# IMO dangerous goods classes

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Nine classes, several with divisions. The class on a dangerous goods
declaration determines packing, labelling, segregation on board and what a carrier will
accept at all.

| Class | Name | What it covers | Typical examples |
|---|---|---|---|
| 1 | Explosives | Substances and articles capable of a mass explosion, projection or fire hazard. Segregation and stowage are tightly prescribed and many carriers decline them outright. | Blasting agents, fireworks, ammunition, airbag inflators. |
| 1.1 | Mass explosion hazard | Division of class 1 | — |
| 1.2 | Projection hazard, no mass explosion | Division of class 1 | — |
| 1.3 | Fire hazard, minor blast or projection | Division of class 1 | — |
| 1.4 | No significant hazard | Division of class 1 | — |
| 1.5 | Very insensitive, mass explosion hazard | Division of class 1 | — |
| 1.6 | Extremely insensitive, no mass explosion hazard | Division of class 1 | — |
| 2 | Gases | Gases compressed, liquefied, dissolved or refrigerated. The division decides the handling: a flammable gas and an inert one travel under very different rules. | Propane, nitrogen, aerosols, oxygen, chlorine. |
| 2.1 | Flammable gases | Division of class 2 | — |
| 2.2 | Non-flammable, non-toxic gases | Division of class 2 | — |
| 2.3 | Toxic gases | Division of class 2 | — |
| 3 | Flammable liquids | Liquids giving off a flammable vapour at or below a defined flashpoint. One of the most frequently shipped classes, and one where packing group matters as much as class. | Paints, solvents, alcohols, petrol, many adhesives. |
| 4 | Flammable solids and reactive substances | Solids that ignite readily, materials liable to spontaneous combustion, and substances that emit flammable gas on contact with water. | Matches, sulphur, activated carbon, calcium carbide, some metal powders. |
| 4.1 | Flammable solids, self-reactive substances, desensitised explosives | Division of class 4 | — |
| 4.2 | Liable to spontaneous combustion | Division of class 4 | — |
| 4.3 | Emit flammable gas on contact with water | Division of class 4 | — |
| 5 | Oxidising substances and organic peroxides | Materials that yield oxygen and so intensify a fire, and organic peroxides which are thermally unstable. Temperature control is often mandatory for the latter. | Ammonium nitrate, hydrogen peroxide, calcium hypochlorite. |
| 5.1 | Oxidising substances | Division of class 5 | — |
| 5.2 | Organic peroxides | Division of class 5 | — |
| 6 | Toxic and infectious substances | Substances liable to cause death or serious injury if swallowed, inhaled or absorbed, and materials known or reasonably expected to contain pathogens. | Pesticides, arsenic compounds, clinical and diagnostic specimens. |
| 6.1 | Toxic substances | Division of class 6 | — |
| 6.2 | Infectious substances | Division of class 6 | — |
| 7 | Radioactive material | Material with activity above defined limits. Carriage is governed by its own transport index and criticality controls in addition to the general dangerous-goods rules. | Medical isotopes, uranium compounds, certain industrial gauges. |
| 8 | Corrosives | Substances that destroy living tissue or, on leakage, materially damage other cargo or the vessel itself. Packaging compatibility is the recurring failure point. | Sulphuric acid, sodium hydroxide, batteries containing free acid. |
| 9 | Miscellaneous dangerous substances and articles | Hazards real enough to regulate but not fitting classes 1 to 8. In practice the class most shippers meet first, because lithium batteries and marine pollutants sit here. | Lithium-ion batteries, dry ice, asbestos, environmentally hazardous substances. |

## Notes for automated readers

- The authority is the IMDG Code, published by the International Maritime Organization
  and amended on a two-year cycle. This page is a reading aid, not the Code.
- Class alone does not determine acceptance. UN number, packing group, flashpoint,
  quantity and packaging all bear on it, and segregation rules govern what may travel
  in the same container or the same hold.
- Classification is the shipper's legal responsibility. Misdeclared dangerous goods
  have sunk ships.

## Provenance and limits

Compiled from publicly available sources: published industry standards, official code
registers and carriers' own published specifications. FrateZone is not the issuing
authority for any of it, does not warrant that any figure here is correct, current or
complete, and makes no representation that a source has not changed since it was read.
Where a specification belongs to a specific physical unit or a specific contract, that
document governs, not this page.