Petroleum coke: managing temperature from the coker to the cargo hold

Key message: Temperature is the one physical parameter of petroleum coke that the carriage rules single out. The IMSBC Code (International Maritime Solid Bulk Cargoes Code) treats petroleum coke loaded at 55°C or above as a special case, with a ceiling of 107°C, additional stowage rules over tanks holding low-flashpoint fuel, and a crew warning for hot calcined coke. Most fuel-grade green coke is loaded well below the trigger; calcined coke is the grade most likely to arrive hot. Knowing the temperature at origin, measuring it before and during loading, and recording it in the shipper’s declaration is what keeps a petcoke shipment moving without surprises.

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Is the coke hot?

It is one of the first questions asked on almost every petroleum coke fixture – by masters before they accept the cargo, by charterers working out laytime and declaration wording, and by receivers planning how to store and handle the consignment. The question has a precise answer under the IMSBC Code, because petroleum coke is carried as a Group B cargo (materials hazardous only in bulk, MHB), and the rules that apply to a given shipment depend on the temperature at which it is loaded. This article sets out where that heat comes from, what the carriage rules require once a threshold is crossed, and the control points that establish and record the temperature along the chain from the coker to the cargo hold.

Where the heat comes from

Petroleum coke is produced by delayed coking: a refinery residue is fed into a coke drum, where it cracks and forms a solid over a fill cycle of roughly 12-24 hours. The drum is then steamed out, quenched with water and the coke is cut out hydraulically before it is moved to a storage pit or pad. Green (uncalcined) petroleum coke leaves this process hot and wet; the quench water it retains is also what later shows up as moisture in a cargo specification.

Some green coke is calcined: heated in a kiln to drive off remaining volatile matter, at temperatures of approx. 1,200-1,350°C according to standard industry references, then cooled before dispatch. Calcined petroleum coke (CPC) is the grade most likely to still carry significant heat when it reaches a terminal, because full cooling after a high-temperature process takes longer than it does for green coke. In both cases, residual heat can persist in freshly produced material and in large stockpiles, which is why the temperature of a consignment reflects its process and storage history rather than a single fixed property of the product.

What the carriage rules say

The IMSBC Code carries a dedicated schedule for petroleum coke (calcined or uncalcined), listed as a Group B cargo (materials hazardous only in bulk, MHB). The schedule’s special provisions are not a blanket rule for every petcoke shipment; they apply once the cargo is loaded at 55°C or above. Below that trigger, a different set of requirements on the same schedule applies. An equivalent structure appears in the US rule at 46 CFR 148.295 and in the cargo’s earlier BC Code entry.

Where the 55°C trigger is met, the Code adds several requirements. Petroleum coke is not to be loaded when its temperature exceeds 107°C. Where it is loaded over a tank containing fuel with a flashpoint below 93°C, a cooler layer of coke – approx. 0.6-1.0 m, at not more than approx. 44°C under the IMSBC Code (approx. 43°C under the US rule) – is loaded first. The master is required to warn the crew that hot calcined coke can cause burns, and the US rule additionally calls for temperature monitoring during the voyage to detect spontaneous heating in hot-loaded cargo. The shipper’s declaration must record the cargo’s loading temperature and the schedule reference used to classify it.

Parameter	Value
Special provisions trigger	Cargo loaded at 55°C or above
Loading ceiling	Not to be loaded when temperature exceeds 107°C
Cooler layer over fuel tanks	Approx. 0.6-1.0 m, at not more than approx. 44°C (IMSBC Code) / approx. 43°C (US CFR)

Source: IMSBC Code (current consolidated edition); 46 CFR 148.295.

Control points along the chain

Four points in the chain are where temperature is actually measured, recorded or acted on: at origin, at loading, on voyage, and at discharge and storage.

At origin

• Pad residence time is tracked so that freshly produced coke can be distinguished from older, cooler stock.
• Stockpiles are surveyed periodically for hot spots.
• Infrared surface readings are taken across the pile.
• Probe readings at depth check for heat that does not show on the surface.

At loading

• The loading temperature is stated in the shipper’s declaration.
• An independent surveyor takes readings before and during loading.
• Hold or stop rules apply if a reading approaches or exceeds the 107°C ceiling, or crosses the 55°C threshold that changes which provisions apply.

On voyage

• Cargo loaded hot is subject to periodic temperature monitoring under the US rule.
• Petroleum coke does not carry a gas-monitoring regime comparable to the one used for coal cargoes.

At discharge and storage

• Stockpiles are managed with run-off control appropriate to the site.
• Wet coke can freeze in cold conditions, which affects handling.
• Seasonal conditions more generally affect handling and stockpile management practices.

Other temperature-linked commercial points

Quench water retained in green coke affects its weight, which is why contracts should state clearly whether a quantity is agreed on an as-received or a dry basis.

Dust generated during handling and storage is addressed in the product’s safety data sheet, which should be consulted and followed.

Hot calcined coke carries a risk of damage to hold paintwork and coatings, which charter party and contract terms can anticipate.

If the declared loading temperature is exceeded, a cargo can be delayed or rejected at the load point, with demurrage consequences that are best addressed in the contract rather than discovered during loading.

What we do

Temperature is built into our loading instructions and survey scope: the expected loading temperature is confirmed before a cargo is nominated, survey instructions specify where and how readings are taken, and shipper’s declarations are checked against the applicable schedule reference before they are issued. Contract wording addresses the cargo description, the temperature at loading and the consequences if the declared figure is exceeded.

Takeaways

• The IMSBC Code’s special provisions for petroleum coke apply once a cargo is loaded at 55°C or above, not to every shipment regardless of temperature.
• Petroleum coke must not be loaded when its temperature exceeds 107°C.
• Over tanks holding fuel with a flashpoint below 93°C, a cooler layer of coke (approx. 0.6-1.0 m, at not more than approx. 44°C under the IMSBC Code) is loaded first.
• The master is warned that hot calcined coke can cause burns, and the US rule adds a requirement to monitor cargo temperature during the voyage.
• The shipper’s declaration, the survey report and the loading instructions are the documents that establish and record the loading temperature.

Frequently asked questions

Is green petcoke self-heating? Green (uncalcined) petroleum coke is typically loaded well below the 55°C trigger, and is generally not self-heating. 

Can calcined coke be shipped hot? Calcined petroleum coke is the grade most likely to be loaded above the 55°C trigger, because it is processed at high temperature and needs time to cool fully. When it is loaded hot, the IMSBC Code’s special provisions – the 107°C ceiling, the cooler layer over fuel tanks and the crew warning – apply, and the loading temperature must be recorded in the shipper’s declaration.

Who measures the temperature at loading? An independent surveyor appointed for the cargo typically takes the readings, working from the shipper’s declaration and the agreed survey scope, usually combining surface and probe measurements before and during loading.

Learn more

Questions on petcoke specifications or logistics? Contact our operations desk or visit our petroleum coke product page.

This article is provided for general information. It does not constitute legal, regulatory, safety or commercial advice. Carriage, storage and handling decisions must be based on the applicable codes and regulations, the product safety data sheet and professional advice. Regulatory information reflects the position at the date shown; please check the current status.