IMDG

IMDG is the International Maritime Dangerous Goods Code, a United Nations document that sets out how vessels must pack, label, stow, and handle materials classified as dangerous or hazardous during sea transport. It governs everything from sulfuric acid and lithium batteries to flammable paints and pesticides. Any ship carrying such cargo must comply with IMDG rules, and port state control officers inspect vessels specifically for IMDG compliance before allowing them to sail.

The code classifies hazardous materials into nine classes based on their primary risk: explosives, flammable gases, flammable liquids, flammable solids, oxidizing substances, toxic and infectious substances, radioactive material, corrosive substances, and miscellaneous dangerous goods. Each class has subdivision codes. A substance may fall into multiple classes; the shipper and vessel must determine which class takes precedence. Copper chloride, for example, can be corrosive and an oxidizer, but IMDG designation rules specify its primary class to avoid confusion.

Proper documentation is central to IMDG compliance. Shippers must provide a dangerous goods declaration form that names the commodity, lists its UN number, indicates its class and subsidiary hazards, specifies packing group (I, II, or III, where I is most hazardous), and gives the proper shipping name. The vessel's master and dangerous goods officer verify this information against the IMDG manual before cargo is loaded. Misdeclaration, either intentional or through error, is a serious violation that can result in port detention, fines, and loss of shipping privileges.

Stowage rules are strict. Incompatible substances must be segregated; flammable liquids cannot be stowed adjacent to oxidizers, for instance. Cargo must be shored and lashed to prevent shifting in rough seas. On container ships, hazardous containers must be marked with correct placard colors and symbols visible on all four sides. The vessel's manifest and cargo plan must show the exact location of every dangerous goods package or container, and this information is typically submitted to port authorities before arrival.

IMDG is updated every two years with amendments reflecting new substances, reclassifications, or procedural changes. The code also addresses training requirements for crew members who handle or supervise dangerous goods, medical first-aid kits suitable for sea voyages carrying specific cargo, and procedures for reporting incidents at sea. While IMDG applies to international maritime transport, many nations incorporate its rules into domestic coastal and inland waterway regulations as well.