A678 Gr B plates API standard 650 unanchored tanks

Generally, the snow load in the API standard 650 unanchored tanks construction area should be considered before the design and construction of the tank. The snow load in the API standard 650 unanchored 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.

In this project, a cylindrical tank 62 ft 6 in. in diameter is designed for an internal pressure of 4 lbf/in.2 gauge in the vapor space. The plate material is ASTM A131 steel with appropriate grades for different plate thicknesses in accordance with Table 4-1 for a design metal temperature less than 65°F but not less than 25°F. No corrosion allowance is required for any portion of the tank. The top course of the butt-welded cylindrical sidewall is 1/4 in. thick. The roof is a single lap-welded spherical dome with an internal radius of 50 ft and a thickness of 1/4 in. The maximum design liquid level is 6 in. below the plane of the juncture of the tank API standard 650 unanchored tanks roof and sidewall.

Before pressure testing, thoroughly flush the API 650 tank floating roof primary drain hose system. Supply API standard 650 unanchored tanks blind flanges, gaskets, and bolting (for other types of blanking covers as may be required) necessary for testing.