SOLAS Chapter VI: Carriage of Cargoes and Oil Fuels

SOLAS Chapter VI concentrates the cargo-carriage obligations that apply across all ship types. Other SOLAS chapters address structural strength, fire, and damage survival; Chapter VI addresses what happens before the ship leaves port: what information the shipper must provide, how the cargo must be stowed, and which subsidiary codes govern specific cargo categories.

Chapter VI structure and scope

Four Parts, three subsidiary codes

Chapter VI maps four Parts to three subsidiary mandatory instruments:

Chapter VI does not contain the operational engineering detail; that detail lives in the subsidiary codes imported by reference. SOLAS Regulation VI/1 sets the application; Regulations VI/2 through VI/9 are the substantive rules.

The CSS Code (Code of Safe Practice for Cargo Stowage and Securing, Resolution A.714(17), 1991, as amended) is a recommended instrument. The Assembly recommended governments implement it at the earliest opportunity. What is mandatory under Regulation 5 is the ship-specific Cargo Securing Manual (CSM), which must be approved by the flag state administration. Flag states use the CSS Code as the technical basis for approving CSMs, so the Code’s standards carry effective regulatory weight in practice.

The IMSBC Code (Resolution MSC.268(85)) has been mandatory since 1 January 2011. It replaced the voluntary BC Code (Code of Safe Practice for Solid Bulk Cargoes). The current amendment is 07-23 (Resolution MSC.539(107)), adopted 8 June 2023, mandatory from 1 January 2025, voluntary from 1 January 2024. Amendment 08-25 (Resolution MSC.575(110)), adopted by MSC 110 in June 2025, will be mandatory from 1 January 2027 and may be applied voluntarily from 1 January 2026.

The International Grain Code (Resolution MSC.23(59)) has been mandatory since 1 January 1994, replacing the 1969 Grain Rules.

The BLU Code (Code of Practice for the Safe Loading and Unloading of Bulk Carriers, Resolution A.862(20)) provides operational guidance on bulk loading and unloading. It is not mandatory under SOLAS but is referenced by some flag states and widely applied in industry practice.

Relationship to other chapters and MARPOL

Chapter VI works alongside:

• Chapter II-1 for ship stability under loaded conditions, including reserve stability after a damage scenario in Part B. The grain heeling moment in Part C feeds the after-damage stability analysis.
• Chapter II-2 for fire protection of cargo spaces, particularly for IMDG cargoes and for the bilge ventilation of holds carrying Class 1 to Class 5 IMDG cargoes.
• Chapter VII for the carriage of dangerous goods. Chapter VII makes the IMDG Code mandatory for packaged dangerous goods; Chapter VI Part B does the same for the IMSBC Code for solid bulk dangerous goods. Some cargoes require compliance with both.
• MARPOL Annex II for noxious liquid bulk cargoes (the IBC Code), Annex III for harmful substances in packaged form, Annex V for garbage from cargo residues, and Annex VI for emissions from bunker fuel.

Amendment history

• 1974: Chapter VI in the original SOLAS 1974 text covered grain only. The legacy BC Code was voluntary.
• 1991 (in force 1994): International Grain Code adopted as Resolution MSC.23(59) and made mandatory through SOLAS reference. The 1969 Grain Rules became obsolete.
• 2008 (in force 2011): IMSBC Code adopted as Resolution MSC.268(85) and made mandatory through SOLAS reference, replacing the voluntary BC Code. The change was driven by recurring liquefaction casualties on ships carrying mineral concentrates above the TML.
• 2014 (in force 1 July 2016): Regulation VI/2 amended by Resolution MSC.380(94) to add the Verified Gross Mass (VGM) requirement for packed containers. Adopted at MSC 94 in November 2014.
• 2015: Amendments tightening shipper declarations under Regulation 2, requiring more rigorous moisture content certification for Group A cargoes. They followed the January 2015 loss of MV Bulk Jupiter carrying bauxite.
• 2023 (in force 1 January 2025): IMSBC Code Amendment 07-23 (Resolution MSC.539(107)), adding 15 new cargo schedules including new DRI by-product fines schedules, electric arc furnace dust, and ground granulated blast furnace slag powder, and introducing the concept of dynamic separation.
• 2025 (in force 1 January 2027): IMSBC Code Amendment 08-25 (Resolution MSC.575(110)), adding 11 new cargo schedules and revising 11 existing ones.

