In collaboration with the cargo experts at CWA International, The Swedish Club has produced cargo advice to assist shipowners and operators in the daily operation of their vessels.
- Ensure that ship’s holds are clean to the level required.
- Ensure that temperature and gas measuring equipment as well as the portable breathing apparatus sets meet the requirements of the IMSBC Code. The thermometer should be in the range 0°C to 100°C and capable of measuring the temperature without requiring entry into the cargo space.
- The ship should have at least two gas meters onboard (in case one should fail) with certificates of calibration that will cover the period of the voyage. At a minimum the meters should measure methane (usually in % of Lower Explosive Limit or LEL), carbon monoxide and oxygen. The LEL is the lower limit, below which a mixture of methane and air will not explode. For normal air (21% oxygen) the LEL is 5% methane. Meters usually measure the percentage of LEL with 100% representing 5% methane in air.
- The ship should also carry on board an instrument to measure the pH value of cargo space bilge samples.
- Obtain a Cargo Declaration for Solid Bulk Cargoes from the Shipper. which should state the cargo’s liability to emit methane and/or to self-heat. If the cargo is also Group A, certificates of testing showing the transportable moisture limit (TML) and the actual moisture content of the cargo as loaded should be provided. The TML is the maximum moisture content of the cargo, which is considered safe for carriage. The actual moisture of the cargo should, of course, be less than the declared TML.
- Care should be taken to ensure that no source of ignition is taken into the hold.
- The cargo should not be loaded at a temperature in excess of 55oC. The Master should be vigilant during loading and if there is any sign of smoke or steam coming from the coal, loading should be stopped to investigate.
- Group A cargoes should not be handled during precipitation and all non-working hatches should be closed. Ports of loading in tropical areas are subjec to heavy rain fall and if the coal is transported in the open, a significant amount of water can be added to the cargo. In this case, the Master should be aware that the moisture content of the coal may exceed its TML.
- Trim cargo as reasonably level as possible. This reduces the likelihood of the cargo shifting and minimises the air entering the cargo, which could lead to spontaneous combustion. Using a bulldozer on the surface of the coal in the hold, compacts the surface of the coal and reduces the access of oxygen to the cargo.
- Once the hold is trimmed, hatches should be closed as soon as possible.
Most voyages with coal cargoes will be uneventful, but sometimes things go wrong. The coal may have been mishandled during storage, loading or may contain hot spots. Coal cargoes require constant monitoring to identify any problems at an early stage. Left untreated, hazards can cause serious damage to vessel and crew. If in doubt seek the advice of an expert.
…Swedish club advised.