Atmosphere evaluation of any cargo tanks or enclosed spaces on-board a carrier is highly necessary as it contains harmful and hazardous substances. These cargoes while transport can react to the tank atmospheric components to cause catastrophic disasters.
FREMONT, CA: Merchant ships are broadly categorized depending on the type of cargo they are transporting. The two primary divisions of cargo ships are dry ships—comprising of containers, general cargo, and bulk carriers. The tanker ships or wet ships are those which transport oil and chemical tankers, gas carriers, which carry the hazardous cargo in liquid, vapor, or solid states.
The cargo carried in the tankers is highly reactive and hazardous as compared to that carried by dry ships. Therefore, it is imperative that the tanks which carry sensitive cargo are of approved classes. The approvals are granted when the tanks comply with the requirements stated by different codes of safety such as IGC, IBC, and IMDG.
Under any circumstances the cargo tank or any enclosed space on-board the ship needs to be evaluated. The tests ensure that the particular area is gas-free and contains a sufficient amount of oxygen for personnel to work in the area if required. Several reasons contribute to the tank atmosphere, and due to these factors, it is necessary to evaluate well ahead to prevent any mishaps in the middle of the sea.
The atmosphere in the internal cargo spaces of tanker ships can be either one or a combination of the factors. Flammability is a primary risk factor when it comes to the handling of oil and petroleum cargos; extra attention should be provided while evaluation depending on the volatility of the shipment. If the processing of cargo is much tedious if the toxicity of the substance is recorded high. Chemical shipments which are carried in bulk are usually toxic. The gas generated from oil or petroleum products can also be considered as toxic as they contain harmful substances like HC.
Most chemical cargoes react with water and form toxic vapors or can even damage the cargo equipment or storage tank. Some respond with air and form unstable oxygen compound leading to an explosion. Either way, to be aware of the reactivity of the goods carried is essential. Chemical cargoes when stored together without knowing the reactivity of the substances may result in causing cataclysmic destruction to the carrier.
Importance of Tank Atmosphere Evaluation:
A cargo tank is the most essential and highly dangerous space on-board since it carries cargo worth millions of dollars. These tanks present a high risk of explosion, spillage, fire, health hazard, or disastrous reactions which can occur when unanticipated.
Data for Tank Atmosphere Evaluation:
An evaluation of the cargo or the enclosed spaces in tanker ships is the only right path to obtain accurate statistics. These describe the characteristic composition of the tank atmosphere to conduct the evaluation operations. All the activities require human interference inside the tank hence the crew responsible for conducting these operations must be acquainted with the compositions in the atmosphere of the tank and entry should be made as per SOLAS Regulation XI-1/7.
Measurement of the tank atmosphere is highly essential and even better when carried out at various points to ensure no existence of harmful gases inside. Gases such as hydrocarbons incline to form pockets of flammable gas that remains trapped within layers of the tank even when the other sections of the tank atmosphere is tested regularly.
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