Some dangerous goods may dangerously react with another dangerous goods, such as acids & alkalis or cyanides and acids. Dangerous reactions may result in combustion and/or evolution of considerable heat, evolution of flammable, toxic or asphyxiant gases, the formation of corrosive substances or the formation of unstable substances.

Some dangerous goods may not dangerously react when they come in contact with each other but when together involved in fire the magnitude of fire may increase or may result in explosion.

Segregation is the process of separating two or more substances or articles which are considered mutually incompatible when their packing or stowage together may result in undue hazards in case of leakage or spillage, or any other accident. Segregation is obtained by maintaining certain distances between incompatible dangerous goods or by requiring the presence of one or more steel bulkheads or decks between them, or a combination thereof.

IMDG Code 40-20

There are four segregation terms used in IMDG Code which applies to packing cargo transport units and segregation on board different ship types

1. “away from”;
2. “separated from”;
3. “separated by a complete compartment or hold from”;
4. “separated longitudinally by an intervening complete compartment or hold from”.

The general provisions for segregation between the various classes of dangerous goods are shown in the segregation table

For full details see chapters

• 7.2 General segregation provisions
• 7.3 Consigning operations concerning the packing and use of cargo transport units (CTUs) and related
• provisions;
• 7.4 Stowage and segregation on containerships;
• 7.5 Stowage and segregation on roll-on/roll-off ships;
• 7.6 Stowage and segregation on general cargo ships; and
• 7.7 Shipborne barges on barge-carrying ships.