IMDG Code Explained
When reading this article reference should also be made to SOLAS Chapter VII and MARPOL Annex III.
The IMDG code became mandatory in 2004 and applies to all ships governed by SOLAS and to cargo ships under 500grt as well as to any other parties involved in the transport of Dangerous Goods. All ships carrying marine pollutants are subject to the IMDG code. Objectives of the code are to enhance the safe transport of Dangerous Goods and protect the marine environment while also facilitating the unrestricted movement of Dangerous Goods.
The IMDG code is Split into three books – Volume 1, Volume 2 and Supplements The Books are updated every two years (current edition 2014, although soon to be 2016). Any changes in a new edition are advisory initially, strongly encouraged after a year and mandatory after two years (when the subsequent edition is published).
Volume 1 Contains:
Part 1 :
- An explanation of how the Code came to be and how to interpret it.
- Advice on training of shore-side personnel.
- Information about the responsibilities of the various parties including consignor, consignee, carrier and port officials.
- Advice on safely transporting radioactive materials.
Part 2:
An explanation of the classification system that the system applies to cargoes. Cargoes are divided into 9 classes which are subdivided into divisions. It is a common mistake to think that the classes advance in order of danger from highest to lowest but this is not the case. There is a general trend within Class 1 (Explosives) that the divisions progress from most volatile (1.1 mass explosion hazard) to least volatile (1.6 extremely insensitive articles with no mass explosion hazard).
Substances other than those in classes 1, 2, 5.2, 6.2 and 7 are also divided into one of three packing groups – high danger, medium danger and low danger. Articles are not assigned to packing groups but have their own packing instructions.
Dangerous goods are assigned UN numbers and Proper Shipping Names for ease of reference to the Dangerous Goods List that constitutes the bulk of Volume 2. Where impurities or stabilising agents are present in a substance it will be considered a mixture or solution but if it retains the same properties and there is no proper shipping name for the mixture it shall be assigned the proper shipping name of the predominant substance. If a substance or article is not specifically listed it can be assigned a Generic shipping name. Dangerous Goods may also be given a Not Otherwise Specified (N.O.S.) shipping name, often because the authorising government wants to keep specific details about them secret. An index of Generic and N.O.S. Dangerous Goods can be found in the back of Volume II.
Substances, mixtures or solutions with multiple hazards shall be assigned the most stringent classification based on a table of hazard precedence provided here.
There follows an explanation of each of the classes 1-9 and Marine Pollutants.
Classes:
1 – Explosives
2 – Gases
3 – Flammable Liquids
4 – Flammable Solids
5 – Oxidizing Substances and Organic Peroxides
6 – Toxic and Infectious Substances
7 – Radioactive Material
8 – Corrosive Substances
9 – Miscellaneous
Class 1 Explosives
This is a restricted class meaning that only listed items can be accepted for transport. However there are some generic shipping names for competent authorities to approve for use on a case by case basis for obscure or new products.
Class 1 has 6 divisions:
1.1 Substances and articles with a mass explosion hazard
1.2 Substances and articles with a projection hazard
1.3 Substances and articles with a fire hazard, minor blast or projection hazard
1.4 Substances and articles with no significant hazard (the packaging prevents most projection hazards)
1.5 Very insensitive substances which have a mass explosion hazard
1.6 Extremely insensitive articles which do not have a mass explosion hazard
Class 1 goods are also assigned Compatibility Group letters (A to L, excluding I) which can be used with a table to determine which goods can be safely stowed together.
Class 2 – Gases
Defines a gas (completely gaseous at 20C), toxic (poisonous), compressed gas (gaseous when transported under pressure above -50C), liquefied gas (partially liquid under the same conditions). Class 2 has three subdivisions:
2.1 Flammable gases – ignitable in a mixture of 13% or less by volume with air or have a flammable range spanning at least 12% regarding of lower limit
2.2 Non-flammable, non-toxic gases – asphyxiant, oxidizing (aids combustion more than air) or don’t fit the other two divisions
2.3 Toxic gases – poisonous or corrosive to humans
A gas fitting both 2.1 and 2.3 will be assigned to 2.3 as this is the greater hazard
Notes that gases contained in foodstuffs like soft drinks, sports balls and tyres are exempt.
Class 3 – Flammable Liquids
Defines flammable liquids as those giving off flammable vapours (the flashpoint) at or below 60°C or any offered for transport above their own, higher flashpoint.
Containers are to be inspected and fitted with a safety approval plate detailing:
- Country of approval
- Approval reference
- Month and year of manufacture
- Manufacturer’s identification number
- Maximum operating gross mass
- Allowable stacking load for 1.8g (allowing for rise of ship)
- Transverse racking test force
- Side wall and end wall strengths
Substances, other than those classified as explosives, which may cause or contribute to a fire.
