Tank Shell Thickness Calculator

Calculator

Provide tank geometry, loading, and material limits. Choose how the governing pressure is selected.

Example Data Table

Sample scenarios for quick validation and training.

Formula Used

This calculator applies a thin-wall hoop-stress model for a cylindrical shell.

• Hydrostatic pressure at a point: P = ρ g h, where ρ = SG × 1000 kg/m³.
• Pressure to thickness (hoop): t = (P × D) / (2 × S × E − P).
• Corrosion allowance: t_with_CA = t + CA.
• Minimum and rounding: t_final = max(t_with_CA, t_min), then round up to your increment.

Where P is pressure (MPa), D is diameter (mm), S is allowable stress (MPa), and E is weld/joint efficiency.

How to Use This Calculator

1. Enter the tank diameter and liquid height for your operating condition.
2. Set the course elevation to evaluate any shell course.
3. Provide specific gravity for stored liquid, plus any internal pressure.
4. Enter allowable stress and weld/joint efficiency from your spec.
5. Add corrosion allowance, a minimum thickness rule, and rounding increment.
6. Pick the governing selection, then press Calculate.
7. Use CSV or PDF exports for submittals and records.

For final design, check wind, seismic, nozzle loads, and code minimums using your governing standard.

Professional Article

Tank shell thickness is a balance between safety, constructability, and lifecycle reliability. In many construction storage tanks, the shell is governed by circumferential hoop stress from hydrostatic head and, when applicable, a specified internal pressure. If the shell is under-sized, weld distress, out-of-roundness, denting, and early corrosion leakage become more likely. If the design is too conservative, plate cost, effort, and welding time increase without improving service performance.

This calculator applies a thin-wall hoop-stress model and includes weld or joint efficiency and allowable stress. Efficiency represents joint quality and inspection level, so select it from the project requirements. Allowable stress should come from the chosen material grade at design temperature. After a strength thickness is calculated, a corrosion allowance is added to preserve future capacity and support inspection intervals. Many projects also enforce a minimum practical plate thickness to improve handling, fit-up, and field robustness.

Example data: Consider a 10 m diameter tank storing diesel (SG 0.83) to 12 m. For the bottom course at elevation 0 m, hydrostatic pressure is about 0.098 MPa. With allowable stress 150 MPa and efficiency 0.85, the strength thickness is roughly 3.9 mm. Adding 2.0 mm corrosion allowance gives 5.9 mm, then a 6.0 mm minimum and 0.5 mm rounding yields a recommended 6.0 mm plate. For a low-pressure process tank at 50 kPa, 3 m diameter, allowable 138 MPa, and efficiency 1.0, the pressure case can control even when the liquid head is modest.

Course elevation matters for multi-course shells because pressure reduces as you move upward. Set elevation to the course bottom you are checking, using the same datum as liquid height. When comparing alternatives, keep allowable stress and efficiency consistent so the comparison reflects geometry and loading. Record the rounding increment because it directly affects purchase thickness, weight, and welding volume. Always review whether the thin-wall assumption is appropriate for thick shells, small diameters, or special load cases.

Use these results for early estimating, procurement planning, and field QA checks. For final design, confirm governing standard requirements for minimum thickness, shell course rules, roof and floor details, wind and seismic demands, anchor design, nozzle reinforcement, settlement, and fabrication tolerances. Capturing inputs and the rounded plate thickness helps align drawings, material takeoffs, and shop packages, reducing rework, delays, and change orders across the project team during construction and commissioning.

FAQs

What does weld or joint efficiency mean?

Efficiency accounts for joint type and inspection quality. Lower efficiency reduces the allowable load carried by the weld, increasing required thickness. Use the value specified by your project documents or inspection plan.

Why add corrosion allowance?

Corrosion allowance provides extra metal so the shell can lose thickness over time and still meet strength needs. It also supports planned inspection intervals and reduces the risk of early leakage.

Which pressure should govern the design?

For liquid storage, hydrostatic head often governs the lower courses. For pressurized tanks, specified internal pressure may control. If both apply, selecting the maximum is a conservative screening approach.

How do I use course elevation?

Enter the height from the bottom to the course being checked. The calculator uses liquid height minus elevation to compute head at that course, so higher courses usually require less thickness.

Why is there a minimum thickness setting?

Projects often adopt practical minimum plate thickness for handling, welding, impact resistance, and fabrication tolerances. This setting helps align calculations with real procurement and site constraints.

What does the rounding increment do?

Plates are purchased in available thickness steps. Rounding up to a chosen increment converts a calculated value into a buyable thickness and supports consistent estimates for weight and welding volume.

Is this a final code design tool?

No. It is a planning and checking calculator using a simplified thin-wall model. Final design should verify governing standards for wind, seismic, nozzles, anchors, settlement, and any minimum thickness rules.