TB 37 - Coal Cargoes: self-heating and monitoring of evolved gas
Club inspectors still come across instances where ships’ crew are not familiar with, or have little knowledge of, the recommendations of the IMO Code of Safe Practice for Solid Bulk cargoes (BC Code) 2005
This Code has now been completely reviewed with effect from January 2011 and is now called the
INTERNATIONAL MARITIME SOLID BULK CARGOES (IMSBC) CODE
As with the previous publication the BC Code, the IMSBC Code 2011 gives particular reference to monitoring and measurement of gases associated with the carriage of coal. These gases include Carbon Monoxide(CO), Methane (CH4 ) and Oxygen (O2 ).
In addition a complete new section has been added relating to self unloaders entitled;- Measurement in cargo and self-unloading spaces of gravity fed self-unloading bulk carriers
The following is the relevant Appendix to the IMSBC Code, for reference:
Procedures for gas monitoring of coal cargoes
1.1 Carbon monoxide monitoring, when conducted in accordance with the following procedures, will provide a reliable early indication of self-heating within this cargo. This allows preventive action to be considered without delay. A steady rise in the level of carbon monoxide detected within a cargo space is a conclusive indication that self-heating is taking place.
1.2 All vessels engaged in the carriage of this cargo shall carry on board an instrument for measuring methane, oxygen and carbon monoxide gas concentrations, to enable the monitoring of the atmosphere within the cargo space. This instrument shall be regularly serviced and calibrated in accordance with the manufacturer’s instructions. Care shall be exercised in interpreting methane measurements carried out in the low oxygen concentrations often found in unventilated cargo holds.
The catalytic sensors normally used for the detection of methane rely on the presence of sufficient oxygen for accurate measurement. This phenomenon does not affect the measurement of carbon monoxide, or measurement of methane by infra-red sensor.
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