Oil Storage Tank

an artificial reservoir for the storage of oil or petroleum products. Oil storage tanks may be of the surface, semisubterranean, or subterranean types and may be made of metal or reinforced concrete, or they may be built underground, within rock salt deposits. In the USSR, metal surface tanks and semisubterranean reinforced-concrete reservoirs are most commonly used.

Surface oil storage tanks are usually of welded metal construction. They may be cylindrical (horizontal or vertical), spherical, or teardrop-shaped.

Low-pressure (“atmospheric” type) vertical steel cylindrical tanks are made with a conical or frame-and-panel roof and with a spherical covering. Conical-roofed tanks have a capacity of 100–5,000 cu m and are intended for storing oil and petroleum products with a density of 0.9–1.0 tons per cu m and an internal pressure of 27 kilonewtons per sq m (KN/m²) in the gas space. Panel-roofed tanks range in capacity from 100 to 20,000 cu m and are used for storing petroleum products with a density of up to 0.9 tons per cu m. Tanks with a spherical covering have greater volume (capacities up to 50,000 cu m) and are intended for storing petroleum products with a density of up to 0.9 tons per cu m. Vertical cylindrical tanks with a pressure of 27–93 KN/m² in the internal gas space are among the high-pressure tanks. White petroleum products are stored in specially designed steel tanks with floating steel coverings, synthetic pontoons, floating roof, anticorrosion coating, and thermal insulation.

Spherical tanks are used for storing liquids and liquefied gases. Multiwall tanks are built for the storage of gases under high pressure. Spherical tanks with a capacity of 300–4,000 cu m, designed for pressures of 0.25–1.80 MN/cm², with an inside diameter of 9–20 m and a wall thickness of up to 38 mm, were under construction in the USSR as of 1974. Spherical tanks with a capacity of 600 cu m have become the most widely used type in the USSR.

Semisubterranean oil storage tanks are usually constructed from reinforced concrete and have a capacity of 500–30,000 cu m. They may be cylindrical (cast or with prefabricated wall and roof), rectangular with prefabricated walls and covering, or of the trench type.

Subterranean storage facilities constructed in rock salt deposits at depths of 100 m or more are taking on great importance for interseasonal storage of petroleum products such as gasoline, diesel fuel, and kerosine. Such storage reservoirs are made by leaching the salt with water through boreholes, which are later used for operating the reservoir. The maximum subterranean reservoir capacity in the USSR is 150,000 cu m. The petroleum products are removed from the storage reservoir by injection of a saturated salt solution.

The history of oil storage tanks in Russia is associated with the development of the Baku petroleum industry. In the 17th century, with the increased production of oil in Baku, earthen oil reservoirs (pits) in clayey soils appeared. The first riveted steel tank, designed by V. G. Shukhov and A. V. Bari, was built in 1878. The first welded metal tank in the USSR, with a capacity of 1,000 cu m, was constructed in 1935. This advanced construction method became widely known and later made possible the transition to industrial production of the main parts of tanks. Some oil storage tanks built in the USSR have a capacity of 50,000 cu m. In 1974 work was under way on the development of storage tanks with a capacity of up to 100,000 cu m.

In other countries, in addition to the construction of metal storage tanks with a capacity of up to 100,000 cu m, work is being done on the problem of storing large quantities of oil, petroleum products, and liquefied gases by creating new types of storage facilities using natural and artificial cavities within the earth. The first underground storage facility for liquefied gases was built in artificial workings of rock salt deposits in the USA in 1950. Some storage facilities in salt beds and domes have a capacity of up to 1.5 million cu m. Large storage reservoirs usually consist of several chambers. For example, an underground storage facility in the state of Texas with a capacity of 905,700 cu m has six chambers. There is a tendency toward the construction of large-volume storage facilities with a large number of chambers. Underground isothermal reservoirs for liquefied gases were under construction in 1974. A storage reservoir of this type, with a capacity of about 8,000 cu m, has been built in Montreal, Canada. The depth of oil storage reservoirs constructed in rock salt deposits ranges from 200 to 1,200 m and is determined according to the highest anticipated vapor pressure of the petroleum product or liquefied gas in the reservoir. Therefore, the depth of an underground storage facility is calculated as follows: the depth of placement of the reservoir is increased by 4.5 m for each 100 KN/m² of pressure in the reservoir’s volume.