water tank - wind girder design

Project : 13 m diameter 4.5 m high tank Project No.

Calculation for Intermediate Wind GirderTank diameter D = 13.00 mTank Height = 4.50 mDesign Wind Speed ( service ) V = 190 km / hThickness of top shell course t uniform = 5 mm

Thickness of top shell course - CA 3 mm

Shell Level from Actual width Actual Actual shell TransposedLayers base of tank of shell shell thickness width offrom base in m in mm thickness minus corrosion each shell

adopted thickness in mmW t actual t actual - CA W tr

0.00 1 2.25 2250 5 3.0 2250.002 4.50 2250 5 3.0 2250.00

Sum 4500.00 mmHeight of Transformed Shell = 4.500 m

Maximum Height of unstiffened shell H1 = 3.149 m

H1 less than Height of Transformed ShellIntermediate Wind Girder Required

Min. Section modulus of the Intermediate Wind Girder = 31.31 cm3

Half height of Transformed shell < H1Second Intermediate Girder Not Required

Reference API 650 11th Edition Clause 5.9.7Transposed width of each shell W tr = W ( t uniform / t actual )

5/2

Maximum Height of unstiffened Shell H1 = 9.47 * t * ( t / D ) 3/2 * (190 / V )2

't' is the actual thickness of top shell in mmMin. Section modulus of the Intermediate Wind Girder = D2 H1 (V / 190)2 / 17

If half the height of transformed shell > H1 , a second intermediate girder shall be used.

Corroded thickness of plates are used in calculation of intermediate wind girders.