The amendment cycle reflects a consistent pattern: a casualty cluster drives a mandatory upgrade of a code that was previously voluntary, with subsequent fine-tuning as new failure modes are identified.

Part A: General provisions

Application (Regulation 1)

Chapter VI applies to all ships engaged on international voyages carrying cargo, whether general, bulk, dangerous, or grain. Specific Regulations apply additionally to specific cargo types. Chapter XII (Additional Safety Measures for Bulk Carriers) carries forward the Chapter VI requirements with additional provisions for bulk carriers.

Ship-type application:

• A container ship is subject to Part A (general cargo information, VGM, stowage and securing) but not Part B unless it is configured for bulk operations.
• A bulk carrier is subject to Part A and Part B for cargoes other than grain, Part A and Part C for grain, Part A and Part D for IMSBC-coded cargoes.
• A general cargo ship is subject to Part A for any cargo, and to the relevant Parts for specific cargo types.

Cargo information and Verified Gross Mass (Regulation 2)

Regulation 2 places the burden on the shipper to provide the master, before loading, with cargo information sufficient to enable safe carriage. The 2014 amendment (Resolution MSC.380(94), in force 1 July 2016) added the Verified Gross Mass requirement for packed containers.

General cargo information

For all cargoes, the required information includes:

• Cargo description: commercial name, technical name, UN number where applicable, product specification.
• Cargo characteristics: mass, stowage factor, angle of repose for bulk cargoes, moisture content for cargoes that may liquefy.
• Properties relevant to safe carriage: chemical hazards, flammable limits, reactivity with water or air, self-heating tendency, oxygen consumption.
• For solid bulk cargoes: IMSBC Code group designation (A, B, or C); the TML for Group A cargoes with a signed declaration that moisture content is below TML at the time of loading; the chemical schedule reference for Group B.
• For dangerous goods: the relevant IMDG Code or IMSBC Code schedule reference.
• For deck cargoes: the lashing and securing instructions.

The information must be in writing and signed by the shipper. The master may refuse cargo where the information is incomplete, inconsistent, or where the master has reason to believe the cargo is mis-declared.

Verified Gross Mass for packed containers

From 1 July 2016, the VGM of a packed container must be provided by the shipper before the container is loaded onto a ship. The VGM is a condition for loading. Two methods are authorized:

• Method 1: Weigh the packed container using calibrated and certified equipment. This is the more direct method and is required for certain cargo types.
• Method 2: Weigh all packages and cargo items individually, including pallets, dunnage, and securing material, then add the tare mass of the container. The method and the weighing equipment must be approved by the competent authority of the state where packing occurred.

The VGM must be stated in the shipping document and submitted to the master and the terminal representative in time for the stowage plan to be prepared before loading. Containers without a VGM declaration cannot be loaded. Implementation guidance is in MSC.1/Circ.1475 (Guidelines regarding verified gross mass of a container carrying cargo).

The Reg VI/2 cargo information calculator steps through the required fields for a given cargo type, including the VGM declaration.

Master’s verification of shipper’s declaration

The master is not required to passively accept the shipper’s declaration. For Group A cargoes, the master may draw cargo samples and submit them to a TML test (Flow Table Test, Penetration Test, or Proctor-Fagerberg Test under IMSBC Code Section 8). If the test indicates moisture above TML, the master must refuse loading or require dewatering. The master may also cross-check the shipper’s certificate of analysis and verify consistency against the IMSBC Code schedule for the declared cargo type.

Master refusal is a recognized regulatory action supported by Chapter VI and the Safety Management System under the ISM Code. MSC/Circ.1380 and its successors provide clarifications on the master’s authority.

Oxygen analysis and gas detection equipment (Regulation 3)

Ships carrying cargoes that may emit flammable, toxic, or oxygen-depleting gases must carry portable oxygen analysers and gas detection equipment, with crew trained to use them. Requirements apply to:

• Solid bulk cargoes that consume oxygen or generate toxic gas: coal (CO and oxygen depletion), sulphide ores (SO2 and H2S), fishmeal (CO2 and oxygen depletion from bacterial action), vegetable seed cake (oxygen depletion), charcoal, direct reduced iron (hydrogen).
• Mineral concentrates that may release sulphur dioxide or hydrogen sulphide on contact with water.
• Cargoes prone to self-heating with associated CO release: coal, fishmeal, certain mineral concentrates.

