Iron Ore Pellets: IMSBC Code Schedule and Carriage

Iron ore pellets are one of the most commercially important solid bulk cargoes in global trade, moving roughly 150 to 180 million tonnes per year between major exporting regions and steel mills. They’re classified under the IMSBC Code as Group C, meaning they’re neither liable to liquefy nor chemically hazardous during sea carriage. The cargo’s dominant operational challenges don’t come from hazard classification but from its extreme density: at 2.0 to 2.6 tonnes per cubic metre, a full hold of pellets can press the tanktop and inner-bottom structure close to or beyond design limits on bulk carriers not sized for heavy-stowage cargo. Understanding how pellets differ from iron ore fines (Group A, liquefaction risk), what the IMSBC schedule actually specifies, and how to manage structural loading and pellet degradation is the practical core of safe pellet carriage.

What iron ore pellets are

Iron ore pellets are agglomerated spheres of iron ore concentrate, fired to a hard, dense product for use as blast-furnace burden or direct-reduction feedstock. The manufacturing sequence converts raw ore into a consistent, premium feedstock with iron content of 63 to 68 percent Fe, far above the 55 to 62 percent Fe of typical direct-shipping iron ore lump. The pelletising route involves:

Crushing and grinding iron ore to a fine concentrate, typically 80 percent passing 0.044 millimetres (325 mesh). Mixing the concentrate with a binder, usually bentonite at around 0.5 percent by mass for blast-furnace pellets, or organic binders for direct-reduction pellets where silica contamination from bentonite is unacceptable. Rolling the wet mixture in a balling drum or disc pelletiser to form green pellets of 9 to 16 millimetres diameter. Firing at approximately 1,250 to 1,350 degrees Celsius in a straight-grate or grate-kiln furnace, sintering the magnetite or hematite particles together. Screening and cooling to produce the finished product.

The firing step is what makes pellets chemically inert for IMSBC purposes. The sintering process drives off virtually all moisture, destroys any organic matter, and bonds the particles into a rigid sphere. Finished pellets have a crush strength typically above 250 daN (decaNewtons) per pellet for blast-furnace grades, a tumble index (fraction surviving 200 revolutions in a test drum) of 94 to 96 percent for premium grades, and moisture content of 0.3 to 0.8 percent by mass. This combination makes them completely unlike iron ore fines in their transport behavior.

Blast-furnace pellets and DR pellets

Two broad product categories move in seaborne trade. Blast-furnace (BF) pellets are acidic or fluxed pellets carrying 63 to 66 percent Fe, designed for use as direct burden in blast furnaces alongside sinter and lump ore. Fluxed pellets contain added limestone or dolomite to adjust the pellet’s basicity and reduce flux requirements at the furnace. Direct-reduction (DR) pellets are premium-grade, low-silica pellets carrying 67 to 68.5 percent Fe, produced specifically for shaft furnace (Midrex, HYL/Energiron) or rotary-kiln DR plants; the DR process has limited slag capacity, so silica and alumina in the pellet burden directly constrain plant productivity, pushing buyers toward very high grades.

Vale produces both grades from Carajas and Minas Gerais iron ore. LKAB’s Kiruna and Malmberget operations produce pellets from magnetite concentrate that is unusually low in silica and phosphorus, making LKAB a preferred DR-pellet supplier to Scandinavian and central European mini-mills. The distinction matters commercially but not for IMSBC carriage: both grades are Group C with the same structural-loading and handling concerns.

IMSBC Code schedule for iron ore pellets

The IMSBC Code schedule for IRON ORE PELLETS appears in Chapter 9 (individual schedule of solid bulk cargoes listed in alphabetical order). The schedule was included in the original 2008 IMSBC Code and has been carried forward through amendments including MSC.500(105) (the 2021 edition, effective 1 June 2023) and MSC.539(107) (the 2023 amendments, effective 1 June 2025).

MSC.501(105) is the IMDG Code amendment, not the IMSBC Code. This distinction matters when citing the regulatory basis: the IMSBC Code amendments are MSC.500(105) for the 2021 edition and MSC.539(107) for the subsequent amendment cycle.

