Sugar is a Group C cargo under the IMSBC Code, carried under the dedicated SUGAR schedule in Appendix 1. It does not liquefy and presents no chemical hazard classification. The practical hazards are hygroscopic caking that hardens the cargo mass in humid conditions, mould and fermentation in cargo that is loaded wet or rain-wetted during loading, fine dust that is mildly explosible in dense suspensions, tenacious molasses residue that makes post-discharge hold cleaning difficult, and contamination sensitivity because sugar is a human foodstuff. Global seaborne sugar trade averages approximately 60 to 65 million tonnes per year, moving predominantly from Brazil, Thailand, India, and Australia to refineries and consumer markets in Asia, the Middle East, and Africa.
Sugar is regulated under the IMSBC Code by its own named schedule entry, SUGAR, listed in Appendix 1. Unlike grain cargoes, which are covered by a collective GRAIN entry cross-referencing the International Grain Code, the SUGAR schedule is self-contained: it states the cargo’s properties, hazard group, and special requirements without reference to a separate stability code. The absence of a companion stability code reflects the cargo’s properties: sugar does not shift in the way grain does, does not liquefy, and does not generate dangerous gases under normal conditions. The hazards that do exist are managed through the schedule’s requirements on hold preparation, moisture, loading condition, and ventilation.
The current operative text is the 2025 IMSBC Code edition, incorporating Amendment 07-23 adopted by IMO Resolution MSC.539(107) on 8 June 2023, which became mandatory on 1 January 2025. The SUGAR schedule particulars in Amendment 07-23 reflect updates to the cargo’s moisture description and the food-grade hold preparation requirements; the Group C classification and the core hazard descriptions have been stable across recent amendment cycles.
The sugar trade: volumes, grades, and shipping routes
Global trade volumes and producing regions
Seaborne sugar trade typically runs at 60 to 65 million tonnes per year, split roughly 75% raw sugar and 25% refined white sugar. Brazil is consistently the world’s largest exporter: in most crop years since 2010 Brazil has exported 25 to 35 million tonnes of raw and refined sugar, shipping from four principal ports. Santos (São Paulo state) handles the largest share, with Paranaguá (Paraná state), Recife (Pernambuco), and Maceió (Alagoas) handling substantial volumes from the northeastern cane belt. Brazilian sugar production is tightly linked to ethanol: the sugar-cane crushing season runs April to November, and the balance between sugar and ethanol production in any year affects both export volumes and international prices.
Thailand is the second-largest exporter in most years, shipping from Bangkok and Laem Chabang to Asian markets, particularly China, Indonesia, and South Korea. Thai raw sugar is predominantly from sugarcane grown in the central plains and northeast of the country; the crop year runs December to March. India is a major but highly variable exporter, with export volumes determined largely by domestic price support policy and global price levels; in peak years India has exported 10 to 12 million tonnes, principally from the ports of Kandla, Mumbai, and Kakinada. Australia exports from Queensland ports including Townsville, Bundaberg, Mackay, and Mourilyan, with the majority going to Asian markets; Australian exports are approximately 4 to 5 million tonnes per year, predominantly raw sugar.
On the import side, China, Indonesia, the United Arab Emirates (as a re-export hub), and Malaysia are consistent large buyers of raw sugar for refinery throughput. African markets including Nigeria, Sudan, and Ethiopia are growing consumers. The EU is a significant net importer in most years, taking both raw sugar for European refineries and refined sugar for food manufacturing.
Raw sugar versus refined sugar: carriage implications
The distinction between raw and refined sugar matters for carriage. Raw sugar is the direct output of the sugar mill: crystalline sucrose with a thin film of molasses coating each crystal. Pol (polarisation) for raw sugar typically runs 96 to 99.5 degrees, with the molasses film contributing color, viscosity, and moisture retention. Raw sugar moisture content at loading is usually 0.1 to 0.6% by weight; commercial specifications commonly specify a maximum of 0.3% free moisture for vessels without moisture-sensitive next cargoes. The molasses film is the key physical and handling difference: it gives raw sugar a tacky surface that promotes crystal-to-crystal bonding and makes caking more likely, and it leaves a dark, viscous residue in the hold that requires intensive cleaning after discharge.
Refined white sugar is the product of further processing: the raw sugar is dissolved, clarified, decolorized (through activated carbon or bone char in some refineries), and re-crystallized. The resulting crystal is pure sucrose with no molasses coating, very low moisture (typically below 0.04% free moisture for granulated sugar), and a bright white color. Because food-grade white sugar buyers specify strict color, moisture, and cleanliness standards, the contamination risk at loading is the dominant carriage concern rather than the caking or fermentation risk that dominates raw sugar voyages.
The IMSBC Code SUGAR schedule covers both raw and refined sugar under a single entry, with the difference in hazard profile acknowledged through the more severe caking and mould guidance for raw sugar.
