Petroleum Coke: IMSBC Code Schedule

Petroleum coke (petcoke) is a solid carbon byproduct of petroleum refining that is regulated under the IMSBC Code in two schedule entries, both classified Group B. Uncalcined (green) petroleum coke carries a maximum loading-temperature criterion of 55 degrees Celsius and requires CO monitoring throughout the voyage; calcined petroleum coke, heat-treated to remove volatiles, shares the Group B classification for its combustible dust and residual self-heating hazard. Global seaborne trade runs to approximately 30 to 40 million tonnes per year, split between fuel-grade green coke and anode-grade calcined coke.

The IMSBC Code, adopted under SOLAS Chapter VI and mandatory from 1 January 2011 under Resolution MSC.268(85), classifies all solid bulk cargoes into three groups based on their principal hazard profile. Group B cargoes present a chemical hazard to the ship without meeting the liquefaction criteria for Group A; petroleum coke is the Group B cargo with the largest annual trade volume after coal. The two petcoke schedule entries in the Code’s Appendix 1 are PETROLEUM COKE (CALCINED OR UNCALCINED), covering both forms under a single title with differentiated handling notes, and in older editions of the Code, separate individual entries were maintained for calcined and uncalcined variants. The current consolidated treatment under Amendment 07-23 (Resolution MSC.539(107), mandatory from 1 January 2025) carries both forms under the unified title.

The cargo is produced when refiners process the residual heavy fraction of crude oil, known as vacuum residue or atmospheric residue, through a delayed coking unit. The unit thermally cracks the heavy residue at approximately 480 to 510 degrees Celsius in a coking drum; the lighter hydrocarbons vaporize and are recovered as naphtha, light cycle oil, and other refinery products, while the heavier carbon-rich fraction solidifies into a porous grey-black mass called green coke or uncalcined petroleum coke. The drum is then hydraulically cut to free the coke, which exits as lumps and fines.

Schedule structure: calcined versus uncalcined

The IMSBC Code treats calcined and uncalcined petroleum coke under the same schedule name but with different property values and handling obligations that practitioners must read carefully from the schedule particulars column.

Uncalcined petroleum coke (green coke)

Green coke is the direct product of the delayed coking drum. Its carbon content typically runs 90 to 92 per cent by mass, with the remainder being volatile matter (2 to 12 per cent), moisture (up to about 10 per cent in wet-quenched product), sulphur (0.5 to 7 per cent depending on the crude source), heavy metals including nickel and vanadium at trace levels, and residual hydrocarbons. The volatile matter fraction is the key variable for hazard assessment: higher volatile content correlates with faster self-heating and greater gas emission during the voyage.

Fuel-grade green coke, destined for cement kilns, power stations, and industrial furnaces, is typically the higher-sulphur product, with sulphur exceeding 3 per cent. Anode-grade green coke, the precursor for calcination, is lower-sulphur (under 3 per cent, ideally under 2 per cent) and carries tighter specifications on nickel, vanadium, and iron because these impurities pass through calcination into the finished carbon anode and affect aluminium smelting efficiency.

The IMSBC Code Group B classification for uncalcined petcoke reflects three chemical hazards that the schedule identifies: self-heating, emission of flammable vapours, and combustible dust. The loading-temperature criterion of 55 degrees Celsius is the most operationally visible control; the shipper must demonstrate through a cargo declaration and temperature measurement that the product does not exceed this threshold at the time of loading. The criterion exists because green coke that is loaded hot from a delayed coking unit or from storage in a hot climate can carry sufficient thermal energy to initiate self-heating during the voyage even before any oxidation reaction adds further heat.

Calcined petroleum coke

Calcined petroleum coke (CPC) is produced by passing green coke through a rotary kiln or rotary hearth furnace at temperatures between 1,200 and 1,400 degrees Celsius. At these temperatures, essentially all volatile matter is driven off, the residual moisture is removed, and the microstructure of the carbon reorders from an amorphous turbostratic arrangement toward a more graphitic structure. The finished product is 99 per cent or more carbon with a well-defined crystallite size that controls its electrical resistivity in anode service.

