Api 650 Tank Calculation Spreadsheet update# These sessions typically involve lengthy discussions of various agenda items that are important to the refinement and development of the code. In this section, there are two methods for consideration: As one would expect, all aspects of the code, both analytical and non- analytical, are addressed in the meetings.īut getting back to one of the previous questions, how do we decide how thick the wall of the tank should be? The answer can be found in section 5.6, Shell Design. 5.6.3 Calculation of Thickness by the 1-Foot Method.5.6.4 Calculation of Thickness by the Variable Point Method.The basic equation in US customary units looks something like this: The 1-foot method computes the required plate thickness at a distance of one foot above the bottom of each shell course and is applicable to tanks 200ft (61m) and less in diameter.
The variable point equation in US units is as follows: The variable point method is an alternative to the 1-foot method and can be used for tanks in excess of 200ft in diameter.
G is the specific gravity of the contents. S is the tank wall material allowable tensile stress for the operating or test condition.ĪPI 650 storage tanks are often designed to work at temperatures of up to 500✯ (260✬). For these higher temperature designs, the allowable stress of the material decreases. As a result, the required wall thickness increases in a linear fashion when using the 1-foot method and in a slightly non-linear fashion when using the variable point method. In addition to causing hoop stress and longitudinal stress in the tank wall, the slight internal pressure causes a tensile force (pressure × area) to be produced. This force pulls upward on the tank wall. This positive upward force is countered by the weight of the tank and roof (if not column-supported). If the net force is upward in any case or condition, the tank must be held down by anchor bolts. The basic internal pressure case is just one example. The net uplift due to design pressure formula from Table 5.21b in API 650 12th Edition, Addendum 2 is as follows: There are several other uplift formulas in Tables 5.21a (metric) and 5.21b (imperial), which must also be considered. Pi is the design internal pressure in inches of water. Api 650 Tank Calculation Spreadsheet code#.Api 650 Tank Calculation Spreadsheet update#.
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