Pig Iron: IMSBC Code Schedule and Carriage

Pig iron is the direct product of the iron blast furnace: molten iron tapped from the furnace and cast into solid metal ingots, typically weighing 6 to 25 kilograms each. For centuries those ingots were cast in rows of short moulds branching off a central channel in a sand floor, the layout resembling piglets nursing at a sow, which is where the name originates. Today the cargo moves in multi-ship parcels from major producing regions in Brazil, Russia, and Ukraine to electric arc furnace (EAF) and basic oxygen furnace (BOF) steelmakers worldwide, with annual seaborne trade of approximately 10 to 15 million tonnes. The IMSBC Code classifies pig iron as a Group C cargo: not liquefiable, no chemical hazard. The companion IMSBC pig iron calculator supports schedule lookups and tanktop load checks for this cargo.

The absence of liquefaction and chemical hazard does not mean pig iron is a simple cargo. It is among the densest solid bulk cargoes in commercial trade, with a stowage factor of roughly 0.28 to 0.40 cubic metres per tonne. That density produces tanktop point loads that are a real structural risk on vessels not rated for high-density cargoes, and the loading sequence and cargo distribution must be designed carefully to keep those loads within the inner-bottom allowable. This article covers the IMSBC Code schedule particulars, the structural-loading physics, hold preparation and tanktop protection, draft survey practice, and the global pig iron trade that drives demand for these carriage procedures.

The IMSBC Code schedule for pig iron

Schedule classification and Group C status

The IMSBC Code, adopted by IMO Resolution MSC.268(85) and carried forward through successive amendments, lists pig iron under the individual schedule entry PIG IRON. The current schedule, as amended through MSC.500(105) (Amendment 06-21) and MSC.539(107) (Amendment 07-23), classifies pig iron as Group C: a cargo that is neither liable to liquefy (Group A) nor possesses chemical hazards in bulk (Group B). Group C classification means the cargo is not subject to the transportable moisture limit (TML) regime that governs iron ore fines or bauxite, and it does not require the gas monitoring or self-heating precautions that apply to certain Group B cargoes such as coal or direct reduced iron.

Group C status does not mean the cargo is without hazard. The IMSBC Code schedule explicitly notes that pig iron has a high bulk density and that the master must verify that the ship’s structure is adequate before loading. This is a mandatory pre-loading check, not a precaution left to the master’s discretion.

Schedule particulars

The key schedule data for pig iron under the IMSBC Code are as follows:

The schedule also covers nodular pig iron (also called ductile pig iron), which is produced by adding a small quantity of magnesium (typically 0.04 to 0.06 per cent by mass) to the molten iron before casting. The magnesium causes the graphite in the solidified iron to form spherical nodules rather than flakes, producing a tougher and more ductile metal suitable for ductile iron castings. From a carriage perspective, nodular pig iron behaves identically to standard pig iron: same Group C classification, same density range, same structural-loading concerns.

What the schedule requires of the master

Under IMSBC Code Section 4 (Assessment of acceptability of consignments for safe shipment), the master has explicit obligations before accepting any solid bulk cargo. For pig iron, the relevant obligation is to verify that the declared bulk density and the expected quantity produce tanktop loads within the rated capacity of the vessel’s inner bottom structure. The IMSBC Code at Section 9 (Stowage) provides that bulk cargoes shall be distributed in a way that avoids undue local stresses in the ship’s structure. This is not a general advisory: it is a legally binding carriage obligation under SOLAS Chapter VI, Regulation 2, which mandates compliance with the IMSBC Code for all voyages.

The shipper is required under SOLAS VI/2 and IMSBC Code Section 4 to provide a cargo declaration that includes the bulk density. For pig iron, a shipper declaration of bulk density outside the 4.0 to 5.0 t/m³ range should prompt the master to question whether the declared cargo is actually pig iron or a different iron product.

Cargo properties: chemistry and physical form

Iron and carbon content

Pig iron from the blast furnace typically contains 92 to 96 per cent iron by mass. The remainder is carbon (3.0 to 5.0 per cent), silicon (0.5 to 3.0 per cent), manganese (0.1 to 1.0 per cent), sulfur (0.01 to 0.10 per cent), and phosphorus (0.01 to 0.50 per cent). The carbon content is what distinguishes pig iron from steel: the iron-carbon phase diagram puts the eutectic at 4.3 per cent carbon, and the high carbon content of blast-furnace pig iron means the metal is brittle and not directly usable in structural applications. It requires remelting and refinement.

The specific composition varies by the downstream application the cargo is destined for. Basic pig iron for BOF steelmaking tolerates higher sulfur and phosphorus because the BOF refining process removes them. Foundry pig iron for casting applications requires lower manganese and a controlled silicon range. Nodular pig iron for ductile iron foundries requires very low sulfur (below 0.025 per cent) because sulfur prevents the magnesium treatment from producing spheroidal graphite. For the master and officer receiving a pig iron cargo, the specific grade matters less than the bulk density and ingot geometry, which determines the structural-loading calculation.

Physical dimensions and packing

Standard pig iron ingots are rectangular parallelepipeds with rounded ends from the mould shape. Typical dimensions are 100 to 150 mm wide, 50 to 80 mm thick, and 300 to 600 mm long. Mass per ingot ranges from 6 to 25 kg, with the most common export grade running approximately 8 to 12 kg per ingot. Specialty foundry grades are sometimes shipped in larger block form, up to 50 kg per block, or in granulated form (granulated pig iron, a product of water-atomization of molten iron that produces roughly spherical particles of 5 to 50 mm diameter).

The packing factor of loose pig iron ingots in a bulk hold is approximately 60 to 70 per cent by volume: the ingots settle into a random packing with air voids accounting for 30 to 40 per cent of the geometric volume. This is what produces the range in stowage factor. A single ingot of solid pig iron has a density of approximately 7.2 t/m³ (close to the density of solid cast iron). In bulk, the void fraction reduces this to the 4.0 to 5.0 t/m³ stowage-factor range.

Density, stowage factor, and the hold-loading geometry

Why stowage factor matters for structural loading

For most bulk cargoes, the stowage factor is primarily a commercial quantity: it tells the charterer how much hold volume the cargo will consume at a given tonnage, and it helps the master plan trim and stability. For pig iron, the stowage factor has a direct structural implication. A cargo with a stowage factor of 0.30 m³/t means that one tonne of cargo occupies only 0.30 cubic metres. If that tonne sits on one square metre of tanktop, the pressure is about 10 kN/m² (roughly 1 t/m²). But if it is piled to a metre of depth, the same mass sits on a smaller effective support area (given the hold geometry), and the pressure per unit area rises.

The SOLAS Chapter XII minimum standard for inner-bottom strength on bulk carriers is expressed as an allowable load in tonnes per square metre at the tanktop. For most handy and handymax bulk carriers built after the mid-1990s, this rating is in the range of 10 to 17 t/m² depending on the vessel design, hold position, and transverse frame spacing. A pile of pig iron ingots just 2.5 metres deep produces a column load of about 10 to 12.5 t/m² at the tanktop surface, which is at or above the limit for lighter-rated vessels. This is not a marginal concern.

The tanktop load relation and pile depth

The static pressure at the tanktop under a column of bulk cargo can be expressed as:

where $P$ is the pressure in Pa (or kN/m² when $\rho_b$ is in t/m³ and $g = 9.81$ m/s²), $\rho_b$ is the bulk density of the cargo in t/m³, $g$ is gravitational acceleration in m/s², and $h$ is the pile depth in metres.

For pig iron at $\rho_b = 4.5$ t/m³:

At $h = 2$ m, $P \approx 88$ kN/m² (8.9 t/m²). At $h = 3$ m, $P \approx 132$ kN/m² (13.5 t/m²). A vessel with a tanktop rating of 12 t/m² is within limits at 2.7 m pile depth and breaches that limit at 2.75 m. These margins are narrow, and the calculation must be done before loading begins, using the vessel’s specific tanktop allowable from the stability booklet or the ship’s trim-and-stability manual.

Dynamic loads at sea increase this static figure. The IACS Unified Requirement S19 for hold loading (since incorporated into the Common Structural Rules for bulk carriers) uses a dynamic amplification factor for seakeeping that increases the effective design load above the static tanktop pressure, particularly for heavy cargoes in rough conditions. The static calculation above is a minimum check; the actual loading plan must use the allowable from the vessel’s class-society-approved loading manual, which already incorporates the dynamic factor.

Comparison with other dense cargoes

It is instructive to compare pig iron with other cargoes at the high end of the density spectrum:

Pig iron sits at the heavy end of this comparison. Only lead-based concentrates and certain manganese or chrome ore grades approach pig iron’s bulk density. The practical consequence is that vessels calling for pig iron cargoes above a certain tonnage must be specifically rated for high-density cargo, and the charterparty or cargo plan should explicitly confirm the tanktop allowable before the vessel is fixed.

Structural loading and SOLAS Chapter XII compliance

SOLAS Chapter XII and bulk carrier structural requirements

SOLAS Chapter XII, titled “Additional Safety Measures for Bulk Carriers,” entered force on 1 July 1999 and has been amended several times since. It imposes structural and operational requirements on bulk carriers that go beyond the baseline SOLAS safety standards, responding to the pattern of catastrophic structural failures and rapid foundering that killed hundreds of seafarers in the 1980s and 1990s.

The Chapter XII requirements include minimum structural standards for single-skin bulk carriers over 150 m in length, requirements for cargo hold and ballast tank surveys, double-skin requirements for new designs, and restrictions on cargo operations that could exceed structural limits. For the present discussion, the directly relevant provisions are those governing the permissible cargo hold loading and the requirement that the ship’s loading manual address the loading of high-density cargoes.

Under SOLAS XII/10, bulk carriers must have an approved loading manual and loading instrument (computerised loading calculator) on board. Both must address the restrictions applicable when carrying heavy cargo. The loading instrument calculates shear forces and bending moments at key sections of the hull girder in real time as loading data are entered, and it must alert the operator when any section would be exceeded by the proposed loading. For pig iron, both the local tanktop check and the global hull girder check matter: a pig iron cargo concentrated in a few holds can produce a severe sagging or hogging condition even before the tanktop limits are approached.

Distribution across holds

The standard industry practice for pig iron is to load the cargo across all cargo holds in a roughly even distribution. Loading a single hold to capacity with pig iron while adjacent holds remain empty or partly loaded creates a severe hogging moment at the loaded hold position, which may exceed the hull girder bending moment limit even if the tanktop load in that hold is acceptable. The loading instrument will flag this if it is functioning correctly, but the chief officer should also apply manual judgment.

For a typical handymax bulk carrier with five cargo holds, an equal-distribution plan would put approximately 20 per cent of the total cargo tonnage in each hold. The resulting pile depth in each hold can be calculated from the hold’s floor area: for a hold with an inner bottom area of roughly 400 m², 9,000 tonnes of pig iron occupies $9{,}000 \div 4.5 \approx 2{,}000$ m³, which spreads to $2{,}000 \div 400 = 5$ m depth. A 5 m deep pile of pig iron at 4.5 t/m³ exerts a static pressure of approximately $4.5 \times 9.81 \times 5 \approx 220$ kN/m² (22 t/m²), well above the typical tanktop rating of 12 to 17 t/m². This illustrates why pig iron cargoes routinely require partial loading across more holds than might be used for lighter cargoes: the pile depth, not just the total tonnage, is the binding constraint.

Interaction with the bilge and hopper structures

Bulk carrier hold cross-sections are not flat rectangles. The inner bottom is bordered by hopper tanks angled upward toward the side shell, and the floor area of the tanktop proper is a trapezoid or near-rectangle in the center of the hold. When pig iron settles against the hopper slopes, the angled surface distributes a component of the cargo load laterally into the hopper structure rather than vertically into the tanktop. The IACS Common Structural Rules (CSR) account for this in the structural design, but for loaded-condition verification the chief officer should use the hold floor area (the projected horizontal area of the inner bottom plating) in tanktop-load calculations, not an estimate that includes the sloped hopper areas. Using projected area is the conservative and correct approach.

Bilge wells are recessed below the tanktop level to collect drainage. Pig iron ingots should not be allowed to settle into bilge wells, where they could block the drainage and make bilge pumping impossible during the voyage. Bilge well covers or planked protection over the well tops is recommended before loading.

Hold preparation and tanktop protection

Cleaning and inspection

Before loading pig iron, holds must be thoroughly cleaned of any previous cargo residue, scale, or debris. Because pig iron is a metallurgical feedstock, residual contamination from fertilizer, chemical, or organic cargoes can contaminate the pig iron and alter the chemistry of the downstream steel heat. Importers and steelmakers routinely specify that holds must have carried either pig iron, scrap, iron ore, or another approved ferrous cargo on the prior voyage, and the chief officer should have a prior-cargo certificate or a detailed cleaning record ready for inspection by the shipper’s surveyor.

The inner bottom plating and ceiling boards (if fitted) must be inspected for structural damage, severe corrosion, or previous damage. The tanktop plating is the structural element through which the entire cargo load transfers to the double-bottom girders and floors below. Any significant corrosion diminishes the effective plate thickness and can reduce the tanktop rating below the value shown in the loading manual, which is based on the as-built thickness. A badly corroded inner bottom that would barely support an iron ore cargo may not safely support pig iron at all.

Tanktop protection measures

Pig iron ingots dropped from grab height onto bare inner-bottom plating produce impact loads many times the static load. Even a 12 kg ingot falling 2 m has a kinetic energy of about 235 J at impact, and thousands of ingots are dropped during a loading operation. The cumulative impact damage to paint, plating, and welded connections can be severe.

The standard mitigation is to place a layer of sacrificial material on the tanktop before loading begins. The options, in order of effectiveness:

1. Timber dunnage: boards of 25 to 50 mm thickness placed across the inner bottom, covering the full floor area. Timber absorbs and distributes impact and protects the paint from direct contact with sharp ingot edges. The most common choice where dunnage is available and cost-effective.
2. Old rubber conveyor belting: single or double layers placed across the tanktop. More durable than timber under repeated loading, and easier to remove at discharge.
3. Sand layer: a thin layer of fine sand (20 to 50 mm) spread across the inner bottom. Distributes point loads over a larger area and acts as a sacrificial cushion. The sand must be confined and prevented from contaminating the bilge system.

In practice, the choice of tanktop protection depends on cost, local availability, and charterer or shipper requirements. Not all charters include a provision for dunnage costs; where the charter is silent, the master should document the condition of the tanktop before and after loading to support any claim for repair.

Hatch covers

Pig iron does not require watertight sealing of the cargo itself for cargo-integrity reasons: the metal is inert to seawater. However, water ingress into the hold can cause rust staining on the cargo surface, which may attract comment from the consignee, and water pooling at the bilge can complicate bilge operations. Hatch covers should be in good repair and the hatch coamings free of scale or debris that would prevent sealing. Hatch cover compression bars and rubber seals should be inspected before loading.

Loading operations

Cargo planning: the three-constraint problem

A pig iron loading plan must simultaneously satisfy three constraints:

1. Tanktop load: pile depth in each hold must be such that the static pressure does not exceed the tanktop allowable, using the vessel-specific value from the loading manual.
2. Hull girder strength: the distribution of cargo across holds must not produce shear forces or bending moments at any cross-section that exceed the class-approved limits, as verified by the loading instrument.
3. Stability: at every stage of loading, the vessel must meet the minimum stability criteria of IS Code 2008 (as incorporated into SOLAS Chapter II-1): minimum GM, minimum righting lever arm at 30 degrees, positive range of stability to at least 25 degrees, area under the righting lever curve meeting the specified values.

For pig iron, constraints 1 and 2 are generally more binding than constraint 3. The cargo is dense and low in the hold, so the center of gravity is low and initial stability is good. A stiff (high GM) condition is the more common concern, since a fast roll period from excess GM can produce accelerations that damage cargo or stress the vessel. Stability should be trimmed to a comfortable GM, not maximized.

Loading sequence and rate control

Loading pig iron begins with spreading the cargo across the inner bottom rather than piling it in one area. The initial filling sequence should place material in all intended holds simultaneously (or in alternation) until the tanktop protection layer is covered uniformly. Only after the tanktop is uniformly covered to a depth of about 1 m should the loading rate increase.

Loading rates for pig iron from shore grabs are typically 1,500 to 3,500 tonnes per hour per crane. For a vessel loading from a single crane, full loading of 45,000 tonnes would take 13 to 30 hours at these rates. The master and chief officer must monitor each hold continuously during loading to ensure even distribution and to prevent a single grab being concentrated over one area.

Trimming is not required in the conventional sense: pig iron ingots have a high angle of repose and do not flow or migrate after placement. A pile of ingots will remain as placed unless it is mechanically redistributed. This means that uneven loading from a single grab dropping in one corner of a hold will not self-correct, and the master must ask the terminal operator to redistribute if the pile is becoming uneven.

Crane and grab selection

Shore cranes loading pig iron use hydraulic orange-peel grabs or clam-shell grabs. Orange-peel grabs (4 or 6 petals) are preferred because they can close around individual or small clusters of ingots and minimize spillage and ingot breakage. Clamshell grabs impose more impact on the cargo surface because the closing action scoops and shears rather than wrapping around the pile. In either case, the grab should be in good mechanical condition: a grab that drops its load in mid-swing will scatter ingots across the hatch and can injure personnel.

Some loading terminals use conveyor-and-chute systems rather than grabs, particularly at Brazilian pig iron export terminals where the cargo volume is high and continuous loading is more efficient. Conveyor loading reduces impact damage but requires that the chute be positioned to distribute the cargo evenly across the hold, and the loading rate is controlled by the conveyor speed.

Magnet handling at discharge

At some receiving ports, particularly those handling iron unit feedstocks, electromagnet-equipped cranes are used for discharge. An electromagnet suspended from a crane hook lifts a mass of pig iron ingots by magnetic attraction and places them on a shore conveyor or stockpile. Magnet discharge is faster than grab discharge for small, dense metal items such as pig iron ingots. It is the dominant discharge method at EAF steelmakers that also handle shredded steel scrap, since the same crane and magnet equipment is used for both.

Electromagnetic cranes draw heavy electrical current during the lift cycle, and the demagnetization drop requires coordinated power interruption. Personnel working in the hold during magnet discharge are exposed to the risk of ingots falling during demagnetization, and the hold should be evacuated before the magnet begins its lift cycle.

Draft survey for pig iron

Why draft survey is the standard quantity check

For most liquid bulk and dry bulk cargoes, cargo quantity is measured by a combination of shore tank gauging, flowmeter totalization, and draft survey. For pig iron, the high density and large parcel sizes make draft survey the primary independent quantity verification tool, supplemented by tally count (counting the number of ingots loaded, multiplied by the mean ingot mass from the batch certificate).

A draft survey works by measuring the change in the vessel’s displacement between the initial (before loading) and final (after loading) conditions. Displacement is the mass of water displaced by the hull, and it equals the total mass of the ship plus all cargo, stores, ballast, and constants. The change in displacement equals the mass of cargo loaded (adjusted for any change in ballast, stores, or constants during the loading operation).

Draft reading and correction procedure

Six draft readings are taken: forward port, forward starboard, midship port, midship starboard, aft port, aft starboard. For each pair (forward, midship, aft), the mean of port and starboard is calculated. The forward and aft means are then used to determine the trim correction, and the midship mean is corrected for hogging or sagging of the hull girder using the “four-sixths rule” (which weights the midship reading more heavily than the forward and aft readings). The corrected mean draft is then read against the vessel’s displacement table at the current waterplane to obtain the displacement in tonnes.

The displacement is calculated at the observed water density (measured by hydrometer in a sample taken from the dock at the ship’s side at waterline depth). The tabulated displacement in the hydrostatic tables is at salt water (1.025 t/m³); displacement at observed water density is:

where $\Delta_{\text{obs}}$ is the displacement at observed density, $\Delta_{\text{table}}$ is the tabulated displacement at 1.025, and $\rho_{\text{obs}}$ is the observed water density.

The net cargo mass is:

For pig iron, where each centimetre of mean draft corresponds to a large mass of cargo (a typical handymax has a tonnes-per-centimetre figure of 40 to 55 t/cm), an error of 5 cm in the draft reading produces an error of 200 to 275 tonnes on the cargo quantity certificate. Careful reading of all six drafts, using calibrated draft marks and cross-checking against each other, is essential. For large pig iron parcels (20,000 to 50,000 tonnes), the draft survey result is often the legally binding quantity for freight calculation.

Reconciling draft survey against tally

For pig iron, a tally count is practical because the cargo consists of discrete, individually countable units. The terminal typically records a running tally of tonnes loaded from their shore scale, which weighs the conveyor belt or records the grab loads. The draft survey and the shore tally should agree within 0.5 per cent for a well-executed operation. A discrepancy larger than 0.5 per cent warrants investigation before the mate’s receipt is signed.

Seagoing care and ventilation

Ventilation requirements

The IMSBC Code schedule for pig iron does not require mechanical ventilation of the holds during the voyage. This is appropriate: pig iron is an inert solid metal that does not evolve gases, does not react with seawater or humidity, and does not require any specific atmospheric condition in the hold to preserve its quality. The holds may be kept closed throughout the voyage without adverse effect on the cargo.

Natural ventilation during dry weather may be used for crew-access purposes (pre-entry atmosphere testing for oxygen deficiency is always required for any enclosed-space entry into cargo holds). However, ventilating a hold containing pig iron during wet or humid weather will introduce moisture into the hold space, which can pool in the bilge or on the cargo surface and contribute to rust staining. The standard practice is to keep holds closed in rain or spray conditions.

Rust and surface condition

Pig iron is not galvanically protected and will form an oxide layer (rust) on its surface if exposed to moisture or salt spray. This rust is superficial and does not affect the metallurgical quality of the metal, since the iron will be remelted at the receiving steelworks and the rust is simply FeO or Fe₂O₃ that will be incorporated into the slag. Receiving steelmakers accept mild surface rust on pig iron without cargo claims.

More significant is moisture that enters the hold and pools on the tanktop, particularly if the bilge drainage is blocked by settled ingots. Standing water in the hold can eventually cause corrosion of the inner bottom plating below the cargo, which is invisible during the voyage and may only be detected at the next dry-docking. The tanktop protection measures described above (dunnage, rubber sheeting) help by lifting the cargo slightly off the tanktop and allowing any drainage to reach the bilge wells. This is one reason to take tanktop protection seriously even for a cargo that is itself immune to water damage.

The global pig iron trade

Production: blast furnace and basic oxygen route

Pig iron is the intermediate product in the integrated (blast furnace to BOF) route for steel production, which accounts for approximately 70 per cent of global crude steel output. In the integrated route, iron ore (pellets, sinter, or lump) is reduced with coke and limestone in the blast furnace to produce hot metal at roughly 1,400 to 1,500°C. Most of this hot metal is converted directly to steel in the adjacent BOF without solidifying. The fraction that is cast into solid ingots and sold as pig iron is material that is either surplus to the BOF’s immediate capacity or is specifically produced for the merchant market.

Merchant pig iron is produced as a primary product at plants without integrated BOF capacity. The dominant example is the Brazilian charcoal-based mini blast furnace sector in the states of Minas Gerais and Maranhão, which uses charcoal from planted eucalyptus forests as the reducing agent instead of metallurgical coke, producing a low-sulfur pig iron particularly valued by EAF steelmakers and ductile iron foundries.

Major exporting regions

Brazil is the world’s largest pig iron exporter, accounting for roughly 50 to 60 per cent of global seaborne merchant pig iron trade. The principal export ports are Vitória (with its Praia Mole terminal) and São Luís (Itaqui), with smaller volumes from Barcarena and Aratu. Brazilian charcoal pig iron carries a premium in international markets because of its low sulfur content (typically 0.02 to 0.04 per cent) and low phosphorus, which reduce refining costs at the receiving steelworks. The Brazilian pig iron sector employs approximately 30,000 workers directly in the production chain from eucalyptus plantation to blast furnace to export terminal.

Russia exports pig iron from integrated steelworks that produce more hot metal than their own BOFs can immediately absorb. Key export plants include Novolipetsk Steel (NLMK), Evraz (Nizhny Tagil and Novokuznetsk), and Severstal (Cherepovets). Russian pig iron exports move through Baltic ports (Saint Petersburg, Ust-Luga) and Black Sea ports (Novorossiysk, Tuapse), targeting European and Turkish buyers.

Ukraine was until 2022 the third-largest seaborne pig iron exporter, with Metinvest’s Mariupol-based Azovstal and Ilyich Steel plants producing for export through Mariupol (Azov Sea) and Yuzhny and Odesa (Black Sea). The Russian invasion in February 2022 and the subsequent destruction of Mariupol’s steel plants caused a near-total collapse of Ukrainian pig iron export capacity. As of 2024, Ukrainian pig iron exports remain at a small fraction of pre-war levels, with only partial capacity operating at western Ukrainian plants using ore from elsewhere.

India has emerged as an additional pig iron exporter, particularly from the BOF-surplus production of SAIL (Steel Authority of India Limited) at its Rourkela and Durgapur plants, and from private producers in Orissa and Chhattisgarh. Indian pig iron exports move primarily from Visakhapatnam and Paradip, typically targeting Southeast Asian buyers.

Major importing regions

The United States Gulf and East Coast steelmakers are the largest single destination for seaborne pig iron imports. The EAF mini-mill sector that dominates US domestic steel production uses pig iron as a complementary charge material alongside scrap steel: adding pig iron to the EAF charge lowers the residual tramp-element content (copper, tin, nickel) that accumulates in recycled scrap and limits the quality grades that an all-scrap heat can produce. A typical EAF charge might be 70 to 85 per cent shredded scrap and 15 to 30 per cent pig iron or direct reduced iron. Major receiving ports are New Orleans, Mobile, and Baltimore.

The European Union imports pig iron principally at Mediterranean ports (Taranto, Piombino, Fos-sur-Mer) for southern European electric steelmakers and at Baltic ports (Gdansk, Hamburg, Ghent) for northern European producers. Türkiye is a significant importer, with Iskenderun and Aliağa receiving pig iron for the large EAF steelmaking sector that also dominates Turkish steel production. South Korea and Japan import specialty grades, particularly nodular pig iron for their ductile iron casting industries.

Vessel sizes used

Pig iron is primarily exported in handymax (38,000 to 65,000 DWT) and supramax (52,000 to 65,000 DWT) bulk carriers. The dominant trade lanes from Brazil to the US Gulf and from Russia/Ukraine to Europe and Turkey fit the handymax vessel size well given port depth and berth length restrictions at many pig iron terminals. Cape-size or Panamax-size vessels are rarely used for pig iron because the product is a specialty, high-value cargo that moves in parcels matched to individual steelmaker purchase orders, which are typically 10,000 to 50,000 tonnes rather than the 100,000 to 200,000 tonne parcels that fill capesizes.

Some pig iron is shipped in conventional general-cargo ships or tweendeck vessels where the parcel is small (below 10,000 tonnes), though this is rare for export grades. The irregular ingot shape means pig iron can also, in principle, be unitized on pallets or in big bags for container shipment, and small parcels of specialty pig iron (nodular grades, low-sulfur foundry grades) are occasionally shipped in containers.