Vessel types and voyage patterns
Handy and Handymax bulk carriers (25,000 to 45,000 DWT) carry the majority of sugar tonnage. The reason is the port infrastructure at many sugar loading terminals: berths are sized for Handymax vessels, draft restrictions at shallow ports limit maximum vessel size, and the relatively high value of sugar per tonne (compared with coal or iron ore) makes full Panamax or Capesize loadings less common. Some Brazilian export terminals at Santos can load Panamax vessels (65,000 to 80,000 DWT) on certain berths, and occasional Panamax loadings from India and Thailand occur when the destination port can accommodate the draft.
Voyage distances range from the short Brazil-to-Caribbean or Brazil-to-US Gulf routes (7 to 10 days) to the long Brazil-to-Middle-East (approximately 20 to 25 days via the Cape) or Brazil-to-China (30 to 40 days) trades. Voyage length is relevant to caking: a longer voyage at humid tropical conditions gives more time for moisture absorption and crystal bonding in the cargo mass.
IMSBC Code SUGAR schedule: the particulars
Schedule overview
The IMSBC Code Appendix 1 lists SUGAR as an individual Bulk Cargo Shipping Name (BCSN). The schedule covers raw sugar (cane or beet origin), refined white sugar, and brown (partially refined) sugar in bulk. The key schedule fields are summarized in the table below.
| Property | Typical value |
|---|---|
| Bulk Cargo Shipping Name | SUGAR |
| Hazard group | Group C |
| UN number | Not applicable |
| Bulk density (raw sugar) | 850 to 1,000 kg/m3 |
| Bulk density (refined white) | 750 to 900 kg/m3 |
| Stowage factor (raw) | 1.0 to 1.2 m3/t |
| Stowage factor (refined) | 1.1 to 1.3 m3/t |
| Angle of repose | 35 to 45 degrees |
| Size | Fine to coarse granules; 0.3 to 3.5 mm typical |
| Moisture content | Raw: 0.1 to 0.6%; refined: below 0.1% |
| Class | Not applicable |
| Group | C |
| Flammable | No (bulk form); fine dust is mildly explosible |
The angle of repose for sugar (35 to 45 degrees) is notably higher than for grain (20 to 25 degrees). This reflects the bonding between molasses-coated crystals in raw sugar and the tendency of refined sugar granules to interlock. A high angle of repose is commercially useful: it means the cargo forms a stable pile during loading and does not flow freely to the ship’s sides in the way a low-angle cargo such as iron ore concentrates would. It also means the cargo does not self-level during the voyage; any surface irregularity formed at loading stays in place unless the cargo is physically disturbed.
Group C classification: what it means and what it does not
Group C under the IMSBC Code means the cargo neither liquefies (Group A criterion) nor meets the classification criteria for a Material Hazardous only in Bulk as a Group B cargo. For sugar, this is correct: sucrose is chemically stable, non-reactive with seawater or air under normal conditions, non-flammable in bulk form, and non-toxic. The Group C classification places sugar alongside a wide range of other dry bulk commodities described at IMSBC Group C cargoes.
Group C status does not mean the cargo is hazard-free. It means the hazards are physical and microbiological rather than chemical. A Group C classification does not remove the obligation to comply with the schedule’s special requirements, and the SUGAR schedule’s requirements on moisture, hold preparation, and ventilation are substantive. The IMO has in recent amendment cycles added or tightened the food-grade language in the SUGAR schedule; Amendment 06-21 (MSC.500(105)) clarified the moisture and infestation provisions.
The schedule’s special requirements
The IMSBC Code SUGAR schedule includes a Special requirements section. The key provisions are:
Food-grade requirement. Sugar is a human foodstuff. Holds must be food-grade clean before loading. The schedule requires that holds be free from previous cargo residues, free from odors, free from pests and vermin, and that hold coatings and surfaces be acceptable for contact with a foodstuff. This is a schedule-specific requirement over and above the general IMSBC Code hold preparation expectations.
Moisture and loading condition. The schedule requires that the cargo at loading be free from excessive moisture. Free water on the cargo surface or in the cargo mass at loading is explicitly noted as a spoilage risk. The shipper is responsible for providing a cargo declaration that includes moisture content.
Caking caution. The schedule notes the tendency of sugar to cake and harden in contact with moisture or over time, and flags the hold structure must be weather-tight to prevent moisture ingress during the voyage.
Dust. The schedule acknowledges fine sugar dust as a nuisance and notes the mild explosion risk for dust in suspension. Precautions against ignition sources are required.
Ventilation. Ventilation of sugar cargoes should be used with caution. The schedule’s guidance for ventilation aligns with the general Group C cargo principle: ventilate only when the dew point of outside air is below the dew point of hold air, to avoid condensation on the cargo surface.
Hazard 1: hygroscopic caking
The mechanism of caking
Sugar is one of the most hygroscopic dry bulk cargoes in commercial trade. The sucrose molecule has multiple hydroxyl (-OH) groups that form hydrogen bonds with water molecules, meaning the crystal surface actively attracts water vapor from humid air. At relative humidity above approximately 60% (the so-called “critical relative humidity” for sucrose at 20°C), sucrose absorbs moisture from the air at a measurable rate. At tropical sea temperatures of 25 to 35°C and typical marine humidity above 80%, the absorption rate is significant if the hold is not weather-tight.