Three subdivisions:
4.1 Flammable Solids – solids that may catch fire under transport conditions due to friction or their self-reactive nature
4.2 Substances liable to spontaneous combustion – self heating and liable to catch fire
4.3 Substances which emit flammable gases on contact with water – may result in flammable atmosphere or ignition due to self-heating
Class 5 – Oxidizing Substances and Organic Peroxides
Two Subdivisions:
5.1 Oxidizing Substances – substances that contribute to combustion by yielding oxygen, not necessarily flammable themselves
5.2 Organic Peroxides – Substances that have an unstable pair of bivalent oxygen atoms and are therefore prone to rapid, exothermic decomposition.
Class 6 – Toxic and Infectious Substances
Two subdivisions:
6.1 Toxic Substances – Poisonous substances which will cause death or injury to human health through ingestion, inhalation or skin contact
6.2 Infections Substances – Containing microorganisms (pathogens) that can cause disease in humans or animals.
Class 7 – Radioactive Material
Materials containing radionuclides with activity levels exceeding values set down in this section. Consignments may be excepted from this class if their packaging reduces radiation levels sufficiently across their entire outer surface.
Class 8 – Corrosive Substances
Substances that will cause severe damage on contact with living tissue or other materials.
Class 9 – Miscellaneous Dangerous Substances and Articles
Items not covered in other classes which experience has shown to be of a dangerous character or meeting the criteria of MARPOL Annex III ‘bioaccumulated and harmful to people or aquatic life or liable to taint seafood’ (bioaccumulated means gathered up in a living creature through eating, drinking and breathing in that environment as per DDT). Contains items like lithium batteries, possibly contained in other items, and electrically initiated LSA.
Marine Pollutants – Environmentally Hazardous Substances
Substances that are toxic to marine life or prone to harmful bioaccumulation.
Part 3 Is the Dangerous Goods List that makes up the bulk of Volume 2
Part 4 Packing and Tank Provisions
Effectively Closed – liquid-tight
Hermetically Sealed – Vapour-tight
Securely Closed – Dry contents cannot escape during normal handling. This is the minimum closure required the Code
Specifies the packaging required for substances and lays down the maximum quantities that can be contained in a single package based on the packing group.
Part 5 Consignment Procedures
Advance notification, marking, labelling, documentation, certification and placarding required for dangerous goods. Overpack procedures.
Part 6 Construction and Testing of Packagings, Intermediate Bulk Containers (IBCs), Large Packagings, Portable Tanks, Multiple-Element Gas Containers (MEGCs) and Road Tank Vehicles
Part 7 Provisions Concerning Transport Operations
Gives guidance on how to stow cargo on board. Class 1 cargoes are divided into Stowage categories A to E while cargoes of Classes 2-9 are split into Stowage Categories 01-05.
The Dangerous Goods List may specify that a cargo must be kept ‘clear of living quarters’. This was defined in 2012 as being at least 3m from accommodation, machinery spaces, air intakes, enclosed spaces and any other spaces where crewmembers work
Tables give guidance on the separation required between cargoes of different types. By comparing cargoes on one table you obtain an instruction such as ‘away from’ or ‘separated from’. Take this instruction into another table that factors in whether one or both of the cargoes are in open or closed containers and whether the separation will be vertical or horizontal. This table will provide specific instructions such as that the two cargoes must be stowed ‘one bulkhead and minimum horizontal distance of 24m’ apart. Different tables are used for hatchless ships and ships with closed holds or RORO vessels.
Volume 2 Contents
Part 3
This is the Dangerous Goods List and it’s presented in a table format with information for each unique good displayed in individual rows each with 18 columns. Information provided for each cargo includes a 4-digit UN number and the Proper Shipping Name to help you identify the cargo. Other columns provide the class of the cargo, its packing group, subsidiary risks, stowage and segregation requirements (see Part 7) and the relevant Emergency Schedules (see Supplements) should there be a fire or spill involving the cargo.
Supplements
The supplement contains a copy of the Emergency Response Procedures for Ships Carrying Dangerous Goods including:
The Emergency Schedules (EmS) that detail the correct actions to take in the event of fire or spillage. To find the appropriate response for a particular cargo simply find the EmS code (F-A to F-J for fire and S-A to S-Z for spills) in the Dangerous Goods list
The Medical First Aid Guide for use in Accidents Involving Dangerous Goods (MFAG). This will give advice on treatment following exposure to particular Dangerous Goods and will advise ships on any medicines they need to hold on board while carrying certain cargoes
Reporting Procedures for incidents involving Dangerous Goods
Recommendations for the Safe Use of Pesticides in Ships offering guidance on the fumigation of holds
International Code for the Safe Carriage of Packaged Irradiated Nuclear Fuel, Plutonium and High-Level Radioactive Wastes on board Ships – INF Code
DOC
Ships shall be certified compliant with the SOLAS Regulations concerning Carriage of Dangerous Goods in Packaged or Bulk Form by their Flag State. This Document of Compliance (DOC) shall be issued for not more than 5 years.
