Dangerous goods on cargo ships are handled through a rigorous system:
How DG is stowed on a vessel:
- Stowage positions are prescribed by the IMDG Code (categories SW1–SW8)
- On deck stowage (D/D) vs under deck (U/D) depends on the hazard class
- Flammable liquids/gases often stowed on deck away from heat sources
- Radioactive materials get dedicated separated stowage
- The cargo manifest identifies every DG container with its UN number, class, and stowage position
- Incompatible goods must be segregated (e.g., acids away from cyanides)
Who checks compliance:
- Shipper: Responsible for correct declaration, packing, and marking
- Freight forwarder: Verifies documents before booking
- Shipping line: Reviews DG declaration; may refuse mis-declared cargo
- Port authority: Inspects a percentage of DG containers before loading
- Class Society (Lloyds, DNV, ABS): Surveys vessel for DG carriage compliance
- Flag State/Coast Guard: Spot checks
If an incident occurs at sea:
- Fire: Vessels carry CO2 or dry chemical systems for DG areas; containers may be jettisoned
- Toxic spill: Emergency procedures per IMDG EmS guide; crew uses SCBA (breathing apparatus)
- The Master must file a Dangerous Occurrence Report to the nearest coastal state
- General Average may be declared — all cargo owners share in losses proportionally