IMDG Code
The IMDG Code (International Maritime Dangerous Goods Code) is the international regulation governing the safe transport of dangerous goods by sea. Developed by the International Maritime Organization (IMO), it is mandatory under SOLAS Chapter VII. It is updated by amendment every two years.
Answer in Brief
The IMDG Code classifies all dangerous goods into 9 classes, specifies packaging and labelling requirements, defines stowage and segregation rules for ships, and sets emergency response procedures. Every ship carrying packaged dangerous goods must comply.
The 9 Dangerous Goods Classes
| Class | Hazard | Examples |
|---|---|---|
| Class 1 | Explosives | Ammunition, fireworks, airbag inflators |
| Class 2 | Gases | LPG, acetylene, oxygen cylinders, fire extinguishers |
| Class 3 | Flammable liquids | Gasoline, alcohol, solvents |
| Class 4 | Flammable solids, self-reactive, pyrophoric | Matches, metal powders, calcium carbide |
| Class 5 | Oxidising substances and organic peroxides | Hydrogen peroxide, ammonium nitrate |
| Class 6 | Toxic and infectious substances | Pesticides, medical waste |
| Class 7 | Radioactive material | Nuclear fuel, medical isotopes |
| Class 8 | Corrosives | Battery acid, hydrochloric acid |
| Class 9 | Miscellaneous dangerous goods | Lithium batteries, dry ice, magnetised material |
Key IMDG Code Requirements
Packaging
Dangerous goods must be packaged in UN-approved packaging — tested and marked with the UN mark (circle with UN designation, packaging group, testing authority). Packaging must contain the goods safely under transport conditions.
Labels and Placards
- Labels: Diamond-shaped, colour-coded, numbered (class number). Attached to packages.
- Placards: Larger versions of labels placed on freight containers.
- Marks: UN number, Proper Shipping Name, shipper/consignee details.
The Dangerous Goods Declaration
Before loading, the shipper must provide a Dangerous Goods Declaration confirming the goods are properly classified, packaged, marked, and labelled. The ship’s officer receives and verifies this before accepting the cargo.
Stowage and Segregation
The IMDG Code specifies where dangerous goods can be stowed on the ship:
- On deck or under deck
- Away from heat sources, living quarters, or incompatible goods
- Segregation requirements: Many classes must be separated from each other (e.g., flammables away from oxidisers, poisons away from food). Segregation categories: “away from”, “separated from”, “separated by a complete compartment or hold from”, “separated longitudinally…”
Emergency Response
The IMDG Code includes Emergency Response Procedures (EmS) for each substance — what to do in a fire involving the cargo and what to do in a spillage. Referenced in the ship’s SOPEP and cargo emergency plans.
Seafarer Responsibilities
Chief Officer / Cargo Officer:
- Verify dangerous goods declarations before accepting cargo
- Plan stowage in compliance with IMDG segregation requirements
- Ensure proper labelling/marking on board
- Maintain a Dangerous Goods Manifest (list of all DG cargo onboard)
- Brief crew on emergency procedures for DG cargo onboard
All Officers:
- Know where the IMDG Code supplement (EmS guide) is kept
- Know which cargo is onboard and its hazard class
- Know the emergency response for that cargo
The Master:
- Has the right to refuse dangerous goods that are improperly declared, packaged, or documented
Frequently Asked Questions
Q: What is the UN number on a dangerous goods label? A 4-digit number (e.g., UN 1203 for petrol, UN 1072 for oxygen) that uniquely identifies the dangerous substance. Used by emergency responders and referenced in EmS guides.
Q: What is Packaging Group (PG)? Indicates the degree of danger within a class: PG I (great danger), PG II (medium danger), PG III (minor danger). Affects packaging requirements.
Q: Is IMDG Code mandatory? Yes — mandatory under SOLAS Chapter VII for all ships carrying packaged dangerous goods. The flag state enforces compliance, and port state control inspectors check DG compliance.
Questions about dangerous goods handling, stowage planning, or cargo documentation? Chat with SailorGPT