IMDG Code – Basic Principles and Latest Changes
What is IMDG Code?
International Maritime Dangerous Goods Code (IMDG Code) is a globally recognized legal regulation that establishes uniform and binding rules for the transport of dangerous substances and articles by sea. Its administration is ensured by the International Maritime Organization (IMO), a specialized UN agency responsible for safety and environmental protection in maritime transport.
IMDG Code is binding for all ships sailing under the flag of a state that is a signatory to the SOLAS (Safety of Life at Sea) and MARPOL (Prevention of Pollution of the Seas) conventions. The rules are implemented into national legislation and practically determine the entire process – from packaging through documentation to handling emergency situations.
Main Objectives of IMDG Code
- Protection of human life: Minimization of risk to crews, port and transport personnel.
- Prevention of sea pollution: Protection of the environment from leakage of dangerous substances.
- Support for efficiency of international transport: Uniform rules reduce bureaucracy and confusion in global trade.
The Code is mandatory for all parties in the transport chain, including shippers, carriers, packers, ports and shipping companies. Violation of the rules can result not only in high fines, but also in endangerment of life and extensive environmental damage.
History and Development: From Fragmented Regulations to Unified Standards
The first need for unified rules for the transport of dangerous goods arose in 1929 during the preparation of the first SOLAS convention. Until then, states had their own, often incompatible standards, which complicated international trade and increased safety risks.
A key milestone was the creation of the UN Recommendations on the Transport of Dangerous Goods – Model Regulations. These define a system of classification, packaging, marking and documentation applicable to all modes of transport – road, rail, air and maritime.
Based on these recommendations, the first IMDG Code was created in 1965. Since 2004, the Code has been mandatory under the SOLAS convention for all signatory states. Every two years it is updated (“amendment”) to reflect developments in technology, accidents and scientific findings.
Basic Principles of IMDG Code
IMDG Code is built on a logical and detailed risk management system:
Classification and Identification
Dangerous goods are divided into 9 classes according to the main hazard (see table below):
| Class | Name | Examples |
|---|---|---|
| 1 | Explosive substances and articles | Pyrotechnics, explosives |
| 2 | Gases | Propane, oxygen, acetylene |
| 3 | Flammable liquids | Gasoline, acetone, paints |
| 4 | Flammable solids, self-igniting substances | Sulfur, phosphorus, sodium |
| 5 | Substances supporting combustion (oxidizing) | Peroxides, ammonium nitrate |
| 6 | Toxic and infectious substances | Cyanides, pesticides, viruses |
| 7 | Radioactive materials | Medical isotopes, uranium |
| 8 | Corrosive substances | Acids, hydroxides |
| 9 | Miscellaneous dangerous substances and articles | Batteries, asbestos, genetically modified organisms |
Each substance/article is assigned a four-digit UN number (e.g., UN 3480 – lithium batteries) and an official shipping name. This unambiguous identification is key to rapid and safe handling in emergency situations.
Classification process includes:
- Chemical analysis and physical testing (e.g., flash point, toxicity, reactivity with water)
- Assignment of UN number and shipping name
- Determination of packing group (PG) according to degree of hazard – I (high), II (medium), III (low)
- Determination of subsidiary hazards (e.g., toxic and corrosive at the same time)
Packaging (Packing) and Container Requirements
Containers must protect the contents from leakage under all conditions of normal and exceptional maritime transport. The Code establishes:
- Types of containers: from canisters and drums to large IBC (Intermediate Bulk Containers), approved for specific classes of goods
- Container testing (drop, tightness, hydrostatic tests)
- Marking with UN code (e.g., UN 4G/Y30/S/23/CZ/ABC1234 for a cardboard box for solids, PG II)
- New (from 2025) is the permission to manufacture IBC from recycled plastics – must meet special requirements for material, aging and durability
Marking, Labeling, Safety Signs (Placarding)
- Marking: UN number and shipping name must be clearly legible on each piece
- Labeling: Mandatory diamond-shaped labels (min. 100×100 mm) according to hazard class, often multiple labels
- Placarding: Large safety signs on CTU (containers, tanks) – min. 250×250 mm, on each side and front of the container
- Special marks for batteries, substances hazardous to the marine environment, radioactivity, etc.
Documentation
Each shipment must be accompanied by:
- Dangerous Goods Declaration (DGD) – contains complete information about the dangerous substance, quantity, packaging, method of transport, contacts, etc.
- New (42-24) e.g. requirement to state the date of manufacture and packaging and temperature during packaging for coal (UN 1361)
- A certificate of exemption is also required (if a specific SP – Special Provision is used)
Storage and Segregation (Stowage and Segregation)
IMDG Code establishes detailed rules for:
- Storage in ship’s hold (below/on deck, in special locations)
- Segregation of incompatible substances (e.g., acids and bases, oxidizers and flammables)
- Requirements for ventilation, protection from moisture, temperature limits
- Prohibition of joint storage of substances with risk of dangerous reaction
- New (e.g., for some UN numbers) change of stowage category to “D” = deck only, prohibition of transport on passenger ships
Procedures for Emergency Situations (Emergency Response)
Each item has its own EmS code for fire (F-x) and leakage (S-x), plus clear instructions in the IMDG Code Supplement:
- Measures for leakage, fire, explosion, contact with water
- Special requirements for protective equipment and emergency equipment
- Procedure for crew rescue and minimization of environmental damage
Training
According to IMDG Code, all employees who handle dangerous goods must be trained in the following areas:
- General knowledge of IMDG Code
- Specific skills according to job position (e.g., packaging, documentation, stacking containers)
- Safety and emergency procedures
Training is mandatory, regularly renewed and documented.
