Segregation on a Partly Loaded Container Ship

The proposal is not acceptable as described. Class 3 flammable liquids and Class 5.1 oxidizers must be segregated; the Code's segregation table treats the combination as requiring separation, typically "separated from" at minimum, and the presence of a flash point of 4 degrees C makes Unit A a serious fire load.

Reasoning steps:

1. Identify each unit's class and any subsidiary risk. Toluene is Class 3, PG II. Ammonium nitrate is Class 5.1, PG III. Carbon dioxide is Class 2.2.
2. Apply the segregation table for the class pairs. Class 3 versus Class 5.1 is a segregation case; Class 5.1 versus Class 2.2 is generally less restrictive but still subject to the table.
3. Apply the segregation codes for the specific substances. Ammonium nitrate carries special provisions and stowage codes that restrict proximity to combustible and flammable materials; those codes override a casual reading of the general table.
4. Translate the required segregation into physical distance on deck, using the Code's definitions of "away from," "separated from," and "separated by a complete compartment or hold."

So A and B cannot sit in adjacent stacks on the same tier. They must be separated by the distance the applicable segregation level requires, and the ammonium nitrate must be kept clear of combustible packaging and the toluene drums. Unit C should be checked against both, but the critical conflict is A versus B.

The crew member's reasoning is not sound. Explosivity is only one hazard relationship. Segregation exists because a fire in a flammable liquid can raise the oxidizer to temperatures where it decomposes or accelerates combustion, and because an oxidizer spill can intensify a fire involving the flammable liquid. The combination is more dangerous together than either alone, which is precisely what segregation is meant to prevent.

On-deck location helps: it provides ventilation for vapours and allows firefighting access, and it may satisfy stowage codes that require "on deck" for certain oxidizers or flammable liquids. But on-deck stowage does not erase the segregation requirement between A and B; it changes the physical means of achieving it, such as greater horizontal distance or a complete compartment separation.

The flash point of 4 degrees C means Unit A is a low-flash-point liquid that will evolve flammable vapour readily at ambient Halifax temperatures. That raises the priority for keeping it away from the oxidizer and from any heat source, and it should be stowed with due regard to the vapour hazard for the crew working the bay.

The planner should confirm that each unit has a complete multimodal dangerous goods transport document with the proper shipping name, UN number, class, packing group, number and kind of packages, and total quantity, and that the container/vehicle packing certificate is present for each containerized unit. The stowage plan should record the segregation decision and the basis for it.

Checks:

• Verify the declared classes match the labels and placards on the units.
• Confirm any special provisions on the entries for ammonium nitrate and toluene are reflected in stowage.
• Confirm the vessel's Document of Compliance covers the classes loaded and any quantity limits are respected.
• Confirm the emergency response information (EmS and MFAG references) is available to the crew for each entry.

With a valid Document of Compliance and full declarations, the remaining issue is purely stowage. The planner should revise the bay plan to achieve the required separation, document the change, and brief the crew on the firefighting considerations for the oxidizer and the low-flash-point liquid.