Equipment requirements:

• Portable oxygen analyser, measurement range 0 to 25 percent oxygen, accuracy of at least 0.5 percent of full scale.
• Portable combustible gas detector covering the lower explosive limit (LEL) range, calibrated for methane, propane, or the relevant gas.
• Specific toxic gas sensors (CO, H2S) for cargoes releasing those gases.
• Battery-operated with sufficient duration for hold entry surveys and emergency response.
• Calibration records showing periodic calibration with reference gases.
• Crew trained to operate the equipment and to interpret the readings.

IMO MSC.1/Circ.1264 (Recommendations on the carriage of bulk cargoes liable to liquefy or to develop oxygen-deficient atmospheres) provides operational detail.

Use of pesticides (Regulation 4)

Pesticides may be used on board for in-transit fumigation of cargo (particularly grain and other agricultural cargoes), for fumigation of empty holds before loading, and for treatment of crew accommodation. Regulation 4 requires:

• Use of approved fumigants only: typically aluminium phosphide or methyl bromide for grain; sulfuryl fluoride for dry stores; phosphine for various agricultural products.
• Pre-fumigation notification to the master with safety procedures.
• In-transit fumigation only with the master’s agreement and only where ventilation permits residual gas dissipation before crew entry.
• Post-fumigation gas check before any crew entry to the fumigated space.
• Fumigation operator training and certification.
• Documentation: gas type, application rate, application time, expected dissipation time, ventilation requirements.

Aluminium phosphide tablets generate phosphine gas (PH3) on contact with atmospheric moisture. Phosphine is lethal at concentrations above approximately 7 ppm with prolonged exposure; the required clearance level before crew entry is below 0.3 ppm. Warning signs must be posted at all entries during fumigation.

Methyl bromide use is increasingly restricted under the Montreal Protocol for its ozone-depleting effect. Maritime critical-use exemptions remain in place for specific high-value cargo applications.

Stowage and securing (Regulation 5)

Cargo must be stowed and secured to prevent damage to the ship and cargo and to prevent risks to persons. Regulation 5 is the mandatory requirement. Implementation is through:

• The Cargo Securing Manual (CSM), mandatory: prepared at delivery, approved by the flag state, kept on board, updated when securing arrangements change.
• The CSS Code (Code of Safe Practice for Cargo Stowage and Securing, Resolution A.714(17)), which is a recommended instrument but functions as the technical basis for CSM approval. Flag states and port state control use its standards in enforcement.
• The shipper’s lashing instructions for non-standard cargoes.

The CSM contains the description and specifications of fixed and portable cargo securing equipment, stowage and securing instructions for typical cargo types, procedures for inspection and maintenance of securing equipment, and cargo information forms for each consignment.

The Reg VI/5 stowage and securing calculator and the Cargo Securing Manual article provide further detail.

Container lashing

Container ships use a lashing system involving twist locks between containers (preventing horizontal slip and lift), lashing rods from container corner castings to the deck or lashing bridges, and turnbuckles for tensioning. Heavier containers go at the bottom; lighter at the top. Each ship’s CSM specifies maximum stack heights for various container weight distributions and weather conditions. The loading computer generates the lashing arrangement and verifies that the resulting forces (transverse, longitudinal, vertical, racking) are within the certified strength of the lashing equipment.

Ro-ro lashing

Ro-ro vessels use web lashings from cargo to deck pad eyes, cradles or chocks for unwheeled cargo, trestles for trailers without wheels, and hold-fast clips for containers on chassis. The CSM specifies the lashing pattern by cargo type and weather condition.

Heavy-weather adjustments

The CSS Code recognizes that the design lashing arrangement may not be adequate for severe weather. Operational practice includes reducing speed to limit ship motions, making for shelter if the weather forecast deteriorates, and pre-voyage weather routing under Chapter V Regulation 34.

