The International Maritime Dangerous Goods (IMDG Code) Explained

The IMDG Code regulates the transport of dangerous goods by sea in order to prevent injury to persons or damage to ships and their cargoes. Dangerous Goods means the substances, materials and articles in packaged form covered by IMDG Code.

Transport of marine pollutants is primarily regulated to prevent harm to the marine environment. The objective of the IMDG Code is to enhance the safe transport of dangerous goods while facilitating the free unrestricted movement of such goods.

The IMDG Code contains details of all the numerous dangerous cargoes offered for carriage by sea and includes solid, liquid and gaseous substances. Explosive, flammable, oxidising and radioactive substances are also included and recommended means of their containment or packing are listed, as is all manner of other information relating to the product. Future updating of the Code, on two-year basis, are foreseen in order to take into account technological developments.

The IMDG Code applies to all ships carrying dangerous goods in packaged form, which are covered by the code.


The objective of IMDG Code is to:

  • Protect human life.
  • Prevent marine pollution
  • Facilitate the free movement of dangerous goods.
  • to give an uniform approach for the handling and for the safe transport of dangerous goods by sea.
  • to guide the technical information for all dangerous cargoes in order for them to be carried by ship safely without causing damage to the environment.

The IMDG Code also covers:

  • Packing;
  • Marking;
  • Labelling;
  • Placarding;
  • Documentation;
  • Stowage;
  • Segregation


The International Maritime Dangerous Goods (IMDG) Code was adopted in 1965 as per the SOLAS (Safety for Life at Sea) Convention of 1960. This code was formed to prevent all types of pollution at sea.

IMDG Code or International Maritime Dangerous Goods Code was accepted by MSC (Maritime Safety Committee) as an international guideline to the safe transportation or shipment of dangerous goods or hazardous materials by water on vessel. The  Code is intended to protect crew members and to prevent marine pollution in the safe transportation of hazardous materials by vessel. It is recommended to governments for adoption or for use as the basis for national regulations’s mandatory in conjunction with the obligations of the members of united nation government under the SOLAS Code and the MARPOL 73/78. It is intended for use not only by the mariner but also by all those involved in industries and services connected with shipping.

IMDG Code contains advice on terminology, packaging, labelling, placarding, markings, stowage, segregation, handling, and emergency response. The HNS Convention covers hazardous and noxious substances that are included in the IMDG code.

The code is updated and maintained by the CCC (formerly DSC) Sub-Committee of the IMO every 2 years.

The IMDG Code’s latest 2018 Edition (inc. Amendment 39-18) comes into force on 1 January 2020 for two years and may be applied voluntarily as from 1 January 2019. 

The IMDG Code Supplement, 2018 Edition renders obsolete the previous 2014 edition.

Contents of IMDG Code

  • Volume 1
    • Part 1 General Provisions, definitions and training
      Application, Definitions, Training, Security, general provisions for radioactive material
    • Part 2 Classification: The IMDG goods classes, 1 to 9, explained
    • Part 3 Dangerous goods list – contained in Volume 2
    • Part 4 Packing and tank provisions
    • Part 5 Consignment procedures
    • Part 6 Construction and testing of packages, IBCs, portable tanks, MECGs and road tank vehicles
    • Part 7 Provision concerning transport operations
  • Volume 2
    • Part 3
      • 3.1 General
      • 3.2 Dangerous goods list
      • 3.3 Special provisions applicable to certain substances, materials or articles
      • 3.4 Dangerous goods packed in limited quantities
      • 3.5 Dangerous goods packed in excepted quantities
  • Appendix A List of generic and N.O.S. proper shipping terms
  • Appendix B Glossary of terms

Classification of Dangerous Goods

  • Class 1: Explosives;
    e.g. Nitroglycerine, Cyclonite (RDX), Ammunition
    • Division 1.1: Substances and articles which have a mass explosion hazard;
    • Division 1.2: Substance and articles which have projection hazard but not a maximum explosion hazard;
    • Division 1.3: Substance and articles which have a fire hazard and either a minor blast hazard or a minor projection hazard or both, but not a mass explosion hazard;
    • Division 1.4: Substance and articles which present not significant hazards;
    • Division 1.5: Substance and articles which are very insensitive substances which have a mass explosion hazard;
    • Division 1.6: Extremely insensitive articles which do not have a mass explosion hazard
  • Class 2: Gases, Compressed, Liquefied or Dissolved under pressure;
    e. g.- Argon (Ar), Nitrogen (N2)
    • Class 2.1: Flammable Gases;
    • Class 2.2: Non-flammable, Non-toxic Gases;
    • Class 2.2: Toxic Gases
  • Class 3: Flammable Liquids
  • Class 4: Flammable Solids, Substances liable to spontaneous combustion, substances which, in contact with water emit flammable gases
    • Class 4.1: Flammable Solids, Self reactive substances and desensitised explosives;
      E.g. Zinc Dust, Paint;
    • Class 4.2: Substances liable to spontaneous combustion;
      Eg. Iron and Steel Phosphorus;
    • Class 4.3: Substances which in contact with water, emit flammable gases;
      Eg. Sodium (Na), Potasium (K)
  • Class 5: Oxidising Substances and Organic Peroxides
    • Class 5.1: Oxidizing Substances,
      Eg: Potassium Chlorinate, Sodium Peroxide;
    • Class 5.2: Organic Peroxide,
      Eg: Peroxyacetic Acid
  • Class 6: Toxic and Infectious Substances
    • Class 6.1: Toxic Substances,
      Eg: Tear Gas, Prussic Acid;
    • Class 6.2: infectious Substances,
      Eg: Biological Substances
  • Class 7: Radioactive Materials,
    Eg: Thorium, Cobalt and even Iron
  • Class 8: Corrosive Substances;
    Eg: Sulphuric Acid. Caustic Soda
  • Class 9: Miscellaneous Dangerous Substances and Articles;
    Eg: Dry Ice, Ammonium Nitrate Fertilisers