The dominant end-use for CPC is the production of carbon anodes for the aluminium industry. A primary aluminium smelter using the Hall-Heroult electrolytic reduction process consumes approximately 0.4 to 0.45 tonnes of carbon anode per tonne of aluminium produced; global aluminium output of approximately 70 million tonnes per year therefore sustains a demand for roughly 28 to 30 million tonnes of CPC per year, a large part of which moves by bulk carrier. Secondary uses for CPC include graphite electrode production for electric arc furnaces in steel and ferroalloy smelting, and specialty carbon products.

Because calcination has removed the volatile fraction, CPC presents a lower self-heating rate and effectively no gas-emission hazard compared to green coke. The IMSBC Code still classifies it Group B, primarily because CPC dust is combustible and abrasive, and because the residual carbon is still susceptible to slow oxidation at temperatures achievable in a cargo hold on a long voyage. The 55-degree loading-temperature criterion applies to both forms under the consolidated schedule.

Schedule comparison: calcined versus uncalcined

The loading-temperature criterion

The 55-degree Celsius loading-temperature limit in the IMSBC Code is one of the more specific physical pre-conditions in the Code’s entire Appendix 1 corpus. It does not appear for coal, which has no scheduled loading-temperature ceiling, and it is not shared with most other Group B cargoes. Its presence in the petcoke schedule reflects the operational reality of the production process: a delayed coking drum discharges product at temperatures that can exceed 150 degrees Celsius, and the wet quench used to cool the coke in drum operations brings the temperature down rapidly but not always to ambient. Coke transported from drum to stockpile may still hold elevated core temperatures. In warmer producing regions, particularly the Middle East and South Asia, stockpile temperatures can remain elevated for extended periods during summer.

The 55-degree criterion is applied at the time of loading. Practically, this means the shipper is obliged to take cargo-temperature readings from representative locations in the stockpile or loading hopper before and during loading, document them, and provide this evidence on the cargo declaration to the master. The master is not prohibited from accepting cargo that is warmer at surface level if the bulk temperature within the cargo mass is demonstrably below 55 degrees, but the documentation burden lies with the shipper.

A cargo accepted above this threshold carries two compounding risks. First, the elevated initial temperature reduces the margin before the self-heating reaction (which is exothermic) raises the cargo above temperatures at which carbon monoxide production accelerates, generally above 70 to 80 degrees Celsius in enclosed bulk holds. Second, at temperatures above approximately 80 degrees Celsius, the coke surface oxidizes at a rate that produces measurable CO concentrations in the hold headspace within hours, making detection straightforward but the problem already advanced.

The Code provides no explicit voyage temperature limit, so once a cargo is accepted below 55 degrees and loaded, the crew’s monitoring obligation shifts to CO concentration and hold temperature where instrumentation is available, not to checking whether loading-temperature documentation was correct.

Self-heating mechanism and progression

Carbon oxidation is exothermic. The reaction of carbon with atmospheric oxygen proceeds by:

and the partial oxidation that produces carbon monoxide:

Both reactions release heat. In a bulk carrier hold where the cargo fills the space to within a metre or two of the hatch coaming, the insulating mass of the cargo itself retards heat dissipation. If fresh air can enter the hold through small hatch seal gaps, ventilation trunk leaks, or intentional surface ventilation at a rate sufficient to supply oxygen but insufficient to remove heat, the cargo temperature can rise.

Green coke is more vulnerable to self-heating than CPC for two reasons. First, the volatile fraction contains partially polymerized hydrocarbon species that oxidize at lower temperatures than pure carbon, providing a lower-temperature initiation pathway. Second, the porous, freshly cut surface of green coke has a higher reactive surface area per unit mass than the denser, more ordered CPC crystal structure.

Self-heating in petcoke holds broadly follows the same progression seen in coal:

1. Slow temperature rise from ambient to approximately 50 degrees Celsius, detectable as a gradual hold-temperature increase and mild CO production.
2. Transition zone at 50 to 80 degrees Celsius where CO production accelerates measurably and the hold atmosphere begins to register CO concentrations above background.
3. Active self-heating above 80 degrees Celsius with CO concentrations rising sharply; the cargo approaches the threshold for surface smouldering.
4. Above approximately 200 degrees Celsius the carbon undergoes rapid surface combustion. At this stage direct fire-fighting in the hold may feed the reaction; the accepted intervention is CO2 or inert-gas flooding and hold sealing.

