Input Data
Enter casing geometry, material strength, and loading conditions.
Formula Used
1) Effective wall thickness: t_eff = (t_nominal - corrosion allowance) × (1 - mill tolerance / 100)
2) Nominal inside diameter: ID_nominal = OD - 2 × t_nominal
3) Effective inside diameter: ID_effective = OD - 2 × t_eff
4) Nominal burst, OD basis: P_nominal = 2 × SMYS × t_nominal / OD
5) Derated burst, OD basis: P_OD = 2 × SMYS × t_eff × joint factor × temperature factor / OD
6) Derated burst, ID basis: P_ID = 2 × SMYS × t_eff × joint factor × temperature factor / ID_effective
7) Governing burst capacity: P_governing = min(P_OD, P_ID)
8) Design burst capacity: P_design = P_governing × design factor
9) Applied differential pressure: P_applied = max(internal pressure - external pressure, 0)
10) Safety margin: Margin = P_design - P_applied
How to Use This Calculator
- Choose a casing grade or enter a custom yield strength.
- Enter outside diameter and nominal wall thickness from the pipe specification.
- Add corrosion allowance and mill tolerance for a realistic effective wall.
- Apply joint, temperature, and design factors required by your project standard.
- Enter internal and external pressures at the same reference depth.
- Press the calculate button to display capacities, utilization, and pass or fail status.
- Use the CSV and PDF buttons to save a calculation record.
Example Data Table
| Grade | OD (in) | Wall (in) | Corrosion (in) | Mill Tol. (%) | Yield (psi) | Joint | Temp | Design | Internal (psi) | External (psi) | Design Burst (psi) | Status |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| N80 | 9.625 | 0.545 | 0.030 | 12.5 | 80,000 | 1.00 | 0.97 | 0.90 | 7,200 | 1,200 | 6,539.56 | PASS |
Engineering Notes
This tool gives a practical screening estimate for pipe-body burst resistance. Final acceptance should follow your governing standard, connection details, temperature profile, material traceability, and project-specific load cases.
Compare results with collapse, tension, triaxial loading, and connection performance before approving a casing design.
FAQs
1) What does burst pressure mean for casing?
Burst pressure is the internal differential pressure that can cause the casing wall to yield or fail. The calculation compares inside pressure against outside support and adjusts capacity using strength, thickness, and design factors.
2) Why is corrosion allowance included?
Corrosion allowance reduces the effective wall thickness before burst capacity is estimated. This makes the output more conservative and better aligned with expected metal loss during service.
3) What is mill tolerance?
Mill tolerance represents allowable manufacturing variation in wall thickness. When the wall could be thinner than nominal, burst capacity should be checked using the reduced effective thickness rather than the catalog value alone.
4) Why does the calculator show OD and ID based results?
Different simplified burst expressions use either outside diameter or inside diameter. Showing both values helps you review sensitivity, while the calculator selects the lower value as the governing screening capacity.
5) What does the design factor do?
The design factor reduces the theoretical governing burst capacity to a working design limit. It provides margin for uncertainty, operating variability, and required conservatism in the selected engineering basis.
6) Can I use this for tubing or liner strings?
Yes, the same pressure-capacity logic can be used for tubing, liners, or similar tubulars when dimensions and strength data are known. Always confirm the proper standard and connection assumptions for the product.
7) Why does external pressure reduce the applied differential?
Burst loading is driven by the pressure difference across the wall. Higher outside pressure partially supports the tubular, so the applied burst differential becomes lower than the inside pressure alone.
8) Is this calculator enough for final design approval?
No. It is best used for screening, comparison, and quick documentation. Final design should include applicable standards, connection ratings, safety philosophy, temperature effects, combined loading, and qualified engineering review.