API 650 aboveground oil storage tanks greater than 60 m in diameter

In this project, an elemental area of API 620 oil storage tank wall is constructed of ASTM A516 Grade 55 steel plate subjected to a meridional unit force, T1, of 2620 lbf/in. tension and a latitudinal unit force, T2, of 2880 lbf/in. compression. The meridional radius of curvature, R1, is 132 in., and the length of the normal from the surface to the axis of revolution, R2, is 409 in. The joints in the wall are spot-radiographed, double-welded butt joints, and no corrosion allowance is required.
The problem in this example is to graphically find the minimum thickness of tank wall required for the given conditions (see API 620 tank standard 5.10.3.3).
Solution: As determined from Table 5-1, the maximum, allowable tensile stress value, Sts, for ASTM A516 Grade 55 steel plate in simple tension is 16,500 lbf/in.2. Since the compressive stress is latitudinal, the governing value of R for this situation is R1, or 132 in.

Storage tanks API 650 aboveground oil storage tanks designed in accordance with the rules and guidelines of API 650 are called API 650 storage tanks. API 650 is a control rule for welded storage tanks that work normally in the normal pressure range.

Requirements for prefabrication of the top of large vertical API 650 aboveground oil storage tanks: The prefabrication of the tank top shall be prefabricated in blocks according to the drawings. Pay attention to the spacing of the welds after installation when setting out the material. Reinforcing ribs should be formed and inspected with an arc-shaped template. When a single top plate needs to be spliced, butt joints should be used. The forming of a single top plate should be welded between the reinforcing ribs and the top plate on the mould. After forming, check with an arc-shaped sample plate, and the gap should not be greater than 10 mm.