Wednesday, July 29, 2009


This calculation base on ASME section VIII Div.1


(a) The thickness of shells under internal pressure shall be not less than that computed by the following
formulas. In addition, provision shall be made for any of the other loadings listed in UG-22, when such
loadings are expected. (See UG-16.)

(b) The symbols defined below are used in the formulas of this paragraph.
t = minimum required thickness of shell, in.
P = internal design pressure (see UG-21), psi
R = inside radius of the shell course under consideration in.
S = maximum allowable stress value, psi
E = joint efficiency for, or the efficiency of, appropriate joint in cylindrical or spherical shells, or
the efficiency of ligaments between openings, whichever is less.
For welded vessels, use the efficiency specified in UW-12.
For ligaments between openings, use the efficiency calculated by the rules given in UG-53.

(c) Cylindrical Shells. The minimum thickness or maximum allowable working pressure of cylindrical
shells shall be the greater thickness or lesser pressure as given by (1) or (2) below.
(1) Circumferential Stress (Longitudinal Joints).
When the thickness does not exceed one-half of the inside radius, or P does not exceed 0.385SE, the
following formulas shall apply:

(2) Longitudinal Stress (Circumferential Joints).16
When the thickness does not exceed one-half of the inside radius, or P does not exceed 1.25SE, the following formulas shall apply:

(d) Spherical Shells. When the thickness of the shell of a wholly spherical vessel does not exceed 0.356R,
or P does not exceed 0.665SE, the following formulas shall apply:

(e) When necessary, vessels shall be provided with stiffeners or other additional means of support to prevent overstress or large distortions under the external loadings listed in UG-22 other than pressure and temperature.

(f) A stayed jacket shell that extends completely around a cylindrical or spherical vessel shall also meet
the requirements of UG-47(c).

(g) Any reduction in thickness within a shell course or spherical shell shall be in accordance with UW-9.

I have been made some computer program to calculate minimum required thickness of cylindrical shell and Maximum Allowable Working Pressure (MAWP). Please see picture bellow.

This program is simple, you only input value on design data and then click calculate button, and the result in design calculation.
This program also can show and print the report of calculation, please see sample report bellow.


  1. When i download the file from ziddu and run the program it is generating an run time error
    which says "actskin4.ocx or one of the dependencies is not correctly registered: A file is Missing or invalid"
    Please help

  2. How to Install Ellipsoidal Head Calculation Software
    1. Download File EllipHeadCalc.rar in
    Download File actskin4.rar in
    Download File VB5DB.rar in

    2. Extract All file, example to d:\software\Pressure Vessel

    Use Password : dede

    3. Copy actskin4.ocx and vb5db.dll to c:/windows/system32
    4. Run Program Double clic eliphead.exe
    5. Enter password : dede