The caking process in raw sugar is two-stage. First, the molasses film on each crystal absorbs atmospheric moisture and softens. Second, as the hold temperature cycles (warmer by day, cooler at night in tropical trade), the moisture on the crystal surface evaporates and re-deposits, causing surface recrystallization at crystal-to-crystal contact points. The result is an interlocked crystal mass with mechanical strength substantially higher than the loose cargo at loading.
In refined white sugar, the same crystal-to-crystal recrystallization occurs, but there is no molasses film to accelerate the process, so caking is slower and requires higher moisture exposure. Refined sugar can still form hard blocks during long voyages in humid holds, particularly at the cargo surface in contact with the hold atmosphere and at the cargo perimeter where it contacts the (often cooler and more humid) hold sides.
Practical consequences of caking
A caked sugar cargo presents serious discharge problems. Grabs fitted to shore cranes cannot penetrate a hard-caked surface: the grab teeth skid on the surface rather than biting in. Shore workers must hydraulically lance the caked surface, breaking it into chunks that the grab can handle. On some voyages where caking has been severe, stevedores have resorted to jackhammers and manual labor to break the cargo loose. These operations extend discharge time from the expected one to three days to five or more days on a 30,000 tonne parcel, with corresponding detention and demurrage costs.
Caking also creates safety hazards at discharge. Hard blocks of sugar at the hold sides and under the hatch can fall on workers when the adjacent cargo is removed. This risk is particularly acute in the under-hatch areas where surface-caked blocks are not visible from above.
Ship operators and their P&I clubs receive cargo claims related to caking regularly. The central legal question is whether the caking arose from a condition that existed at loading (wet cargo) or from moisture ingress during the voyage (ship’s responsibility). Hold tightness surveys conducted at the loading port, and hold temperature and humidity monitoring logs maintained throughout the voyage, are the primary evidence used to assign responsibility.
Preventing caking
Hold weather tightness is the primary control. Hatch covers must be inspected for watertightness before and after loading; compression bars, drains, and cleating are examined. Any open drain or corroded compression bar is a potential moisture entry point. Hatch cover ultrasonics testing (UltraSonic Leakage Detector, USLD) is standard practice before grain and sugar loadings; a chalk test or hose test is the minimum where ultrasonic equipment is not available.
Bilge wells within the cargo hold must be sealed and dry. Bilge pump suctions must be functional but bilge well covers must prevent sugar from entering the pump system while still allowing any water that does enter the hold to drain to the bilge. Any standing water in the bilge at loading is unacceptable.
Loading during rain or high-humidity weather is avoided wherever the commercial schedule permits. When rain falls at the loading terminal, loading is suspended and hatch covers closed. On voyages where the trade route passes through humid equatorial regions, the cargo’s exposure time in port should be minimized.
Hazard 2: mould and fermentation
Why sugar ferments
Sucrose itself is not directly fermentable by most micro-organisms: it must first be hydrolyzed to glucose and fructose by the enzyme invertase (sucrase). Raw sugar contains invertase in the residual molasses and yeast populations including Saccharomyces cerevisiae and various Candida species. When free water is present, these organisms activate: invertase hydrolyzes sucrose to the monosaccharides, and yeast ferments the glucose and fructose to ethanol and carbon dioxide. At scale, a fermenting cargo generates heat (the fermentation reaction is exothermic), carbon dioxide that displaces oxygen in enclosed hold spaces, and acidic by-products that lower cargo pH and degrade quality.
Refined white sugar does not carry yeast populations or invertase in the same concentrations as raw sugar, but it is not sterile: post-refining contamination from the air, from packaging surfaces, or from inadequately cleaned vessels can introduce fermentation organisms. Refined sugar in a closed, humid hold can still support mould growth from ubiquitous airborne Penicillium and Aspergillus species, producing visible surface mould and off-flavors.
Wetted cargo: the risk at loading
The most common cause of fermentation and mould is cargo that is already wet at loading. In the cane sugar production chain, raw sugar exits the centrifugal separator with a target moisture of approximately 0.3% to 0.5% by weight. At the bulk sugar terminal, the sugar may be stored in open-air or enclosed bulk stores for days to weeks before vessel loading. Rain penetration into open-air storage, condensation on store floors, or inadequate drainage can raise the surface moisture of the sugar pile. If that wet surface sugar is loaded directly into the vessel without segregation, wet pockets within the cargo mass can initiate fermentation within 24 to 48 hours at tropical temperatures.
The IMSBC Code’s requirement for the shipper to declare moisture content is the regulatory safeguard. In practice, moisture testing is done by a surveyor at the loading terminal using standardized methods (Karl Fischer titration or loss-on-drying); the result is the basis of the cargo declaration. Masters and supercargoes who observe a dark, wet-looking, or heavily scented cargo stream during loading are entitled to request additional moisture tests and to refuse loading of wet parcels.
Rain damage during loading
Rain falling directly into open holds during loading is a major source of cargo wetness. Sugar loading rates of 1,000 to 3,000 tonnes per hour mean that a 15-minute rain shower at a tropical loading port can deposit hundreds of tonnes of rainwater onto the exposed cargo surface in the hold. A single rain event at the wrong moment can wet the top layer of cargo so severely that the entire parcel is at risk.
Standard practice at quality-conscious sugar terminals is to close hatch covers immediately on any rainfall, halting loading until the rain stops and the exposed cargo surface can be inspected. If wetted cargo is identified, some shippers will attempt to blend it by covering the wet layer with dry cargo from the next loading bucket; this is not a solution to the underlying wetness and can result in a cargo with uniformly elevated moisture rather than a localized wet layer. Receivers take composite samples at discharge to determine average moisture; a blended wet cargo may still fail moisture specifications.
The ship owner’s protection against rain-damage claims includes maintaining a log of all rain events during loading, noting the time loading was suspended and resumed, and having a surveyor present to inspect the cargo after each rain interruption. Some charterparties explicitly require that the ship’s officer or surveyor certify the cargo condition after each rain interruption before loading resumes.
Carbon dioxide accumulation from fermentation
A fermenting sugar cargo generates carbon dioxide as a by-product of yeast respiration. In a sealed or poorly ventilated hold, CO2 accumulates and displaces oxygen, creating an atmosphere that is life-threatening to personnel entering the hold. This hazard is identical in principle to the enclosed-space risk documented for fermenting grain, organic scrap, and coal.
At tropical temperatures, a fermenting pocket of raw sugar can generate sufficient CO2 to reduce hold oxygen from the normal 20.9% to below 10% within two to three days. At oxygen concentrations below 16%, cognitive impairment occurs within seconds; below 6%, unconsciousness follows within one breath. A seafarer who enters a CO2-enriched hold atmosphere to investigate an unusual smell (a symptom of fermentation) can lose consciousness before being able to self-rescue.
The precaution is the same as for all enclosed-space entry on bulk carriers: atmospheric testing for oxygen, CO2, and any other relevant gas before entry, using calibrated instruments in good working order, with testing at multiple levels in the hold (the hatch rim, mid-hold, and bilge level), and a valid entry permit issued by the master or a designated responsible officer. The IMSBC Code section 3.2 and the ISM Code enclosed-space entry procedures apply.
Hazard 3: sugar dust
Dust generation during loading and discharge
Bulk sugar generates fine dust primarily at the cargo transfer points: when sugar falls from a conveyor belt into the loading spout, and when the spout discharges into the hold. The particle size distribution in commercial raw and refined sugar spans a wide range: the dominant fraction is 0.3 to 3.5 mm granules, but attrition during conveyor transfer produces a fine fraction below 100 micrometres. This fine fraction is airborne during loading and settles as a visible white or brown haze around the shiploader.
The explosible fraction of sugar dust is the fraction below approximately 420 micrometres (420 micron sieve). Sucrose dust has a minimum explosible concentration of approximately 35 to 45 g/m3, with an ignition energy minimum of around 10 to 30 mJ and a Kst value of approximately 70 to 100 bar.m/s. These figures place it in the St 1 explosion class: moderate hazard, lower than coal or aluminium dust but sufficient to cause a damaging explosion if a concentrated dust cloud contacts an ignition source. Documented sugar dust explosions have occurred at onshore sugar storage and milling facilities; on ships the dust cloud from loading operations is transient and the risk is lower, but not negligible.
Coarse raw sugar crystals (1 to 3 mm) generate far less fine dust than fine-grained or powdered sugar. Icing sugar (powdered sugar below 0.1 mm) is not typically carried in bulk by sea but if it were, the dust explosion risk would be substantially higher. Commercial granulated raw and refined sugar presents a mild risk that is managed by standard ignition-source controls during loading and by hold ventilation after loading is complete, before any hot work is permitted.
Nuisance dust and crew health
Beyond the explosion risk, the dust cloud around sugar loading operations is a nuisance and an occupational health concern. Inhalation of sugar dust is not acutely toxic, but high concentrations can irritate the upper respiratory tract. The principal health concern for crew and dock workers at sugar terminals is the dust mixed with mould spores in raw sugar: mouldy cargo generates fungal spores that are irritating to the airways and can trigger asthma in sensitized individuals. Dust masks rated FFP2 or equivalent are appropriate for crew members on deck during sugar loading.
Hazard 4: molasses residue and hold cleaning
The nature of molasses residue
Raw sugar’s distinguishing feature at discharge is the tenacious dark residue it leaves throughout the hold. Molasses is a viscous mixture of sucrose, glucose, fructose, water, organic acids, and mineral salts. At ambient temperatures, fresh molasses flows slowly; as it cools or dries, it becomes increasingly sticky and ultimately sets to a hard, brittle layer. In the cargo hold, molasses residue accumulates on:
- The cargo hold plating (sides, transverse web frames, longitudinal stiffeners, and floors)
- Bilge wells and their strainer covers
- The lower surfaces of hatch coamings and underdeck framing
- Sounding pipes, bilge pipe penetrations, and ladder rungs
Where sugar has caked against the hold sides (a common outcome on voyages with moisture ingress), the molasses-rich cake leaves a dark stain and a sticky deposit that cannot be removed by dry sweeping. Pressure washing with hot fresh water is necessary to dissolve and flush the molasses residue; cold-water washing is less effective because molasses viscosity increases sharply below 15°C.
The hold cleaning challenge for subsequent cargoes
Hold cleaning after a raw sugar cargo is one of the most demanding exercises in the bulk carrier operating cycle. The sequence of operations required before the hold is acceptable for most subsequent dry bulk cargoes is:
Sweeping. After discharge, the hold is swept down by hand or mechanical brooms to collect residual sugar from the bilges, frames, and tank-top plating. Even with grab discharge, typically 0.5 to 1.5% of cargo remains in the hold after commercial completion.
Washing. Pressure washing with hot fresh water is applied to all hold surfaces. Hot water is important: molasses dissolves far more effectively in water above 60°C than in cold water. Many terminals and hold-cleaning companies operate truck-mounted steam lance systems for this reason. Multiple washing passes are needed: the first wash mobilizes the surface molasses layer; subsequent washes flush the dissolved residue to the bilge.
Bilge pumping and flushing. The wash water and dissolved molasses accumulated in the bilge must be pumped out and the bilge re-flushed with clean fresh water until the bilge pump discharge runs clear. Molasses in bilge water can solidify around bilge pump impellers if allowed to dry; pumping must continue until the system is flushed clean.
Drying. The hold must be dried after washing before loading the next cargo. Moisture left on hold surfaces after a sugar voyage can trigger corrosion and can contaminate moisture-sensitive subsequent cargoes. Good holds use ventilation fans directed into the hold from on deck to accelerate drying.
Inspection. An independent surveyor inspects the hold for residual molasses, sugar crystals in the bilge system, odors, and surface stains before the hold is accepted for a new cargo.
On hard-working vessels that carry multiple sugar cargoes per year, the hold steel suffers elevated corrosion because molasses is mildly acidic and because repeated hot-water washing accelerates the breakdown of hold paint systems. The cargo hold preparation standards article covers the technical and commercial requirements in full detail.
Why refined sugar is easier to clean
Refined white sugar carries no molasses. After discharge, hold residues are white crystalline sucrose deposits that dissolve readily in any temperature of water. Hold cleaning after a refined sugar cargo is substantially easier and quicker than after raw sugar, and the staining of hold steel is negligible. This is one commercial reason that vessels on regular refined sugar trades often achieve better hold cleanliness with less cleaning effort and can turn around to the next cargo more quickly.
Food-grade hold preparation
The food-grade standard
Sugar is an ingredient in human food. The supply chain from the bulk vessel to the food processor or retailer demands that the cargo not be contaminated during transit. The food-grade hold preparation standard for sugar is therefore higher than the general “cargo-clean” standard applied to industrial commodities. The specific requirements are:
No previous cargo residues. The previous cargo must have been completely removed. Cargoes that make achieving food-grade condition most difficult include: petroleum products or fuel oil (any trace of hydrocarbon renders the hold unacceptable without specialist cleaning and certification); fishmeal or animal meal (strong organic odors that taint sugar); fertilizers including urea, ammonium nitrate, and di-ammonium phosphate (leave hygroscopic residues and odors); clinker and cement (alkaline residues and fine dust); and coal (carbon dust that would visibly contaminate white sugar).
No pest infestation. Insects, rodents, and birds must be absent from the hold. Rat droppings, feathers, or insect casings found during inspection fail the food-grade check. Fumigation of the hold before a food cargo is sometimes required by national regulations at the loading port.
No unacceptable paint condition. Hold paint must be intact and non-toxic when in contact with food. Many sugar shippers specify that holds have a full coating of food-grade-certified paint (typically epoxy-based systems approved to FDA 21 CFR or equivalent food-contact standards). Bare steel that is rusting, flaking paint, or coatings of unknown composition are not acceptable. Where the hold has been repaired with a non-food-grade paint, a food-grade coating must be applied and cured before loading.
No residual odors. The hold interior is sniffed by the surveyor during inspection. Petroleum, solvent, chemical, or biological odors (from fertilizer, fishmeal, or a previous wet organic cargo) are grounds for rejection. Odor is a particular concern for refined white sugar, which absorbs foreign odors readily.
No rust scale or loose metal. Loose rust scale falling from hold frames into the cargo contaminates white sugar visibly. Holds with active corrosion on underdeck frames or heavy pitting on the tank top that allows rust scale to shed must be remediated before loading.
Survey and certification at loading
Independent hold inspection before loading is commercial standard practice, not an IMSBC Code requirement in itself. The shipper’s surveyor typically boards the vessel at the loading anchorage, inspects each hold in turn, and either issues a clean hold certificate or provides a deficiency list specifying what additional cleaning is required. The vessel owner or charterer is responsible for achieving a hold condition that the surveyor accepts.
The clean hold certificate is commercial protection for the shipper: if cargo contamination is discovered at discharge, the shipper can demonstrate that the holds were accepted as food-grade at loading, pointing liability toward any subsequent event (hatch cover failure, bilge ingress, or contamination from an adjacent hold). For the vessel owner, the certificate confirms that the hold was in acceptable condition at the time the cargo was loaded, protecting against claims for pre-existing contamination.
Some charterparties specify which organization’s surveyor is entitled to carry out the inspection (the shipper’s surveyor, an independent third-party inspection company, or a government food authority inspector). National food-safety regulations at the loading country may impose additional requirements: Brazilian MAPA (Ministry of Agriculture, Livestock and Food Supply) regulates sugar export quality; Indian FSSAI (Food Safety and Standards Authority of India) has standards for sugar in food use. These national requirements do not replace but supplement the IMSBC Code’s food-grade language.
Loading operations: terminals, rates, and weather
Loading terminal types
Sugar loading terminals range from dedicated bulk sugar export facilities to general bulk handling ports that also load sugar. The principal dedicated sugar terminals at major export ports are equipped with:
Enclosed bulk storage. Rather than open stockpiles (which are normal for coal or iron ore), quality sugar terminals store sugar in enclosed shed warehouses or domed silos that protect the cargo from rain and humidity. This is a direct response to sugar’s hygroscopic nature; open-air storage of raw sugar is acceptable only in very arid climates or for short periods.
Covered belt conveyors. Conveyors from the storage shed to the shiploader are covered to prevent rain exposure and to reduce dust emissions. Many terminals have covered galleries along the full conveyor route.
Enclosed shiploaders. The loading spout itself is often fitted with a telescoping enclosed chute that descends into the hold, directing the cargo stream and containing dust rather than allowing it to billow over the vessel’s deck. Some terminals use vibratory belt-type shiploaders or pneumatic conveying systems.
Dehumidification at loading. A few high-specification terminals maintain dehumidified air around the cargo handling system to prevent moisture absorption during loading operations. This is particularly important at tropical ports with ambient humidity consistently above 80%.
Loading rates
Loading rates at major sugar export terminals are typically 1,000 to 3,500 tonnes per hour per berth. At Santos, the larger berths can achieve 3,000 to 3,500 t/h with well-matched vessels and good weather. Paranaguá and the northeastern Brazilian ports operate at 1,500 to 2,500 t/h. Thai terminals at Laem Chabang run at 1,500 to 2,000 t/h. Indian ports are more variable, with rates of 1,000 to 2,000 t/h at major terminals.
A 30,000 tonne Handymax parcel loaded at 2,000 t/h requires 15 hours of loading time, typically spread over 18 to 24 hours with weather stoppages and hatch shifts between holds accounted for. A 50,000 tonne Panamax parcel at 3,000 t/h requires 17 hours of net loading time.
Weather stops and their documentation
Rain stoppages during loading must be carefully logged. The vessel’s mate’s receipt and the Statement of Facts (SOF) document each rain interruption with the time loading halted, the time it resumed, and the weather conditions. The surveyor attending loading countersigns these records. When cargo claims arise later, the SOF is the primary evidence of what weather occurred during loading and whether the hatch covers were closed appropriately. A vessel that continued loading through rain without closing hatch covers has a weak defense against a cargo wetness claim even if subsequent moisture tests show only marginal exceedance.
Hatch sequencing
On multi-hold vessels loading sugar, the sequence in which holds are loaded affects several practical concerns. The IMSBC Code does not specify a loading sequence for Group C cargoes (unlike the Grain Code, which specifies sequences for stability compliance). Commercial practice is to load holds in sequence from aft to forward, or to open multiple holds simultaneously depending on the terminal’s loading arm arrangement. Where multiple loading arms are available, parallel hold loading reduces total loading time but requires coordinated hatch cover management to close covers promptly on any hold that is not being actively loaded.
Voyage: ventilation, monitoring, and stowage
Ventilation guidance
The IMSBC Code SUGAR schedule recommends that ventilation of sugar cargoes be used cautiously. The governing principle is the same as for other hygroscopic bulk cargoes: ventilate only when the dew point of the incoming outside air is below the dew point of the hold air. If outside air is cooler and drier, ventilation draws away moisture vapor from the hold. If outside air is warmer or more humid than the hold, introducing it causes condensation on the cooler cargo surfaces, which is the condition to be avoided.
