IMDG Code: The Complete Guide to Shipping Dangerous Goods by Sea (2026 Edition)
- Capt. Anuj Chopra
- 13 hours ago
- 22 min read
Quick Answer: The IMDG Code (International Maritime Dangerous Goods Code) is the mandatory IMO framework governing classification, packaging, marking, documentation, stowage, and segregation of dangerous goods shipped by sea. It is mandatory under SOLAS Chapter VII and MARPOL Annex III, enforced across 150+ countries covering 98% of the global merchant fleet. The current mandatory edition is Amendment 42-24, effective 1 January 2026.
During my years at RightShip vetting vessels and reviewing operator safety records, I kept seeing the same pattern in incident investigations: the IMDG Code had not failed. It had been bypassed. A freight forwarder substituted a trade name for the Proper Shipping Name. A shipper assigned the wrong packing group. A terminal overrode a segregation plan because the cargo needed to move. The paperwork looked fine until there was a fire.
In 2024, approximately 250 fire and explosion incidents occurred across all vessel types worldwide, a 20% increase on the prior year and the highest figure in at least a decade, per the Allianz Safety and Shipping Review 2025. The World Shipping Council recorded 576 containers lost at sea in 2024. Behind both numbers is a single recurring root cause: dangerous goods moving without proper compliance with the framework designed to govern them.
This guide covers the IMDG Code from structure to enforcement, how it works, what changed in Amendment 42-24, where the compliance chain breaks, and what operators and freight forwarders actually need to do differently.
Who this guide is for: freight forwarders, ship operators, cargo superintendents, DG compliance officers, and logistics managers handling hazardous cargo by sea.
What Is the IMDG Code and Why Is It Mandatory?
The IMDG Code is the international regulatory framework, published by the International Maritime Organization, that governs the classification, packaging, marking, labelling, documentation, stowage, and segregation of dangerous goods transported by sea in packaged form.
It is not a set of guidelines. Two of the most consequential international maritime conventions make it mandatory.
SOLAS Chapter VII, Part A: prohibits the carriage of dangerous goods in packaged form unless the shipment complies with the Code. There is no carve-out for small quantities, expedited shipments, or commercial necessity.
MARPOL Annex III extends the obligation to harmful substances and marine pollutants. A substance classified as a marine pollutant under the IMDG Code carries documentation, marking, and stowage requirements beyond what its hazard class alone would require.
The Code applies across more than 150 countries whose fleets represent over 98% of global merchant fleet tonnage. Every flag state that has ratified SOLAS incorporates these requirements into its national maritime law. Port state control authorities enforce them at the berth. The legal exposure runs from the shipper who misclassifies a substance through to the ship operator whose crew accepts undocumented cargo.
Where the Code came from
In 1956, the United Nations Committee of Experts on the Transport of Dangerous Goods, the body behind what became the UN Orange Book, presented its first recommendations for international harmonisation. The IMO began drafting what would become the IMDG Code in 1961. The Maritime Safety Committee adopted it in 1965, initially as a recommendation. It remained recommendatory until 2004, when it became mandatory under SOLAS amendments adopted in 2002.
Since 2004, the Code has been updated every two years. Amendments are proposed, reviewed by the Sub-Committee on Carriage of Cargoes and Containers (CCC), and adopted by MSC resolution. Odd-numbered years are transition periods during which compliance can follow either the expiring or incoming edition. The new edition becomes mandatory on 1 January of the following even-numbered year.
The current mandatory edition is Amendment 42-24, adopted under IMO Resolution MSC.556(108). It became mandatory on 1 January 2026.
How the IMDG Code Is Structured: Volumes, Parts, and Supplement
The single most common compliance mistake I saw at RightShip, across vetting questionnaires, audits, and incident reports, was shippers treating a DGL lookup as the whole job. They searched their UN number in Volume 2, noted the class and packing group, and moved on. They never read the packing instructions in Volume 1. They missed the special provisions that modified their stowage category. They shipped.
The two volumes are a single system. They cannot be split.
Volume 1 contains:
Part 1: General provisions, definitions, and training obligations. Part 1.3 sets out the training requirements for shore-based personnel, a section that gets far less attention than the classification tables.
Part 2: Classification criteria. This is where you determine whether a substance meets the criteria for a given class and, if so, which packing group applies.