Structure of IMDG Code (2024/2025)
IMDG Code is an extensive document consisting of several main parts:
Volume 1
- Part 1: General provisions, definitions, training
- Part 2: Classification
- Part 4: Requirements for packaging, IBC and tanks
- Part 5: Marking, labeling, documentation
- Part 6: Construction and testing of containers, IBC and tanks
- Part 7: Rules for transport operations, storage and segregation
Volume 2
- Part 3: List of dangerous goods (Dangerous Goods List – DGL), special provisions (SP), exemptions
- Appendices: Generic and N.O.S. items, glossary of terms, alphabetical index
Supplement
- EmS Guide (emergency procedures)
- Medical First Aid Guide (MFAG)
- Guidelines for packing cargo units (CTU Code)
- Other IMO recommendations
List of Dangerous Goods (DGL)
Contains key information for each UN number in 18 columns:
| Column | Meaning | Example (UN 3480) |
|---|---|---|
| 1 | UN number | 3480 |
| 2 | Official shipping name | Lithium Ion Batteries |
| 3 | Class | 9 |
| 4 | Subsidiary hazard | – |
| 5 | Packing group (PG) | – |
| 6 | Special provisions (SP) | 188, 230, 310, 957 |
| 8, 10 | Packing instructions, IBC | P903, LP903, IBC08 |
| 15 | EmS codes | F-A, S-I |
| 16 | Storage/segregation instructions | Category A, SW2, SW22 |
Latest Changes in IMDG Code (Amendment 42-24, Effective from 1.1.2025)
Overview of Main Changes
1. Expansion of Definitions and Terminology:
- New definition of “degree of filling” – important for pressure containers.
- Expansion of the definition of recycled plastics (now includes IBC).
- Relabeling of data loggers and devices with dangerous substances as “Devices containing dangerous goods”.
2. Classification:
- New UN number 3555 for liquid desensitized explosives.
- New items for sodium-ion batteries (UN 3551, 3552) – standalone, with device, in device.
- Specific items for vehicles with various types of batteries – allows different requirements for fire safety and response.
- Changes in the classification of some metal powders and pyrotechnic substances.
3. List of Dangerous Goods (DGL):
- Carbon (UN 1361):
- Removal of SP925 (exemption from IMDG Code can no longer be used).
- Introduction of SP978 – new requirements for ventilation, packaging, temperature during packaging.
- Prohibition of use of certain types of bags in closed containers.
- Activated Carbon (UN 1362):
- SP979 – new exemptions and documentation obligations.
- UN 3423 (Tetramethylammonium hydroxide, solid form):
- Reclassification to class 6.1 with subsidiary corrosivity (PG I), prohibition in LQ, stricter limits for EQ, transport in IBC only with authority approval.
- UN 3536 (Lithium batteries installed in cargo transport unit):
- Stowage category D – deck only, prohibition of transport on passenger ships.
- New items: fire extinguishing devices with dispersion, sodium-ion batteries, disilane, gallium in articles, trifluoromethyltetrazole-sodium salt in acetone, vehicles with lithium/sodium-ion batteries.
4. Special Provisions (SP):
- SP28: Expansion to liquid desensitized explosives.
- SP388: New items for hybrid vehicles, modification of rules for ro-ro ships.
- SP406: Increase of limit for limited quantities of selected gases to 1000 ml.
- SP409: Transitional period allowing use of older version of Code for certain UN items.
5. Packaging:
- Permission to manufacture IBC from recycled plastics (must meet specific durability criteria).
- New guidelines for packaging battery vehicles (P912).
- For coal (UN 1361) must state date of manufacture, packaging and material temperature during packaging.
6. Documentation:
- New requirement to provide exemption certificate if special provision is used.
- New requirements for data in documents (e.g., for coal, activated carbon).
7. Storage and Segregation:
- Change of stowage category for several UN items – e.g., deck only, prohibition on passenger ships.
- New stowage codes for some chemicals – e.g., SW31 instead of SW5.
8. Other Changes:
- New rules for transport of data loggers and devices with dangerous substances.
- Expansion of exemptions for transport of UN 3077 and UN 3082 (if in quantity <5 kg/l, even if not marked as marine pollutants).
Practical Significance and Implementation of Changes
Example: Transport of Sodium-Ion Batteries in 2025
- Must use newly added UN number (3551, 3552)
- Specific requirements for packaging, marking (class 9 label, new mark for sodium-ion/lithium batteries)
- Obligation to update documentation and staff training on new battery types
- Special emergency procedures (EmS) for new battery types
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