Closed- and open top API standard 650 liquid-storage tanks

The inner and outer tanks may be decoupled for seismic design of the tank and anchorage and assumed to act independently. However, if the inner and outer tanks API standard 650 liquid-storage tanks are supported by a common foundation, the seismic foundation loading shall be calculated using the lesser response modification values for either the inner tank or outer tank for both tanks and a dynamic analysis shall be performed to determine the combined effect.
Allowable Stresses: For Appendix R tanks, design allowable stresses shall be per API 620 large low pressure storage tank, Section R.3.3.

The application of API 650 is as stated by the American Petroleum Institute: The production and installation of our ground welded steel API standard 650 liquid-storage tanks storage tanks are generally used in industry; under normal circumstances, the storage tanks installed on the industrial site in the United States are in accordance with API 650, API 620 and API 12d Standards are established.

Static storage loss is also known as "small breathing" consumption. The rise and fall of the temperature in the API standard 650 liquid-storage tanks leads to the increase and decrease of the pressure in the tank, which makes the mixed oil gas discharged from the tank, and the external air is sucked into the tank, resulting in the oil consumption. Fluid level loss is also called "big breathing" loss. It is the oil consumption caused by the change of gas space volume in the API standard 650 liquid-storage tanks during the oil receiving and sending operation, which causes the mixed oil gas to be discharged out of the tank, and the external air is sucked into the tank, resulting in the oil consumption due to the change of liquid level height.