West of England Club has reminded Members that self-heating of coal was more likely when the coal was of low rank, geologically immature material sourced from open cast mines such as that commonly shipped from Kalimantan in Indonesia.
West noted that the IMSBC Code sets out that, for self-heating coals, the temperature of the cargo must be monitored prior to loading and cargo will only be accepted for loading when the temperature of the cargo is not higher than 55°C.
It said that in most cases any coal loaded in Kalimantan was from barges. The Club said that it had noticed a growing trend of increased pressure from shippers to load cargo from barges where temperatures in excess of 55°C had been recorded. Shippers were either pressing for cargo to be loaded from areas on the barge where no excessive temperatures had been recorded, or after “cooling“ of the cargo on the barge.
Methods used in an attempt to cool cargo were varied, but included:
- Turning the cargo over with a payloader or using grabs
- Spraying with fresh or, more frequently, salt water
- Spraying with chemicals which are designed to inhibit the oxidation reaction.
The Club said that in its experience none of these remedial actions were very effective.
Although some localized cooling might be measured, coal was thermally insulating, and any action that can be taken on a barge would not deal with the fundamental problem of the bulk of the coal being too hot.
West said that the only reliable method to cool coal that had started to self-heat was to unload it ashore onto a wharf or similar, and then spread it out in a relatively thin layer, thus enabling it to cool and stabilize. Crushing of the coal with a roller and dousing with fresh water could accelerate this cooling process, although clearly none of these methods would be practicable or achievable on a barge.
In two recent cases West said that it had seen cooler cargo (taken from an area of the barge where no temperatures in excess of 55°C were recorded, although temperatures above 55°C were found in other areas on the same barge), or cooled cargo (initially found to have a temperature in excess of 55°C, but after treatment on the barge was then found to be below 55°C) loaded into cargo holds.
Within the cargo holds this cargo then continued to self-heat to temperatures in excess of 55°C, as well as giving off smoke/steam. If cargo already loaded was seen to be smoking/steaming or the temperature is found to be greater than 55°C, then no further cargo should be loaded in these hold(s). The affected cargo hold(s) should be closed without delay with no ventilation, and gas monitoring as per the IMSBC Code instigated. Expert advice should then be obtained.
Although there is nothing in the IMSBC Code to prevent loading of cooler or cooled coal, the Club’s recommendation remained that, if just one of the temperature readings was found to exceed 55˚C, the entire barge should be rejected, even if all other readings are satisfactory. Similarly, even if all readings were satisfactory, coal should not be loaded if seen to be smoking or steaming, or exhibiting any other signs of self-heating.
West said that, given the pressure being applied by shippers, it recommended that when fixing, the charter party should include a provision that acceptance of cargo for loading was always to be at the absolute discretion and final control of the Master.
With regard to fixing vessel for coal cargoes, the Club said that it often saw allowable cargo described within the charter party as “harmless lawful coal in bulk only” or similar. “Given that the IMSBC Code categorizes coal as Group B (“cargoes which possess a chemical hazard which could give rise to a dangerous situation on a ship”), and possibly Group A (“cargoes which may liquefy if shipped at a moisture content in excess of their transportable moisture limit”), and also considering the guidance in the Club’s Loss Prevention Safety Alert Coal Cargoes – Know the Dangers, coal can never be harmless and a better description that could be considered would be “coal that is not liable to emit methane or self-heat”.”