What are the classification and structural characteristics of storage tanks？

Storage tanks are used to store extracted chemicals such as acids, bases, alcohols, gases, and liquids. Storage tanks are widely used in North China, including polyethylene tanks, polypropylene tanks, fiberglass tanks, ceramic tanks, rubber tanks, stainless steel tanks, etc.

In terms of cost-effectiveness of storage tanks, steel lined polyethylene storage tanks are now superior, with excellent corrosion resistance, high strength, long service life, etc. The appearance can be manufactured in various types such as vertical, horizontal, transportation, and mixing.

Steel sealed containers used for storing liquids or gases are called steel storage tanks. Steel storage tank engineering is an essential and important infrastructure in industries such as petroleum, chemical, grain and oil, food, fire protection, transportation, metallurgy, and national defense. Our economic life always relies on steel storage tanks of all sizes, and the important role played by steel storage tanks in the development of the national economy is irreplaceable. With the continuous development of the storage tank industry, more and more industries and enterprises are using storage tanks, and more and more enterprises are entering the storage tank industry. Steel storage tanks are specialized equipment for storing various liquid (or gas) raw materials and finished products. For many enterprises, normal production cannot be achieved without storage tanks, especially for strategic material reserves, which cannot do without various capacities and types of storage tanks. Our country's oil storage facilities are mainly composed of above ground storage tanks, and are mostly made of metal structures.

Due to the different storage media, there are also various forms of storage tanks.

Classified by location: can be divided into aboveground storage tanks, underground storage tanks, semi underground storage tanks, offshore storage tanks, underwater storage tanks, etc.

Classified by oil products: can be divided into crude oil storage tanks, fuel oil storage tanks, lubricating oil tanks, edible oil tanks, fire water tanks, etc.

Classified by purpose: can be divided into production oil tanks, storage oil tanks, etc.

Classified by form: can be divided into vertical storage tanks, horizontal storage tanks, etc.

Classified by structure: can be divided into fixed roof storage tanks, floating roof storage tanks, spherical storage tanks, etc.

Classified by size: Large storage tanks above 50m3 are mostly vertical tanks; Storage tanks below 50m3 are small and mostly horizontal.

According to the material of the storage tank: The materials required for storage tank engineering are divided into tank body materials and ancillary facility materials. Tank materials can be divided into low strength steel and high strength steel according to their tensile yield strength or tensile standard strength. High strength steel is mostly used for storage tanks with a capacity of over 5000m3; The ancillary facilities (including wind resistant ring beams, locking ports, spiral ladders, guardrails, etc.) are made of ordinary carbon structural steel with lower strength, while other accessories and attachments are made of other materials according to different purposes. The commonly used domestic steel for manufacturing tanks includes 20, 20R, 16Mn, 16MnR, and Q235 series.

The widely used and mature production and installation technologies in China are arch roof storage tanks, floating roof storage tanks, and horizontal storage tanks.

Vaulted

A dome shaped storage tank refers to a steel container with a spherical crown on the top and a cylindrical body. Dome shaped storage tanks are easy to manufacture and cost-effective, so they are widely used in many industries both domestically and internationally. The commonly used capacity is 1000-10000m3, and the capacity of dome shaped storage tanks in China has reached 30000m3.

Bottom of the tank: The bottom of the tank is assembled from steel plates, with the steel plate in the middle being the center plate and the surrounding steel plates being the edge plates. The edge board can be made of strip board or bow board. In general, when the inner diameter of the storage tank is less than 16.5m, strip edge plates should be used, and when the inner diameter of the storage tank is ≥ 16.5m, bow edge plates should be used.

Tank wall: The tank wall is composed of multiple rings of steel plates welded together, divided into sleeve type and straight type.

The circumferential welds of the sleeve type tank wall panel are overlapped, and the longitudinal welds are butt welded. This form is commonly used for arch top storage tanks, which has the advantage of being easy to assemble the wall panels of each ring, and the use of inverted construction method is relatively safe.

The circumferential weld seam of the straight tank wall panel is butt joint. The advantage is that the overall diameter of the tank wall is the same from top to bottom, which is particularly suitable for internal floating roof storage tanks, but the installation requirements are high and the difficulty is also high.

Tank roof: The tank roof has multiple fan-shaped plates welded together to form a spherical crown. The inner side of the tank roof is reinforced with flat steel bars, and the fan-shaped plates are overlapped with each other through welding seams. The entire tank roof is welded together with the angle steel ring (or lock mouth) on the upper part of the tank wall panel.

Floating roof type

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

Bottom of the tank: Floating roof tanks generally have a relatively large volume, and their bottom plates are made of arched edge plates.

Tank Wall: Linear tank wall is used, and the butt welds should be polished smooth with a flat inner surface. The upper part of the floating roof storage tank is open. In order to increase the stiffness of the wall panel, wind resistant ring beams and reinforcement rings should be installed at the top of the tank wall according to the wind load in the area.

Floating roof: Floating roofs are divided into single disc floating roofs, double disc floating roofs, and float type floating roofs.

Single disc floating roof: a circular floating vessel composed of several independent compartments, with a single disc top plate on the inner side of the ring. The bottom of the single disc top plate is reinforced with multiple circular steel rings. Its advantages are low cost and easy maintenance.

Double disc floating roof: composed of upper plate, lower plate, and cabin edge plate, separated into several independent annular cabins by radial and circumferential partitions. Its advantages are high buoyancy and good drainage effect.

Internal floating roof type

An internal floating roof storage tank is formed by adding a floating roof inside a dome roof storage tank. Adding a floating roof inside the tank can reduce the volatilization loss of the medium, while the external dome roof can prevent rainwater, snow, dust, etc. from entering the tank, ensuring the cleanliness of the medium inside the tank. This type of storage tank is mainly used for storing light oils, such as gasoline, aviation kerosene, etc. The inner floating roof storage tank adopts a straight tank wall, with wall panels welded together, and the arch crown made according to the requirements of the arch top storage tank. There are two types of internal floating roofs in China: one is a steel floating roof that is the same as the floating roof storage tank; Another type is an assembled aluminum alloy floating roof.

horizontal

The volume of horizontal storage tanks is generally less than 100m3 and is usually used in production processes or gas stations. Horizontal storage tanks use lap joints for circumferential welds and butt joints for longitudinal welds. Arrange the circular plates in an interactive manner, taking odd numbers to ensure that the end caps have the same diameter. The end caps of horizontal storage tanks are divided into flat end caps and disc-shaped end caps. Flat end cap horizontal storage tanks can withstand an internal pressure of 40kPa, while disc-shaped end cap horizontal storage tanks can withstand an internal pressure of 0.2Mpa. Underground horizontal storage tanks must be equipped with reinforcement rings, which are also made by bending angle steel.