OIL TREATMENT, TRANSPORTATION AND STORAGE

EXERCISE 1 Read and translate the text "Types of storage tanks", using the words after the text.

Types of storage tanks

Every facility involved in the production of petroleum and related products requires some type of storage. Manufacturers also should be consulted for specific design information on a particular type of storage. During the early days of oil production, the method of storing was almost exclusively white-pine wooden tanks, which were followed by cypress tanks, and then redwood tanks. However, because of the constant and steep rise in the cost of redwood lumber and the diminution of skilled erectors required, the installation of new wooden tanks is nearly non-existent. The bolted-steel tank was developed next and replaced the wooden tank.

Bolted-steel tanks

Bolted tanks are designed and furnished as segmental elements assembled on location to provide complete vertical, cylindrical, above-ground, closed and open-top steel storage tanks. Standard API bolted tanks are available in nominal capacities of lOOto lO.OOObbl, and are designed for approximately atmospheric internal pressures. Bolted tanks offer the advantage of being easily transported to desired locations and erected by hand. To meet changing requirements for capacity of storage, bolted tanks can be easily dismantled and re-erected at new locations. If a tank develops a hole from corrosion or becomes damaged, a single sheet or more may be replaced. A complete tank bottom may be replaced in the field without dismantling the tank. Also, a section may be removed from the tank, a new connection installed in the sheet and the section replaced without danger. No special equipment is required for the erection of bolted tanks. These tanks are erected by non-specialized crews using hand tools and usually an impact wrench. Bolted tanks are available with painted, galvanized and special coatings, including factory-baked coatings. Painting on both sides of the sheets during fabrication gives the inside of the tank some corrosion protection. Galvanizing the sheets and all tank parts by the "hot-dip" process or applying a factory-baked coating affords high corrosion protection. Generally, bolted tanks are fabricated from 12- or 10-gauge steel, and if not galvanized or furnished with a protective coating for corrosion protection, they do not have the expected life of the welded - steel tanks, which are usually constructed of heavier steel.