Container loss incidents in 2020 to 2022 (ONE Apus, Maersk Eindhoven) drove industry-led initiatives to tighten lashing patterns and to integrate weather routing more closely with stowage planning. IMO MSC has amendments under development to the CSS Code addressing parametric rolling.

Part B: Special provisions for solid bulk cargoes other than grain

Acceptability for shipment (Regulation 6)

Before solid bulk cargo is accepted for loading, the master must verify that cargo information has been provided under Regulation 2, that the cargo is suitable for carriage on the ship, that the ship is suitable for the cargo (hold preparation, ventilation, fixed CO2 capability, hold geometry), and that no part of the cargo presents an unacceptable hazard. For Group A cargoes, this includes random moisture content sampling.

IMSBC cargo group summary

Some cargoes are classified as both Group A and Group B (the electric arc furnace dust schedule added in Amendment 07-23, for example).

Group A cargoes and liquefaction

Liquefaction is the process by which fine-particle cargoes (typically below 1 mm particle size) at sufficient moisture content can transition from a solid-like packed state to a viscous fluid under cyclic vibration from ship motion. The sequence:

1. Cyclic loading from rolling and pitching compresses pore water in the cargo.
2. Pore water pressure rises until it equals the inter-grain stress.
3. Grains lose contact with each other; the cargo behaves as a fluid.
4. The fluidised cargo flows under gravity, shifting the centre of gravity.
5. The heeling moment from the shifted cargo exceeds the ship’s righting moment; the ship capsizes.

The IMSBC Code addresses liquefaction through Group A classification, TML determination by one of three approved test methods, moisture content monitoring before and during loading, and cargo refusal if moisture is above TML.

Amendment 07-23 introduced the concept of dynamic separation: the formation of a liquid slurry (water and fine solids) above the solid cargo mass. Cargoes prone to dynamic separation are listed in a new sub-category and require additional precautions.

TML test methods

• Flow Table Test (FTT): a sample is placed on a flow table, the table is dropped 25 times in 15 seconds, and the resulting flow is measured. The TML is the moisture content at which flow exceeds defined limits.
• Penetration Test: a cone is dropped onto the cargo surface at increasing moisture contents. The TML is the moisture at which penetration first exceeds the threshold.
• Proctor-Fagerberg Test: the cargo is compacted at various moisture contents; the TML is derived from the optimum moisture content of the compaction curve.

The three tests give similar results for most cargoes but differ for specific types. The IMSBC Code Section 8 permits use of any of the three but recommends specific tests for specific cargoes. Bauxite requires the Modified Proctor-Fagerberg Test because the standard tests under-predict liquefaction risk for bauxite.

The IMSBC Group A liquefaction risk calculator and the IMSBC TML moisture check calculator implement the key compliance checks.

The IMSBC Group A cargoes article covers the test methods in greater depth.

Group B cargoes with chemical hazards

Group B cargoes have chemical hazards beyond simple combustibility:

• Coal: emits CO and depletes oxygen in adjacent spaces; some coals self-heat.
• Direct reduced iron (DRI): emits hydrogen and self-heats violently on contact with water.
• Sulphide ores: emit sulphur dioxide on contact with moisture or air.
• Fishmeal: self-heats and emits CO; spontaneous combustion risk if moisture content is excessive.
• Vegetable seed cake: self-heats and depletes oxygen.

For each Group B cargo the IMSBC Code provides hazard description, stowage and ventilation requirements, segregation from oxidisers and reactive materials, operational precautions, and emergency response.

Group C cargoes

Group C cargoes have neither liquefaction nor chemical hazards but are still subject to general IMSBC requirements: cargo information, loading procedures, stability documentation. Examples: cement, gypsum, salt, sand, scrap metal.

Loading, unloading and stowage (Regulation 7)

Loading and unloading of solid bulk cargo must follow the cargo distribution plan agreed between the master and the terminal, the BLU Code operational framework, the ship-specific loading manual and loading computer (mandatory on bulk carriers under Chapter II-1 and Chapter XII), and the required pre-loading stability documentation.

The BLU Code organises bulk loading and unloading into a four-party framework: the master (ultimate safety responsibility), the terminal representative (terminal-side operations), the ship’s chief officer (in-ship operations), and the surveyor (independent verification). The four parties exchange a Ship-Shore Safety Checklist before commencement.

