Free internal-pressure minimum thickness calculator per ASME Section VIII Division 1 — cylindrical shells (UG-27), hemispherical/ellipsoidal/torispherical heads (UG-32), and conical shells (Appendix 1-4). Calculations run on a protected server; instant, code-compliant results with a full worked solution. Jump to how it works ↓
This calculator determines the minimum required wall thickness for a pressure vessel component under internal pressure, per the relevant paragraph of ASME Boiler & Pressure Vessel Code, Section VIII, Division 1 — the "design by rules" approach used for the overwhelming majority of pressure vessels built worldwide. Select a component type, enter pressure, diameter, allowable stress, joint efficiency, and corrosion allowance, and the calculation runs on a protected server. Only your inputs are sent out; only the required thickness and the intermediate values needed to show a full worked solution come back — the code formulas themselves never reach the browser as executable code.
Checks both longitudinal and circumferential stress; the governing (larger) thickness controls. Circumferential stress governs for essentially all practical L/D ratios.
The most efficient head shape under internal pressure — roughly half the thickness of a cylindrical shell of the same diameter — but the most expensive to form.
The standard 2:1 semi-elliptical head — head height equals one-quarter of the diameter. The most common head type on process vessels.
Also called a "flanged and dished" or F&D head. Cheaper to form than an ellipsoidal head but requires more thickness for the same pressure rating.
Used for transitions between different diameters. Thickness depends on the half apex angle — steeper cones require more thickness.
Joint efficiency (E) reflects how thoroughly the shell/head welds are radiographically examined, and directly affects allowable stress in every formula above: