201625 Hot and bothered coal
Edited from UK P&I Club checklist ‘How To Monitor Coal Cargoes From Indonesia’
Self-heating incidents involving coal cargoes loaded at Indonesian ports have become more frequent in recent years. The problem appears to be related principally to the nature of the coals, and it may be exacerbated by the way they are handled before and during loading. Recommendations for the safe carriage of coal are contained in Appendix 1 of the IMSBC Code (the Code), which became mandatory worldwide on 1 January 2011.
The extensive lessons learned and best practices from recent experience are set out below.
Prior to loading
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Documentation |
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| Coal must be declared either as Group B or as Group A and B. Check that the shipper has not used outdated classifications such as ‘Category A’ when describing the cargo. | |
| If the shipper declares a value for the TML (Group A cargo) check that additional certification as required by the Code is supplied including recent (less than seven days) representative cargo moisture content analysis. | |
| Consider all coal loaded in Indonesia as having the potential to self-heat, irrespective of the wording of the shipper’s declaration. | |
| Hold preparation | |
| All cargo spaces and bilge wells should be clean and dry. | |
| All residues of waste material or previous cargo should be removed. | |
| All electrical cables and components in cargo spaces and adjacent enclosed spaces to be free from defects. | |
| Such cables and components mentioned above to be safe for use in an explosive atmosphere or positively isolated. | |
| Vessel instrumentation | |
| Equipment to measure methane, oxygen and carbon monoxide in the hold atmospheres without entering the cargo space. | |
| Equipment to measure pH value of cargo space bilge samples. | |
| It is recommended that there should be a means of measuring the temperature of the cargo while it is being loaded and during the voyage. | |
| Temperature monitoring | |
| Temperature of the cargo to be monitored prior to loading. Look for ‘hot spots’. | |
| Any cargo at a temperature in excess of 55°C should not be loaded. | |
| Coal cargoes delivered to anchorage in barges may be particularly susceptible to self-heating as they are exposed to the wind. | |
| Shippers and surveyors may quote an ‘average temperature’ measurement in relation to a barge cargo in order to establish a value below 55°C. The Code does not recognise this methodology. |
During loading
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Temperature monitoring |
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Monitor the temperature of the cargo regularly during loading, not just when the first barge arrives. The cargo is likely to be hotter towards the bottom of the stow in the barge. |
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Reject any cargo at a temperature in excess of 55°C. |
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Do not stow cargo adjacent to hot areas. |
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Ingress of air |
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Employ ‘soft loading’ as much as possible. |
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As cargo in partially filled holds will be exposed to ingress of air, avoid undue delays when loading. |
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If delays occur, close partially filled holds and do not ventilate. |
After loading
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Trimming |
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Trim the cargo as level as possible to the boundaries of the cargo spaces. |
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Shippers may resist requests to trim properly, but insist that they do so. |
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Cargo monitoring |
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Close and seal the holds immediately after loading in accordance with the Code recommendations for self-heating coals. |
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Begin monitoring of the hold atmospheres for methane, carbon monoxide and oxygen immediately, recording the results and the time they were obtained. |
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Gas monitoring to be done through proper fittings in the holds as described in the Code, not through open accesses or covers. |
During the voyage
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Cargo monitoring |
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Monitor the hold atmospheres for methane, carbon monoxide and oxygen at least once a day; more frequently if the carbon monoxide and/or methane concentrations begin to rise steadily. Maintain a record of these measurements. |
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A reduction of the oxygen concentration in a well-sealed hold is to be expected. |
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Below an oxygen concentration of about 10%, most instruments in common use will not provide reliable readings of the methane % lower explosive limit (LEL). (Check your instrument manufacturer’s recommendations on the use of a ‘splitter’ at low oxygen levels and/or seek expert advice if there is cause for concern.) |
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Temperatures measured by lowering thermometers into sounding pipes should not be relied upon, as this method will only detect heating coal in the immediate vicinity and will not provide information on the bulk of the cargo. |
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If methane in excess of 20% of the LEL is detected use surface ventilation in accordance with the Code, but only for the minimum time necessary to remove the methane. If this concentration of methane is detected after the oxygen has fallen below 10% seek expert advice before ventilating. |
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If carbon monoxide concentration in a closed cargo hold exceeds 30ppm the Code recommends that the frequency of measurement be increased to twice daily. If the carbon monoxide exceeds 50ppm the Code recommends notifying the owner, who should call for expert advice. With Indonesian coal the carbon monoxide level can be much higher than these values without indicating the presence of self-heating, but the owner should still be notified (in accordance with the Code) particularly if the gas concentration continues to rise steadily for three consecutive days. |