Schedule particulars

The “no TML testing required” entry is one of the most operationally significant parts of the schedule. It directly distinguishes pellets from iron ore fines and iron ore concentrate, both of which require shipper certification of moisture content against the TML before every loading. Pellet masters do not deal with can tests, TML declarations, or Proctor-Fagerberg certificates. The pre-loading documentation burden is substantially lighter.

Group C and the contrast with Group A iron ore fines

The Group C classification for iron ore pellets is the correct one, and it’s worth being precise about why. The IMSBC Code defines Group A as cargoes that may liquefy if shipped at moisture content above their transportable moisture limit. Liquefaction requires a critical combination: fine particles, high porosity (allowing pore-water pressure to build under compaction), and sufficient moisture. Iron ore fines and iron ore concentrate meet all three conditions. Iron ore pellets meet none.

The pelletising and firing process specifically destroys the properties that create liquefaction risk. The fired pellet has very low residual porosity, a smooth hard surface, a spherical shape that reduces inter-particle friction without allowing liquid-like flow at elevated moisture, and moisture content of 0.3 to 0.8 percent, far below any level at which pore-water pressure effects could develop. A cargo arriving at loading with 5 percent moisture (already very unusual for pellets) would still not generate liquefaction in the IMSBC sense because the pellets’ low surface area and rigid structure prevent pore-water pressure buildup.

Group A cargoes like iron ore fines have caused catastrophic casualties at sea. The MV Stellar Daisy, lost in the South Atlantic in March 2017 with 22 lives, was carrying iron ore fines. The Bulk Jupiter was lost in the Gulf of Thailand in January 2015 with 18 lives, carrying bauxite fines. Iron ore pellets don’t carry this risk. The operational hazard on a pellet voyage runs in a completely different direction: structural, not chemical.

IMSBC Group C cargoes as a class include a wide range of ordinary dry-bulk commodities. Iron ore pellets sit at the heavy end of Group C, alongside direct-shipping iron ore lump, pig iron, and copper cathodes.

The bulk density and structural-loading problem

Iron ore pellets are among the densest cargoes carried in bulk. At 2.0 to 2.6 tonnes per cubic metre, a fully loaded hold of pellets generates a tanktop pressure roughly five to six times higher than the same hold depth of coal, and two to three times higher than bagged cement. This is the operative hazard for pellet operations, and it’s where the IMSBC Code and SOLAS Chapter XII intersect.

Bulk density and stowage factor relationship

Bulk density $\rho_b$ and stowage factor $SF$ are inverses:

For pellets with $\rho_b = 2.4 \, \text{t/m}^3$, $SF = 0.417 \, \text{m}^3/\text{t}$. This means 1,000 tonnes of pellets occupy 417 cubic metres, where the same mass of coal at $SF = 1.2 \, \text{m}^3/\text{t}$ would occupy 1,200 cubic metres. The pellets sit in less than 40 percent of the hold depth coal would occupy, concentrating all the weight near the tanktop.

Tanktop pressure

The pressure on the tanktop under a column of cargo is:

where $P$ is pressure in kPa, $\rho_b$ is the cargo bulk density in t/m3, $g$ is gravitational acceleration (9.81 m/s2), and $h$ is the cargo fill depth in metres. For a hold filled 7 metres deep with iron ore pellets at 2.4 t/m3:

This is around 16.8 tonnes per square metre. Bulk carrier tanktops are typically designed to withstand 10 to 20 tonnes per square metre, depending on vessel class and class society rules. A general-purpose capesize built for iron ore fines service is typically rated for 17 to 20 tonnes per square metre. A vessel built for coal or grain service may be rated at only 10 to 12 tonnes per square metre. Loading iron ore pellets into a vessel that doesn’t have the structural rating for heavy-stowage cargo is how tanktops get permanently deformed.

