The cargo tankers carry is often flammable, very highly toxic and corrosive – in short, it can be very dangerous to human health. At times, the cargo is so dangerous that if a seaman was exposed to carcinogenic cargo while on the tanker, there is a real risk of contracting leukemia.
Chemical tankers carry what is known as “liquid bulk”, which ply on routes all across the world – from the US to Japan, from the major oil producing area, the Persian Gulf, to an Asian route that encompasses Taiwan, Indonesia and Singapore because “they are all oil consuming countries.”
Tanker Sections Prone to Danger
According to the United Nations International Maritime Organisation, every year there are approximately 100 deaths on tankers, all of which occurred in the enclosed space of the cargo area.
Rather than the dramatic explosions on tankers occasionally documented by the media, it is the cargo area that poses the greatest risk to life on a tanker. Cargo area, which on average holds about 30,000 tonnes of chemicals, is absolutely prohibited until the cargo itself has been emptied.
The cargo area lacks natural light and has depleted oxygen levels – sometimes to the point where fainting is a likelihood. The Safety of Life at Sea Convention of 1974 (known as SOLAS) requires that a wide variety of personal protective equipment must be on onboard. There are also different types of firefighting equipment.
In order to eliminate the risk of fire and explosion on a tanker, it is necessary to prevent a source of ignition and a flammable atmosphere being present in the same place at the same time. It is not always possible to exclude both these factors simultaneously and precautions are therefore directed towards excluding or controlling one of them.
In the case of cargo compartments, pump rooms, and tank deck, flammable gases are to be expected and the strict elimination of all possible sources of ignition in these locations is essential. Cabins, galleys and other areas within the accommodation block inevitably contain ignition sources such as electrical equipment, matches and/or electric cigarette lighters.
Dangers at Berthing
When a tanker is at a berth, it is possible that an area in the tanker that is regarded as safe may fall within one of the hazardous zones of the terminal. If such a situation should arise, and, if the area in question contains unapproved electrical equipment, then such equipment may have to be isolated whilst the tanker is berthing. During cargo, bunkering, ballasting, tank cleaning, gas freeing, purging or inerting operations, all unapproved electrical equipment should be isolated.
While it is sound practice to minimise and control such sources of ignition, for example by designation of approved smoking rooms, it is essential to avoid the entry of flammable gas.
In a tanker, certain areas/spaces are defined by international convention, flag administrations, legislation and classification societies as being dangerous/hazardous for the installation or use of electrical equipment either at all times or during specific periods such as loading, ballasting, tank cleaning or gas freeing operations.
Air Pressure & Residual Fuels
Air intakes must be set to ensure that the atmospheric pressure inside the accommodation is greater than that of the external atmosphere. In engine and boiler rooms, ignition sources such as those arising from boiler operations and electrical equipment cannot be avoided. It is essential, therefore, to prevent the entry of flammable gases into such compartments. Residual fuel oils and gas oils may present a flammability hazard and the routine checking of bunker spaces for flammability by tanker and terminal personnel is to be encouraged.
It is possible, by good design and operational practice, for both flammable gases and ignition sources to be safely controlled in deck workshops, store rooms, dry cargo holds etc. However, the means for such control must be rigorously maintained and may be subjected to local regulation.
Consequence of a Fire, the Reality
Fire on board a ship is one of the most serious risks for property and persons, as well as for the surrounding environment. A ship is evidently subject to the same risks with regard to fire as a civil or industrial land structure. On board ship, there are tonnes of liquid fuel, electrical equipment, air-conditioning plants, engines, boilers, stores of flammable material and crew accommodation areas (kitchens, mess rooms, lounges, cabins, WCs). To all this, we must add the load, which in cargo vessels consists of a high percentage of solid and liquid goods that are flammable or at least combustible, and often of a dangerous nature.
A ship, however, by its very nature, is bound to spend the greatest part of its working life at sea. In the event of a fire, difficulties related to the meteorological and maritime environment coexist with the need to cope with the emergency. The limited space and possibility of immediate assistance in terms of personnel or facilities, makes the job to combat the fire and to assist casualties even more difficult.
Thus, in the case of tankers, every precaution must be exercised to ensure proper handling of cargo and awareness of the dangers therein.
Sea News Feature, January 8