API 650 welded steel oil storage tanks with open vents

Compared with the external floating roof API 650 welded steel oil storage tanks, the internal floating roof API 650 welded steel oil storage tanks has the advantages of protecting the floating roof from wind and rain and ensuring the quality of liquid storage under the floating roof. At the same time, because the inner floating plate is in the tank, there is no rain and snow load, so the central drainage pipe and escalator and other accessories on the floating plate can be omitted. In addition, under the same sealing conditions, the internal floating roof tank can further reduce the evaporation loss compared with the External floating roof tank.

Bearing on Foundations
Foundations shall preferably be designed to resist the load exerted by the API Standard 620 tank and its contents when the tank is filled with water to the design liquid level. Foundations shall be designed at least for the maximum operating conditions including the wind load. During the API 650 welded steel oil storage tanks water test, the total load on the foundation shall not exceed 125% of the allowable loading. If necessary, the water level during the test may be reduced below the design liquid level line so as not to exceed the 25% maximum overload (see Q.8.1.2).

The API 650 specification provides guidelines for the API 650 welded steel oil storage tanks design, manufacturing, materials, installation and inspection of welded vertical and cylindrical tanks. Such containers must be on the ground and have a closed or open top.