Parts 4–7: Packing and tank provisions, packaging construction and testing requirements, consignment procedures, and transport operations including stowage and segregation rules.
Volume 2 contains:
Part 3: The Dangerous Goods List (DGL), the special provisions index, and appendices. The DGL is the operational heart of the Code. Every entry, indexed by UN number, specifies the Proper Shipping Name, class, subsidiary hazards, packing group, label requirements, limited-quantity threshold, packing instructions, stowage category, segregation codes, EmS reference, and marine pollutant status.
The Supplement provides the emergency response framework used aboard the vessel: the Emergency Schedule (EmS) Guide with fire and spillage schedules keyed to each DGL entry, the Medical First Aid Guide (MFAG) for exposure response, incident reporting procedures, and provisions of the INF Code governing irradiated nuclear fuel.
Part | Volume | Content |
Part 1 | Volume 1 | General provisions, definitions, training |
Part 2 | Volume 1 | Classification criteria |
Part 3 | Volume 2 | Dangerous Goods List, special provisions |
Part 4 | Volume 1 | Packing and tank provisions |
Part 5 | Volume 1 | Consignment procedures |
Part 6 | Volume 1 | Packaging construction and testing |
Part 7 | Volume 1 | Transport operations: stowage, segregation, handling |
Supplement | Separate | EmS Guide, MFAG, reporting, INF Code |
The official IMDG Code publications are available from IMO Publishing. Using an outdated edition is itself a compliance deficiency. Port state control inspectors find it more often than it should occur.
The Nine Classes of Dangerous Goods, With Operator Notes
Every dangerous substance or article transported by sea in packaged form falls into one of nine hazard classes. Classification drives everything downstream: packaging, marking, labelling, stowage position on the vessel, segregation from incompatible cargoes, and emergency response.
Treating classification as a formality is where the compliance chain first breaks.
Class | Divisions | Hazard Type | Common Maritime Cargo Examples |
1 | 1.1 – 1.6 | Explosives | Ammunition, fireworks, airbag inflators, detonators |
2 | 2.1, 2.2, 2.3 | Gases | LPG cylinders, aerosols, compressed oxygen, toxic industrial gases |
3 | , | Flammable liquids | Paints, resins, fuels, adhesives, cleaning solvents |
4 | 4.1, 4.2, 4.3 | Flammable solids / self-reactive / water-reactive | Matches, sulfur, sodium metal, calcium carbide |
5 | 5.1, 5.2 | Oxidising substances and organic peroxides | Ammonium nitrate fertilisers, bleaching agents, organic peroxides |
6 | 6.1, 6.2 | Toxic and infectious substances | Pesticides, pharmaceuticals, biological specimens, diagnostic cultures |
7 | , | Radioactive material | Medical isotopes, industrial radiography sources, low-level waste |
8 | , | Corrosives | Battery acid, caustic soda, hydrochloric acid, electroplating solutions |
9 | , | Miscellaneous dangerous substances and articles | Lithium batteries, dry ice, magnetised material, elevated-temperature substances, EV batteries |
A note on subsidiary hazards
Many substances carry a primary class and one or more subsidiary hazards. A substance classified as Class 8 (corrosive) might also carry a 6.1 subsidiary hazard (toxic). The DGL entry will show both. The subsidiary hazard affects labelling, both labels must appear on the package, and may affect stowage and segregation requirements. Ignoring subsidiary hazards is a frequent source of non-conformities.
Class 9 and lithium batteries
Class 9 has grown considerably in practical importance. Lithium-ion and lithium metal batteries, shipped individually, in equipment, or as cargo, now account for a substantial share of IMDG Code compliance activity. EV shipments bring additional complexity. Amendment 42-24 introduced new UN numbers for sodium-ion batteries and revised stowage categories for lithium battery types based on watt-hour ratings.
How to Read a Dangerous Goods List Entry
The DGL in Volume 2 is a 19-column table. Each row corresponds to a UN number and Proper Shipping Name. Knowing which columns matter, and what each one requires you to do, is the practical skill that separates a compliance professional from someone who looked up a number.
