I would like to ask about the method for determining the slope at the bottom of an oil tank
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I have been in the chemical industry for only a short time; I would like to ask about the methods used for constructing the bottom of storage tanks. I found this online: an atlas of dome-shaped oil tanks, using Tank 60 with a capacity of 40 cubic meters and a diameter of 4.2 meters as an example. In the front view of the tank’s diagram, the bottom of the tank has a slope of 15:1000. Since it is a half-section view, the bottom could be conical or have a single slope. Based on the explanations regarding foundations in this atlas, which mention foundation taper, I conclude that the bottom of this tank is conical, with a higher center and a lower bottom around the edges. It is known that the development of a cone’s base is a sector. However, in the top view, there is a B-B cross-section that shows that the bottom plate is formed by overlapping and welding several plates together. In that case, it will not be possible to achieve a conical bottom. Although a slope of 15:1000 is very small, I find it somewhat contradictory the view to be presented in this way. (1) I wonder how such a tank bottom is constructed in practice? Is it the b conical base at the top, or the d single-slope base? (2) Does the conical foundation base also need to have a corresponding taper? (3) Does the foundation for a single-slope base require a slope? A senior in my office said that the foundation is flat, and reinforcement plates are used to support it beneath the base slab; if the diameter is large, I think those reinforcement plates aren’t reliable.
In practice, the foundation of the oil tank consists of an edge ring beam, with asphalt in the middle; the asphalt is shaped to create that slope. The requirements for slope are basically the same as those in the standards. During construction, there is no need to make a cone separately. During the construction of small oil tanks, this slope is not taken into account; once they are in place, they will naturally deform to match the slope. Large storage tanks are constructed on-site; the mid-span plates and edge plates are laid on the foundation in accordance with the process requirements, following the slope! !
Also, for the final single-slope oil tank, there are actually even fewer! I don’t think I’ve encountered it before; those with a single slope are basically square in shape!
The conical shape of the base is intended to ensure that water filling and pressure testing can compact the structure after the oil tank is constructed. So, a slope is created on this basis; there is no need to consider designing the bottom slope of the tank separately.
The correct approach is to use a D structure.