Today we will take you to learn the classification, characteristics and installation methods of oil storage tanks.

Classification of storage tanks
Due to different storage media, the form of the storage tank is also varied.

Classified by location: It can be divided into above-ground storage tank, underground storage tank, semi-underground storage tank, offshore storage tank, subsea storage tank, etc.
Classified by oil type: it can be divided into crude oil storage tank, fuel oil storage tank, lubricating oil storage tank, edible oil storage tank, fire protection water storage tank, etc.
Classified by use: it can be divided into storage tanks for production, oil storage tanks, etc.
Classified by form: it can be divided into vertical storage tank, horizontal storage tank, etc.
Classified by structure: it can be divided into fixed roof storage tank, floating roof storage tank, spherical storage tank, etc.
Classified by size: large storage tanks above 100m3 are mostly vertical storage tanks; small storage tanks below 100m3 are mostly horizontal storage tanks.

Characteristics of storage tank

Steel storage tank
Steel storage tank is a container welded with steel plate material. The plate used for ordinary metal oil storage tanks is an rimming steel code-named A3F for open hearth; open hearth killed steel A3 is used in cold areas; for large volume oil tanks over 10000m3, low alloy steel with high strength is used.

Common steel storage tank is generally vertical cylindrical, horizontal cylindrical, spherical, etc. According to the structure of the roof, vertical cylindrical storage tanks can be divided into truss roof tanks, roof tanks without torque, beam-column roof tanks, vault roof tanks, sleeve tanks and floating roof tanks, among which the most commonly used is the vault roof tanks and floating roof tanks.

The vault storage tank has a relatively simple structure and is commonly used to store raw oil, refined oil and aromatic products. Floating roof tanks are divided into inner floating roof tanks and outer floating roof tanks. At present, the internal floating roof tank is widely used at home and abroad to store volatile light oil products, and is a popularized storage tank.

Vault storage tank
The vault storage tank refers to a steel container with a spherical crown and a cylindrical tank body. The vaulted storage tank is simple to manufacture and inexpensive, so it is the most widely used in many industries at home and abroad, with the most commonly used volume being 1000-10000m3.

Inner floating roof storage tank
The inner floating roof storage tank is formed by adding a floating roof inside a fixed vault storage tank. The addition of a floating roof that rises and falls with the oil surface in the tank can reduce the volatile loss of the medium. And because the inner floating roof effectively isolates the medium, that is, the material stored in the tank from the air, it also reduces the danger level of fire and explosion to a certain extent. The external vault can prevent rainwater, snow and dust from entering the tank, ensuring that the medium in the tank is clean.

This storage tank is mainly used to store light oil, such as gasoline, aviation kerosene. The inner floating roof storage tank adopts linear tank walls, butt welded wall panels, and the vault is made according to the requirements of the vault storage tank.

Outer floating roof storage tank
The outer floating roof storage tank is composed of a floating roof floating on the surface of the medium and a vertical cylindrical tank wall. The floating roof rises and falls with the increase or decrease of the medium storage in the tank. There is an annular sealing device between the outer edge of the floating roof and the tank wall. The medium in the tank is always directly covered by the inner floating roof to reduce medium volatilization.

Outer floating roof tanks are commonly found in large (at least 10000m³ or more) crude oil, fuel oil, and heavy oil storage tanks.

Horizontal cylindrical storage tank
Horizontal cylindrical oil storage tanks are also widely used. Because it has the ability to withstand higher positive pressure and negative pressure, it is helpful to reduce the evaporation loss of oil products and also reduce the risk of fire. It can be manufactured in batches in machinery and then shipped to the construction site for installation, which is easy to move and demolish, and has good mobility.

The disadvantage is that the capacity is generally small, the quantity used is large, and the floor space is large. It is suitable for small distribution oil depots, rural oil depots, urban gas stations, army field oil depots, or enterprise oil depots. It is also used as an auxiliary storage tank in large oil depots, such as blow tank and metering tank.

Spherical storage tank
Spherical storage tank has the characteristics of pressure resistance and material saving. It is mostly used in liquefied petroleum systems and also used as solvent storage tanks with higher pressure.

Non-metallic storage tank
There are many types of non-metallic oil storage tanks, including clay oil tanks, brick oil tanks, stone oil tanks, reinforced concrete oil tanks, FRP oil tanks, oil-resistant rubber oil tanks, and so on.

Stone oil tanks and brick oil tanks are widely used, and are often used to store crude oil and heavy oil. The striking advantages of this type storage tank are steel saving, good corrosion resistance and long service life. The non-metallic material has a small thermal conductivity. When storing crude oil or light oil, the temperature change in the tank is small, which can reduce evaporation loss and reduce the risk of fire.

And because non-metallic tanks generally have greater rigidity and can withstand greater external pressure, it is suitable for underground or semi-underground oil storage tanks, which is conducive to concealment and heat preservation. However, once the foundation sinks, it is easy to rupture the oil tank and difficult to repair. Another major drawback is its leakage. Although it has been treated with anti-seepage before use, the anti-seepage technology has not yet been completely feasible.

Underground storage tank
Underground oil storage tank refers to an oil tank with the highest oil level in the tank lower than the lowest elevation of the adjacent area by 0.2m, and the thickness of the soil on the top of the tank not less than 0.5m. This type of oil tank has low loss and low fire risk.

Semi-underground storage tank
Semi-underground storage tank refers to an oil tank whose burial depth exceeds half of the tank height, and the highest oil level in the oil tank is not higher than the lowest elevation of the adjacent area by 2m.

Above-ground storage tank
The above-ground storage tank refers to a storage tank whose foundation is higher than or equal to the lowest elevation of the adjacent area, or a storage tank whose buried depth is less than half of its height.

The above-ground storage tank is a common type of oil tank in the current oil refining enterprises. It is easy to construct, convenient to manage and maintain, but it has a large evaporation loss and a large fire risk.
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