Walkthrough: UN 3480, Lithium Ion Batteries
Column | Entry | What it means operationally |
UN No. | 3480 | The number that goes on the package and the Dangerous Goods Declaration |
Proper Shipping Name | LITHIUM ION BATTERIES | Must appear verbatim on the DGD, not "Li-ion batteries," not a brand name |
Class | 9 | Primary hazard: miscellaneous dangerous article |
Subsidiary hazard | , | None for standard shipment; varies with state of charge and damage |
Packing group | , | Class 9 batteries do not carry a packing group |
Labels required | Class 9 + lithium battery mark | Both must appear on the outer packaging |
Special provision | SP 188 | Sets the watt-hour limits that determine whether a shipment is fully regulated or partially exempt |
Packing instruction | P903 | Governs packaging requirements for batteries shipped alone (not in or with equipment) |
Limited quantity | 0 | No limited quantity relief for UN 3480 |
Stowage category | SW1 (Amendment 41-22) / revised in 42-24 | Determines whether cargo must be on deck or under deck, and in which spaces |
Segregation | SG69 | Category-specific segregation from incompatible cargoes |
EmS | F-A, S-I | Emergency fire and spillage schedules to consult from the Supplement |
Special Provision 188 is the threshold that determines whether a lithium battery shipment is fully regulated or exempt from certain requirements. For lithium ion cells, the threshold is 20 Wh. For batteries, it is 100 Wh. Shipments above these thresholds are fully regulated under UN 3480 or UN 3481. Amendment 42-24 tightened several SP 188 criteria for cells and batteries transported as cargo, without equipment, specifically to address the undeclared or misdeclared battery shipments behind several serious container fires.
Packaging, Marking, and Labelling Requirements
Packing groups
Classes 1, 2, 7, and most Class 9 substances do not carry packing groups. For the remaining classes, three packing groups signal the degree of hazard the substance presents:
Packing Group I: Great danger. Highest-performance packaging required.
Packing Group II: Medium danger.
Packing Group III: Minor danger. Least restrictive packaging performance standard.
The packing group determines which packing instruction applies. A Class 3 liquid classified PG I will face different packaging requirements than the same substance classified PG III, typically a higher UN performance testing standard for the outer packaging.
Marking
Every package containing dangerous goods must show the UN number (in the format "UN XXXX"), the Proper Shipping Name, and, where applicable, the consignee name and address. Additional marking requirements apply to limited quantities (the LQ mark), excepted quantities (the EQ mark with shipper and recipient details), and marine pollutants (the marine pollutant mark).
Labelling
Labels are standardised diamond-shaped symbols, 100mm × 100mm minimum for most packages. Each label corresponds to a hazard class or subsidiary hazard. A package carrying a primary Class 8 label with a 6.1 subsidiary hazard requires both labels on the same face of the package. The Dangerous Goods List specifies exactly which labels each entry requires.
Limited quantities and excepted quantities
Not all dangerous goods in small quantities require full IMDG Code compliance. The Code provides two relief provisions:
Limited quantities (LQ): Small inner packages (the threshold varies by class and substance) may be shipped under simplified requirements, reduced marking, no class labels, provided the outer packaging passes drop tests and each inner package remains within the LQ threshold.
Excepted quantities (EQ): Minimal amounts intended primarily for testing or display may qualify for further simplified treatment, with the EQ mark replacing class labels entirely.
Neither provision applies universally. For many Class 1, 4.2, 5.2, 6.1, 6.2, and 7 substances, the limited quantity or excepted quantity thresholds are zero, meaning no relief is available regardless of quantity. Check the DGL column before assuming LQ applies.
Container/Vehicle Packing Certificate
Whenever dangerous goods are packed into a container or vehicle, the person responsible for packing must complete a Container/Vehicle Packing Certificate confirming that the container is fit for purpose, the cargo is properly packed and secured, and all IMDG requirements for the goods in question have been met. This certificate accompanies the transport document and forms part of the documentation package the ship's officer reviews before accepting cargo.
Stowage and Segregation: What the Master Reviews Before Departure
Stowage and segregation are where the IMDG Code moves from paperwork into physical cargo placement. For ship operators, this is where the Master's responsibility becomes direct.