SOLAS Chapter XII provisions

SOLAS Chapter XII applies to bulk carriers carrying solid bulk cargoes with a density at or above 1.78 tonnes per cubic metre. Iron ore pellets exceed this threshold by a factor of roughly 1.35 to 1.46 depending on the specific cargo. Chapter XII requires:

Regulationulation XII/4 (cargo distribution): the ship must be assessed to ensure the cargo hold loadings don’t exceed the design loads for which the ship was built. For pellets, this means checking the tanktop design load against the calculated load for the intended fill depth per hold.

Regulation XII/6 (loading instruments): vessels to which Chapter XII applies must carry an approved loading computer capable of calculating shear forces, bending moments, and, for densities above 1.78 t/m3, tanktop pressures for each loading condition.

The practical consequence is that loading plans for pellet cargoes must be verified through the loading computer before cargo commences. Officers should check not just the global bending moment and shear force curves but also the tanktop strength curve for each hold, especially when the vessel will carry pellets in alternate holds (which concentrates load).

Alternate-hold loading and distribution

Bulk carriers are frequently loaded with cargo in alternate holds (every other hold empty) to adjust trim or to allow rapid loading without waiting for each hold to fill. With coal or grain, alternate loading is routine. With iron ore pellets, alternate loading creates much higher bending moments amidships and higher tanktop point loading in the loaded holds. Some smaller capesize and panamax vessels cannot structurally sustain pellets in alternate holds. The loading plan must confirm that the bending moment envelope for the proposed alternate-load sequence stays within the permissible range at all stages, not just at completion.

Port captains at major pellet-export terminals (Tubarão, LKAB’s Narvik terminal) are experienced with these checks and typically provide loading programs as a standard service, but the master retains responsibility for confirming structural adequacy before loading begins.

Pellet attrition and fines generation

Iron ore pellets degrade during handling. This isn’t a new discovery: the industry has tracked pellet attrition since the 1970s, and pellet specification standards include tumble index (ISO 3271) and abrasion index (ISO 3271) tests precisely because of the commercial and operational consequences of pellet breakage.

Sources of attrition

Attrition occurs at several points in the loading chain. Conveyor transfers are a primary source: each time pellets drop from one belt to another or from a belt to a shiploader chute, the impact load on pellets at the bottom of the pile adds to cumulative breakage. A cargo moving from the mine to the export terminal may pass through six to ten conveyor transfer points. Shiploader chutes, especially those without rock boxes or curved flow-control liners, accelerate breakage by allowing pellets to free-fall onto the cargo already in the hold. Trim passing by pusher blade or dozer during trimming operations breaks pellets at the blade interface.

Discharge adds another attrition cycle. Grab cranes release the grab jaw directly onto the cargo surface, and the initial bite crushes a layer of pellets before the grab closes. Conveyor systems at the receiving terminal add further breakage. By the time pellets reach the blast furnace or DR plant bin, a measurable fines fraction has accumulated.

Operational significance of attrition-generated fines

The fines generated by pellet attrition do NOT convert the cargo from Group C to Group A. The attrition fines from pellets are different from iron ore fines by origin, porosity, and moisture. Fired-pellet fines have very low residual porosity and are already bone-dry; they don’t accumulate pore-water pressure in the IMSBC sense. The Group C classification remains valid for the voyage.

The operational concerns from attrition-generated fines are different. They’re practical, not regulatory:

Fines reduce hold cleanliness and create dust during and after discharge, increasing respiratory exposure risk for shore workers. Pellet dust is not acutely toxic but is an inhalable nuisance particulate and a long-term pulmonary irritant in high-concentration occupational exposure.

Fines accumulate in hold bilge spaces. Bilge strum boxes can become blocked with fine particles, preventing drainage of any water that enters the hold during the voyage.

Fines at the angle-of-repose boundary of the cargo can shift in heavy weather, generating the kind of cargo movement that isn’t liquefaction but that can produce a list. This is a minor concern compared with Group A fines, but it warrants attention in voyage planning for heavy-weather routes.

Attrition fines contaminate the product at the receiving plant. DR pellet buyers specify a maximum fines fraction (typically less than 5 percent minus 6.3 millimetres) in the delivery specification. Excess fines generate commercial disputes and, in some DR plant designs, can cause fluidization problems in the shaft furnace.

