Question 1

Your vessel is due to load 8,000 tonnes of nickel ore at a Philippine port. Your examiner asks: "What is liquefaction, which code governs this cargo, and what pre-loading checks are required?"

Accepted Answer

Liquefaction occurs when a cargo with high moisture content is subjected to vibration and dynamic stress (ship motion) — the particles lose friction contact and the cargo behaves like a liquid. This can cause a catastrophic shift and rapid capsize without warning. Nickel ore is a Group A cargo under the IMSBC Code (International Maritime Solid Bulk Cargoes Code, mandatory under SOLAS VI) — it may liquefy. Pre-loading requirements: the shipper must provide a cargo declaration including moisture content, transportable moisture limit (TML), and flow moisture point (FMP). The cargo moisture content must be below the TML at time of loading. The master may refuse cargo if moisture content is at or above TML — this right is explicitly protected by SOLAS and the IMSBC Code. Request an independent moisture content test if the shipper's declaration is in doubt. Nickel ore liquefaction has caused multiple total losses with all crew perished (MV Asian Forest 2009, MV Nasco Diamond 2010, MV Trans Summer 2011 — all nickel ore liquefaction events). The IMSBC Code (mandatory from 1 January 2011 under SOLAS VI) classifies solid bulk cargoes into three groups: Group A (may liquefy), Group B (chemically hazardous), Group C (neither). Transportable Moisture Limit (TML) = 90% of the Flow Moisture Point (FMP). The cargo must be loaded below the TML. The "can test" is a simple shipboard screening test: fill a can with a sample of cargo, strike the base sharply 25 times, and check for free moisture or surface sheen — a positive result indicates the cargo may be near or above TML. The master's right to refuse cargo: SOLAS VI/7 explicitly protects the master's right to refuse to load cargo if a proper declaration is not provided or if the master has reason to believe the cargo is not as declared. Exercising this right despite charterer pressure is a direct application of ISM Regulation 5 (master's overriding authority).

Question 2

Your examiner asks: "State the nine classes of dangerous goods under the IMDG Code and give one example of each." Give a complete answer.

Accepted Answer

Class 1: Explosives (e.g. detonators, fireworks). Class 2: Gases — 2.1 Flammable (LPG), 2.2 Non-flammable/non-toxic (compressed air), 2.3 Toxic (chlorine). Class 3: Flammable liquids (petrol, acetone). Class 4: Flammable solids — 4.1 Flammable solids (matches), 4.2 Spontaneously combustible (wet fishmeal), 4.3 Dangerous when wet (sodium, calcium carbide). Class 5: Oxidising substances — 5.1 Oxidisers (ammonium nitrate), 5.2 Organic peroxides. Class 6: Toxic and infectious — 6.1 Toxic (pesticides), 6.2 Infectious substances. Class 7: Radioactive. Class 8: Corrosives (battery acid, caustic soda). Class 9: Miscellaneous dangerous goods (lithium batteries, dry ice). The IMDG Code (International Maritime Dangerous Goods Code, made mandatory under SOLAS VII/3) uses UN-based classifications. Key points for OOW orals: Class 4 has three subdivisions — 4.2 (spontaneously combustible materials including wet fishmeal which has caused numerous bulk carrier fires) and 4.3 (dangerous when wet — water reacts to produce flammable gases) are the most hazardous from a watchkeeping perspective. Class 9 (lithium batteries) has become increasingly significant — lithium battery fires in containers and car carriers have caused major incidents (e.g. Felicity Ace). The IMDG Code is updated biennially; the 2022 edition (Amendment 41-22) is the current edition. Segregation requirements between classes are specified in IMDG Chapter 7 — an OOW must understand that certain classes cannot be stowed in the same space (e.g. oxidisers and flammables).

Question 3

You are loading a general cargo consignment. The cargo plan shows ammonium nitrate (Class 5.1) in Hold 2 and petroleum products in drums (Class 3) in Hold 3, which is adjacent. Is this acceptable under the IMDG Code?

Accepted Answer

Ammonium nitrate (Class 5.1, oxidiser) and petroleum products (Class 3, flammable liquids) require segregation of "away from" (separated by an intervening space or hold) at minimum. Adjacent holds sharing a common bulkhead do not satisfy "away from" — the cargoes must be in non-adjacent holds with at least one hold separation. Check the IMDG Segregation Table (Chapter 7.2): oxidisers and flammable liquids require at minimum "away from" and in some cases "separated from." This loading plan requires amendment. IMDG Code Chapter 7.2: segregation categories: "away from" (minimum separation of 3m horizontally in the same space, or in different compartments/holds); "separated from" (separated by a complete compartment or hold — i.e. at least one intervening space); "separated by a complete compartment or hold" and "separated longitudinally by an intervening complete compartment or hold." Ammonium nitrate as an oxidiser can cause catastrophic decomposition if contaminated with fuel oil (the Beirut Port explosion 2020, Texas City 1947 were both ammonium nitrate events). The segregation requirement between Class 5.1 and Class 3 is "away from" at minimum — adjacent holds sharing a bulkhead do not satisfy this. An OOW discovering an incorrect cargo plan before loading must stop operations and refer to the Chief Officer and master. The IMDG Segregation Table in Chapter 7.2.4 provides the complete matrix of segregation requirements between all classes.