IMDG compliance: stowage, segregation and the container that catches fire

Where the code comes from and what it binds

The code is developed through the international maritime organisation and applied under the safety of life at sea framework, which makes its core provisions mandatory for ships flying the flags of contracting states. It works alongside the pollution prevention framework where substances are harmful to the marine environment, and national administrations enforce it through port state control, terminal acceptance rules and penalties. For a shipper this means the code reaches beyond the vessel. Terminals apply it when deciding whether a box may enter the yard, how long it may stay and where it may stand, and carriers apply it when accepting bookings, so a non-compliant consignment usually fails long before it reaches a ship.

Packing the container is a regulated act

The code addresses how packages are secured inside a freight container: compatible goods only, adequate bracing and dunnage, no damaged or leaking packages, correct orientation, and marks and labels visible where practicable. Residues and previous cargo contamination matter, as does the condition of the container itself. The person responsible signs a container packing certificate confirming that packing was carried out in accordance with the requirements. That signature is relied on by the carrier and the terminal, and it is the document most often produced after a fire. A shipper that delegates packing to a third party should be verifying how that party works rather than accepting the certificate as a formality.

Stowage and segregation on board

The code assigns stowage categories that determine whether a container may go under deck or must go on deck, and where relative to accommodation, machinery spaces and sources of heat. Segregation rules then keep incompatible classes apart, expressed as requirements to stow away from, separated from, separated by a complete compartment or hold, or separated longitudinally by an intervening compartment. Those rules are why a booking can be refused even when the goods are perfectly packed: the vessel may have no compliant position left for that class on that voyage. They are also why a wrongly declared container is so dangerous. Placed on a stowage plan as inert general cargo, it may sit directly against a heat source or beneath an inaccessible stack.

Declaration, documentation and marine pollutants

The dangerous goods transport document carries the identification number, proper shipping name, class, packing group, quantity, packing type and any special provisions, together with an emergency contact. Goods classed as marine pollutants take an additional mark, and limited or excepted quantity provisions relax parts of the regime for small packages while imposing their own marking rules. Accuracy here has consequences beyond safety. Carriers levy substantial penalties for misdeclared hazardous cargo, refuse future bookings and pursue recovery for damage, and a misdeclaration will also sit badly with a cargo insurer examining a claim from the same consignment.

Why container fires keep happening

Investigations into serious container ship fires repeatedly identify the same contributing factors: hazardous goods declared as something benign, self-reactive or heat-sensitive substances stowed without regard to temperature, poorly packed boxes allowing packages to shift and leak, and limited firefighting reach into a loaded stack. None of these is a failure of the code; all are failures to apply it upstream. The practical controls a shipper can own are narrow and effective: a documented classification, a competent packer, an accurate declaration, and a policy of never accepting a customer instruction to describe goods in a way that avoids a hazardous booking. Anything that reduces a surcharge by hiding a hazard is transferring risk onto a crew that cannot see the box.

Frequently asked questions

Why was my hazardous booking refused when the packing was correct?

Stowage categories and segregation requirements limit where a class may be carried on a given vessel, and a ship may have no compliant position available for that voyage. Refusal often reflects the stowage plan rather than any defect in the consignment.

Who signs the container packing certificate?

The party responsible for packing the container, confirming that it was packed in accordance with the applicable requirements. Where packing is outsourced, the shipper still carries responsibility for the accuracy of what is declared and should verify how the packer works.

What is a marine pollutant and does it change anything?

It is a substance identified as harmful to the marine environment, and it attracts additional marking and documentation requirements alongside the ordinary hazard information. The pollution prevention framework operates in parallel with the safety provisions.