The distinction from coal self-heating is that petcoke holds no methane. Coal seams absorb methane during geological formation; petcoke does not. This means the principal gas hazard in petcoke is CO from self-heating and, in green coke, flammable hydrocarbon vapours from the volatile fraction, rather than the methane explosion hazard that dominates coal carriage procedures.

Dust hazard: health and ignition

Petroleum coke dust is one of the more challenging aspects of petcoke carriage from both a health and an operational standpoint.

Particle characteristics and explosion risk

Petcoke emerges from the coker drum in sizes from large lumps (50 to 100 mm) down to fines under 100 micrometres. During conveying, loading, and mechanical handling, the fines fraction is generated and becomes airborne. CPC in particular, because of its harder, more crystalline structure, generates a fine, black dust that disperses widely and settles on all exposed surfaces.

Carbon dust is combustible. The minimum ignition energy for fine carbon dusts is typically in the range of 10 to 40 millijoules, depending on particle size and moisture content; dry, fine petcoke dust at particle sizes below 75 micrometres can ignite at these energies and propagate a deflagration in air at concentrations above approximately 40 to 60 grams per cubic metre (the lower explosive limit for fine carbon dust). The minimum ignition temperature for petcoke dust layers is generally in the range of 250 to 400 degrees Celsius depending on moisture and volatile content, well below the temperature of a welding arc, cutting flame, or improperly protected electrical equipment.

These properties mean that loading and discharge operations involve genuine dust explosion risk if ignition sources are present in the area of dust-generating equipment. The IMSBC Code’s schedule requires that loading and unloading be conducted with dust-suppression measures, that hot-work permits be suspended throughout cargo operations and the voyage, and that all potential ignition sources in loading-terminal areas be controlled.

Health hazard of petcoke dust

Beyond explosion risk, petcoke dust is a health hazard for workers involved in loading, trimming, and discharge. The health properties of petroleum coke dust are contested in occupational medicine literature, but the regulatory consensus is that fine carbon dust including petcoke warrants dust-control measures as a nuisance and potential respiratory irritant. High-sulphur petcoke dust may carry sulphur-bearing compounds that add to respiratory irritation. Nickel and vanadium content in green coke from heavy crude oil sources can add toxicological significance at fine particle sizes.

Crew members involved in hold inspection, sounding tube use, or any entry into holds or void spaces adjacent to petcoke cargo spaces must treat hold atmospheres as potentially oxygen-deficient (self-heating consumes oxygen) and CO-contaminated; enclosed space entry procedures under SOLAS Regulation III/19 apply.

Dust migration and vessel contamination

Petcoke dust is oily and very hard to fully remove from bilge spaces, frames, web frames, and structural members. A bulk carrier that has carried petcoke repeatedly will often retain black staining in structural crevices. This becomes a practical problem when the vessel is subsequently chartered for a clean cargo, most acutely grain, where cargo inspectors will condemn holds if petcoke residue is present. Grain handling associations and shipping companies have documented the difficulty of achieving grain-clean standards from petcoke, and many bulk carrier operators factor additional cleaning time and cost into voyage estimates for vessels coming off petcoke charters.

Ventilation policy

The IMSBC Code distinguishes between through-ventilation and surface ventilation, and the distinction matters for petcoke.

Surface ventilation applies airflow to the headspace above the cargo, venting any accumulation of CO, flammable vapours, or dust. The airflow path does not penetrate the cargo mass. Surface ventilation is the prescribed method for petroleum coke; it removes potentially hazardous gases from the hold without introducing fresh oxygen into the cargo body that could accelerate self-heating.

Through-ventilation passes air from the duct keel or lower ventilation ducts upward through the cargo mass and out at the top. For methane-emitting coals, surface ventilation is similarly preferred over through-ventilation because through-ventilation feeds oxygen to the entire cargo body. The principle is the same for petcoke: the objective is gas removal without oxygen supply to the oxidizing reactions.

In practice, surface ventilation on a bulk carrier at sea is achieved by opening hatch covers partially or using hatch-mounted ventilation cowls or fans to draw air across the cargo surface, while keeping through-ventilation ducts closed. The exact regime depends on weather conditions; in heavy sea states the hatch covers are fully secured and ventilation ceases until weather improves, at which point CO and temperature monitoring becomes especially important because the sealed, possibly self-heating cargo has been deprived of even surface ventilation for an extended period.

