Dangerous Goods Shipping Basics: IMDG Classes
Dangerous goods can be found in ordinary supply chains: paints, aerosols, batteries, chemicals, fuels, cleaning products, machinery containing fuel and many industrial materials. Their transport is controlled because a leak, fire, reaction or other incident can put crews, port workers, road users, cargo and the environment at risk. A shipment cannot be classified safely by relying on the product name or an informal description such as “chemical” or “non-hazardous”.
For sea freight, the International Maritime Dangerous Goods (IMDG) Code sets out the main requirements for classification, packaging, marking, labelling, documentation, stowage and segregation. This guide introduces the nine classes and the practical information a shipper needs before booking. For the wider container equipment context, see the shipping container guide.
Before a dangerous-goods booking
- Obtain the correct transport classification for the specific substance or article and mode.
- Identify the UN number, proper shipping name, primary class, subsidiary risk and packing group where assigned.
- Use approved packaging and follow the applicable packing, marking, labelling and segregation provisions.
- Give the carrier complete and accurate dangerous-goods information before the cargo is delivered.
- Check current sea and Australian road rules separately; compliance in one mode does not automatically satisfy the other.
Which rules apply to sea freight?
The IMDG Code is the international framework for dangerous goods carried by sea in packaged form. It sets out the requirements for individual substances and articles, including packaging, container traffic, stowage and segregation of incompatible goods. The International Maritime Organization's dangerous goods overview explains its role under SOLAS.
As at 11 November 2026, the IMDG Code 2024 Edition incorporating Amendment 42-24 has been mandatory since 1 January 2026. The IMO identifies this edition in its IMDG Code publication information. Always check the edition and amendments required for the shipment date, carrier and route rather than relying on an old supplier form.
In Australia, maritime carriage is also governed by the applicable domestic framework, including Marine Order 41 (Carriage of dangerous goods) 2017. Road movements are subject to the applicable Australian Dangerous Goods Code and state or territory implementation. The National Transport Commission lists ADG Code Edition 7.9 as the latest edition in its official code listing; check commencement and local requirements with the relevant competent authority.
The nine IMDG dangerous goods classes
The class identifies the type of hazard. Some classes have divisions, and a substance can also have a subsidiary risk. The class is not a rating of how dangerous a product seems in everyday use; it is part of a defined transport classification.
| Class | Hazard group | Examples and notes |
|---|---|---|
| 1 | Explosives | Explosive substances and articles; divided into divisions according to the nature of the hazard. |
| 2 | Gases | Flammable, non-flammable non-toxic and toxic gases; includes compressed, liquefied and dissolved gases. |
| 3 | Flammable liquids | Liquids that give off flammable vapour under the conditions defined by the Code, such as many fuels, solvents and certain paints. |
| 4 | Flammable solids and related hazards | Flammable solids, substances liable to spontaneous combustion, and substances that emit flammable gas when in contact with water. |
| 5 | Oxidising substances and organic peroxides | Materials that may cause or intensify combustion, including oxidisers and certain temperature-sensitive organic peroxides. |
| 6 | Toxic and infectious substances | Toxic substances and infectious substances capable of causing disease in humans or animals. |
| 7 | Radioactive material | Material containing radionuclides above the relevant activity concentration and total activity limits. |
| 8 | Corrosive substances | Substances that can cause severe damage to living tissue or corrode materials, such as certain acids and alkalis. |
| 9 | Miscellaneous dangerous substances and articles | Hazards not covered by the other classes, including certain environmentally hazardous substances, lithium batteries and other regulated articles. |
These are introductory descriptions only. The detailed class definitions, divisions, exclusions and specific entries are set out in the current IMDG Code and Dangerous Goods List.
UN number, proper shipping name and packing group
Each regulated entry is identified through information that must be declared accurately. The UN number identifies the dangerous-goods entry; the proper shipping name is the formal transport name; the class or division identifies the main hazard; and a subsidiary risk records an additional hazard where applicable. Many entries also have a packing group, which indicates the degree of danger for the purposes of the relevant packing provisions.
Packing groups are generally assigned as I, II or III where the Code provides for them. Not every class or entry uses a packing group. Do not infer the group from a product's retail label, concentration or general hazard statement. Use the applicable transport classification and the relevant Dangerous Goods List entry.
Why the safety data sheet is not the whole declaration
A safety data sheet (SDS) is an important starting point, particularly its transport information section. However, it should not be treated as a substitute for confirming the classification and shipping description required by the applicable transport code. An SDS may be out of date, may cover a product formulation different from the goods being shipped or may not address every mode-specific requirement.
Ask the manufacturer or supplier for a current SDS and transport classification. Check the UN number, proper shipping name, class, subsidiary risk, packing group if assigned, marine pollutant status, flash point where required and any special provisions. Where the classification is unclear, obtain advice from a competent dangerous-goods specialist before booking or packing.
