying goods which must be separated from foodstuff or for tainting commodity.

For goods which require temperature control during transport for safety reason, the Control and Emergency Temperatures shall be indicated on the dangerous goods declaration, as follows:

“Control Temperature: … °C Emergency temperature: … °C”.

Below sections of IMDG Code identifies the actual Control and Emergency Temperatures for certain substances:

– 2.4.2.3.2.3 List of currently assigned Self-reactive substances in packagings

– 2.5.3.2.4 List of currently assigned Organic Peroxides in packagings

– 4.1.4 IBC520 – List of currently assigned self-reactive substances and organic peroxides in IBCs

– 4.2.5.2.6 T23 – List of currently assigned self-reactive substances and organic peroxides in in tanks

For full details on temperature controlled shipments of Dangerous Goods refer to Chapter 7.3 of IMDG Code.

While shipping dangerous goods in Reefers always remember that the “Reefer is a source of ignition”!

Dry Ice for shipments of chilled cargo

Shipments of perishable goods are extremely time-sensitive and must be managed at all stages of handling and transport correctly. Airfreight is often used as a solution for transporting perishable goods to avoid the long transit time of seafreight; shipments can conceivably arrive on the other side of the world the next day, not the next month!

But how is temperature control managed on an aeroplane compared to a mammoth container ship ? On a container ship reefer containers are plugged into power to maintain required temperature; probes inside the container will measure the temperature of the packed cargo and also ambient air temperature where required. This onboard temperature control, together with powered reefer plugs at the terminals, means that temperature can be controlled and monitored from the time the container is packed to when it is destuffed.

On an aeroplane, the first factor is of course space. The cargo must be packed into dedicated smaller airfreight containers, as seafreight containers are simply too big. An airfreight container is usually only big enough to carry about 1.3 ton of packed product, yet you can literally walk into a shipping container and walk about 10 paces from end to end without ducking your head.

This demonstrates the main outcome of airfreight; you send smaller shipments more often. True, there are dedicated “super” planes where the nose lifts up and you can drive a tank onto them without touching the sides . But the majority of the flights used for perishable goods are also commercial flights with passengers aboard. The flights are literally packed with cargo and travellers.

The smaller size of the airfreight containers means that the cooling mechanism will need to focus on non-electric cooling as opposed to a traditional powering found in reefer plugs and gensets ( diesel powered “generators” to allow cooling of containers whilst being trucked ) than that found in a seafreight container. We must look to alternative means to maintain temperature once the product is removed from powered temperature control.

The way in which dry ice prevent spoilage of chilled cargo is through replacing oxygen with carbon dioxide ( CO2 ). The indirect fumes from the dry ice will keep the cargo chilled.

With regards to dangerous goods regulations, unless the dry ice is being used to refrigerate another dangerous good then a separate dangerous goods declaration is not required. The package containing the dry ice would need to be appropriately marked with UN number, net weight and packaging group ; this information would also be included on the air waybill.

DG Reefer – Commercial Reasons

Certain Dangerous Goods require mandatory transport in reefer containers due to safety reasons. These are some of the Self-reactive Substances under Class 4.1 and some of the Organic Peroxides, Class 5.2. This requirement is listed in column 16 of DG List in chapter 3.2 and respective sub sections in chapter 2.4 & 2.5 of IMDG Code (35-10).

Let us look at the provisions of other dangerous goods which do not require refrigerated containers but are offered sometimes as temperature controlled.

So what goods which do not require a reefer is sometimes transported in reefer? Generally these are Perfumes ( UN 1266), Safety Matches ( UN 1944), Paint (UN 1263), Lithium Batteries (UN 3090,3091,3480,3481). Some shippers transport these in live reefers to maintain the product quality. Of course Calcium Hypochlorite require live reefers by most of the shipping lines due to its bad past.

IMDG Code has certain provisions for Dangerous Goods in reefers for commercial reasons, these are specifically related to Flammable Gases ( Class 2.1) and Flammable liquids ( Class 3). When Flammable liquids having flashpoint less than 23 °C c.c is transported in live reefer then

1/ Substance shall be precooled and

2/ Transported at a temperature at east 10 Deg C below its flashpoint

Or explosion proof reefer is required.

At any moment during transport In case the reefer fails then power supply shall be disconnected and must not be switched on again.

No line will accept flammable gas in live or non-live reefers. ( For full details refer 7.7 of IMDG Code)