Cool heads must prevail when handling self-heating coal

Simon Hodgkinson, Head of Loss Prevention at West P&I, explains the dangers of transporting coal and how shipowners can limit the risks.

Coal will remain an important bulk commodity in many regions for some time to come, as nations and industries weigh up energy transition and energy security concerns. Bulk shipping makes up the backbone of global coal logistics, yet the sector often underestimates the risks associated with carrying coal cargoes.

Self-heating coal is one of the more dramatic risks that coal carriers face. Many seafarers, port staff, and others involved in the loading of cargoes have some quite dramatic misconceptions about what these risks are and how to mitigate them. The consequences of failing to correct this could be catastrophic for crews, for the environment, and for a vessel.

HIGH-RISK AREAS AND STRATEGIES

The chances of coal self-heating are higher with geologically low-rank material sourced from open cast mines, such as that commonly shipped from Kalimantan. Irrespective of its quality, coal should always be monitored before loading to ensure it is cooler than 55°C. Any cargo with a higher reading must not be loaded onto the ship, to comply with IMSBC Code requirements.

There are, however, some shortcomings with the code. In West’s, experience, Cargo Declarations for Coal are often presented with errors or missing required information. The appendix to the IMSBC Code schedule for coal sets out that, “As a minimum, the cargo’s contract specifications for moisture content, sulphur content and size shall be stated, and especially whether the cargo may be liable to emit methane or self-heat”.

To counter this, some shipowners or charterers will push for the cargo to be loaded from areas of the barge where no excessive temperatures have been recorded, or after the coal has had time to cool. This is not an effective or safe solution, and variations in the temperature of loaded coal could easily exceed 55°C.

Others will douse self-heating coal with fresh, or more frequently salt water. While localized cooling can, to an extent, be measured, this type of cargo is thermally insulating and may get hotter on the barge even after a temperature reading showing it is below 55°C.

Other common methods used in an attempt to cool cargo on barges include spraying self-heating coal with chemicals that are designed to inhibit the oxidation reaction and turning the cargo over with a payloader also fail this test. The core temperature of the cargo, or the temperature below the surface, is insulated and likely to continue to rise when onboard a bulker.

Our assessment is based on recent cases where cooler coal was loaded into a vessel’s cargo hold, having been taken from an area of the barge where no temperature above 55°C was recorded. However, the heat in other areas of the same barge did exceed this temperature. In other scenarios we have come across, cargo initially found to be above 55°C was cooled sufficiently following treatment on the barge. Once the coal was transferred to the cargo hold, it self-heated to temperatures over the threshold and began giving off smoke and steam.

The upshot is that any action taken on the barge will not deal with the fundamental issue of the bulk of the coal being too hot.

MAKING SELF-HEATING COAL SAFE

Shipowners should ensure any charterparty agreement includes a provision that acceptance of cargo for loading is at the Master’s discretion — and that they have the final say on the matter. In our experience, allowable cargo is often described within the charter party as “harmless lawful coal in bulk only”, or words to that effect, when it comes to fixing vessel for coal cargoes. A better description for allowable cargo would be “coal that is not known to be liable to emit methane or self-heat.”

When any reading onboard a coal barge exceeds 55°C, a ship’s master should ensure that the coal is unloaded onto a wharf or similar shoreside spot and spread out to a relatively thin layer. This is the only reliable method for uniformly cooling coal that has started to self-heat. Shippers can speed up the cooling process by crushing the coal with a roller and dousing it in fresh water. This cannot be carried out on a barge.

Any sign of smoking or steaming from cargo already placed on a vessel should serve as a warning to halt loading of the coal. Loading should also be suspended if the temperature of the coal in the hold is greater than 55°C. In either scenario, the affected cargo hold(s) should be closed immediately with no ventilation, and gas monitoring carried out as per the IMSBC Code. Expert advice on the next steps must then be sought.

Our advice is to take no risks when it comes to self-heating coal. If one reading is found to exceed 55 C, the entire barge should be rejected — even if all other results are within the limit. While the IMSBC Code does not cover whether cooler or cooled coal can be loaded, it is always best to remain cautious. Loading should not commence — or be stopped immediately — if there are any concerns about the cargo’s temperature. The same actions apply to coal that is smoking, steaming or exhibiting any other signs of self-heating, even if all temperature readings are below 55˚C.

While taking measures to prevent coal from self-heating is essential, there are no guarantees of a completely risk-free load. This is because coal, categorized by the IMSBC Code as Group B, “possesses a chemical hazard which could give rise to a dangerous situation on a ship.” Coal may additionally be categorized as group A, if this is the case the cargo “may liquefy if shipped at a moisture content in excess of its transportable moisture limit.”

Transporting coal, a potentially dangerous cargo, always comes with an element of risk. As such, shipowners and charterers who encounter any issues should always contact their maritime insurer’s loss prevention department for guidance on how to load and carry coal as safely as possible.