Loading rate-arm calculations

The loading rate-arm calculation determines the maximum loading rate for each hold based on hull girder structural strength at intermediate loading states. Rapid loading of a small number of holds can create high local hull-girder stresses while the rest of the ship is still light. The bulk loading rate-arm calculator implements the calculation, taking ship type, hull girder section modulus, and loading sequence as inputs.

Part C: Carriage of grain

The International Grain Code

Grain (cereals: wheat, maize, rice, barley, oats, rye; processed forms; pulses: peas, beans, lentils; seeds with similar properties: rapeseed, sunflower seed, soybean) presents a specific shifting hazard. In a partially-filled compartment, grain shifts during a voyage as the ship rolls. The shifted grain creates a heeling moment that can degrade stability or cause capsize.

The International Grain Code (Resolution MSC.23(59), mandatory 1 January 1994) sets out the calculation methodology and carriage criteria.

Volumetric assumption

In a partially-filled compartment:

• The grain settles by 2 percent of compartment height during normal voyage, leaving a void at the top.
• Compartments fully loaded with overstow: no shift assumed.
• Compartments partially loaded: shift assumed during a 25-degree heel, with the grain surface tilting to a new angle equal to the angle of repose (typically 25 to 35 degrees) measured from horizontal.

Heeling moment computation

The heeling moment is calculated by integrating the volumetric shift over the compartment geometry. For a rectangular compartment of dimensions L (length), B (breadth), H (height):

• The void at the top is 0.02 × H (the 2 percent settlement assumption).
• After 25-degree heel and shift to angle of repose, the shifted volume is approximately (B² × tan(angle of repose) × L) / 8.
• The moment equals the product of the shifted volume, the cargo density, and the shift distance from the centreline, divided by displacement.

The detailed calculation accounts for actual compartment geometry: bulk carrier holds have hopper sides and sloped bottoms that change the shift calculation.

Stability criteria after grain shift

The ship must satisfy all three criteria after the assumed grain shift:

• The angle of heel from the assumed shift must not exceed 12 degrees (for ships 100 m and above).
• The residual GZ must give a positive area between the GZ curve and the heeling moment curve up to the angle of progressive flooding.
• The maximum residual GZ must not be less than 75 percent of the maximum GZ in intact condition.

Compliance methods

Compliance is achieved through one of:

• Filled compartments: loaded to the maximum extent practicable; the residual void is small.
• Partial loading with strapping or lashing: the grain surface is overstowed with bagged grain or covered with a structure that prevents shifting. Strapping uses synthetic mesh, tarpaulin, or specialised flexible bags.
• Saucers or shifting boards: portable longitudinal or transverse bulkheads limiting the volume into which grain can shift.
• Compliance by calculation only: ships with sufficient reserve GM may carry grain in partial loading without physical securing, documented in the loading calculation.

Document of Authorization to carry grain

A ship loading grain in bulk must hold a Document of Authorization issued by the flag state (or a recognized organization on its behalf), valid for a defined period, listing the conditions under which the ship is authorized to carry grain: approved holds, loading conditions, any restrictions. The document is required at port state control inspections of grain-loaded ships.

The grain heel calculator and the bulk cargo displacement grain calculator compute the grain heeling moment and resulting heel angle for a given ship and grain stowage. Cargo-specific schedules for corn, wheat, rice bran, and soybeans provide IMSBC-aligned data for the principal grain cargoes.

Part D: Carriage of solid bulk cargoes under the IMSBC Code

The IMSBC Code, mandatory under Resolution MSC.268(85) since 2011 and currently in Amendment 07-23 (mandatory from 1 January 2025), governs the carriage of solid bulk cargoes other than grain. It is structured into 13 Sections:

• Section 1: General provisions.
• Section 2: General loading, carriage, and unloading precautions.
• Section 3: Safety of personnel and ship.
• Section 4: Assessment of acceptability of consignments for safe shipment.
• Section 5: Trimming procedures.
• Section 6: Methods of determining angle of repose.
• Section 7: Cargoes that may liquefy (Group A).
• Section 8: Test procedures for cargoes that may liquefy.
• Section 9: Materials with chemical hazards (Group B).
• Section 10: Carriage of dangerous goods.
• Section 11: Security provisions.
• Section 12: Stowage factor conversion tables.
• Section 13: References to related information.

Appendix 1 contains the Individual Schedules of Solid Bulk Cargoes: alphabetically organized entries for each cargo with stowage factor, angle of repose, group classification, hazards, weather precautions, ventilation requirements, segregation requirements, and emergency procedures.

The IMSBC Code article covers the Code in greater depth. The IMSBC Group A/B/C classification calculator provides an interactive lookup.

Amendment 07-23 changes (mandatory from 1 January 2025)

Amendment 07-23 (Resolution MSC.539(107)) made several changes of practical significance:

• 15 new cargo schedules added to Appendix 1, including celestine concentrate, brown fused alumina, dunite, ground granulated blast furnace slag powder, and electric arc furnace dust (classified both Group A and Group B).
• Fourth DRI schedule: DRI by-product fines with moisture content exceeding 2 percent.
• Dynamic separation concept: new definition and sub-category for cargoes forming a liquid slurry above the solid mass.
• Bulk density requirement: shippers must now provide bulk density as required cargo information per SOLAS Regulation XII/10.
• Fire system exemption update: the list of cargoes exempt from fixed gas fire extinguishing system requirements updated to Rev.6 of MSC.1/Circ.1395.
• Fish meal modification: schedule updated to align stabilization requirements between IMSBC and IMDG codes.

Amendment 08-25 changes (mandatory from 1 January 2027)

Amendment 08-25 (Resolution MSC.575(110), adopted MSC 110, June 2025) adds 11 new cargo schedules and revises 11 existing ones. Voluntary use is permitted from 1 January 2026.

Notable casualties

MV Derbyshire, 1980

The British-flagged bulk carrier MV Derbyshire foundered in Typhoon Orchid south of Japan on 9 September 1980 with 44 dead. The investigation, completed in 2000 after one of the most extensive inquiries in maritime history, identified failure of the No. 1 hatch cover as a contributing factor. The casualty was a foundational driver of Chapter XII and contributed to the tightening of shipper declarations under Regulation 2. Conclusions drove strengthened hatch cover design, strengthened forward deck plate scantlings to withstand green seas, and independent forecastle as reserve buoyancy.

MV Vinalines Queen, 2011

The Vietnam-flagged bulk carrier MV Vinalines Queen capsized in the Pacific on 25 December 2011 carrying nickel ore from Indonesia, with 22 of 23 crew lost. Liquefaction of the Group A nickel ore cargo was identified as the cause. The casualty drove post-IMSBC Code amendments tightening Group A moisture content verification.

MV Bulk Jupiter, 2015

MV Bulk Jupiter sank in the South China Sea on 2 January 2015 carrying bauxite from Malaysia, with 18 of 19 crew lost. Liquefaction of the bauxite cargo led to the addition of bauxite fines to Group A in subsequent IMSBC amendments. The bauxite case illustrated the static limitation of the Code: a cargo considered safe became unsafe when shipped from a different source with different moisture characteristics. The amendment cycle now includes explicit pathways for adding cargo entries to Group A based on field experience.

MV Stellar Daisy, 2017

The Marshall Islands-flagged Very Large Ore Carrier MV Stellar Daisy split and sank in the South Atlantic on 31 March 2017 carrying iron ore fines from Brazil to China, with 22 of 24 crew lost. The casualty triggered investigation of structural integrity in converted VLOCs and contributed to IACS unified requirements on bulk carrier structure.

Container losses overboard

Recurring container loss incidents in heavy weather have driven attention to lashing standards:

• MOL Comfort, 2013: split in two and sank in the Indian Ocean carrying about 4,500 TEU.
• ONE Apus, 2020: lost approximately 1,800 containers overboard in the Pacific; parametric rolling identified as a contributing factor.
• Maersk Eindhoven, 2021: lost approximately 260 containers overboard.
• Tokio Express, 2022: lost approximately 65 containers overboard.

Post-incident analyses identify parametric rolling (resonance between encounter wave frequency and ship’s natural roll frequency), lashing system limits exceeded at roll angles above approximately 25 to 30 degrees, and stack heights that have grown faster than lashing standards have updated.

Container fires from mis-declared dangerous goods

A separate cluster of container ship casualties (Maersk Honam 2018, X-Press Pearl 2021) involved fires from mis-declared dangerous goods, bridging Chapter VI (cargo information) and Chapter VII and Chapter II-2. The CINS (Cargo Incident Notification System) industry database tracks mis-declared cargo incidents at scale.

Specific cargo operational considerations

Iron ore

Iron ore is the largest bulk cargo by tonnage, with annual world trade exceeding 1.5 billion tonnes. The principal IMSBC categories:

• Iron ore (lump and sinter feed): typically Group C; general IMSBC procedures.
• Iron ore fines (IOF): Group A, liable to liquefy if shipped above TML. The IOF schedule was added following the Vinalines Queen investigation and the cluster of Vale Brazil incidents.
• Iron ore concentrate: fine-particle concentrate from beneficiation plants; typically Group A, TML test required.

Iron ore is loaded at major terminals (Port Hedland, Dampier, Saldanha Bay, Tubarão, Ponta da Madeira) at rates up to 12,000 tonnes per hour from a single shiploader. The high rate requires careful management of the loading sequence to avoid stress concentration in the hull girder.

The IMSBC iron ore fines calculator implements the moisture verification. The iron ore fines moisture check calculator provides a quick field check.

Coal

Coal annual world trade is approximately 1.3 billion tonnes, with multiple hazards:

• Self-heating: coal produces methane, carbon monoxide, and hydrogen sulphide. Inadequate oxygen restriction can lead to spontaneous combustion.
• Oxygen depletion: bacterial oxidation depletes oxygen in adjacent enclosed spaces. Crew entry to coal-stowed holds requires gas testing for both oxygen content and CO concentration.
• Methane release: coal beds release methane as the cargo is loaded; accumulation risk in enclosed spaces.
• Liquefaction risk: certain fine coal cargoes (slurries, beneficiation tailings, some run-of-mine cargoes with high moisture) are Group A.

Hot work near coal cargo is forbidden during voyage.

Bauxite

Following the loss of MV Bulk Jupiter (2015), bauxite fines were added to Group A in 2017 IMSBC amendments. The IMSBC schedule distinguishes between lump bauxite (run-of-mine, typically above 25 mm particle size: Group C, no liquefaction hazard) and bauxite fines (Group A, requiring the Modified Proctor-Fagerberg Test for TML determination).

Direct reduced iron (DRI)

DRI is metallic iron produced by reduction below the melting point. It is highly reactive with water (releasing hydrogen with high heat) and atmospheric oxygen (self-heating). Three forms appear in the IMSBC Code:

• DRI(A): hot-briquetted iron, Group B, requires inerting.
• DRI(B): lumps/pellets/cold-moulded briquettes, Group B, requires inerting.
• DRI(C): by-product fines, Group B, requires inerting.

Amendment 07-23 added a fourth schedule for DRI by-product fines with moisture content above 2 percent, addressing the hydrogen concentration and cargo temperature monitoring requirements.

DRI carriage requires an inert gas system maintaining cargo space oxygen below 5 percent, continuous monitoring of oxygen, hydrogen, and hold temperature, and a watertight hold to prevent water ingress.

Ballast water management interaction

Bulk carriers operate with substantial ballast water exchange between voyages. The interaction with the Ballast Water Management Convention is significant: ballast loading sequence must be matched with cargo discharge to maintain hull strength and stability throughout, and the ballast water treatment system (UV, electrolysis, or active substance) operates during ballast intake. Ballast tanks on bulk carriers are also subject to close-up inspection under the Enhanced Survey Programme of Chapter XII due to the corrosive environment.

Bunker fuel as cargo

Although the chapter title refers to “cargoes and oil fuels”, the carriage of bunker fuel is governed in practice through Chapter II-1 (engineering arrangements including the IGF Code for low-flashpoint fuels: LNG, methanol, ammonia, hydrogen), MARPOL Annex I (oil pollution prevention), and MARPOL Annex VI (sulphur limits, NOx limits, EEDI, EEXI, CII).

Chapter VI Part A applies in two specific senses: the Bunker Delivery Note (BDN) under MARPOL Annex VI and ISO 8217 serves the same regulatory purpose as a cargo information declaration; stowage and securing apply to bunker drums and IBCs carried as deck cargo.