Stowage categories
Each DGL entry carries a stowage code that assigns the cargo to one of five categories:
Category | Stowage requirement |
A | On deck or under deck |
B | On deck or under deck, subject to master's discretion |
C | On deck only |
D | On deck only, away from living quarters |
E | On deck or under deck, away from heat sources |
Some entries carry additional stowage handling codes (SW codes) that add specific restrictions, temperature control requirements, ventilation conditions, prohibition in certain spaces.
Segregation terms
Four terms describe the required physical separation between incompatible dangerous goods. They represent escalating distances:
Away from: Keep a minimum separation between the cargoes. Under deck, a minimum distance or an intermediate deck between the goods.
Separated from: A complete bulkhead or deck between the two cargoes. Under deck, a single intervening space.
Separated by a complete compartment or hold from: A complete intervening hold or compartment, not just a bulkhead.
Separated longitudinally by an intervening complete compartment or hold from: The strictest separation. The cargoes must be in different holds with an uninvolved hold between them, and not in adjacent deck positions.
The segregation table
Volume 1, Chapter 7.2.4 contains the segregation table. It cross-references 14 segregation groups against each other, Acids against Alkalis, Oxidisers against Flammables, Explosives against Corrosives, and so on, producing a required segregation term for each pair. The DGL entry's segregation codes (SG codes) then add substance-specific requirements on top of the group requirements.
In practice, the cargo plan for a container vessel carrying multiple DG consignments involves cross-referencing every dangerous goods entry against every other, an exercise that cargo planning software handles, but which the Chief Officer and Master remain responsible for verifying.
Where terminal schedules override segregation plans
The most dangerous practical failure I saw repeatedly in vessel vetting: a terminal overrides a cargo plan because a container arrived late, or because a slot was available, or because no one checked. The IMDG Code does not provide a commercial exception to segregation requirements. When terminal software flags a segregation conflict, the container does not load. That is the correct outcome, however inconvenient.
Documentation Required for Shipping Dangerous Goods by Sea
The documentation chain runs from the shipper to the competent authority. A break at any point in that chain creates liability that attaches to the party who broke it, and in maritime dangerous goods law, courts have held shippers liable even when they delegated declaration completion to freight forwarders.
Dangerous Goods Declaration
The DGD is the primary document. It must include:
UN number
Proper Shipping Name (not a trade name, not an abbreviation)
Class and, where applicable, subsidiary hazard
Packing group (where applicable)
Total quantity (by mass or volume)
Number and type of packages
Packaging specification code
Marine pollutant designation (if applicable)
Shipper and consignee details
Emergency contact information
The DGD is the shipper's declaration. The freight forwarder may complete it, but the shipper signs it and bears legal responsibility for its accuracy. Using a trade name instead of the Proper Shipping Name is a non-conformity that can result in cargo rejection at port. Using a wrong UN number is a potential criminal offence under many national implementations of SOLAS.
Multimodal Dangerous Goods Form
When a consignment moves by more than one transport mode, for example, road to port, then sea, the same document serves across modes, provided it meets the requirements of each mode's regulations. The IMDG Code accepts the multimodal form specified in the UN Model Regulations.
Container/Vehicle Packing Certificate
As noted above, this accompanies any DG consignment packed in a container. The Officer of the Watch who signs for the container on acceptance is confirming, among other things, that this certificate is present and complete.
Transport document requirements for the vessel
Part 5.4 of the Code sets out what must be on board the ship at departure: a complete manifest or stowage plan showing the location of all dangerous goods on board, with class and UN number. The Master must be able to locate any DG consignment and access its emergency response information at any time during the voyage.
IMDG Code Training Requirements
Part 1.3 of the Code sets out training obligations for shore-based personnel. It receives far less attention in compliance programmes than the DGL or documentation chapters, which is exactly why it keeps appearing as a deficiency in port state control inspection reports.
Shore-based personnel
Anyone involved in the preparation, shipment, or transport of dangerous goods by sea must have training appropriate to their responsibilities. The Code distinguishes between:
Awareness/familiarisation training: General dangerous goods awareness for personnel with limited DG contact.
Function-specific training: Detailed training in the classification, documentation, packaging, or handling requirements relevant to the person's role.
Safety training: Handling procedures, protective measures, and emergency response.
Training must be renewed before records lapse. The standard certification validity is three years. Employers must retain training records and produce them on request from the competent authority.
