Why are gas storage tanks designed to be spherical?
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In the chemical industry, spherical storage tanks are generally used for storing gases such as hydrogen, liquefied gas, and light hydrocarbons. We can provide an explanation from the following aspects. 1. Spherical shapes are suitable for compression; the stress is more evenly distributed in spherical tanks, and under the same wall thickness, spherical shells have the highest load-bearing capacity. 2. The internal pressure of the spherical tank is evenly distributed; there are no concentrated stresses inside the tank, which also contributes to its greater safety. 3. Spherical tanks are safe and reliable. Their welds are of high quality, which reduces the risk of leaks; as a result, they are safer compared to vertical or horizontal storage tanks. Horizontal storage tanks, being pressure vessels, cannot exceed 200 cubic meters in volume, whereas spherical tanks can have a larger volume while remaining safe and reliable. 4. Saving in manufacturing materials: Under the same internal pressure, a spherical shell requires the thinnest wall thickness, which is only 1/2 of that of a cylindrical shell with the same diameter and material ； Under the same volume conditions, a spherical shell has the smallest surface area; its wall thickness is thin and its surface area is minimal, which allows for savings in steel usage during manufacturing. 5. Spherical tanks require less floor space, making them more economical. 6. Compared with other storage tanks, spherical tanks have the largest capacity and can hold more medium for the same surface area. In summary, the spherical tank is the most ideal shape for pressure vessels. However, spherical storage tanks also have some drawbacks; for example, they are difficult to manufacture and require high labor costs. For large spherical tanks, due to transportation constraints, the spherical segments must first be fabricated in the factory before being transported to the site for assembly. Poor construction conditions may result in uncertain quality.
Gas storage tanks are designed to be spherical mainly because a spherical shape allows for even pressure distribution, strong load-bearing capacity, no concentrated stresses inside, fewer welds which reduces the risk of leaks, and thus ensures safety and reliability. At the same time, under the same pressure, it requires the thinnest wall thickness, uses less material, and results in lower manufacturing costs. Furthermore, spherical storage tanks occupy less space, have a large volume, can store more medium, and are more cost-effective. However, spherical storage tanks also have disadvantages, such as being difficult to manufacture, resulting in high labor costs, and being cumbersome to transport and assemble for large-scale tanks. .