API 650 storage tank alternate designs

Design of Reinforcement for Single Openings in Tank Walls
The 20 in. x 29 in. obround manhole shown in Figure F-5 is located in solid plate in the sidewall of a cylindrical storage tank 45 ft in diameter in an area where the thickness of the wall plate, tw, is 1/2 in. No corrosion allowance is required. The total internal pressure, Pl + Pg, at the horizontal centerline of the opening is 27.5 lbf/in.2 gauge. The thickness of the wall plate, t, required by 5.10.3 for the latitudinal unit forces, T2, acting at this level is 0.485 in. The manhole neck is fabricated by welding from 3/8 in. plate. The materials in the API 620 tank wall, the manhole neck, and the reinforcing pad conform to ASTM A516 Grade 60. The joints in the welded steel storage oil tank wall and the longitudinal joint or joints in the manhole neck are double-welded butt joints, spot radiographed in accordance with 7.16 and 7.17.

API 650 external floating roof storage tanks are generally called external floating roof API 650 storage tank tanks, which means that the storage tanks are externally open tanks without a dome design, and are equipped with vertical floating roofs. API 650 external floating roof storage tanks are usually used for large More than 20,000 cubic meters of open steel API 650 storage tank storage tanks for storing volatile petroleum products such as crude oil, gasoline, kerosene, etc.

The main reason of "small breathing" loss of API 650 storage tank is the change of atmospheric temperature. When the temperature rises with the increase of solar radiation from dawn, the temperature of oil in the API 650 storage tank also changes, resulting in the acceleration of evaporation speed and the increase of evaporation pressure. When the pressure exceeds the positive pressure rating of the breathing valve, the oil-gas mixture in the API 650 storage tank is discharged into the atmosphere through the breathing valve, which is the "exhalation" process of the oil tank.