Answer
Solid bulk cargoes are classified into three distinct hazard groups under the IMSBC Code (International Maritime Solid Bulk Cargoes Code), Section 1.7. Memorizing these definitions verbatim is essential for Class 1 orals.
Group A (Cargoes which may Liquefy)
Definition: This group consists of cargoes which contain a certain proportion of fine particles and a high moisture content. If shipped with moisture exceeding their Transportable Moisture Limit (TML), the cargo can undergo liquefaction due to compaction caused by the ship’s vibrations and rolling motion.
Hazards: The cargo shifts from a solid state to a fluid slurry, creating a free surface effect that can cause a sudden, catastrophic loss of vessel stability and capsize.
Examples: Iron ore fines, Nickel ore, Copper concentrates, Bauxite fines.
Group B (Cargoes possessing Chemical Hazards)
Definition: Cargoes which possess chemical hazards that can endanger the ship's structure, safety, or the health of the crew.
Hazards: These include self-heating, spontaneous combustion, toxic gas emission, flammable gas generation, oxygen depletion within the hold, or severe corrosivity to the ship’s steel structure.
Examples:
Coal: Emits flammable methane gas and is prone to spontaneous self-heating.
Direct Reduced Iron (DRI): Reacts with moisture to generate highly explosive hydrogen gas.
Ammonium Nitrate Fertilizers: Strong oxidizing agents susceptible to decomposition when exposed to heat.
Group C (Cargoes which are neither Liable to Liquefy nor Possess Chemical Hazards)
Definition: Cohesive or non-cohesive cohesive solid bulk materials that are relatively stable chemically and do not liquefy, but still pose physical structural risks due to high density or shifting.
Hazards: High-density cargo (like iron ore lumps) can overload the tank top structural plating if improperly distributed. Large grain cargo can shift if the hold is not completely trimmed, creating a permanent listing angle.
Examples: Cement, Sand, Quartzite, Iron ore lumps, Salt.