Reinforced concrete tanks are quite common for petroleum products storage. The following benefits when comparing them with metal tanks are:
- Durability. The reinforced concrete tanks serve 40 to 60 years.
- Metal expenditure for 1 gallon reduces twofold.
- Capability to store sulfur crude oils and oil-products.
- Reduced heat exchange with environment and reduced heat loss during storage of oil and oil-products that require heating.
- Reduction of loss due to petroleum products evaporation 5 – 10 times.
- Fire safety due to burying of tanks.
Penetrating quality and permeability of oil into concrete is generally negligible. Heavy oil fractions have low permeability level, while light fractions have enhanced permeability.
Adding special substances like pumice, aquagel, clay, ferric hydroxide, calcium chloride or sodium into concrete can improve its impermeability and durability.
Round tanks for oil and oil-products storage have most rational shape. This is due to the fact that tank walls are working in a horizontal section for tension and compression. All points of the horizontal section have equal pressure, which is not typical for tanks with other shapes.
Round tanks have smaller surface area and less material is used in comparison with rectangular tanks of the same capacity.
Reinforced concrete tanks coverings are pyramidal, lacunar, girderless, ribbed, dome, and other types of coverings for reinforced concrete tanks. Girderless coverings are most common among monolithic coverings. They are significantly easier to use and save steel. But at the same time they use a lot of concrete. Spatial coverings are more economical than girderless ones, but their production is characterized by great complexity.
The tank walls are designed in keeping with the tank size. Their thickness is determined by calculation. Walls are usually thinner at the top of the tank and thicker at the bottom.
The tank bottom thickness is not less than 8 cm. The bottom inner surface has the gradient of 0.005 in relation to the tank center for sludge removal.