Pellet quality standards and their relation to carriage

Pellet producers publish crush-strength and tumble-index figures in product specifications. Crush strength above 250 daN per pellet (ISO 4700) and tumble index above 94 percent (fraction surviving 200 revolutions in a 1-metre diameter drum at ISO 3271) are industry benchmarks for premium-grade pellets. Cargoes near the lower bound of these specifications will generate more fines at each transfer point. Where charter parties specify delivery on a final product fines specification, the receiver may claim damages if the discharged cargo’s fines fraction exceeds contract limits, regardless of pellet condition at load port. Masters taking pellets should be aware that the discharge condition, not just the loading condition, is commercially significant.

Major producers and trade routes

Iron ore pellet seaborne trade runs on three principal axes: Brazil to global buyers, Sweden to northern Europe, and a smaller number of other exporters.

Brazil

Vale is the world’s largest pellet producer, with operating capacity across nine pellet plants located at the Tubarão complex in Vitória, Espírito Santo, and at Itabira and other inland locations in Minas Gerais. The Tubarão complex alone has nominal pelletising capacity above 40 million tonnes per year. Vale’s pellets are loaded at the Tubarão and Ponta da Madeira export terminals via ship loaders that can sustain loading rates of 5,000 to 8,000 tonnes per hour on large ore carriers.

Brazilian pellets flow to China (the largest single buyer of Brazilian pellets by volume), South Korea, Japan, and to Middle Eastern DR plants. The Cape route (around South Africa) is standard for East Asian destinations; Suez is used for Mediterranean and Middle Eastern buyers.

Sweden: LKAB

LKAB (Luossavaara-Kiirunavaara Aktiebolag) operates underground iron ore mines at Kiruna and Malmberget in northern Sweden, both above the Arctic Circle. The ore is transported by the Ore Line railway to the coast: Kiruna ore goes 170 kilometres north to the ice-free Norwegian port of Narvik; Malmberget ore goes south 100 kilometres to the Swedish Baltic port of Luleå.

LKAB’s pellets are produced from magnetite concentrate, which is among the highest-purity iron ore in the world: very low silica (typically below 2 percent SiO2), low phosphorus, and 68 to 71 percent Fe in the concentrate before pelletising. The finished pellets carry 67 to 68 percent Fe for blast-furnace grades and above 68 percent for DR grades. LKAB supplies pellets principally to European steel mills (ArcelorMittal, SSAB, and others) and to Middle Eastern DR plants. The Narvik terminal can load Panamax and small Capesize vessels; Luleå handles smaller vessels constrained by Baltic ice and bridge air-draft restrictions.

LKAB’s HYBRIT project and the H2 Green Steel venture at Boden, Sweden, both intend to use LKAB DR pellets with hydrogen-based DR reduction as a decarbonization pathway, representing a potentially significant shift in the pellet trade from blast-furnace to DR applications.

Other exporters

Russia produced substantial pellet volumes from Kursk Magnetic Anomaly operations, principally from Lebedinsky GOK and Mikhailovsky GOK, exported through Baltic ports (Ust-Luga, Vysotsk) and the Black Sea. Volumes fell sharply after 2022.

Canada’s Iron Ore Company (IOC), a Rio Tinto, Mitsubishi, and Labrador Iron Ore joint venture, operates a pellet plant at Sept-Iles, Québec, exporting through the Port of Sept-Iles on the St. Lawrence. IOC produces both BF and DR pellets from Labrador City concentrate.

Iran operates pellet plants at Mobarakeh, Gol-e-Gohar, and MIDHCO associated operations, primarily for domestic consumption but with periodic export volumes.

India has developed substantial pellet capacity associated with operations by NMDC, ESSAR (now AM/NS India), and Tata Steel, with exports primarily to South and Southeast Asia.

Hold preparation

Hold preparation for iron ore pellets is straightforward by comparison with Group A and Group B cargo requirements, but that relative simplicity doesn’t mean it’s casual. Several specific checks matter.

