Coal can self-heat up, can emit explosive gas, corrode the hull, and liquefy. Fully implementing the process, coal will be transported from the loading port to the unloading port safely without causing unfortunate incidents, otherwise the transport can lead to loss of life and serious wealth. Currently, coal production, import, transportation and use are larger than any other period in our country’s development.
STONE CARBON AND ITS PROPERTIES
Coal is formed from dead vegetation, kept about 300 million years ago, through the combination of biochemical and geological processes. One of the difficulties in transporting coal in large quantities is that it is capable of self-heating up to the point of causing an explosion, which often poses a serious challenge for transportation.
Self-heating will start from exothermic reactions leading to an increase in temperature in flammable materials. This occurs when the heat production rate exceeds the heat loss, resulting in increased oxidation speed, the possibility of ignition and fire.
The necessary conditions for self-heating goods to reach ignition include:
– Supply of oxygen available from the air;
– Large cargo surface area, through which oxidation reactions can take place;
– Presence of moisture;
– Insulation makes internal heat impossible to spread.
Like self heating, coal emits methane, a flammable gas with a low explosion limit (LEL) of 4.4% in the air. Explosions occur due to methane ignition in goods, which can lead to damage to ships, injuries and loss of life. Bituminous coal has a low concentration of methane, while Anthracite (antracit) coal can contain several times more.
The shipper should provide the ship with detailed data on safe cargo transport. By ventilating cargo holds, methane concentrations can be reduced to less than LEL. It should be noted that, unfortunately, while ventilating the goods to remove methane, it is also possible to create an opportunity to introduce oxygen into the cargo hold, creating a situation that leads to self-heating. It is important to know exactly the level of carbon monoxide and LEL to make decisions about permissible ventilation levels.
Like all bulk cargoes, SOLAS safety rules for coal transport are provided as follows:
SOLAS REQUIREMENTS AND LAWS IMSBC FOR PROFESSIONAL STONE CARBON
Under SOLAS, coal is defined as dangerous goods in bulk form in bulk.
1. The necessary documents
In all documents relating to the transport of dangerous solid goods in bulk cargo by sea, the bulk cargo shipping must be used correctly.
Each ship carrying dangerous goods in solid and bulk form must have a List / manifest (List / Manifest) of dangerous goods on board and its location. A set of copies of these documents must be provided to the person or organization designated by the Port State Authority before departure.
2. Loading and requirements
Coal loading must be carried out safely and in accordance with the nature of the goods. Because coal can heat or burn itself, it cannot be transported without proper precautions to minimize the possibility of fire.
Coal is a commodity that is transported in accordance with the IMSBC International Code. The law requires shippers to provide cargo details including steam content, sulfur content, particle size, and information on whether the goods have methane emissions. The law also requires the ship to have:
– Oxygen, carbon monoxide and methane measuring instruments
– Gas sampling tubes on all cargo holds
– A measuring instrument for pH values of water samples
On the other hand, the IMSBC Code recommends that ships have tools to measure cargo temperatures, both during loading and on the journey, such as infrared thermometers.
The IMSBC Code also recommends that coal should not be placed in a cargo hold if its temperature exceeds 55 ° C. After loading, and unless otherwise advised, it is necessary to keep the cargo hold ventilated for the first 24 hours or until when methane concentration is low, such as less than 20% LEL.
Once the goods have been unloaded and the lid is closed, the heating evidence can easily be checked by monitoring the carbon monoxide level. The air in each cargo hold should be monitored daily. If the goods are ventilated to remove methane, ventilation should be stopped at least four hours before sampling. Under the IMSBC Code, if the level of carbon monoxide gas exceeds 50 ppm, or the temperature of the cargo increases steadily for three consecutive days, it indicates that the natural heat increase is taking place, so the Captain should report to the Shipowner. and Shipper. Because coal is a good insulator, hot spots in the cargo can still be detected even if the sailor measures the temperature of the water holes or measures the surface temperature.
Before departing, and during the journey, the Captain must also ensure that:
– Flattened goods to reduce its surface area;
– Must maintain the gas monitoring equipment on board and calibrate in accordance with the manufacturer’s instructions;
– All enclosed spaces beside cargo holds must be monitored regularly and fully ventilated;
– Do not allow people to enter enclosed spaces without prior confirmation that doing so is safe;
– If the goods show different signs from the goods in the declaration, the Captain must report to the Shipper, with his Technical Director and P & I.
If the fire or self-heating proceeds in the cargo hold to a dangerous state, the vessel should:
– Close all ventilation into the cargo hold;
– Start cooling the boundaries of the affected tunnels and consider running to the nearest port for refuge;
– Immediately notify P & I because an emergency response from this organization may be needed including the presence of professionals;
– Ensure that all spaces near the cargo hold are inspected before entering and no one enters the enclosed space without being confirmed that it is safe.
– Provide ship owners and P&I all records of temperature and gas monitoring in the itinerary;
3. Gas detectors and heat measuring devices
The IMSBC Code requires coal transport ships to be equipped with gas detectors, and their crew must be trained to use it. First, the gas detector must be inspected in a free gas area, before entering the enclosed space or taking measurements in the cargo hold. Most gas detectors are equipped with electrolytic sensors to detect flammable gases and are capable of reliably operating in the atmosphere with more than 15% oxygen. When the air is below 10% oxygen, the level of flammability by electrolyte sensor is not reliable. Coal carriers should be equipped with gas detectors with infrared sensors without oxygen to accurately measure flammable gas parameters.
Although the IMSBC Code does not require, having an infrared thermometer can assist seafarers to control the surface of coal before and during loading, to ensure no loading above 55 ° C.
In summary, when transported in large quantities, loose coal has the ability to self-heat, leading to the ignition point. However, most of these freighters will not be exposed to risks when complying with the requirements and recommendations in the IMSBC Code. Using precision gas and temperature detection equipment will provide the information needed to manage safe coal transport. However, to be effective, the detection device must be maintained in good working condition and properly used.
Coal transport vehicles, especially small vehicles running inland short routes 2, 3 days along the coast of Vietnam, also need to pay close attention to the safety of fire and explosion prevention and fighting. Even when the number of coal in the tunnel is not large, the phenomenon of spontaneous heat can also occur. The weather allows the hatch cover to be ventilated, the hot sun can pump water to cool the deck.
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