Shell Thickness Calculation

The body of static equipment under pressure is in many cases a cylindrical shape. More complex equipment such as destilation columns can also have on or more conical part. LPG tanks however have usually a spherical body.

The Shell Thickness calculation page is to calculate the wall thickness of a cylinder, cone and sphere under pressure without holes. The calculation does not take into account the extra stress around holes for nozzles and is therefore a basic strength calculation. Calculation codes are ASME, Dutch Rules and the EN Euronorm.

Below figure gives the an indication of the dimensions used in the calculations. The calculation also require the user to enter a stress value depending the material. The calculation page has a link to a material property page, but the values on the material pages are for reference only and are not to be used in actual calculations. Type of shell Cylinder Cone Sphere Design pressure Pd N/mm2 ( = 1 MPa = 10 Bar ) Design temperature Td 0C Material description - Select yield stress and specific gravity from material database Yield stress, design temp. Re(Td) N/mm2 Specific gravity ρ kg/m3 Outside diameter De mm Length tangent to tangent L mm (If not a sphere) Nominal wall thickness dn mm Corrosion allowance Ca mm Tolerance tol mm Strength reduction coëfficient z - Semi angle at apex cone α degree (For cone only) Design Code - ASME Dutch Rules Euronorm (PED) (ASME, Dutch R., PED) Note: Without warranty and for estimating purposes only. Results should be checked and approved by qualified engineer.

Wall thickness calculation of Cylinder
according Dutch Rules

Allowable stress f = f1 = 0.67 * Re(Td) = 0.67 * 175.2 = 117.38 N/mm2
Calculation thickness d = dn - Ca - tol = 8.2 - 1 - 1.03 = 6.17 mm

Cylinder:

Inside diameter Di = De - 2*d = 219.1 - 2*6.17 = 206.76 mm
Required wall thickness
dr =
 Pd*De (2*z*f + Pd)
=
 0.5 * 219.1 (2*1*117.384 + 0.5)
=
0.47 mm
Nominal required thickness drn = dr + Ca + tol = 0.466 + 1 + 1.03 = 2.50 mm
Required strength reduction
zmin =
 Pd*(Di + d) 2*d*f
=
 0.5*(206.76 + 6.17) 2*6.17*117.384
=
0.07350
Thickness analysis, d > dr ? dn = 8.2 mm is OK

Weight     96.22 kg
Enclosed volume     0.073 m3