Questions regarding the construction methods for on-site manufacturing of storage tanks
Thread Content
Dear sea friends, what are the advantages and disadvantages of the inverted and upright construction methods for on-site manufacturing of storage tanks? What are the respective applicable conditions? Last year, I was involved in 5 storage tanks with a capacity of 2,000 cubic meters, using water as the medium; all of them were constructed in an inverted configuration. Is there any difference in the inspection points for this method compared to the upright construction method? Who has records of inspection stop points? Please share them, thanks! ! :P
The last edit to this post was made by coolidge11 on 2016-8-13 at 13:30. The installation method in which the tank wall panels are assembled one by one starting from the bottom ring, section by section upward until the entire tank is installed, is called the normal installation method. Conversely, using the bottom of the tank as the reference plane, the top ring wall panels are installed first; thereafter, the already installed panels are lifted (or raised) to create space for assembling the lower ring wall panels. Once the lower ring wall panels have been installed, the connected panels are raised upward, and this process is continued until all the bottom ring wall panels are in place. This construction method is known as the reverse installation method. Advantages of the regular welding method: it allows for full utilization of large lifting equipment, enables greater prefabrication depth, is easy to master, facilitates the adoption of automatic welding techniques for storage tanks, and is suitable for floating roof tanks with a capacity of 50,000 to 100,000 m3. Disadvantages: Requires a large construction site, involves high technical difficulty, involves a lot of work at heights, and is unsafe. Inverted construction methods include central column inverted construction, air lift inverted construction, hydraulic lift inverted construction, etc. Inverted construction method has the following advantages: (1) Fast construction speed, high work efficiency, and easy quality control. (2) It eliminates the need for work at heights and scaffolding; it allows for larger construction areas and is safer. (3) The required lifting equipment and construction tools are relatively simple. Based on my personal experience, I have been involved in the installation of 14 3000 m3 tanks, 2 5000 m3 tanks, 6 20000 m3 tanks, and 2 10000 m3 tanks. Among them, 6 storage tanks with a capacity of 20,000 m3 and 2 tanks with a capacity of 10,000 m3 are external floating roof tanks, while the rest are internal floating roof tanks (arched roof tanks). Out of the 6 storage tanks with a capacity of 20,000 m3, 4 are installed in an upright position, while the remaining tanks are installed in an inverted position. Generally, the inverted method is more commonly used for tanks of 20,000 m3 and below. The vertical method allows for effective use of automatic welding machines, but it is highly affected by wind conditions; welding at the top is dangerous when the wind is strong (for vertical automatic welding machines mounted on the tank wall). Another potential issue with the upright installation method is that, in strong winds, the storage tank cannot be lifted together with the wall panels as it can be in the inverted installation method, due to the wind-resistant ring; this poses a risk of the tank being flattened by the wind.