Port state control inspections

Port state control inspections of cargo carriage focus on:

• Cargo manifest verification against the Document of Compliance for Dangerous Goods and against the IMSBC Code.
• Shipper declaration verification for sampled containers or bulk consignments.
• Stowage and securing inspection of deck cargo: actual stowage vs. lashing plan and CSM.
• CSM examination: recent amendments and loading conditions documented for the voyage.
• Loading instrument review: loading computer used, calculated stresses within limits.
• Group A moisture certification: random sampling for verification.
• Hatch cover and hold integrity: especially after voyages with green-water exposure.
• Fumigation certificate verification: residual gas levels measured before crew entry confirmed.

Major PSC regimes (Paris MOU, Tokyo MOU, US Coast Guard, AMSA, China MSA) include cargo carriage in their inspection categories.

Documentation carried on board

Every ship covered by Chapter VI must carry:

• The Cargo Ship Safety Construction Certificate (under Chapter I) with evidence of compliance with IMSBC Code, Grain Code, and CSS Code as applicable.
• The ship-specific Cargo Securing Manual approved by the flag state.
• The Document of Authorization to carry grain (under the Grain Code).
• Cargo information declarations from the shipper for each consignment (including VGM declarations for containers).
• Hold preparation and inspection records.
• Fumigation certificates and post-fumigation gas check records.
• The IMSBC Code copy on board (current amendment: 07-23, mandatory from 1 January 2025).
• The International Grain Code copy on board.
• Pre-loading stability documentation including loading computer outputs.
• For container ships: the bay plan and lashing plan from the loading computer.
• For ro-ro vessels: the deck stowage plan with cargo securing details.

Limitations

This article describes Chapter VI as amended through MSC.539(107) (IMSBC Amendment 07-23, mandatory 1 January 2025) and notes the adoption of Amendment 08-25 (MSC.575(110)) in June 2025. The IMSBC Code individual cargo schedules are updated with each amendment cycle; users must verify against the current published Code for the schedules of specific cargoes. TML values for Group A cargoes are cargo- and source-specific and must be determined by approved laboratory testing, not from this article. Flag state and terminal requirements may be more stringent than the IMO minimum.

See also

• SOLAS Convention
• SOLAS Chapter II-1: Construction, Subdivision, Stability, Machinery and Electrical Installations
• SOLAS Chapter II-2: Fire Protection, Detection and Extinction
• SOLAS Chapter V: Safety of Navigation
• SOLAS Chapter VII: Carriage of Dangerous Goods
• SOLAS Chapter XII: Additional Safety Measures for Bulk Carriers
• IMSBC Code
• IMSBC Group A cargoes
• Cargo Securing Manual
• Bulk Carrier
• Container Ship
• MARPOL Convention
• Ballast Water Management Convention
• ISM Code
• IMDG Class 1 Explosives
• IMDG Class 4 Flammable Solids

References

• IMO, International Convention for the Safety of Life at Sea (SOLAS), 1974, as amended, Chapter VI.
• IMO, International Maritime Solid Bulk Cargoes Code (IMSBC Code), Resolution MSC.268(85), 2008, as amended by Resolution MSC.539(107) (Amendment 07-23, mandatory 1 January 2025) and Resolution MSC.575(110) (Amendment 08-25, mandatory 1 January 2027).
• IMO, Resolution MSC.380(94) (adopted 21 November 2014): amendments to SOLAS Regulation VI/2 for the Verified Gross Mass of packed containers, in force 1 July 2016.
• IMO, MSC.1/Circ.1475, Guidelines regarding the verified gross mass of a container carrying cargo.
• IMO, International Code for the Safe Carriage of Grain in Bulk (International Grain Code), Resolution MSC.23(59), 1991, as amended.
• IMO, Code of Safe Practice for Cargo Stowage and Securing (CSS Code), Resolution A.714(17), 1991, as amended.
• IMO, Code of Practice for the Safe Loading and Unloading of Bulk Carriers (BLU Code), Resolution A.862(20).
• IMO, MSC/Circ.1380 and successor circulars on liquefaction risk and Group A cargoes.
• IMO, MSC.1/Circ.1264, Recommendations on the carriage of bulk cargoes liable to liquefy or develop oxygen-deficient atmospheres.