The marine cargo hold ventilation article covers the general principles of bulk carrier ventilation and the distinction between surface and through ventilation in more depth.

Temperature monitoring in service

The IMSBC Code calls for temperature monitoring of petroleum coke throughout the voyage where practicable. The phrase “where practicable” acknowledges that most bulk carriers do not have permanently installed temperature probes in cargo holds; the monitoring is done by lowering calibrated probes through sounding pipes or hatch openings to contact the cargo surface or upper cargo layers.

The frequency of monitoring is not fixed at an exact interval in the Code text, but industry practice and P&I guidance typically call for at minimum once-daily measurement in all holds during the loaded voyage, with results logged and forwarded to the operator and charterer. More frequent measurement is warranted when CO monitoring shows an upward trend, when the cargo was accepted at or close to the 55-degree loading-temperature limit, or when ambient conditions are hot.

Temperature measurement alone is less sensitive than CO measurement as an early warning indicator. CO starts accumulating at detectable concentrations (above 5 to 10 parts per million in the headspace) before the bulk cargo temperature has risen by even a few degrees. CO measurement is accordingly regarded as the primary monitoring parameter, with temperature providing corroboration and a means to confirm whether a CO rise is associated with genuine self-heating or with condensation effects at the measurement point.

The IMSBC Coal Self-Heating Indicator calculator provides a useful reference tool for evaluating self-heating indicators, and its underlying logic applies to petcoke cargoes where CO readings are the primary alert signal.

Carbon monoxide monitoring

CO monitoring for petcoke follows the same practical procedure as for coal. At each monitoring interval, a sample of hold atmosphere is drawn from the headspace sampling tube (typically installed at hatch coaming level) and tested with a calibrated CO detector. The reading is compared against prior readings and logged. Instruments used must be calibrated against reference gas mixtures at intervals set by the manufacturer; uncalibrated electrochemical sensors can drift substantially and give false reassurance.

The IMSBC Code does not set a numerical CO threshold at which emergency action is triggered for petroleum coke; the coal schedule gives clearer threshold guidance. In practice, masters and operators use the coal thresholds as informal guidance for petcoke: CO readings below 50 ppm with a flat trend are generally treated as non-alarming, while readings above 100 to 200 ppm or a sustained rising trend warrant escalated monitoring, consultation with the operator and P&I, and preparation of the fire-control equipment (CO2 systems, hold-atmosphere flooding capability).

Two aspects of CO measurement require attention. First, sampling through sounding pipes may draw gas from the lower cargo body rather than the headspace; the hold layout and the sampling tube position must be verified before interpreting readings. Second, a sudden drop in CO after a rising trend can indicate that the CO is being consumed faster by combustion than it is being produced by oxidation, a sign of active fire rather than smouldering self-heating.

Hold preparation before loading

The IMSBC Code requires cargo hold preparation that ensures holds are clean, dry, and structurally sound before petcoke is loaded. For petcoke, the standard checks are:

• All previous cargo residues removed; holds swept and washed. Petcoke succeeding a grain cargo is straightforward; the reverse takes multiple wash cycles and a lime wash to achieve grain-clean standard.
• Bilge wells clean, clear of oil or organic matter, and tested to confirm free flow. Petcoke can compact around bilge strums and reduce their effectiveness.
• Hatch cover seals inspected and confirmed watertight or near-watertight. Water ingress into a petcoke cargo during the voyage does not create liquefaction risk (petcoke is Group B, not Group A) but can accelerate self-heating in uncalcined grades and creates handling complications at discharge.
• All hot-work permits suspended. The prohibition applies at loading berth, on passage, and at discharge. Any temporary repairs to hatch cover fittings or cargo-space equipment during a petcoke voyage require the master to assess the ignition risk carefully and to apply appropriate precautions; welding and cutting adjacent to cargo spaces should be avoided entirely.
• Internal surfaces dry. Wet holds produce steam when loaded with warm cargo, which can affect sensor readings and accelerate the surface oxidation of green coke fines.

The cargo hold preparation standards article provides a systematic hold-preparation checklist and the pre-loading survey documentation expected by cargo surveyors and P&I clubs.