Structural inspection. Before any pellet loading, the officer responsible should physically inspect the tanktop and inner-bottom of each hold to be loaded. Look for pre-existing deformation of the tanktop plating (oil-canning), cracked or corroded floor stringer webs, and damaged tanktop drain holes. Loading pellets into a hold with compromised tanktop structure risks permanent deformation or structural failure. Classification societies require that any visible damage be reported and assessed before loading heavy-stowage cargo.

Bilge system clearance. Iron ore pellets can block bilge strum boxes if fines accumulate. Confirm that all bilge strums are intact, properly seated, and clear of debris from any prior cargo. Test the bilge pump capacity and confirm that bilge alarms are operational. If the vessel has had a dusty prior cargo, the bilge lines may contain accumulated dust that will combine with pellet fines and cement into a hard mass. Flush and inspect.

Hatch cover integrity. Water ingress into a pellet cargo hold doesn’t create a liquefaction risk but it does create problems: it can corrode hold structure, generate rust staining that will transfer to the pellets and may trigger receiver quality complaints, and it can accumulate in bilges and mask structural damage. Confirm hatch cover gasket condition, drain channel cleanliness, and compression test results before loading.

Residue from prior cargo. Pellets are chemically inert but they pick up surface contamination easily. If the prior cargo was coal, sulphur, or any chemically active material, the hold must be washed down and inspected for cleanliness. A pellet cargo arriving at a DR plant with visible coal contamination will be rejected or subject to large commercial deductions.

Hold coating condition. Many bulk carriers trading heavy ores have abrasion-resistant epoxy coatings on hold frames, webs, and tanktop areas that bear the most abrasion load. Check coating condition and repair any areas where bare steel is exposed, particularly on frames and stringer edges that will be contacted during grab discharge.

Loading operations

Loading iron ore pellets follows the standard heavy-ore loading sequence with attention to the structural-loading constraints established in the voyage loading plan.

Loading rate and sequence

Major pellet export terminals load at 3,000 to 8,000 tonnes per hour using shiploaders with variable boom-angle systems that can distribute cargo across the width of the hold. The loading plan should specify the fill sequence for each hold and the intermediate stop-and-check points where the officer on watch confirms via loading computer that the current condition is within permissible limits before the next hold commences.

For vessels that will carry pellets in all holds (all-hold loading rather than alternate holds), the sequence matters less structurally, but the draft progression should be monitored to confirm that port-to-starboard trim and list stay within the master’s comfort range throughout loading. Shiploaders at terminals like Tubarão use conveyor-belt monitoring and ship-motion sensors to maintain loading symmetry, but the master retains authority to pause loading if the vessel’s behavior indicates a problem.

Shiploader chute design and attrition

Modern pellet shiploaders at LKAB’s Narvik and Vale’s Tubarão terminals use rock-box or cascade chute designs that break the fall height of pellets before they reach the cargo pile, reducing impact attrition. Older or less sophisticated terminals use straight-fall chutes that allow pellets to free-fall significant heights, accelerating attrition. There’s no IMSBC requirement on chute design, but commercially aware charterers include terminal specifications that require controlled-fall loading where a premium-product specification is commercially important.

Trimming

The IMSBC Code schedule for iron ore pellets specifies that trimming is not required. Pellets are spherical and free-flowing, so they self-level on loading and do not accumulate the unstable cone angles that coarser, irregular-shaped cargoes can produce. In practice, most pellet cargoes are loaded level at the completion of each hold, and the only trimming concern is ensuring that the forward and after parts of each hold are adequately filled to avoid excessive slack space that could allow cargo movement in heavy weather.

The self-leveling property also means that the final draft survey measurement can typically be taken within a short time of completion of loading, without waiting for the cargo to settle further.

Draft survey

Draft survey is the standard quantity-determination method for iron ore pellet cargoes. It’s not IMSBC-mandated for Group C cargoes specifically, but virtually all iron ore pellet charter parties require a joint draft survey at load and discharge ports, with the survey results determining the quantity for demurrage and freight calculations.

