API Std 650 aboveground petroleum storage tanks with a self-supporting roof

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.

While GB50341 generally takes the weld coefficient as 0.9;When the minimum yield strength of API Std 650 aboveground petroleum storage tanks steel plate is greater than 390 MPa, take 0.85. The thickness of API 650 tanks is generally smaller than that of GB50341, and this difference is particularly evident in the design of large tanks, where the overall weight of the tanks varies greatly.

Generally, the snow load in the API Std 650 aboveground petroleum storage tanks construction area should be considered before the design and construction of the tank. The snow load in the API Std 650 aboveground petroleum storage tanks construction area has an impact on the tank roof design and operation, especially in the area with large snow load, the roof load of large storage tank with large diameter increases. Anti freezing, heat preservation and waterproof measures shall be taken for the additional facilities of storage tanks, such as pumps, breathing valves, flame arresters, detection instruments and thermal insulation layers.