The practical test is the dew-point rule: measure the dry-bulb temperature and relative humidity of the outside air; calculate or look up the corresponding dew point; measure the air temperature inside the hold; if the outside dew point is more than 3°C below the hold air temperature, ventilation may be beneficial. If the outside dew point is within 3°C of or above the hold air temperature, ventilation should not proceed. This decision should be made by the officer of the watch and logged at each watch.
Through-hold ventilation (forcing air through the cargo mass from top to bottom) is not recommended for sugar, unlike grain. The high angle of repose and compact structure of the cargo mass means air does not pass freely through the bulk, and forcing ventilation through the cargo can create preferential channels that dry some areas while leaving others undisturbed. Surface ventilation (circulating air above the cargo surface to remove moisture vapor without driving airflow through the bulk) is the preferred mode.
Cargo monitoring during the voyage
Daily inspection of hatch covers for watertightness, bilge-well checks to confirm no water ingress has occurred, and inspection of the cargo surface at each hatch opening are standard practice. On a sugar voyage, the cargo surface at the hatch rim area is the most exposed to any moisture that enters along hatch cover joints; a caked or discolored band just inside the hatch coaming is a sign that moisture has been entering at that point.
Temperature monitoring is less critical for sugar than for grain or fishmeal, because fermentation in dry sugar is much slower. However, if a cargo is suspected of having been loaded wet, temperature monitoring through the cargo using thermometer tubes inserted at loading or through ventilator ducting can identify fermenting hot spots by their elevated temperature. A 5°C rise above ambient cargo temperature in a specific zone, maintained over multiple days, is a sign of microbial activity.
Cargo shifting and structural considerations
Sugar’s high angle of repose means the cargo does not shift in the way grain does. There is no Grain Code equivalent for sugar; the master does not need to calculate heeling moments or hold securing arrangements. The stability calculation for a sugar voyage is a conventional loading condition: deadweight, cargo mass, centres of gravity, free-surface corrections for liquid tanks, and intact stability criteria under the vessel’s stability booklet.
The mass of sugar per hold is significant because bulk density is high (0.85 to 1.0 t/m3 for raw sugar). A Handymax vessel loading 30,000 tonnes of raw sugar into five holds carries roughly 6,000 tonnes per hold. The bulk carrier design accounts for the structural loads from dense cargoes, but cargo officers must verify that the loading plan respects the maximum allowable bending moment and shear force for the vessel’s class, and the maximum allowable hold mass specified in the ship’s loading manual. Heavy cargo in alternate holds is the configuration most likely to exceed allowable shear forces; alternating full-empty loading patterns are normally avoided on sugar voyages.
Discharge operations: receivers, terminals, and problems
Discharge at refineries
Most raw sugar is discharged directly at sugar refineries, which have dedicated berths equipped for bulk handling. Refineries want raw sugar delivered at the lowest possible moisture content, at consistent particle size, and without contamination; they process it within hours of delivery to avoid moisture absorption in the refinery storage.
Discharge is by grab crane (on most conventional bulk carrier/refinery berth combinations) or by continuous chain unloaders or pneumatic unloaders at higher-capacity terminals. Grab capacities of 8 to 15 tonnes per grab are typical for raw sugar discharge. Discharge rates depend on grab size, crane cycle time, and conveyor capacity at the berth: 500 to 1,500 t/h is the common range, making discharge of a 30,000 tonne parcel a 20 to 60 hour operation.
At refineries where sugar is taken directly to a storage silo rather than open stocking, the quality at discharge must meet the refinery’s specification. Samples are taken from the discharge conveyor belt at regular intervals and composited for analysis of moisture, pol (polarisation/sucrose content), color, and invert sugar content. Out-of-specification cargo can be rejected or accepted at a discount.
Discharge complications from caking
Where caking has occurred, the grab teeth cannot penetrate the caked surface and the grab drops away without cargo. The stevedore supervisor must bring in hydraulic lancing equipment (a high-pressure water gun fed from a hose) to break the caked surface into loose fragments before the grab can resume. This takes time and introduces additional water into the cargo: the water from hydraulic lancing dissolves the caked surface sugar, which then runs into the bilge as a molasses-rich liquor that complicates bilge management and clean-up.
On severe caking events, dockhands are lowered into the hold with picks and pneumatic chisels to break up the caked mass around the hold sides and under the hatch coaming area. This operation, called “caging,” is physically demanding and hazardous: workers in the hold risk injury from falling lumps of caked sugar and from the instability of a hold with partial caked walls and partially removed cargo.
Post-discharge cleaning
Post-discharge cleaning is the commercial responsibility of the vessel owner in most charterparties, unless the charterparty specifies otherwise. After a raw sugar cargo, the cleaning sequence (sweeping, hot-water washing, bilge flushing, drying, and inspection) described in the molasses residue section above applies. The time required ranges from 12 to 48 hours depending on the severity of the caking, the effectiveness of the discharge (less residue left means less to clean), and the port facilities available (hot water availability, shore power for ventilation fans).
Cargo hold preparation standards provides detailed cross-cargo comparisons, cleaning time estimates, and the technical basis for the food-grade standard.