Packaging, marks and labels
Dangerous goods must be packed in accordance with the applicable packaging instructions and any performance or approval requirements. The chosen package must be compatible with the contents and able to withstand the handling and transport conditions. Closures, inner packaging, absorbent material, cushioning and overpacking rules can be important for the specific entry.
Packages must carry the required marks and hazard labels, including the correct UN number and other prescribed details. Additional marks may be required for marine pollutants, limited quantities, elevated-temperature substances or other special cases. The outside of a freight container may also need placards and marks depending on the nature and quantity of the goods. Do not assume that a product's retail label meets the shipping rules.
Segregation and container loading
Some dangerous goods must be kept apart from incompatible goods. Segregation can apply between packages within a container, between containers on board a vessel, and between cargo and sources of ignition or heat. The exact requirements depend on the classes, subsidiary risks, quantities, packaging and relevant Code provisions.
Do not use a generic “keep apart” rule. Check the segregation provisions for the actual UN entries and the carrier's acceptance conditions. Consolidators may decline certain goods or impose restrictions on mixed loads. If the shipment is packed into a container or vehicle, the packing must also be suitable for the transport unit and the declaration must accurately describe the contents.
The IMO/ILO/UNECE CTU Code provides wider guidance on packing and securing cargo transport units, including dangerous goods. Our practical guide to packing and loading cargo to prevent damage covers restraint, load distribution and container checks.
Documentation for dangerous goods by sea
The shipper must provide the information and declarations required by the IMDG Code and the applicable Australian maritime rules. Depending on the movement, this includes the dangerous goods transport document or declaration, accurate package and quantity information, emergency contact details where required, and the container or vehicle packing certificate when applicable.
The Australian Maritime Safety Authority provides the AMSA 250 Multimodal Dangerous Goods Form. When it is used as a container or vehicle packing certificate only, the form does not replace the dangerous-goods declaration for each consignment packed in that unit. AMSA explains the form's intended use and submission process on its official site. Follow the carrier's process and deadlines, and ensure the person responsible for packing signs the required certificate.
Never conceal dangerous characteristics by using vague or inaccurate descriptions. Misdeclaration can lead to refusal, repacking, fines, delay, emergency response costs and serious safety consequences. If goods are not accepted by one carrier or service, do not simply change the description to obtain a booking.
Australian road transport is a separate check
A shipment may travel by road before export or after arrival. The relevant Australian Dangerous Goods Code requirements can include vehicle placarding, documentation, segregation, packaging, training and emergency information. The detailed requirements depend on the goods, quantities, packaging and applicable state or territory rules. Confirm the road leg with the dangerous-goods transport provider rather than assuming the sea documentation covers it.
Marine Order 41 and the ADG Code serve different transport contexts. A shipment may need to meet both sets of requirements during a multimodal journey. Confirm the regulations and competent authority requirements for each jurisdiction on the route.
Booking checklist for shippers and importers
- Identify the exact product, composition, concentration and physical state.
- Obtain a current SDS and verified transport classification for sea and road modes as applicable.
- Confirm the UN number, proper shipping name, class, subsidiary risk, packing group and marine pollutant status where relevant.
- Check carrier acceptance, route restrictions, quantity limits and any special handling requirements before making the booking.
- Select approved, compatible packaging and follow the specific packing instruction.
- Apply all required package marks, hazard labels and container placards.
- Confirm segregation from incompatible cargo and safe stowage arrangements.
- Prepare dangerous-goods documentation and any container/vehicle packing certificate required.
- Verify the road transport arrangements and local requirements for every Australian leg.
- Keep copies of declarations, classification evidence, packing records and emergency contact information.
Frequently asked questions
Are there nine dangerous goods classes?
Yes. The IMDG framework uses nine main classes, with several classes divided into subdivisions and some entries carrying subsidiary risks.
Are lithium batteries dangerous goods?
Many lithium battery shipments are regulated under Class 9, but the requirements depend on battery chemistry, whether batteries are standalone or contained in equipment, configuration, capacity, condition and the applicable special provisions. Use the exact entry and current Code requirements.
Can dangerous goods be shipped in a standard container?
Some can, provided the cargo, packaging, quantity, container, stowage and segregation meet the applicable requirements and the carrier accepts the booking. Other goods require specialist equipment or are restricted by the carrier or route.
Does an SDS make a shipment ready to book?
No. It is supporting information, not a complete shipping instruction. The transport classification, packaging, marks, labels, segregation and required declarations must all be checked against the applicable rules.
Get the classification right before cargo moves
Dangerous-goods compliance starts with accurate identification and continues through packaging, marking, declaration, segregation and transport. Confirm the current IMDG requirements for the sea leg and the relevant Australian rules for road movements. If the classification or packing instruction is uncertain, resolve it with the manufacturer or a competent specialist before cargo is tendered to the carrier. For additional guidance on safe container loading, read packing and loading cargo to prevent damage and return to the shipping container guide.