What this calculator is used for
This calculator estimates the minimum required thickness for pressure vessel heads under internal pressure. Unlike cylindrical shells, vessel heads have complex stress distributions due to their curved geometry, making proper thickness design essential for safe pressure containment.
Typical engineering use cases
- Preliminary mechanical design of pressure vessels
- Comparison of different head geometries for cost and weight optimization
- Supporting ASME and JIS code-compliant calculations
- Initial manufacturability and cost assessments
- Material specification for fabrication procurement
Governing equation and methodology
Different formulas apply depending on head geometry:
- Hemispherical heads: Thinnest but highest fabrication cost
- 2:1 Semi-ellipsoidal heads: Common balance of strength and manufacturability
- Torispherical (dish-shaped) heads: Economical for low-pressure applications
These equations are derived from classical shell theory and align with ASME Section VIII and equivalent international standards.
Engineering assumptions and limitations
- Internal pressure loading only
- External loads and nozzle reinforcement not considered
- Uniform material properties assumed
- Weld joint efficiency applied as specified
Practical design notes
Hemispherical heads require the thinnest material but are typically more expensive to fabricate. Semi-ellipsoidal heads are commonly selected as a balance between strength and manufacturability. Final thickness must include corrosion allowance and fabrication tolerances. Always verify designs against the applicable pressure vessel code.