API 650 unanchored flat-bottom tank operating at elevated temperatures

In cylindrical tank walls, the longitudinal weld joints in adjacent shell courses, including compression ring welds, shall be offset from each other a minimum distance of 12 in. The butt-weld around the periphery of a thickened insert plate, or the fillet weld around the periphery of a reinforcing plate, shall be at least the greater of 10 times the shell thickness or 12 in. from any butt-welded seam or the bottom-to-shell or roof-to-shell joint. As an alternative, the insert plate (or the API 650 unanchored flat-bottom tank reinforcing plate in an assembly that does not require stress relief) may extend to and intersect a flat-bottom-to-shell corner joint at approximately 90 degrees.

Under the action of the earthquake, API 650 storage tank is mainly damaged by the phenomenon of the lower part of the API 650 unanchored flat-bottom tank tank wall. Therefore, the key point of seismic calculation is to prevent the tank wall from buckling under axial pressure.

With the continuous development of large-scale oil storage tanks, the foundation of API 650 unanchored flat-bottom tank has also continued to grow. Among them, API 650 unanchored flat-bottom tank vertical oil tanks are storage tanks commonly used to store crude oil, diesel, gasoline and other oil materials. This type of storage tank is set up as a cylindrical shape. The bottom of the tank is a circular flat bottom plate, and the load surface of the oil tank is basically horizontal, which can generally be regarded as a uniform load, and has greater flexibility.