Shipping dangerous goods by sea involves far more than placing a warning label on a container. Every shipment must be correctly classified, packaged, marked, documented, stowed and segregated.
The IMDG Code provides the international framework for doing this safely and consistently.
For freight forwarders, shippers, warehouse teams, container packers and vessel operators, understanding the Code is essential. A classification error or missing declaration can delay cargo, trigger penalties and – more importantly – put people, vessels and the marine environment at risk.
This guide explains what the IMDG Code is, how its two volumes work, where classification rules appear, what the Dangerous Goods List contains, which documents may be required and why role-specific training matters.
What Is the IMDG Code in Shipping?
IMDG stands for the International Maritime Dangerous Goods Code. Developed by the International Maritime Organization (IMO), it governs dangerous goods and marine pollutants transported by sea in packaged form.
The Code translates international safety principles into practical requirements covering:
- Classification of dangerous goods
- Packaging and tank selection
- Package marking and labelling
- Container placarding
- Shipping documentation
- Stowage and segregation
- Emergency response information
- Training for shore-based personnel
The Code supports the mandatory dangerous-goods provisions in Chapter VII of the International Convention for the Safety of Life at Sea, better known as SOLAS. The IMO’s overview of dangerous goods carried by sea explains that the framework was created to harmonise safe carriage requirements and help prevent marine pollution.
The IMDG Code applies to dangerous goods carried by sea in packaged form, including goods in packages, intermediate bulk containers, large packaging and portable tanks. These goods may be transported in cargo transport units such as freight containers and vehicles.
Why the IMDG Code Matters ?
A dangerous-goods consignment can pass through several hands before reaching a vessel. A manufacturer may classify the product, a shipper may prepare the declaration, a warehouse may pack it, a forwarder may arrange transport, and a terminal may position the container for loading.
One incorrect decision can affect every party downstream.
The IMDG Code gives these organisations a common system for identifying hazards and communicating the controls required. Correct compliance helps teams:
- Select packaging suitable for the substance and its level of danger
- Apply the correct UN number and proper shipping name
- Identify primary and subsidiary hazards
- Keep incompatible materials apart
- Provide carriers and emergency responders with accurate information
- Reduce rejected bookings, port delays, incidents and enforcement action
A safety data sheet can assist with classification, but it does not replace the shipper’s obligation to verify the applicable transport requirements.
IMDG Code Volumes at a Glance
The IMDG Code is published in two main volumes, supported by a separate Supplement. The table below provides a practical overview.
| Resource | Main contents | Typical use |
| IMDG Code Volume 1 | General provisions, training, classification, packing and tank provisions, consignment procedures, construction and testing, and transport operations | Establishing how dangerous goods must be classified, prepared and handled |
| IMDG Code Volume 2 | Dangerous Goods List, special provisions, limited and excepted quantity information, appendices and alphabetical index | Looking up the requirements for a particular UN-numbered substance or article |
| IMDG Code Supplement | Emergency schedules, medical first-aid guidance, reporting procedures and related supporting texts | Emergency planning, incident response and specialised operational guidance |
These resources work together. Volume 2 may provide the shipment-specific entry, but the codes and instructions in that entry frequently direct the user back to provisions in Volume 1.
What Is in IMDG Code Volume 1?
IMDG Code Volume 1 contains Parts 1, 2 and 4 through 7. Its subjects include:
- Part 1: General provisions, definitions and training
- Part 2: Classification
- Part 4: Packing and tank provisions
- Part 5: Consignment procedures
- Part 6: Construction and testing of packagings, intermediate bulk containers, large packagings, portable tanks and related equipment
- Part 7: Transport operations, including stowage and segregation
Volume 1 is where users interpret the rules behind a shipment. It explains how to determine a hazard class, select and use approved packaging, prepare marks and labels, complete documentation and apply the correct handling and segregation controls.
What Is in IMDG Code Volume 2?
IMDG Code Volume 2 contains Part 3 and the main reference tools used for individual substances and articles. These include:
- The Dangerous Goods List
- Special provisions
- Limited-quantity and excepted-quantity provisions
- Appendix A, covering generic and not-otherwise-specified proper shipping names
- Appendix B, containing a glossary of terms
- The alphabetical index
In practice, users often begin with the alphabetical index or a known UN number. They then locate the relevant entry in the Dangerous Goods List and follow its references into the applicable parts of Volume 1.
The IMO’s current IMDG Code publication page identifies the edition presently in force and should be checked before relying on an older printed or electronic copy.
Which Part of the IMDG Code Is Concerned with Classification?
Part 2 of the IMDG Code is concerned with classification.