Cargo declaration and shipper responsibilities

The shipper of petroleum coke must provide a cargo declaration that includes, at minimum:

• Bulk cargo shipping name: PETROLEUM COKE (CALCINED OR UNCALCINED), with the specific variant stated
• IMSBC group: B
• UN number: not applicable (petroleum coke is not a UN-classified dangerous good under IMDG, though it is regulated under IMSBC as a Group B cargo)
• Bulk density: the actual measured stowage factor and bulk density for the specific shipment
• Angle of repose: not typically required for Group B cargoes that are not susceptible to liquefaction, but informative for trimming
• Moisture content: for green coke with significant moisture from wet quench
• Sulphur content: relevant to the health hazard assessment for dust and to port reception requirements in MARPOL-controlled areas
• Temperature at time of loading: the critical criterion; the declaration must confirm the cargo does not exceed 55 degrees Celsius
• Any special hazard notes for the specific cargo, such as elevated heavy metal content in green coke from heavy crude

Where the shipper provides incomplete or absent declarations, the master has the right and the duty to refuse loading under SOLAS Chapter VI Regulation 2. P&I clubs have documented incidents where masters accepted cargoes with deficient declarations and subsequently faced difficulty establishing liability when self-heating occurred.

Major trade routes and volumes

Petroleum coke seaborne trade is a byproduct of global refinery geography. Refineries concentrate in major crude-producing regions and near large consumer markets, and petcoke exports tend to flow outward from export-oriented refinery complexes.

The United States is the world’s largest petcoke exporter, with Gulf Coast refineries (Texas, Louisiana) and West Coast facilities exporting through Houston, Corpus Christi, Beaumont, and Long Beach. US exports of green coke run approximately 15 to 20 million tonnes per year, with fuel-grade coke going predominantly to India, China, Turkey, and Mexico. The US is also the leading CPC producer, with calcination facilities at multiple Gulf and West Coast locations supplying aluminium smelters in the Middle East, Canada, and Southeast Asia.

Saudi Arabia, the UAE, Kuwait, and other Gulf Cooperation Council refineries represent the second major export origin, with growing petcoke output from refineries at Jubail, Ruwais, and related industrial sites. Gulf petcoke flows primarily to South Asian and Southeast Asian markets.

India is both an importer and, from its own refineries, an exporter. India’s cement industry is the dominant consumer of imported fuel-grade petcoke; Indian cement manufacturers displaced coal with petcoke when petcoke prices fell below coal equivalence on a heat-content basis, a shift that occurred broadly between 2010 and 2015. Environmental regulations restricting high-sulphur petcoke combustion in certain Indian industrial zones have created some demand-side constraints since 2017, though enforcement has been uneven.

China imports CPC for aluminium anode production and green coke for fuel, with import volumes fluctuating based on domestic Chinese refinery output and aluminium industry growth. China is also a significant domestic producer.

Vessels typically employed are Supramax (52,000 to 62,000 DWT), Ultramax (60,000 to 65,000 DWT), and Panamax (70,000 to 82,000 DWT) bulk carriers for the mid-range trade lanes, with Capesize vessels used for large anode-grade CPC shipments to major smelter supply ports. The bulk carrier article covers vessel type selection and hold configuration in more depth.

Loading operations

Petcoke loading operations share many characteristics with coal loading, with the dust suppression and hot-work controls being the defining safety differentiators. Shore-based operations use conveyor belts, shiploader booms, and trimming chutes. The loading rate depends on the shiploader capacity at the terminal; major US Gulf petcoke export terminals can achieve loading rates of 2,000 to 4,000 tonnes per hour.

Dust suppression at the loading point is required by the IMSBC Code. Methods include:

• Water misting at the point of cargo drop-off onto the conveyor and at the shiploader head
• Enclosed chutes with dust extraction at transfer points
• Windbreak fencing or enclosures at terminal stockpiles

The shiploader must be positioned to minimize the cargo drop height onto the vessel, reducing both dust generation and cargo degradation by impact breakage. Trimming within the hold is done with the shiploader or with bulldozers lowered into the hold to create a level, compacted cargo surface that allows secure hatch closure and reduces void spaces that could allow air circulation.

Masters and chief officers should be present or have a designated officer present during loading to monitor cargo temperature at the loading point (before the cargo enters the hold), observe the condition and color of the cargo, and verify that the cargo matches the declaration. Petcoke that is visibly steaming on arrival at the hold is almost certainly above the 55-degree loading threshold and should not be accepted without a measured temperature confirming otherwise.

