The required thickness of a dished head of semi ellipsoidal form, in which half the, minor axis (inside depth of the head minus the skirt) equals one-fourth of the inside diameter of the head skirt, shall be determined by
Where;
t = minimum required thickness of head after forming, in. (mm)
P = internal design pressure (see UG-21), psi (kPa)
D = inside diameter of the head skirt; or inside length of the major axis of an ellipsoidal head; or inside diameter of a conical head at the point under consideration, measured perpendicular to the longitudinal axis, in. (mm)
S = maximum allowable stress value in tension as given in the tables referenced in UG-23, psi (kPa)
E = lowest efficiency of any joint in the head; for hemispherical heads this includes head-to-shell joint; for welded vessels, use the efficiency specified in UW-12
Same as previously, I also make the computer program (software) to make easier for us in conducting calculation. Please see picture bellow.
This program also can show and print the report of calculation, please see sample report bellow.
Please download sample program in http://www.ziddu.com/download/6044170/EllipHeadCalc.rar.html