13.5m diameter API Std 650 SUG III tanks

Foundations and subgrade shall safely carry the weight of the tank API Std 650 SUG III tanks and its contents when the tank is filled with water to the highest level required for a hydrostatic test or other water-loading operations, even though the tank itself may be designed for some lesser density of liquid. However, in cases where the character of the soil justifies it and a competent soil expert advises it, allowance may be made for the relatively short duration and intermittent nature of the water loadings if suitable account is taken of all such loadings that may be expected to occur during the life of the tank, including not only those loadings that are incidental to periodic repetitions of the hydrostatic test in accordance with 7.18 but also water-filling operations for gas-freeing purposes.

All edges of the inner wall of the API 650 petroleum storage tank to be lined or coated must be rounded and flat to a minimum radius of 3mm. The API Std 650 SUG III tanks internal welding seam must be completely sealed welding, with a smooth surface and no air holes, air pockets and local protrusions. Remove welding spatter. As specified in API 650 petroleum storage tank design drawings, the seller must perform additional surface treatment.

Under the condition of static storage without receiving and sending operation, the temperature of gas space, evaporation rate, depth and pressure of vapor in the API Std 650 SUG III tanks will change with the change of temperature and pressure in a day. The oil loss caused by the process of discharging oil vapor and inhaling air gas is called "small breathing" loss, which is also called static storage loss of oil tanks.