Draft survey accuracy at high density

Iron ore pellets present specific accuracy challenges in draft survey. The cargo’s high density means that small measurement errors translate directly into large tonnage errors. A 10-millimetre error in reading a single draft mark corresponds to roughly:

where $\rho_{SW}$ is seawater density, $TPC$ is tonnes per centimetre immersion, and $\Delta d$ is the draft error in centimetres. For a large capesize vessel with TPC of around 110 tonnes per centimetre, a 1-centimetre error produces a 110-tonne discrepancy. At pellet densities, the cargo volume corresponding to 110 tonnes is about 46 cubic metres, easily within the margin of error of a hold dip measurement. Draft survey for dense cargoes therefore relies principally on the waterplane area measurement, not on hold dip, which makes calibration of the vessel’s displacement table critical.

Both the load-port and discharge-port surveys should use the same vessel hydrostatic tables and the same correction procedure for hog/sag, trim, and density. BIMCO’s standard guidelines and the Society of Maritime Surveyors’ protocols are the reference documents most commonly used. A disagreement between load-port and discharge-port surveys of more than 0.3 percent of the cargo mass should trigger a formal dispute and investigation rather than routine acceptance.

Density measurement

The density of seawater at the load and discharge ports affects the draft survey result materially at pellet densities. The surveyor should take a water sample from the waterplane at mid-ship and measure density with a calibrated hydrometer. A 1.0-unit difference in specific gravity (for example, between 1.022 and 1.023) shifts the displacement by approximately 0.1 percent on a large vessel, which at 200,000 DWT amounts to about 200 tonnes.

Discharge operations

Discharge of iron ore pellets is by grab crane or, at some modern unloading facilities, by continuous screw unloader (CSU). Grab discharge is far more common for bulk pellet receivers.

Grab crane operations

Grab cranes at iron ore receiving terminals (integrated steel plants at IJmuiden, Dunkirk, Pohang, and similar locations) are sized for the maximum cargo density they’ll handle. For pellets at 2.4 t/m3, a 45-tonne grab holds only about 19 cubic metres of cargo. Discharge rates of 1,500 to 3,000 tonnes per hour per crane are typical at well-equipped terminals; multi-crane operations can sustain 5,000 to 8,000 tonnes per hour on a capesize vessel.

The grab crane operator faces a specific challenge with pellets: because pellets are dense and free-flowing, the cargo flows away from the grab jaw as it tries to close, reducing the fill factor compared with coal or grain. Experienced operators compensate with faster jaw closure speeds and by positioning the grab to bite from the edge of the cargo pile rather than the center.

Hold cleaning after discharge

Iron ore pellets leave a distinctive residue in the hold: a fine, reddish-brown iron oxide dust coating on all hold surfaces, plus a scattered layer of broken pellet fragments (abrasion debris) on the tanktop and frame faces. This residue is iron-rich and mildly abrasive but not chemically hazardous. Residue removal is important if the next cargo is sensitive to iron contamination (some agricultural products, some chemical cargoes, white cement), but for a vessel cycling back to another iron ore cargo, thorough sweeping of the tanktop before the next load is adequate.

Bilge wells should be emptied and inspected after discharge. The residue from pellets can accumulate over multiple voyages into a hard-packed mass in the bilge well if not removed. Once hardened, it requires mechanical removal or high-pressure washing.

Vessel selection and charter party considerations

The vessel type most commonly used for pellet trade is the Capesize bulk carrier (130,000 to 210,000 DWT), followed by Panamax and Kamsarmax vessels on smaller-volume routes and port-constrained trades.

Structural suitability

The most important vessel selection criterion for iron ore pellets is tanktop structural rating. Classification societies issue certificates or loading manuals that specify the design tanktop pressure or the maximum cargo density the vessel was built to carry. Vessels classified as “strengthened for heavy cargoes” or with tanktop ratings explicitly validated for iron ore (density above 2.0 t/m3) are appropriate for pellet carriage. Vessels whose manuals specify a maximum uniform tanktop load of 10 to 12 t/m2 are not suitable for pellets in full-hold loading.