Packaging of Dangerous Goods

  • Packaging including Intermediate bulk containers and large packaging is to be of good quality and capable of withstanding shocks normally encountered during transportation.
  • The packaging should be constructed and closed so as to prevent loss of content by vibration or by change in temperature, humidity or pressure during transportation.
  • No dangerous residue shall adhere outside of packages
  • The packaging part which are in direct contact with Dangerous Goods should not be weakened, react or catalysis a reaction.
  • Packaging should be tested for vibration, drop test, etc.
    Outer packaging material should not produce heat while transport.
  • An ullage to be kept sufficient to allow for expansion at temperatures during transportation.
  • Dangerous Goods and other substances shall not be packed together as they may react.
  • Cushioning and absorbent material should be inert and suitable to the nature of the content.
  • Packages containing dangerous cargo which evolve flammable, toxic, corrosive gases or vapours or become explosive if allowed to dry or which may react dangerously with the atmosphere should be hermetically sealed (Vapour tight closure)

Marking, Labelling and Placarding of Dangerous Goods

  • Labels has to be 100 x 100 mm in size and fixed to individual packages.
  • Placards will show same information i.e. Class Number, and Dangerous Properties but are larger in size 250 x 250 mm and fixed to cargo transport unit.
  • The proper Shipping Name and the corresponding UN Number shall be marked on each package.
  • These marking, labels and placards shall be readily visible, on a background of a contrasting colours and on the external surface of the package.
  • Labels should be placed placed near the markings, with subsiding risk labels.
    Information provided on label, markings and placards should be still identifiable if immersed in sea for three months.
  • Salvage packaging shall be marked by word SALVAGE (Salvage means defective packaging)
  • Large packaging should be marked on two opposing sides and placards pasted on CTU on four sides.
  • Package containing marine pollutants shall be marked with environmentally hazardous substance mark.
  • Class 7 packages shall be marked with the name of the Consigner or Consignee or both and if over 50 kg shall also be durably and legibly marked with the Gross Mass.
  • A package containing Dangerous Goods of a low degree of danger may be exempted from labelling requirements and will be indicated in the Dangerous Goods list.

Documents required as per IMDG Code

  • Shipping Declaration;
  • Document of Compliance (DOC);
  • Dangerous Goods Manifest

These documents should be retained on board.

IMDG Manifest

Shipper of a Dangerous material required to prepare a shipping document that should be as per IMDG Code. Manifest should contain at least:

  • Container Number;
  • Number and kind of packages
    Proper Shipping Name;
  • IMO Class;
  • UN Number;
  • Packaging Group;
  • Subsiding Risk;
  • Flash Point;
  • Marine Pollutant;
  • Dangerous Goods Net Mass;
  • Stowage Location;
  • Port of loading;
  • Port of Discharge;
  • EMS;
  • MFAG Table Number

Stowage Requirements

  • Stowage means proper placement of dangerous goods on board the ship to ensure safety and environmental protection during transport.
  • Stowage on deck means on weather deck and stowage under deck means, not on the weather deck.
  • Closed transport unit means fully enclosed unit that enclosed contents by permanent structures and can be secured to ship structure and is serviceable.
  • Dangerous Goods of Class 1, except for Division 1.4 shall be stowed on cargo ship and passenger ship in one of the five stowage categories, which specify where and how the Dangerous Goods can be stowed. 12 m away from living quarters, LSA and Public access areas, B/8 or 2.4 m away from the ship-side which even is greater and 6 meters away from sources of ignition.
  • Dangerous Goods of Class 2-9 shall be stowed in cargo and passenger ships in one of the five stowage categories (A to E) which specifies where cargo can be stowed.
  • Marine Pollutants should preferably be stowed under deck but if required to be stowed on deck then they should be stowed inboard in sheltered areas on well protected decks.


