How this pressure vessel shell thickness calculator works
A cylindrical pressure vessel shell carries different stresses around its circumference and along its length. This page works out the calculated thickness for both directions from the design pressure, inside radius, allowable stress and weld joint efficiency, treats the larger one as governing, and adds the corrosion allowance to give a minimum thickness.
The formulas applied are circumferential t = P R / (S E - 0.6 P) and longitudinal t = P R / (2 S E + 0.4 P), with R the inside radius. They apply while the design pressure is no more than 0.385 times S E and no more than 1.25 times S E respectively; outside that range nothing is calculated and the limits are shown. These are the cylindrical shell formulas used in pressure vessel work, taken from secondary sources, so checking the originals is advised. Figures reflect October 2026.
The allowable stress varies with material and design temperature and was not confirmed from an authoritative source, so no stress table is offered and you enter the value from your own data. Pressure and allowable stress are entered in psi and the radius and corrosion allowance in inches. Thicknesses are shown in inches with millimeters in parentheses, and the minimum thickness is the unrounded governing value plus the allowance, rounded only for display. Heads, nozzles, reinforcing pads, external pressure buckling and relief valve sizing are not covered. This calculator is for reference and does not replace design. Review by a qualified engineer is required.
Frequently asked questions
It depends on the material and the design temperature, so no table is offered here. Take the value for your design temperature from the allowable stress data of the pressure vessel standard you work to.
A cylindrical shell carries circumferential and longitudinal stress separately, and the two formulas give different thicknesses. The larger one governs, so the corrosion allowance is added to that value.
The hoop formula applies when the design pressure is no more than 0.385 times the product of allowable stress and joint efficiency, and the longitudinal formula up to 1.25 times. Outside that range the page stops and shows the limits. Thick wall design needs different formulas.