Charter parties for iron ore pellets typically specify that the vessel must be “suitable for carriage of iron ore or similar heavy bulk cargoes” and that the master must provide a loading plan acceptable to the charterer’s nominated loading master. These provisions exist precisely because structural damage claims from over-laden tanktops are a recognized category of loss in the iron ore trade.

Hatch size and shiploader compatibility

Some shiploaders at pellet export terminals have fixed boom positions that limit the hatch widths they can work. Vessels with narrow hatches or offset hatches may require additional shiploader passes or may not be able to load efficiently at certain berths. Terminal specifications for berth and hatch dimensions should be checked before fixing a vessel.

Hold coating specification

Pellets are abrasive. Hard surfaces (hold frame faces, stringer edges, bilge wells) that are in direct contact with the cargo will wear through coating and erode bare steel over multiple voyages. Vessels that regularly trade pellets should have hold frames treated with abrasion-resistant coatings (typically zinc-rich primer plus epoxy topcoat, or specialized ceramic-filled abrasion-resistant products). Class survey intervals for hold coating condition may be shortened for vessels in continuous heavy-ore service.

Safety precautions in port and at sea

Iron ore pellets carry no significant chemical hazard and present no flammability, toxicity, or reactive-chemical risk during normal handling. The safety precautions are operational.

Dust during loading and discharge. Pellet fines become airborne during loading, discharge, and hold cleaning. Workers on deck and in the holds during cargo operations should wear appropriate respiratory protection (at minimum P2-class dust respirators for close-contact operations; FFP3 for extended hold cleaning). The pellet dust is primarily iron oxide, which is a nuisance particulate at low concentrations but can cause siderosis (iron deposition in the lungs) at sustained high occupational exposure over years.

Enclosed space entry. Cargo holds must be treated as confined spaces under SOLAS and ISM procedures. Any hold entry during or after the voyage requires gas testing (oxygen content must be between 20.8 and 23.5 percent), appropriate permit-to-work authorization, and standby rescue provisions. Iron ore pellets don’t consume oxygen or generate toxic gas, but the hold atmosphere can become oxygen-deficient through displacement by ship’s exhaust, through rust reactions on the hold structure, or through prior cargo residues. Standard enclosed-space precautions apply.

Heavy weather securing. Pellets self-level and do not have the unstable shear-surface behavior of fine powders, but they can shift in extreme rolling. Where the loaded vessel will transit through heavy weather, the master should confirm that the cargo is filled to a level that minimizes free surface in each hold (partial-hold loading creates the greatest shift risk) and that hatch covers are secured to full compression.

Tanktop inspection after discharge. Every pellet discharge is an opportunity to inspect the tanktop while the hold is accessible. Deformation of tanktop plating, cracks in floor stringer webs, and weld failures at the tanktop-to-frame connections are the damage patterns to look for. Class surveyors should be notified of any visible tanktop damage before the next heavy-cargo loading.

Regulatory context and recent amendments

The IMSBC Code is a mandatory instrument under SOLAS Chapter VI, Regulation 1-1, applicable from 1 January 2011. It is revised on a two-year amendment cycle through the IMO Maritime Safety Committee (MSC).

MSC.500(105) adopted at MSC 105 in April 2022 is the basis for the 2021 edition of the IMSBC Code (mandatory from 1 June 2023). This edition updated several cargo schedules and added new entries, but the IRON ORE PELLETS schedule structure and Group C classification were unchanged.

MSC.539(107) adopted at MSC 107 in June 2023 (mandatory from 1 June 2025) introduced further schedule updates and clarifications, again without altering the fundamental Group C classification or handling requirements for iron ore pellets.

The current Group C classification for iron ore pellets is well-established and has not been subject to reclassification proposals. There have been discussions in the IMO’s Carriage of Cargoes and Containers (CCC) Sub-Committee about whether pellet degradation at sea could create a secondary Group A risk through fines accumulation, but the consensus of submitted correspondence to date is that fired pellets do not accumulate moisture to TML-relevant levels in any realistic sea condition, and the Group C classification is appropriate.