Pre-shipment documentation
Cargo declaration and moisture certificate
The IMSBC Code section 4 requires the shipper to provide cargo information before loading. For sugar, the cargo declaration states the Bulk Cargo Shipping Name (SUGAR), the hazard group (C), the estimated quantity in tonnes, the stowage factor, and confirmation that the cargo is or is not subject to fumigation treatment. The moisture content of the cargo must be stated; the declaration is supported by a moisture test certificate from an accredited laboratory.
Fumigation of sugar for insect control is less common than for grain but does occur, particularly on long voyages or where the origin terminal has a history of storage pest infestation. Where the cargo has been fumigated before loading, or where in-transit fumigation is planned, the IMSBC Code requires this to be stated in the cargo declaration and supplemented by fumigation certificates as required by IMO MSC.1/Circ.1358/Rev.2.
Bills of lading and quality certificates
Commercial bills of lading for sugar voyages routinely carry quality clauses. Raw sugar quality certificates include the pol analysis (ICU method), color (ICUMSA units), moisture, and grain size distribution. These are commercial documents beyond the IMSBC Code’s scope but travel with the cargo documents and are part of the shipper’s package to the receiver.
For export from Brazil, a certificate of conformity from MAPA and, for EU-bound cargoes, compliance documentation under EU food import regulations are required. For exports from India, FSSAI registration and export permits apply. These national-level requirements are jurisdiction-specific and change with trade policy; the master should confirm the current documentation requirements for the specific trade from the charterer or ship’s agent before loading commences.
Related cargoes and IMSBC schedules
Sugar sits within a cluster of hygroscopic, food-adjacent, or organic dry bulk cargoes whose handling requirements share common themes. Several are covered by their own wiki articles:
Maize IMSBC Schedule covers the closest comparable in terms of food-grade handling demands and hold cleanliness requirements. Maize carries the additional Grain Code stability requirement that sugar does not. The self-heating and mould hazards for maize are analogous to those for wet sugar but arise from a different biological mechanism.
Soya beans IMSBC Schedule shares the food-grade designation and the self-heating risk. Soya beans also have a higher oil content that presents spontaneous combustion risk if excessively heated; the hold cleaning challenge after soya beans includes oil residues that sugar does not produce.
Wheat IMSBC Schedule is the reference article for grain schedules under the Grain Code. Wheat and maize share the collective GRAIN schedule; sugar has its own named SUGAR schedule, which is a material regulatory difference.
Rice IMSBC Schedule covers paddy and milled rice, which are also hygroscopic food cargoes with hold cleanliness demands comparable to sugar.
Salt IMSBC Schedule covers another hygroscopic Group C cargo with significant hold-cleaning demands, though salt is not a foodstuff cargo in the same regulatory sense and its post-cargo cleaning challenge is corrosion management rather than food contamination control.
IMSBC Group C cargoes provides the classification framework. IMSBC Code covers the full Code structure, Appendix 1 schedule format, documentation requirements, and amendment cycle.
Cargo hold preparation standards has the full technical framework for food-grade hold preparation, with worked examples across cargo types. Marine cargo hold ventilation covers the dew-point ventilation decision in detail, relevant to both sugar and comparable hygroscopic cargoes.
The IMSBC Group A/B/C classification calculator confirms the cargo group for any BCSN declaration. The IMSBC TML moisture check calculator is not directly applicable to Group C sugar (moisture is a quality and spoilage concern, not a liquefaction risk) but is relevant context for understanding how moisture thresholds work across cargo groups.
Limitations
The IMSBC Code SUGAR schedule, as amended by Resolution MSC.539(107) (Amendment 07-23, mandatory from 1 January 2025), is the authoritative source for sugar bulk carriage requirements. This article describes the schedule and the associated carriage practice as of June 2026. Future IMSBC amendments may revise the schedule; the current drafting cycle is Amendment 08-25.
Stowage factors, bulk densities, moisture thresholds, and physical property ranges cited here are representative values for commercial raw and refined cane sugar. Beet sugar and specialty sugars (muscovado, demerara, turbinado) have similar but not identical physical properties. Actual values for any specific cargo must be obtained from pre-shipment analysis and declared on the cargo information form.
The food-grade requirements described in this article reflect the IMSBC Code schedule language and standard commercial practice. National food-safety regulations at the loading and discharging country (including MAPA in Brazil, FSSAI in India, EFSA/EU regulations in Europe, and FDA regulations in the United States) impose jurisdiction-specific requirements that are not fully covered here. The chartered vessel’s operator is responsible for confirming current national requirements for each specific trade.
Stability, structural, and load-line calculations for any sugar voyage must be performed using the vessel’s approved stability booklet and loading manual. Nothing in this article constitutes a certified stability or structural assessment for any vessel or voyage.
Hold cleaning costs, discharge rates, and survey requirements described here reflect general commercial practice and are indicative only. Charterparty terms govern the allocation of cleaning costs, laytime, and survey obligations in any specific fixture.