Steel casing pipe is a key component of oil and gas wells, used to line the wellbore and ensure structural integrity during drilling and production. One of the most important parameters in casing pipe design is wall thickness, which directly determines the casing's ability to resist external and internal loads. Selecting the correct wall thickness is crucial to maintaining wellbore stability, preventing collapse, and ensuring the long-term safety of the well. The following mainly introduces some details of steel casing pipe wall thickness.
Factors affecting the wall thickness of steel casing pipe
1. Formation pressure and mechanical load: The thickness of shallow, low-pressure formations can be slightly thinner; deep wells and high-pressure oil and gas layers need to be thickened to resist deformation and rupture; at the same time, the mechanical stress of casing pipe and cement pressure must be considered.
2. Corrosive environment: When the environment contains corrosive media such as H₂S, CO₂, and high salt, additional thickness is required to reserve corrosion allowance to offset erosion loss. For example, the thickness of acidic oil and gas wells needs to be increased by 5%-15%.
3. Material steel grade strength: Low steel grade (such as J55) has low strength and needs to be thickened to improve performance; high steel grade (such as P110) has high strength and can be thinned under the same working conditions. For example, P110 used in deep wells is 10%-20% thinner than J55.
4. Application Scenarios and Standards: Surface casing pipe thickness for oil and gas wells is 8-15mm, and production casing pipe is 12-25mm (API Spec 5CT). Municipal road/river casing pipe is 30% thicker than ordinary buried casing (GB/T 21835). Shallow water well casing pipe is 4-8mm, and deep water well casing pipe is 10-15mm.
Steel casing pipe wall thickness chart
The above data is for reference only, and the actual wall thickness may vary depending on different standards and application scenarios. For example, steel casing pipes used in oil and gas wells need to comply with relevant API 5CT standards, and their wall thickness specifications will be more detailed and specific.
Calculation of Required Thickness
Design engineers calculate casing thickness based on:
Collapse Pressure Formula – Determines minimum thickness to resist external formation pressure.
Burst Pressure Formula – Ensures casing can withstand maximum internal pressure from well fluids.
Axial Stress Considerations – uates combined stresses during running and production.
Safety Factors – Industry standards apply safety margins to account for uncertainties in material performance.
Importance of steel casing wall thickness
1. Ensure structural strength: Sufficient wall thickness can withstand formation pressure and external extrusion (such as soil and water impact), avoid casing deformation and rupture, and prevent well wall collapse or pipeline damage;
2. Resistant to corrosion loss: The wall thickness can reserve a "corrosion margin" to offset the erosion of media such as H₂S and high salt, extend the service life of the casing pipe, and reduce the risk of leakage;
3. Meet pressure requirements: Adapt to different pressure scenarios (such as high pressure in oil and gas wells and low pressure in municipal pipelines). Insufficient wall thickness can easily lead to failure due to pressure overload, affecting operational safety;
4. Adaptable installation and standards: The wall thickness complies with industry standards (such as API, GB), which can ensure the adaptability of casing pipe, joints and accessories, ensure the connection is sealed, and avoid installation failures.
Read more: Steel well casing pipe sizes
Factors affecting the wall thickness of steel casing pipe
1. Formation pressure and mechanical load: The thickness of shallow, low-pressure formations can be slightly thinner; deep wells and high-pressure oil and gas layers need to be thickened to resist deformation and rupture; at the same time, the mechanical stress of casing pipe and cement pressure must be considered.
2. Corrosive environment: When the environment contains corrosive media such as H₂S, CO₂, and high salt, additional thickness is required to reserve corrosion allowance to offset erosion loss. For example, the thickness of acidic oil and gas wells needs to be increased by 5%-15%.
3. Material steel grade strength: Low steel grade (such as J55) has low strength and needs to be thickened to improve performance; high steel grade (such as P110) has high strength and can be thinned under the same working conditions. For example, P110 used in deep wells is 10%-20% thinner than J55.
4. Application Scenarios and Standards: Surface casing pipe thickness for oil and gas wells is 8-15mm, and production casing pipe is 12-25mm (API Spec 5CT). Municipal road/river casing pipe is 30% thicker than ordinary buried casing (GB/T 21835). Shallow water well casing pipe is 4-8mm, and deep water well casing pipe is 10-15mm.
Steel casing pipe wall thickness chart
| Nominal Diameter | Outer Diameter (mm) | Wall Thickness (mm) |
| 2 inches | 60.3 | 2.77/3.18/3.56 |
| 3 inches | 88.9 | 2.87/3.18/3.97 |
| 4 inches | 114.3 | 3.18/3.56/4.78 |
| 6 inches | 168.3 | 4.78/5.16/6.35 |
| 8 inches | 219.1 | 4.78/5.16/6.35 |
| 10 inches | 273.0 | 5.56/6.35/7.92 |
| 12 inches | 323.9 | 5.56/6.35/7.92 |
The above data is for reference only, and the actual wall thickness may vary depending on different standards and application scenarios. For example, steel casing pipes used in oil and gas wells need to comply with relevant API 5CT standards, and their wall thickness specifications will be more detailed and specific.
Calculation of Required Thickness
Design engineers calculate casing thickness based on:
Collapse Pressure Formula – Determines minimum thickness to resist external formation pressure.
Burst Pressure Formula – Ensures casing can withstand maximum internal pressure from well fluids.
Axial Stress Considerations – uates combined stresses during running and production.
Safety Factors – Industry standards apply safety margins to account for uncertainties in material performance.
Importance of steel casing wall thickness
1. Ensure structural strength: Sufficient wall thickness can withstand formation pressure and external extrusion (such as soil and water impact), avoid casing deformation and rupture, and prevent well wall collapse or pipeline damage;
2. Resistant to corrosion loss: The wall thickness can reserve a "corrosion margin" to offset the erosion of media such as H₂S and high salt, extend the service life of the casing pipe, and reduce the risk of leakage;
3. Meet pressure requirements: Adapt to different pressure scenarios (such as high pressure in oil and gas wells and low pressure in municipal pipelines). Insufficient wall thickness can easily lead to failure due to pressure overload, affecting operational safety;
4. Adaptable installation and standards: The wall thickness complies with industry standards (such as API, GB), which can ensure the adaptability of casing pipe, joints and accessories, ensure the connection is sealed, and avoid installation failures.
Read more: Steel well casing pipe sizes
