Cylindrical steel tanks



Types of steel tanks

Stiffening of membrane of single deck floating roof

Methods of erection

Typical damages of aboveground steel tanks

Inspection of steel tanks

Realized projects of tanks

Typical drawings of tanks


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The tanks are vessels constructed for acceptance, storage, technological possessing and transportation of different liquid and semi fluid products independently on their form, material, situation and construction. The conditions for their exploitation are different. They can be vertical and horizontal, aboveground, semi underground and underground, to carry static and dynamic loads to work under vacuum and over pressure, upon the wind, seismic and temperature influences.
The biggest part from this group engineering facility which are widely used in almost all industrial sectors are the Aboveground Steel Vertical Tanks, which are the sheet constructions with cylindrical form.

View of Aboveground Steel Tanks
View of Aboveground Steel Vertical Tanks

In Bulgaria intensive construction of Aboveground Steel Tanks began in the 60 years of 20th century, and the necessity for such facilities provoked their introduction. So a trend for growing of the total storage tank volume is imposed and developed.
The consequences of this trend have the two connected directions: total increase of the tank construction annually and increase of the single volume V1.  In chronological aspect, the tank construction has the following three periods:

(I)  Formation – tanks have relatively small volumes (V1 ≤ 2000 m3), done according to foreign projects and workshop constructions. This period is from 1900 to 1950 year. Typical representative: steel tank for which is used the German project and delivery and with volume V1 = 1 000 m3, constructed in the Bourgas port in 1917 year.

(II)  Establishment – During the period after 1950, and it can be said that the period ends in 1980. The tanks with considerable volumes have been constructed (V1 = 5 000 50 000 m3), according to our typical or individual projects: of КИПП "Хранпроект" ( for light oil products which volume is V1 ≤ 5000 m3) in 1967 and of НИППИЕС "Енергопроект" (for fuel oil with V1 10000 m3) from 1970. The improvements of the theoretical methods optimization and automation of the tanks projects have been made. The construction of the steel tanks was industrialized through implementing of the facilities for rolls sheets production in  НХК "Бургас" and later in ЗЛМК "Септември". Typical representatives of this period are steel tanks in НХК "Бургас", НХК "Плевен" (now "Плама"), Thermal power plant "София", Thermal power plant "Тр. Костов", Thermal power plant "Пловдив", ОЦ "Земляне", ОЦ "Люлин" and different production plants in our country ( Stara Zagora, Bourgas, Sliven, Iliantzi etc.) with volume up to 10 000 m3 – with roll method of erection, and from 15000 m3 to 50 000 m3 – sheet by sheet  technology  for  erection.

(III) Technical inspection, repairing works and reconstruction – The extreme values of two trends in tank construction in our country(MAX VΣ and MAX V1) are reached in the period between 1975 – 1979. On the other part the period of use of the steel tank is accepted to be B = 25 years. Obviously we are in the period in which the normal term for exploitation of the steel tanks is expiring or even is expired.
So the next period must be the period of the intensive and responsible technical inspection, repairing and reconstruction of steel tanks in our country.