Pig iron versus direct reduced iron: a carriage comparison

Both pig iron and direct reduced iron (DRI) are metallic iron products carried in bulk, but their IMSBC Code classifications and carriage requirements differ completely. Direct reduced iron, in its sponge, hot-briquetted, or cold-briquetted forms, is a Group B cargo with pyrophoric and hydrogen-evolution hazards: it can oxidize rapidly in the hold, generating heat and hydrogen gas in concentrations that risk fire or explosion. The IMSBC Code schedules for DRI products carry detailed requirements for moisture exclusion, hold atmosphere monitoring, and temperature limits that are wholly absent from the pig iron schedule.

Pig iron has been fully reduced and then solidified as a metallic alloy. Its surface area is small and its oxidation rate is negligible under normal carriage conditions. There is no pyrophoric risk, no gas evolution, and no temperature-sensitive chemistry. The carriage challenge is purely physical: managing the weight. DRI, by contrast, is manageable structurally (it is lighter, with a stowage factor of 0.45 to 0.60 m³/t for hot-briquetted iron) but imposes demanding atmospheric and temperature requirements. The two cargoes should never be confused in the charterparty or cargo plan.

Comparison with iron ore for carriage planning

Iron ore lump (Group C) and pig iron are both Group C cargoes, and they share the absence of liquefaction or chemical hazard. But they differ in density. Lump iron ore has a bulk density of about 2.0 to 3.5 t/m³, and stowage factors of 0.28 to 0.50 m³/t overlap with pig iron at the denser end. A vessel with a tanktop rating adequate for lump iron ore at 3.0 t/m³ may not be adequate for pig iron at 4.5 t/m³ at the same pile depth, because the load per unit area scales directly with bulk density at constant depth.

The practical implication: a vessel that regularly carries iron ore lump cargoes should not automatically be assumed suitable for pig iron without checking the tanktop load calculation against the higher pig iron density. The loading manual check is not optional. Some bulk carriers have explicit notes in their loading manuals prohibiting pig iron or any cargo above a density threshold without specific approval from the shipowner or classification society.

Limitations

The IMSBC Code schedules are updated through the IMO amendment cycle. Amendment 06-21 (MSC.500(105)) entered into force on 1 June 2023. Amendment 07-23 (MSC.539(107)) was adopted on 22 May 2024 and enters into force on 1 January 2025. Readers should verify the current applicable amendment text directly with the IMO or via the official IMSBC Code publication, since specific numerical parameters (bulk density ranges, stowage factors) can be refined through the amendment process.

Tanktop allowable loads cited in this article (10 to 17 t/m²) are indicative ranges based on typical handymax and supramax designs. Actual values vary by vessel, hold, and classification society. The vessel’s loading manual is the authoritative source; this article cannot substitute for that document.

The pig iron trade volumes and export data cited here represent approximate pre-2024 figures drawn from public industry sources. The Russian invasion of Ukraine in February 2022 materially changed Ukrainian pig iron export flows and continues to affect Russian export logistics due to sanctions. These trade flows are subject to change as the geopolitical situation evolves.

Draft survey accuracy depends heavily on surveyor skill, instrument calibration, and dock conditions (current, swell, vessel movement). The 0.5 per cent reconciliation tolerance between draft survey and shore tally is a practical guideline and not a contractual standard; charterparties specify their own tolerance clauses.

See also

• IMSBC Code
• IMSBC Group C Cargoes
• Iron Ore: IMSBC Code Schedule and Carriage
• Steel Scrap: IMSBC Code Schedule and Carriage
• Direct Reduced Iron: IMSBC Code Schedule and Carriage
• SOLAS Chapter XII: Additional Safety Measures for Bulk Carriers
• Bulk Carrier
• Chrome Ore: IMSBC Code Schedule and Carriage
• Manganese Ore: IMSBC Code Schedule and Carriage

Related calculators

• IMSBC - Pig Iron
• IMSBC Group A/B/C Classification
• IMSBC Angle of Repose
• IMSBC Cargo Density and Stowage
• IACS UR L5 Bulk Carrier Hold Loading
• IACS UR S16 Bulk Carrier Bending Moment
• Bulk Carrier Ship Type Reference
• IMSBC - Reduced Iron Briquettes
• IMSBC - Iron Ore