• The IMDG Code offers segregation requirements for various materials to ensure that incompatible substances do not come in contact with one another during shipping.

Segregation refers to the process of separating incompatible substances to avoid undue hazards should the packages leak or spill, or otherwise come in contact with one another in an accident.

The segregation table can be found in the International Maritime Dangerous Goods (IMDG) Code Section 7.2.4.

The codes listed in the table are as follows:

• X – Consult the Dangerous Goods list to verify whether there are specific segregation provisions
• * - See the IMDG section 7.2.7.1 for the segregation provisions of Class 1 explosives
• 1 – “away from”
• 2 – “separated from”
• 3 – “separated by a completed compartment or hold from”
• 4 – “separated longitudinally by an intervening complete compartment or hold from”

Additional segregation groups and special provisions and exceptions can be found in the IMDG Code Sections 7.2.5 and 7.2.6.

A helpful segregation flow chart can be found in the IMDG Code Chapter 7.2 Annex (for informational purposes only).

Segregation and stowage on containerships

Chapter 7.4 of the IMDG Code covers the stowage and segregation requirements on containerships. Containers meet the definition of a container in the International Convention for Safety Containers, 1972. These are containers transported on deck and in the cargo holds of containerships or on deck and in the cargo holds of other types of ships (provided the positions are fitted to give permanent stowage of containers during transport). If ships are not properly fitted for the permanent stowage of containers, then refer to IMDG Code Chapter 7.6.

Segregation and stowage on roll-on/roll-off ships

Chapter 7.5 of the IMDG Code covers the stowage and segregation of cargo transport units (CTUs) that are transported in roll-on/roll-off (ro-ro) cargo spaces. If a ro-ro ship has stowage positions that are fitted to give a permanent stowage of containers during transport, then the IMDG Code Chapter 7.5 applies. If the ro-ro ship has conventional cargo spaces, then refer to IMDG Code Chapter 7.6.

Segregation and stowage on general cargo ships

Chapter 7.6 of the IMDG Code covers the segregation and stowage of dangerous goods stored conventionally on board general cargo ships.

There are stowage and handling provisions based on class of dangerous goods. In general for all classes of dangerous goods:

• The minimum stacking height for testing packages is 3 meters.
• Drums must always be in an upright position.
• Dangerous goods must be arranged to provide clear walkways and access to all parts of the ship necessary for its safe operation.
• Fiberboard packages, paper bags, or other packages that could be damaged by water must be stowed under deck, or, if stowed on deck, protected so that they aren’t exposed to weather or seawater.
• Portable takes cannot be overstowed unless they are designed for that purpose.
• Cargo spaces and decks must be kept dry and clean and free of dust (to reduce ignition risks).
• If packages are found to be damaged or leaking, they cannot be loaded on the ship. Excess water, snow, ice, etc., must be removed before loading onto a ship.
• Packages must be braced and secured against movement and fittings must be protected.

Consult IMDG Code Chapter 7.6 for additional provisions specific to dangerous goods class.