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MARINE | Safe carriage of coal In association with Hawkins Group
Gas monitoring and ventilation key in coal transport
Paul Willis, fire and explosion investigator at Hawkins Group, the UK-based forensic investigations company, explains how to safely carry coal in a marine context When transported or stored in bulk, coal can be hazardous because it can: > Create a flammable atmosphere; > Self-heat; > Deplete the oxygen concentration; and, > Corrode steel structures. All of these properties are especially hazardous in a marine context and as such the International Maritime Organisation (IMO) Solid Bulk Cargos (IMSBC) Code provides specific guidance for ship owners and masters on the safe carriage of coal. Central to the code and the safe carriage of coal is regular and reliable monitoring of the gas within the cargo holds and surrounding spaces. The IMSBC code requires that vessels transporting bulk coal should carry appropriate instruments for remotely measuring the methane, oxygen and carbon monoxide concentrations within a cargo space, i.e. without requiring entry into the cargo space. The code The Marine Insurer | March 2022
also requires the ship to carry equipment to measure the ph of cargo space bilge samples.
GAS DETECTING EQUIPMENT
At Hawkins, we use a range of detection and monitoring equipment, the most popular and modern of which is the Draeger X-AM 8000. However, it is expensive both to purchase and maintain. Therefore, the devices commonly used on most coal carrying ships are the less expensive handheld gas detectors, similar to the BW Gas Alert Max XT II, (picturedon page 00.) The sensors employed by these gas detectors are fitted into the body of the device and the gases are sampled either by diffusion or through a flexible tube and a length of spark-proof metal tubing fitted with a collar. The metal tubing is to make inserting the tube into the gas sample port as easy as possible. The collar is to seal the port opening against the tube to reduce the risk of erroneous readings. Often a damp rag is used rather than the collar to seal the tube into the sample port. Correct insertion of the tube is important to enable a representative sample to be obtained from the cargo hold. Ideally, the gas detector and/or the tube should incorporate an in-line particle and water contamination filter to prevent damage to the sensors. In accordance with the IMSBC Code, the gas detector used when transporting coal must be fitted with at least oxygen (O2), flammable gas (LEL), and carbon monoxide (CO) sensors. Most of the modern handheld devices will also include a hydrogen