SOLAS Chapter XII, which applies to pellet carriers by virtue of the density threshold, was last substantively amended by Resolution MSC.170(79) in 2004 and MSC.277(85) in 2008. The Chapter XII provisions for loading instruments (Regulation XII/6) and cargo distribution assessment (Regulation XII/4) apply continuously and are not amendment-dependent; any vessel loading iron ore pellets must comply with these provisions regardless of which IMSBC amendment cycle is current.

Distinguishing iron ore pellets from related cargoes

Several related cargoes in the iron ore family appear in the IMSBC Code, and the distinctions between them have regulatory and operational significance.

Iron ore (lump and fines): The IMSBC Code entry “IRON ORE” includes both Group C lump ore (coarse, low-fines content, not liquefiable) and Group A iron ore fines (susceptible to liquefaction). The schedule distinguishes these by particle size: material with at least 10 percent of particles below 1 millimetre and at least 50 percent below 10 millimetres is classified as fines and must comply with TML requirements.

Iron ore concentrate: Iron ore concentrate is the beneficiated fine-particle product of grinding and flotation, typically 80 to 95 percent passing 0.075 millimetres. It’s Group A, highly liquefiable, and among the most hazardous of all bulk cargo designations from a liquefaction standpoint. Iron ore concentrate is the input material to the pelletising plant; once it’s been pelletised and fired, it becomes Group C pellets.

Direct reduced iron: DRI is what pellets become after direct-reduction processing. Iron ore pellets are the feedstock to DRI plants. DRI (in its cold lump, pellet, and fines forms) is Group B, chemically hazardous due to self-heating and hydrogen evolution. This is a striking contrast: the pellet (Group C, inert) is transformed into DRI (Group B, reactive) by the reduction process that converts iron oxide to metallic iron.

Sintered iron ore (sinter): Sinter is a coarse, irregular-shaped agglomerate produced by burning fine ore on a conveyor grate without the full pelletising-and-firing cycle. Sinter is Group C but has lower iron content and less uniform size than pellets, and it’s not commonly shipped in seaborne trade; it’s typically produced adjacent to the blast furnace it serves.

Limitations

The IMSBC Code schedule and the structural-loading analysis in this article reflect the regulatory provisions in force under MSC.500(105) and MSC.539(107). Specific tanktop design loads and loading computer outputs are vessel-specific: the numbers used in illustrative calculations above are representative of typical capesize ore-carrier design but are not a substitute for consulting the vessel’s class-approved loading manual. Structural adequacy assessments must be carried out on the vessel’s actual hydrostatic and structural data, not on generic representative values.

The bulk density range of 2.0 to 2.6 t/m3 cited throughout this article covers commercially traded pellets from a wide range of producers and feed ores. Specific cargo parcels may fall outside this range; always use the shipper’s declared density in structural loading calculations and in draft survey calculations rather than a generic value.

Draft survey methodology, including correction procedures for trim, hog/sag, density, and block coefficient effects, is beyond the scope of this cargo-schedule article. Practitioners should consult the vessel’s hydrostatic tables, BIMCO draft survey guidance, and the instructions of the engaged maritime surveyors for specific-quantity-determination procedures.

Information on pellet attrition, pellet quality specifications (crush strength, tumble index, abrasion index), and plant performance at the receiving DR facility is commercially sensitive and highly producer- and lot-specific. The values cited in this article are representative of industry benchmarks published by the ISO and by major producers in product specifications; they’re not contractually binding values for any specific shipment.

See also

• IMSBC Code: International Maritime Solid Bulk Cargoes Code
• IMSBC Group C Cargoes
• IMSBC Group A Cargoes
• Iron Ore: IMSBC Code Schedule and Carriage
• Iron Ore Concentrate: IMSBC Code Schedule and Carriage
• Direct Reduced Iron: IMSBC Code Schedule and Carriage
• SOLAS Chapter XII: Additional Safety Measures for Bulk Carriers