Design Inputs
Default coefficients are shape- and support-based screening values. You can override them when your design method, standard, or handbook specifies different coefficients.
Example Data Table
| Case | Shape | Span / Diameter | Pressure | Yield Strength | Safety Factor | Corrosion Allowance | Typical Result |
|---|---|---|---|---|---|---|---|
| Tank Access Cover | Rectangular | 800 × 1200 mm | 0.12 MPa | 250 MPa | 1.5 | 1.0 mm | 10 mm stock plate |
| Machine Guard Panel | Rectangular | 600 × 900 mm | 0.05 MPa | 275 MPa | 1.6 | 0.5 mm | 6 mm stock plate |
| Circular Cover Plate | Circular | 1000 mm diameter | 0.20 MPa | 240 MPa | 1.8 | 1.5 mm | 16 mm stock plate |
Formula Used
σallow = (Yield Strength × Joint Efficiency) ÷ Safety Factor
tstruct = L × √[(C × p) ÷ σallow]
tnom = (tstruct + Corrosion Allowance) ÷ (1 − Mill Tolerance)
σactual = (C × p × L²) ÷ teff²
wmax = (K × p × L⁴) ÷ (E × teff³)
- L is the governing span in mm, usually the short span for a rectangle or the full diameter for a circle.
- p is pressure in MPa, equivalent to N/mm².
- C and K are screening coefficients based on shape and edge restraint, or user overrides.
- teff is the in-service effective thickness after tolerance loss and corrosion deduction.
How to Use This Calculator
- Select the plate shape and support condition.
- Enter the governing dimensions in millimetres.
- Enter design pressure and choose its unit.
- Add material properties like yield strength, modulus, and density.
- Set design controls such as safety factor, joint efficiency, corrosion allowance, and mill tolerance.
- Optionally override the default stress and deflection coefficients if you are following a handbook or code method.
- Press the calculate button to display thickness, stress, deflection, weight, and the pressure-thickness chart.
- Use the CSV and PDF buttons to export the design summary.
Frequently Asked Questions
1) What does this plate thickness calculator estimate?
It estimates preliminary flat-plate thickness for a pressure-loaded metal plate. The tool also checks bending stress, deflection, effective service thickness, mass, and a recommended stock thickness for quick design screening.
2) Which span controls a rectangular plate?
For this simplified method, the short span controls the thickness calculation because bending severity usually rises with the shorter unsupported dimension in pressure-loaded flat plates.
3) Why are corrosion allowance and mill tolerance included?
They convert structural need into a practical purchase thickness. Corrosion allowance protects long-term service, while mill tolerance accounts for negative manufacturing thickness variation.
4) What is the meaning of joint efficiency?
Joint efficiency reduces the effective material strength when weld quality, attachment detail, or fabrication conditions lower the plate section’s dependable capacity.
5) Can I use my own coefficients?
Yes. If your project follows a handbook, research paper, or code rule with specific plate coefficients, enter them in the manual coefficient fields to override defaults.
6) Is this suitable for code compliance?
It is best for screening, option comparison, and early-stage sizing. Final engineering should confirm loads, boundary conditions, dynamic effects, openings, welds, and governing code requirements.
7) Why might the result show CHECK instead of PASS?
CHECK appears when estimated stress exceeds allowable stress or when predicted deflection exceeds the reference span/250 limit. Increase thickness or revisit design assumptions.
8) What does the graph show?
The graph plots required nominal thickness against pressure. It helps visualize how rapidly thickness demand grows as load increases and supports quick sensitivity checks.