Segregation Table

Types of Segregation

1. Away from:

Effective segregation is required but may be carried in the same compartment or deck provided minimum horizontal separation of three meters projected vertically is maintained.

2. Separated from:

Can be carried in the same compartment if the intervening deck is resistant of fire and liquids, otherwise separate holds. On deck, horizontal separation of at least six meters.

3. Separated by a complete compartment or hold from

These must be either a vertical or longitudinal separation by a complete hold or compartment and two bulkheads or decks resistant to fire and liquids. On deck, 12 meters horizontal separation even if the package is stowed below deck.

4. Separated Longitudinally by an intervening complete compartment or hold from

A vertically separation is not allowed. The packagers must be horizontally separated by a complete compartment. On Deck, a 24 meters Horizontal separation and between deck packages and and under deck packages, 24 m + an intervening compartment.

Precautions while loading Dangerous Goods

  • General inspection of hold which include structural damage and defects
    Refer to the IMDG Code and find the particulars of cargo to be loaded with regards to hazards, compatibility, stowage and segregation.
  • Appropriate International Code Signals by day and by night is to be posted.
  • No Bunkering operation to be done during loading or discharging.
  • Wireless transmission should not be done of voltage exceeding 50v
  • Radars should not be operated during loading or discharging of Dangerous Cargo.
  • Forklift should not be used in vicinity of Dangerous Goods
    Defective packages should not be accepted.
  • Port regulations are to be complied with.

Precautions while loading Explosives

Explosives must be stowed in magazines, tht is a wood or wooden compartment.
No electric cable should pass through the magazine. If not possible, them cable should be coated by approved, sealed, non-combustible barrier.
Explosives are unstable when wet, should be stowed in dry, cool, well ventilated space.
Masts must be fitted with an efficient lightening conductor, as lighting presents a grave danger.

Dangerous Goods List

The Dangerous Goods List is contained in Chp 3.2 in Volume 2 of IMDG Code. This list contains the data from each dangerous substances which can be transported by the sea.
Information contained in the Dangerous goods list of IMDG Code is as follows:

  • UN number;
  • Proper shipping name;
  • Class or division;
  • Subsidiary risks;
  • Special provisions;
  • Limited and excepted;
  • Quantity provisions;
  • Packing;
  • IBC Portable tanks and bulk containers;
  • EMS;
  • Stowage and handling;
  • Segregation;
  • Properties and observations

This list contains 18 columns. Which are:

  • Column 1 – UN Number Contains the United Nations Number assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods (UN List).
  • Column 2 – Proper Shipping Name (PSN) Contains the Proper Shipping Names in upper case characters which may have to be followed by additional descriptive text in lower-case characters.
  • Column 3 – Class or Division Contains the class and, in the case of class 1, the division and compatibility group.
  • Column 4 – Subsidiary Risk(s) Contains the class number(s) of any subsidiary risk(s). This column also identifies dangerous goods as a marine pollutant or a severe marine pollutant as follows: P Marine pollutant PP Severe marine pollutant ? Marine pollutant only when containing 10% or more substance(s) identified with ‘P’ or 1% or more substance(s) identified with ‘PP’ in this column or in the Index.
  • Column 5 – Packing Group Contains the packing group number (i.e. I, II or III) where assigned to the substance or article. Column 6 – Special Provisions Contains a number referring to any special provision(s) indicated in chapter 3.3.
  • Column 7 – Limited Quantities Provides the maximum quantity per inner packaging.
  • Column 8 – Packing Instructions Contains packing instructions for the transport of substances and articles.
  • Column 9 – Special Packing Provisions Contains special packing provisions.
  • Column 10 – IBC Packing Instructions Contains IBC instructions which indicate the type of IBC that can be used for the transport. A code including the letters ‘IBC’ refers to packing instructions for the use of IBCs described in chapter 6.5.
  • Column 11 – IBC Special Provisions Refers to special packing provisions applicable to the use of packing instructions bearing the code ‘IBC’ in
  • Column 12 – IMO Tank Instructions This column only applies to IMO portable tanks and road tank vehicles.
  • Column 13 – UN Tank and Bulk Container Instructions Contains T codes (see applicable to the transport of dangerous goods in portable tanks and road tank vehicles.
  • Column 14 – Tank Special Provisions Contains TP notes (see applicable to the transport of dangerous goods in portable tanks and road road tank vehicles. The TP notes specified in this column apply to the portable tanks specified in both columns 12 and 13.
  • Column 15 – EmS Refers to the relevant emergency schedules for FIRE and SPILLAGE in ‘The EmS Guide – Emergency Response Procedures for Ships Carrying Dangerous Goods’.
  • Column 16 – Stowage and Segregation Contains the stowage and segregation provisions as prescribed in part 7.
  • Column 17 – Properties and Observations Contains properties and observations on the dangerous goods listed.
  • Column 18 – UN Number Contains the United Nations Number assigned to a dangerous good by the United Nations Committee of Experts on the Transport of Dangerous Goods (UN List).