API standard 650 anchored tanks roof and top-angle joints

Compared with the external floating roof API standard 650 anchored tanks, the internal floating roof API standard 650 anchored 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.

API 620 Crude Oil Tank Pneumatic Pressure
An air pressure equal to 1.25 times the pressure for which the vapor space is designed shall be applied to the enclosed space above the water level. In the case of a double-wall tank with an open-top inner tank, where the air pressure acts against the outer tank and the inner tank is thus not stressed by the air pressure, the inner API standard 650 anchored tanks may be emptied of water before the pneumatic pressure test begins. The test pressure shall be held for 1 hour.

The tank wall design of API 650 oil storage tank. Since there is no ventilation pipe directly connected with the outside on the top of the API standard 650 anchored tanks tank, the ventilation between the inside and outside of API 650 oil storage tank is realized by the respiration valve. The constant pressure of the respiration valve is 0.3kPa, so the pressure on the top of the tank is 0.3kPa.