Seafarers
Crew members directly involved with dangerous cargo must have STCW-compliant dangerous goods training. STCW Table A-VI/3 covers dangerous, hazardous, and harmful cargoes. For passenger ships, Table A-V/2 adds passenger safety and cargo handling requirements. The seafarer's Certificate of Competency demonstrates basic STCW compliance; the IMDG Code adds the requirement that crew directly handling DG cargo have function-specific training beyond the STCW minimum.
IMDG Certification for freight professionals
Several national competent authorities and industry bodies offer IMDG Code certification for shore-based logistics and compliance professionals. These typically cover classification, DGL navigation, documentation, and packaging requirements. Certification usually runs three years before renewal is required.
Amendment 42-24: What Changed and What It Means Operationally
Amendment 42-24, adopted under IMO Resolution MSC.556(108), became mandatory on 1 January 2026. For operators and freight forwarders who handle new energy vehicles, battery cargo, or carbon products, several changes required immediate action.
New UN numbers: Sodium-ion batteries
Amendment 42-24 introduced dedicated UN numbers for sodium-ion batteries, which had previously been carried under existing lithium battery entries or as Class 9 miscellaneous substances without a specific UN number. The new entries follow the same structure as the lithium battery entries:
Sodium-ion batteries (UN 3551): batteries shipped alone
Sodium-ion batteries in equipment (UN 3552): batteries installed in a device
Sodium-ion batteries packed with equipment (UN 3553): batteries accompanying the device they power
Shippers who had been classifying sodium-ion battery shipments under general Class 9 or as non-dangerous goods needed to reclassify and update all documentation.
New UN number: Carbon electrodes and related articles
Amendment 42-24 added a new entry for carbon electrodes, following incidents involving spontaneous heating of certain carbon-based articles during sea transport. The entry carries specific stowage and ventilation requirements.
Lithium battery stowage category revisions
Several lithium battery entries received upgraded stowage categories under Amendment 42-24, specifically, a move from Category A (on deck or under deck) to Category C (on deck only) for certain cell types above defined watt-hour thresholds. For operators carrying significant battery cargo in container holds, this required a review of cargo planning procedures and physical hold allocation.
Enhanced documentation for EV cargo
New requirements for electric vehicle shipments under Amendment 42-24 include enhanced pre-shipment condition verification and state-of-charge documentation. Operators carrying roll-on/roll-off EV cargo faced the most immediate operational impact, with several major ferry and RoPax operators updating their acceptance checklists and crew briefing materials ahead of the January 2026 mandatory date.
Special Provision 188 changes
SP 188, which governs whether a lithium battery shipment qualifies for partial exemptions from full IMDG Code requirements, was revised to tighten several threshold conditions. The most significant change affected batteries shipped as cargo (not in or with equipment) above certain watt-hour levels, those shipments moved from partial exemption to full regulation under the DGL entry requirements.
Misdeclared Cargo: The Root Cause of Container Ship Fires
The fire statistics I cited at the opening of this article point to a systemic problem that the IMDG Code cannot solve by itself. The Code works when it is applied. When it is bypassed, through misdeclaration, outdated editions, inadequate training, or terminal pressure to load non-compliant cargo, the physical chemistry of incompatible or self-reacting substances does not pause to wait for compliance.
The most common misdeclarations
From incident investigations and PSC reporting data, the patterns are consistent:
Trade name substituted for Proper Shipping Name. A substance shipped as "XYZ Industrial Cleaner" rather than "CORROSIVE LIQUID, ACIDIC, INORGANIC, N.O.S." cannot be identified by emergency responders from its documentation. The EmS schedule cannot be located. The stowage category is unknown. This happens constantly.
Wrong class or wrong packing group. Deliberate misclassification to avoid handling surcharges, or genuine misclassification through inadequate knowledge of classification criteria. PG I substances shipped as PG III face weaker packaging requirements and different stowage terms.
Undeclared subsidiary hazard. A substance with a 6.1 toxic subsidiary hazard declared only under its Class 3 primary hazard. Labels missing. Segregation from food cargo ignored.
Undeclared marine pollutant. The marine pollutant mark and the enhanced documentation requirement it triggers are omitted. Common with substances that carry a marine pollutant status only in certain concentrations.
Lithium battery state of charge. Batteries shipped at a higher state of charge than SP 188 permits for exempted quantities.
PSC enforcement patterns
Port state control inspections increasingly include a dangerous goods documentation check, particularly for container vessels. The most common deficiencies recorded involve: incorrect or missing Dangerous Goods Declarations, absent or incomplete Container/Vehicle Packing Certificates, stowage plan discrepancies between declared cargo location and actual position, and outdated IMDG Code editions in use aboard the vessel.
An inspection that finds DG documentation deficiencies can result in detention until the deficiency is corrected. For a loaded container vessel that is already scheduled to berth at the next port, detention is commercially severe.
Consequences of IMDG Code Non-Compliance
Flag state detention
A flag state surveyor who identifies IMDG Code non-conformities during a survey or in response to an incident report can detain the vessel. Detention continues until the deficiency is corrected to the surveyor's satisfaction.
Port state control deficiencies and detention
PSC inspection results are published in the Equasis database and the relevant MOU databases, Tokyo MOU, Paris MOU, Indian Ocean MOU. A vessel with a record of DG-related PSC detentions faces increased inspection frequency. Persistent deficiency patterns can trigger a ban from port state control regimes.
Financial penalties
National implementations of SOLAS set their own penalty structures for IMDG Code violations. Some examples:
United States (US PHMSA): Civil penalties for hazardous materials violations can reach USD 81,993 per violation per day. Criminal penalties for knowing violations can reach USD 500,000 and five years imprisonment.
United Kingdom (UK MCA): Prosecution under the Dangerous Goods in Harbour Areas Regulations can result in unlimited fines.
Singapore (MPA): Deliberate misdeclaration under the Merchant Shipping (Dangerous Goods) Regulations carries fines up to SGD 10,000 and potential imprisonment.
Criminal liability for deliberate misdeclaration
Multiple jurisdictions have prosecuted shippers and logistics companies for deliberate IMDG misdeclaration. In cases where fire or death followed a misdeclared shipment, prosecutions have resulted in significant prison sentences. The legal burden falls on whoever signed the Dangerous Goods Declaration, which is why the shipper's signature on that document carries genuine weight.
P&I club coverage exclusions
P&I clubs have consistently held that losses arising from deliberate misdeclaration of dangerous goods fall outside coverage. An operator who accepts a container with a fraudulent DGD and suffers fire damage may face a coverage dispute if the club can demonstrate the operator's crew should have identified the non-conformity at acceptance.
IMDG Code vs IMSBC Code: Which Applies?
The IMDG Code governs dangerous goods in packaged form. The IMSBC Code (International Maritime Solid Bulk Cargoes Code) governs solid bulk cargoes. The distinction is the form in which the cargo reaches the vessel.
A consignment of ammonium nitrate fertiliser in bags, drums, or intermediate bulk containers is packaged form, IMDG Code applies. The same substance shipped as bulk cargo poured directly into a hold is a solid bulk cargo, IMSBC Code applies. The regulatory framework differs substantially between the two, including classification criteria, documentation requirements, and the shipper's obligations to provide cargo information.
Some substances appear in both frameworks. Certain bulk cargoes carry a subsidiary hazard classification that refers back to the IMDG Code for emergency response information. Conversely, some Class 4 and Class 5 IMDG substances in large packagings begin to behave like bulk cargoes at sufficient quantity and require evaluation under IMSBC criteria as well.
For Class B substances under the IMSBC Code, substances that pose a chemical hazard when shipped in bulk, the dangerous goods classification from the IMDG Code is cross-referenced for emergency response. A shipper declaring a Class B solid bulk cargo needs to know its IMDG Code class to complete the IMSBC cargo declaration correctly.
When in doubt about which code applies, the decisive question is: is the cargo enclosed in packaging, or is it loose bulk?
Frequently Asked Questions
What is the current mandatory edition of the IMDG Code?
Amendment 42-24, adopted under IMO Resolution MSC.556(108), became mandatory on 1 January 2026. Amendment 41-22 remained in force as an alternative during the 2025 transition year. Using Amendment 40-20 or earlier editions aboard a vessel now is a compliance deficiency.
Who is responsible for completing the Dangerous Goods Declaration?