Discharge operations

Petcoke discharge is typically by grab cranes at the receiving terminal. The discharge of dry green coke or CPC generates significant dust, and receiving terminals in regulated jurisdictions operate enclosed discharge facilities or require dust suppression at the grab discharge point. In bulk, petcoke is discharged into hoppers, conveyors, or directly onto terminal stockpiles.

Because petcoke is dense and potentially compacted after a long voyage, the upper cargo layer may be harder to penetrate with a grab; in some cases, a bulldozer or front-end loader is lowered into the hold to break up compacted sections. This operation requires careful enclosed-space entry procedures, as the hold atmosphere may still contain elevated CO even after opening the hatches.

Residue removal after petcoke discharge requires thorough hold washing. Black petcoke dust adheres to all surfaces and resists straightforward washdown. The standard practice for grain-clean preparation after petcoke involves multiple wash cycles, lime-washing to address staining, and independent surveyor inspection. The cargo hold preparation standards article details the steps expected for grain-clean certification.

Emergency response: incipient fire

If temperature monitoring or CO readings indicate active self-heating progressing toward or past the threshold for combustion, the master’s options are defined by IMSBC Code Section 9 (Emergency response for bulk carriers). For petroleum coke, the primary intervention is:

1. Seal the hold as completely as practicable to cut off oxygen supply to the reaction. Do not open hatches to inspect unless fitted with adequate CO and atmosphere protection equipment; the headspace atmosphere may be toxic and oxygen-deficient.
2. Activate fixed CO2 or inert gas flooding if the vessel is fitted and the master judges that active combustion is occurring. CO2 flooding displaces oxygen and suppresses combustion; it also fills the headspace with a toxic atmosphere that eliminates the possibility of personnel entry without breathing apparatus.
3. Do not apply water to the cargo surface of a petcoke cargo where self-heating is suspected but open flame is not confirmed. Water on a thermally active petcoke cargo generates steam that can propagate heat within the cargo body and may create pressure in the hold headspace.
4. Contact the shipper, the operator, the P&I correspondent, and the nearest Maritime Rescue Coordination Centre as the situation escalates. Decisions about port of refuge, discharge to minimize risk, or tow may all become relevant.

The critical error in petcoke fire incidents has historically been opening hatches to inspect or ventilate a self-heating cargo without controlling the atmosphere; the sudden oxygen supply can convert smouldering self-heating into an open fire that is near-impossible to suppress once established in the deep cargo body.

IMSBC Code amendment history relevant to petcoke

The IMSBC Code has been amended in multiple cycles since its 2009 adoption, with Amendment 07-23 (Resolution MSC.539(107)) being the current mandatory edition as of 1 January 2025. The petroleum coke schedule has seen the following significant amendments:

• Amendment 02-13 (Resolution MSC.393(95), mandatory from 1 January 2015): strengthened the cargo declaration requirements, including explicit requirements for temperature documentation at loading for Group B cargoes with loading-temperature criteria. Petcoke’s 55-degree criterion received additional documentation guidance.
• Amendment 05-19 (Resolution MSC.468(101), mandatory from 1 January 2021): consolidated the PETROLEUM COKE (CALCINED) and PETROLEUM COKE (UNCALCINED) entries into the unified PETROLEUM COKE (CALCINED OR UNCALCINED) title with a schedule that distinguishes the two variants by their physical property values.
• Amendment 07-23 (Resolution MSC.539(107), mandatory from 1 January 2025): general housekeeping amendments across multiple schedules, updated bulk density declaration requirements. The petcoke schedule itself was not materially changed in this cycle.

The authoritative text is IMO’s current edition of the IMSBC Code, which operators and masters should access directly through the IMO bookshop rather than relying on third-party reproductions that may lag behind the current mandatory amendment.

Interaction with other regulations

Petroleum coke carriage does not occur in regulatory isolation. Several other instruments affect the cargo:

MARPOL Annex VI and sulphur content: petcoke itself is not a bunker fuel, so MARPOL’s sulphur limits for fuel oil do not directly govern the cargo. However, petcoke combusted ashore as an industrial fuel is subject to emission controls in the receiving country. High-sulphur fuel-grade petcoke (above 3 per cent sulphur) is effectively restricted to cement kilns, power plants, and industrial users with flue gas desulfurization installed. Buyers specify sulphur content tightly, and the cargo declaration should include the sulphur assay.