It establishes the principles used to assign substances and articles to one or more of nine hazard classes:
- Explosives
- Gases
- Flammable liquids
- Flammable solids and related substances
- Oxidising substances and organic peroxides
- Toxic and infectious substances
- Radioactive material
- Corrosive substances
- Miscellaneous dangerous substances and articles
Classification may require more than choosing a class. Depending on the material, teams may also need to establish:
- A division or subsidiary hazard
- The applicable UN number
- The proper shipping name
- A packing group
- Whether the material is a marine pollutant
- Whether special provisions or exemptions apply
The IMDG framework is aligned with the wider UN system. The UN Model Regulations on the Transport of Dangerous Goods provide the underlying international model for classification, hazard communication and transport controls across different modes.
Where test data or reliable product information is incomplete, classification should be handled by a competent person rather than estimated from a commercial product name.
Understanding the IMDG Code Table
When freight teams refer to the IMDG Code table, they usually mean the Dangerous Goods List in Chapter 3.2 of Volume 2.
Each row relates to a UN number and contains columns that direct the user to requirements such as:
- Proper shipping name and description
- Hazard class or division
- Subsidiary hazard
- Packing group
- Special provisions
- Limited and excepted quantities
- Packing instructions
- Portable tank instructions
- Emergency schedules
- Stowage and handling category
- Segregation requirements
- Marine-pollutant status
The table should not be read one column at a time. A compliant decision depends on interpreting the complete entry and following every referenced provision.
For example, identifying a flammable liquid as Class 3 is only the beginning. The concentration, flash point, packing group, quantity, packaging type, additional hazards and planned stowage can all change the requirements.
How Often Is the IMDG Code Revised?
The IMDG Code is generally amended on a two-year cycle. A new amendment is normally available for voluntary application during a transition year and becomes mandatory on the following effective date.
As of 2026, the 2024 Edition incorporating Amendment 42-24 is mandatory from 1 January 2026. Older procedures, templates or software settings should therefore be reviewed before they are used for current shipments.
The amendment cycle allows the Code to reflect:
- New products and technologies
- Changes to the UN Model Regulations
- Emerging risks such as developments in battery transport
- Revised classification criteria
- Updated packing provisions
- New or amended UN entries
- Operational lessons from incidents
A company can own the correct edition and still be non-compliant if its forms, standard operating procedures, booking systems or employee knowledge remain based on an earlier amendment.
IMDG Code Training: Who Needs It?
IMDG Code training is not only for vessel crews or designated dangerous-goods specialists. Shore-based personnel whose duties concern dangerous-goods transport must receive training appropriate to their responsibilities.
This may include employees who:
- Classify dangerous goods
- Prepare shipping documents
- Pack or fill packages and tanks
- Mark, label or placard packages and cargo transport units
- Load or unload containers
- Prepare stowage plans
- Accept dangerous-goods bookings
- Arrange transport or freight forwarding
- Enforce or audit compliance
Training should normally address general awareness, function-specific responsibilities and safety. Security awareness may also be required, with additional security training for personnel who have duties under a dangerous-goods security plan.
The crucial phrase is function specific. An employee preparing documentation needs different practical knowledge from someone selecting packaging or supervising container loading. Training should reflect what the individual does.
Records should be maintained in accordance with the applicable requirements, and refresher training should be provided when regulatory or operational changes affect the employee’s role.
A Practical IMDG Compliance Checklist
Before offering dangerous goods for sea transport, confirm that:
- The product has been classified by a competent person
- The correct UN number and proper shipping name are being used
- Primary and subsidiary hazards have been identified
- Packing-group and marine-pollutant status have been checked
- Packaging is permitted, tested and suitable for the contents
- Quantity limits and special provisions have been reviewed
- Packages carry the required marks and labels
- The container or vehicle is correctly labelled
- Incompatible goods have been segregated
- The transport document is complete and accurate
- The packing certificate is completed when applicable
- Carrier, port and national requirements have been checked
- Everyone performing a regulated function has suitable, current training
A checklist supports consistency, but it should never replace a consignment-specific review of the current Code.
Build Safer, More Confident Dangerous-Goods Operations
The IMDG Code becomes easier to use once employees understand how classification, the Dangerous Goods List, packing instructions, documentation and segregation connect. That understanding must extend beyond one compliance specialist: every person whose work affects a shipment needs enough role-specific knowledge to identify errors before cargo reaches the port.
The Allied Group provides IMO/IMDG Code general-awareness and function-specific training tailored to operational responsibilities.
Equip your team to classify, document and handle dangerous goods with greater confidence – Explore Allied group and start a conversation today !
This article provides general educational information and is not a substitute for the current IMDG Code, applicable national law, carrier instructions or advice from a qualified dangerous-goods professional.