The shipper (consignor) bears legal responsibility for the accuracy of the DGD. A freight forwarder may prepare the document on the shipper's behalf, but the shipper's signature confirms the declaration. If the DGD contains errors, liability attaches to the shipper regardless of whether a third party prepared it.
What is the Proper Shipping Name, and why must it appear verbatim?
The Proper Shipping Name is the official name assigned to each DGL entry. It appears exactly as written in the Dangerous Goods List, in capitals, with the technical name following where the entry includes an NOS (Not Otherwise Specified) designation. Using a trade name, a brand name, or an abbreviated form is a non-conformity and can prevent emergency responders from identifying the substance's hazard class and EmS schedule.
Can dangerous goods be shipped in limited quantities without a Dangerous Goods Declaration?
Limited quantity relief simplifies certain requirements, marking, labelling, but a transport document describing the goods as limited quantities is still required. Some classes carry a zero limited quantity threshold, meaning no relief is available. The DGL column for limited quantities confirms whether relief applies.
What is the Emergency Schedule (EmS) Guide and where is it used?
The EmS Guide is part of the IMDG Code Supplement. It provides fire schedules (F-series) and spillage schedules (S-series) keyed to each DGL entry. A vessel with a dangerous goods incident uses the EmS reference from the DGL entry, for example, F-A, S-I for UN 3480, to locate the correct emergency response procedures. The MFAG in the same Supplement covers medical response to human exposure.
What does "packing group" mean, and does it apply to all classes?
Packing groups I, II, and III indicate the degree of danger a substance presents: great, medium, and minor, respectively. They do not apply to all classes. Class 1, 2, 7, and most Class 9 substances do not carry packing groups. The packing group determines which packing instruction applies and the performance standard required of the packaging.
What are the stowage categories and what do they require?
Five stowage categories govern cargo placement: Category A (on deck or under deck), Category B (on deck or under deck, master's discretion), Category C (on deck only), Category D (on deck, away from living quarters), and Category E (on deck or under deck, away from heat sources). Additional SW codes add specific conditions beyond the category requirement.
How does segregation work when carrying multiple DG consignments?
The segregation table in Chapter 7.2.4 cross-references 14 segregation groups to produce a required segregation term for each combination. The four terms, "away from," "separated from," "separated by a complete compartment or hold from," and "separated longitudinally by an intervening complete compartment or hold from", represent escalating physical separation requirements. SG codes in the DGL add substance-specific requirements on top of group requirements.
What changed for lithium batteries in Amendment 42-24?
Amendment 42-24 revised stowage categories for certain lithium battery types based on watt-hour thresholds, tightened Special Provision 188 criteria for batteries shipped as cargo, and introduced new UN numbers for sodium-ion batteries. Shipments that were partially exempt under the prior edition may be fully regulated under Amendment 42-24.
Is IMDG Code training a legal requirement for freight forwarders?
Yes. Part 1.3 of the IMDG Code requires function-specific training for shore-based personnel involved in the classification, documentation, packaging, or handling of dangerous goods for sea transport. Employers must retain training records and produce them on request from the competent authority. The standard certification period is three years.
Can a port state control inspection result in ship detention for DG non-conformities?
Yes. PSC inspections can and do result in detention when dangerous goods non-conformities are found, particularly missing or incorrect DGDs, absent packing certificates, or stowage plan discrepancies. Detention results in commercial disruption and generates a deficiency record in the Equasis and MOU databases, increasing future inspection frequency.
What is the difference between the IMDG Code and the IMSBC Code?
The IMDG Code covers dangerous goods in packaged form. The IMSBC Code covers solid bulk cargoes poured directly into holds. The form in which cargo arrives at the vessel determines which code applies. Some substances appear under both frameworks, particularly those that carry IMDG Code class designations as part of their IMSBC cargo information.
Glossary
Amendment 42-24: The current mandatory edition of the IMDG Code, effective 1 January 2026, adopted under IMO Resolution MSC.556(108).
CCC Sub-Committee: The IMO Sub-Committee on Carriage of Cargoes and Containers. Responsible for maintaining and updating the IMDG Code.
Class: The primary hazard category assigned to a dangerous substance or article. Nine classes exist under the IMDG Code.
Container/Vehicle Packing Certificate: The document completed by the party who packs dangerous goods into a container, confirming compliance with IMDG Code packing and securing requirements.