SOLAS Chapter XII (additional safety measures for bulk carriers): SOLAS Chapter XII applies to bulk carriers of 150 metres length and upward carrying solid bulk cargoes with a density of 1,000 kg/m³ or more. Petroleum coke has a bulk density typically below 1,000 kg/m³ (approximately 700 to 900 kg/m³), placing most petcoke cargoes below the Chapter XII density threshold and outside its specific structural and stability requirements. The SOLAS Chapter XII article provides detail on this density threshold and its implications for cargo planning.

ISM Code and SMS obligations: the vessel’s Safety Management System must include procedures for carrying Group B cargoes, covering the cargo declaration review, loading-temperature verification, CO monitoring, ventilation regimes, and emergency response. P&I clubs regularly examine vessels’ SMS records when assessing cargo-related claims; the absence of documented procedures or monitoring logs for petcoke cargoes has been a recurring factor in cases where P&I coverage has been contested.

Comparison with coal carriage

Because petcoke and coal share a Group B self-heating profile and are both carried on the same vessel types, a direct comparison is useful for practitioners who move between cargo types.

CO monitoring: both cargoes require it; the IMSBC Code gives coal more detailed threshold guidance (CO above 50 ppm warrants increased monitoring; CO above 200 ppm or sharp upward trend warrants emergency procedures). Practitioners typically apply the same thresholds informally to petcoke.

Methane: coal may emit methane, petcoke does not. This eliminates one monitoring parameter for petcoke but does not reduce CO vigilance.

Loading-temperature criterion: petcoke has a 55-degree Celsius loading criterion; coal’s schedule does not include a specific loading-temperature ceiling (self-heating potential is assessed indirectly through cargo testing). The petcoke criterion is therefore more operationally specific.

Liquefaction: coal has some Group A variants (fine wet coal); petcoke is Group B only and does not liquefy. No TML testing is required for petcoke.

Hold cleaning: both cargoes leave dark, difficult residue; petcoke residue is generally harder to remove than coal residue because of its oily, adhesive character.

The Coal: IMSBC Code Schedule article is the primary cross-reference for coal carriage procedures and their points of overlap with petcoke.

Limitations

The schedule properties in this article reflect the current IMSBC Code text through Amendment 07-23, mandatory from 1 January 2025. Mandatory amendments follow a regular cycle at approximately 18-month intervals; masters and ship operators should verify that the edition of the Code on board is the current mandatory version and that any interim amendments have been incorporated.

Physical property values (bulk density, stowage factor, moisture content, sulphur content) are ranges that cover the wide variety of crude oil sources and refinery configurations from which petcoke is produced; the actual values for any specific cargo must be obtained from the shipper’s cargo declaration and analysis certificate rather than from reference tables. High-sulphur petcoke from heavy crude sources (Venezuela, Canada’s oil sands, and certain Middle Eastern crudes) can exceed the sulphur ranges cited here by a wide margin.

The 55-degree loading-temperature criterion, the CO monitoring obligation, and the surface-ventilation policy are established IMSBC Code provisions, but the Code’s implementation and enforcement quality varies by flag state, port state, and terminal operator. Instances of petcoke being loaded above the temperature criterion have been documented in industry safety investigations; the absence of enforcement action does not establish that the criterion is unimportant.

Medical and toxicological characterization of petcoke dust remains an active area. Occupational exposure limits for petcoke dust vary by jurisdiction and have been revised in some countries as epidemiological data has accumulated. The health information in this article does not constitute occupational health advice; ship operators should consult the current SDS (Safety Data Sheet) for the specific petcoke product and follow the guidance of their flag state occupational health regulations.

See also

• IMSBC Code
• IMSBC Group B Cargoes
• Coal: IMSBC Code Schedule and Carriage
• Cargo Hold Preparation Standards
• Marine Cargo Hold Ventilation
• Bulk Carrier
• SOLAS Chapter XII: Additional Safety Measures for Bulk Carriers
• Sulphur: IMSBC Code Schedule and Carriage

Related calculators:

• Coal Self-Heating Indicator
• IMSBC Group A/B/C Classification
• IMSBC Petcoke Uncalcined
• IMSBC Coke Breeze