API 650 ground supported flat-bottom tanks height

The most popular standards for API 650 ground supported flat-bottom tanks are API Std 650, JIS B8501, BS2654, GB50341, etc. The formulas used in each standard are derived from the hoop stress calculation formula of membrane theory. Combined with the stress characteristics of API 650 ground supported flat-bottom tanks, plus the allowable stress, weld coefficient and additional wall thickness, the wall thickness calculation formula is complete. The allowable stress and weld coefficient are determined according to the material performance characteristics and construction technology level of each country. According to different API 650 ground supported flat-bottom tanks standards, the calculation results of tank wall thickness are sometimes quite different.

The insert plate weld shall not cross any shell seams and shall be at least the greater of 10 times the shell thickness or 12 in. from any other weld in the API 650 ground supported flat-bottom tanks shell including shell seams, shell-to-bottom weld or attachment welds. The butt weld around the periphery of the plate shall be examined over 100% of its length by both liquid penetrant method and radiographic method. The liquid penetrant examination is required on the root pass, on the back-gouged surface, and on the inside and outside finished weld surfaces. Additionally, the weld shall be vacuum box leak tested.

Corrosion allowance, if specified, shall be added to calculated API 650 tanks shell and self-supporting roof thicknesses; to minimum nominal thicknesses of bottom and supported API 650 ground supported flat-bottom tanks roof plates; to nozzles and manholes; and to all exposed surfaces of internal structural members and non-removable internals.