Dangerous Goods Declaration (DGD): The shipper's document declaring the nature, class, quantity, and packaging of dangerous goods in a consignment. A mandatory part of the transport document set.
Dangerous Goods List (DGL): The 19-column table in Volume 2 (Part 3) of the IMDG Code, indexed by UN number, that provides the regulatory parameters for each dangerous substance or article.
Division: A subdivision within a hazard class. Class 1 (Explosives) has six divisions. Class 2 (Gases) has three.
EmS Guide: Emergency Schedule Guide. Provides fire and spillage response schedules keyed to each DGL entry. Part of the IMDG Code Supplement.
Excepted Quantities (EQ): A relief provision allowing minimal quantities of certain dangerous goods to be shipped with reduced requirements, the EQ mark replacing class labels.
Limited Quantities (LQ): A relief provision allowing small packages of certain dangerous goods to be shipped with reduced marking and labelling requirements, provided inner package quantities remain within class-specific thresholds.
Marine Pollutant: A substance designated in the IMDG Code as harmful to the marine environment. Carries additional marking (marine pollutant mark), documentation, and stowage requirements beyond those of its primary class.
MARPOL Annex III: The annex to the International Convention for the Prevention of Pollution from Ships covering harmful substances in packaged form. Establishes the legal basis for IMDG Code enforcement over marine pollutants.
MFAG: Medical First Aid Guide. Part of the IMDG Code Supplement. Provides treatment guidance for crew members exposed to dangerous goods.
MSC: Maritime Safety Committee. The IMO body responsible for adopting IMDG Code amendments.
Not Otherwise Specified (NOS): A generic DGL entry covering substances in a class that do not have a specific UN number. Requires a technical name in parentheses after the NOS designation.
Orange Book: The UN Recommendations on the Transport of Dangerous Goods. The model regulations that underpin all modal dangerous goods transport codes, including the IMDG Code.
Packing Group (PG): An indicator of the degree of danger a substance presents within its class: PG I (great danger), PG II (medium danger), PG III (minor danger). Determines packing instruction and packaging performance requirements.
Port State Control (PSC): The system by which national maritime authorities inspect foreign vessels in their ports. PSC inspectors verify IMDG Code compliance during inspections.
Proper Shipping Name (PSN): The official name assigned to each DGL entry, used verbatim on the Dangerous Goods Declaration and package markings.
Segregation: The physical separation required between incompatible dangerous goods on the same vessel, specified by four escalating terms.
SG Code: Segregation code. A code in the DGL entry specifying substance-specific segregation requirements beyond what the class segregation group requires.
SOLAS Chapter VII: The chapter of the International Convention for the Safety of Life at Sea governing the carriage of dangerous goods. Part A covers packaged dangerous goods and incorporates the IMDG Code as mandatory.
Special Provision (SP): A code in the DGL that modifies the general requirements for a specific substance. SP 188, for example, governs lithium battery exemption thresholds.
Stowage Category: One of five codes (A through E) in the DGL that determines where dangerous goods must be placed on the vessel relative to deck position and adjacent spaces.
Subsidiary Hazard: A secondary hazard class carried by a substance whose primary classification does not fully describe its hazard profile. Both labels must appear on the package.
SW Code: Stowage and handling code. A code in the DGL that adds specific conditions to the stowage category, temperature limits, ventilation requirements, or prohibition in certain spaces.
UN Number: The four-digit number assigned by the UN Committee of Experts to identify a specific dangerous substance or article in international transport.
Volume 1: The first volume of the IMDG Code, containing Parts 1, 2, and 4–7: general provisions, classification criteria, packing, packaging construction, consignment procedures, and transport operations.
Volume 2: The second volume of the IMDG Code, containing Part 3: the Dangerous Goods List, special provisions, and appendices.
References
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Capt. Anuj Chopra
Advisor / Contributing Author
Capt. Anuj Chopra ExC FNI FICS is a maritime industry executive with over 40 years of experience. As former VP Americas at RightShip and co-founder of ESGplus LLC, he specialises in maritime risk, ESG, and environmental compliance. He is an Adjunct Professor at the University of Houston and Fellow of both The Nautical Institute and the Institute of Chartered Shipbrokers.
