Design, Installation and Application of Large Reticulated Shell Oil Tank

Large reticulated shell storage tank or reticulated shell oil tank is a physical structural form of curved grid structure and bar structure on the top of storage tank. The thin shell structure has reasonable stress. At present, triangular reticulated shell, socket reticulated shell or meridian reticulated shell technology is mainly used to design the top structure of large storage tank, which has large spanning capacity, uniform stress, good stiffness, less material consumption, convenient assembly, safety and reliability, It is an important long-span spatial structure with high safety. Generally, large storage tanks with a diameter of 21-60m or a volume of more than 20000 cubic meters should adopt reticulated shell technology, which has been widely promoted and adopted in the global and domestic petrochemical industry for more than 30 years.

1、 Advantages of large reticulated shell tanks in factory manufacturing and on-site construction:

The storage tank reticulated shell is mainly in the form of single-sided spherical layer, which has many advantages in factory production and on-site installation:

1. All parts are produced in factory and in a standardized way, with good quality, high precision and high efficiency;

2. The on-site construction is convenient and fast, basically without welding, which saves the construction cycle and does not require large lifting equipment;

3. Suitable for large storage tanks with a diameter of 21-60m;

4. The skin plate is laid in herringbone shape, which saves a lot of material costs than the melon skin plate;

5. The installation of reticulated shell roof is applicable to both upside down installation and forward installation of storage tank;

6. The reticulated shell of large storage tank can be installed together with the bottom plate and wall plate of the tank to avoid the safety of high-altitude operation.

2、 Features of steel reticulated shell in large reticulated shell storage tank:

The storage tank reticulated shell is generally applicable to the occasions where the corrosion of storage medium to carbon steel is relatively slight, otherwise, the steel reticulated shell must be subject to anti-corrosion treatment. At home and abroad, the steel latticed shell is mainly used on the top covers of various tanks, and it has the following characteristics:

1. The tank top cover is composed of reticulated shell and top plate. The reticulated shell is used as the stressed component of the top cover, and the top cover plate (skin) is only used as the sealing component. Therefore, the top cover plate can be thinner, which greatly reduces the weight of the top cover plate. The top cover plate is laid on the grid members arranged in a triangle. At the same time, the middle of each triangle member is added with a supporting point of the member, which is not welded with the reticulated shell. Therefore, the roof construction is convenient and the appearance curve is smooth and beautiful.

2. The structure weight is light, and the material saving rate of the storage tank reticulated shell top cover with a diameter of more than 30m is 20%~50% compared with the conventional plate rib structure. With the tank diameter increasing, the material saving is more obvious, which has obvious economic benefits.

3. The steel reticulated shell is connected with the inverted channel steel on the tank wall, which increases the wind resistance of the top tank wall plate.

4. The oil tank accessories on the top cover of the steel latticed shell shall be placed within the triangular grid of the latticed shell. If they collide with the latticed shell members, they shall be offset accordingly.

5. The steel reticulated shell structure can ensure that the top cover structure will not be damaged due to the lack of welding between the top cover and the reticulated shell in the event of an accident. Only the damaged top plate needs to be partially repaired, so the repair is convenient.

3、 Characteristics of aluminum latticed shell in large latticed shell storage tank:

The aluminum alloy materials used for aluminum reticulated shell of storage tank are characterized by light deadweight and corrosion resistance. In Europe and America, aluminum alloy reticulated shell is widely used on the top cover of storage tank with strong corrosion environment to steel. It has the following personality:

1. After the aluminum alloy latticed shell and aluminum alloy top cover are adopted, the structural weight is greatly reduced, and the bearing capacity of tank, pool and its foundation is correspondingly reduced. For example, the aluminum roof with a diameter of 30-60m is 1/4~1/9 of the weight of the steel reticulated shell roof.

2. The aluminum alloy material has good corrosion resistance, so it is unnecessary to conduct anti-corrosion treatment on the top cover of the aluminum reticulated shell, saving the anti-corrosion cost and indirect engineering cost. There is no need for maintenance during the whole service life, which saves a lot of inspection and maintenance costs.

3. The radiant heat reflected by aluminum can reach 95%, so when the aluminum alloy reticulated shell top cover is used on the dome roof tank, the volatilization loss of volatile media can be reduced.

4. The strength of aluminum alloy material at low temperature is higher than that at normal temperature, and it is an ideal material under low temperature working conditions. Therefore, the use of aluminum latticed shell and roof can save additional insulation materials and costs to prevent low-temperature brittleness of materials throughout the service life.

5. After the aluminum alloy latticed shell and top plate are used, the accessories set on the top of the oil tank, such as platform, escalator, light transmission hole, oil measuring hole, column passage device, etc. can also be changed to aluminum alloy materials, and designed and manufactured synchronously with the latticed shell.

6. The aluminum alloy top cover is connected with the inverted channel steel on the tank wall through the transition of the stainless steel support on the reticulated shell, and the sealing connection between aluminum and steel is ensured through the special sealing structure, which also increases the stability of the tank wall plate.

7. The safety of large aluminum latticed shell is relatively high: the safety factor is high, the structure is reasonable, and the aluminum skin can be installed to carry 15 people in a triangular grid; The aluminum cover plate skin of the reticulated shell can not only bear the weight, but also release the overpressure in the tank, which will cause local damage first, effectively protecting the reticulated shell on the tank top and the overall structure of the oil tank from being affected; With good quality and long service life, aluminum latticed shells of large storage tanks at home and abroad for more than 30 years are still in safe use.

4、 Examples of general contracting for the design and construction of our large-scale reticulated shell tanks:

Wuhan Zhongheng Petrochemical Technology has been engaged in the research, design and construction of GB GB50128 American standard API650 storage tank technology for a long time, and has the design capability of large reticulated shell storage tanks, ASME welding capability certification, pressure vessel design and manufacturing license, GC2 pressure pipeline design and installation license, petrochemical equipment and pipeline general contracting qualification, safety production license, international trade import and export certificate and other special qualifications, The design and construction performance of large storage tanks has spread all over the world, including the oil tank farms of East Timor Haila Power Plant, Comodo Power Plant, Southern Power Plant, Ecuador oil tank and demineralized water tank, Venezuela heavy oil tank farm, the overall design and construction of oil storage tank and demineralized water tank of Turkey Power Plant Phase I and II, the design and construction of storage tank of African Niger Armenian Power Plant, etc; Especially for the contract project for the design and construction of 30000m3 heavy oil tank in Venezuela in 2015, we adopted triangular reticulated shell technology for top safety design and general contracting for on-site construction. After three months of overseas on-site construction, we put it into use once and safely put it into use for power generation, which was highly praised by the owner and made important contributions to the development of Venezuela's electric power industry.

(Picture) The working site of 30000 m3 heavy oil storage tank of Venezuela Central Power Plant designed and built by our company in 2015: