AO - Oiler / Tanker
A tanker is a general term for bulk liquid cargo ships such as oils, liquefied gases, and liquid chemicals. The oil tanker include product oil tankers and crude oil ship. The former have a tonnage of less than 110,000 tons, and the latter have a tonnage of 500,000 tons, which is called a Very Large Crude Carrier (VLCC). Most oil tankers are tail-type, single-deck, single-layer bottom. In order to prevent pollution to the sea, the newly built marine oil tankers are all made double-shell to avoid leakage and pollute the ocean.
A tanker is a vessel that specializes in carrying petroleum liquid cargo. It is easily distinguished from the average dry cargo ship in appearance and arrangement. The superstructure and engine room of the tanker are located at the crotch, and the longitudinal section of the upper deck is arranged with oil pipelines and step bridges that run through the entire ship. The oil is housed in oil-tight tanks. The tanker is transported by oil pumps and pipelines when loading and unloading oil. Therefore, it does not require lifting booms and cargo lifters, and large cargo tank openings are not required on the deck.
The oil tank of the oil tanker is equipped with a steam heating pipeline. When the temperature is low, the viscosity of the oil increases, and it is not easy to flow. With the heating oil in the heating chamber, the oil can flow and facilitate loading and unloading. The nacelle of the tanker is located at the stern, which avoids the risk of explosion of the shaft tunnel and the explosion of combustible gas caused by the slurry shaft passing through the oil tank. In addition, the cabin is located in the crotch, and the Mars brought out by the chimney is blown away backwards, and does not fall into the snorkel of the oil tank and cause a fire. The hull structure of the tanker is usually a single-deck, single-story low-rise structure, but there are also oil tankers with double bottom structure. The tanker has a small freeboard and is close to the water when it is fully loaded.
Early oil was transported in barrels from ordinary dry cargo ships. In 1886, the British "Good Luck" sailboat was built to divide the cargo compartment into a number of long square cabins, which could hold 2,307 tons of oil. This marine pump and piping system is the first bulk tanker with the characteristics of a modern tanker. To 1914, the world's tanker tonnage of the world merchant shipping gross tonnage accounted for 3%. After the Great War, with the rapid growth of oil production and transportation volume, the oil tanker has become a special special transport ship with specialization and large-scale development. At the beginning of 1980, the total load capacity of the world oil tankers reached 330 million tons. However, since 1975, due to the oil crisis, the excess tanker transportation capacity has exceeded 100 million tons. A large number of oil tankers have been idle, and the growth rate of tanker tonnage has stagnated or even declined.
With the development of the petrochemical industry, the transportation of crude oil and refined oil tends to be specialized, and special crude oil carriers and product oil tankers appear. In terms of crude oil transportation, in order to overcome the weakness of one-way transportation economic benefits, in the late 1950s, a variety of dual-use vessels capable of transporting oil and other bulk cargoes appeared. With the development of the port of single point mooring technology, large crude carriers must as far as possible under the channel conditions permit, in order to achieve greater economic efficiency.
During the closure of the Suez Canal from 1967 to 1975, the transportation of crude oil from the Persian Gulf to Europe and the United States had to bypass the Cape of Good Hope and promoted the enlargement of crude oil ships. In 1980 the world tanker fleet constitution VLCC (load 20 tons or more) and large oil tankers (carrying 30 tons or more) tonnage exceeded a majority. In the late 1970s, there were large oil tankers of more than 500,000 tons, such as the 550,000- ton sister ship "Batirus" and "Bella Meiya" built in France from 1976 to 1977. In 1980, Japan converted a 420,000- ton oil tanker into a "sea giant", the total length of 458.54 meters long, with a width of 68.8 meters, a depth of 29.8 meters, a draft of 24.6 meters and a carrying capacity of 560,000 tons. It was the largest ship in the world. With the reopening of the Suez Canal and the adoption of energy-saving measures by various countries, there has been a large surplus of giant oil tankers, and the process of large-scale crude oil ships has been terminated.
Due to the quantity of goods and the conditions of the port and refinery equipment, the product tanker generally has a load capacity of 20,000 to 40,000 tons and a maximum of 70,000 tons. Due to the variety of refined oil products, it is not suitable for mixing. There are more independent loading and unloading oil pumps and piping systems on the product oil tankers.
Oil is a fluid that is easy to volatilize, burn, and explode. Therefore, the tanker has the specific characteristics in terms of construction, equipment, and operation. The fire safety requirements are strict. Intergovernmental Maritime Consultative Organization (now changed to the International Maritime Organization) 1978 provisions of the Protocol, new tankers shall have an inert gas explosion-proof facilities; cargo or oil and gas in order to avoid leakage of the cargo tanks with the first There shall be a compartment between the tip tank, the engine room and the pump room; the engine room shall be located at the rear to prevent fire caused by the falling of the chimney to the cargo tank area.
Special oil pump and oil pipe are used for loading and unloading, and all cargo oil can be loaded and unloaded in a few hours to one night; in order to facilitate the unloading of bilge residual oil, a sweeping pipe system is provided; in order to reduce the viscosity of heavy cargo oil for loading and unloading There is a heating pipe system; there is generally no lifting equipment and large cargo hatches on the deck. When the full load is sailing, the freeboard is very small and the deck is easy to go up. Therefore, step bridges are often built on the deck to facilitate the crew. ? hull length to depth ratio, the bending moment is large, so the use of multiple longitudinal framing structure, to increase the longitudinal strength.
Transportation is usually unidirectional, and a certain amount of ballast water must be loaded to maintain a certain amount of draught when the return is empty. If the oily ballast water is discharged into the sea before reaching the loading port, it will cause serious pollution. To this end, the tanks must be washed before ballasting and the washing water should be stored in a special slop tank; at the same time, a water separator should be provided to strictly control the oil content of the discharged ballast water. Effective in October 1983 the International Convention for the Prevention of Pollution from Ships in 1973 requires new crude oil carriers with a capacity of more than 20,000 tons and oil tankers with a capacity of more than 30,000 tons to be equipped with special ballast tanks. New tankers must be equipped with crude oil washing equipment.
|Join the GlobalSecurity.org mailing list|