Wall Thickness Requirements of Steel Casing Pipe

The requirements for steel casing pipe wall thickness depend on multiple factors such as well depth, annular structure, geological conditions and process requirements. Its calculation method and standard requirements need to be reasonably determined based on specific circumstances.

Calculation method of steel casing pipe wall thickness

The calculation methods for steel casing pipe wall thickness generally include hydrostatic pressure method, high constant method and Lao Gu formula method, among which the most commonly used is Lao Gu formula method. This method is derived based on actual production data of the petroleum industry and a large amount of test data. Its calculation method is:

H=0.875×σt×(do-di)/2Sy

Wherein, H represents the wall thickness of steel casing pipe, σt represents the maximum tensile stress, do and di represent the outer diameter and inner diameter of the casing pipe respectively, and Sy represents the yield strength.

Steel casing pipe wall thickness specification table

The following table is a wall thickness specification table of some common steel casing pipes for reference only.

Note: The wall thickness shown in the table is for reference only. It needs to be adjusted according to specific circumstances when it is actually selected.

Standard requirements for steel casing pipe wall thickness

Depending on different standard requirements and use environments, the wall thickness of steel casing pipe varies. The main requirements include:

1. As an OCTG pipe, the wall thickness of the casing pipe should meet the control requirements and engineering requirements of the well to ensure the integrity, stability and safety of the annulus.

2. The casing pipe wall thickness should be adapted to factors such as well depth, well diameter, annulus structure, geological conditions and process requirements.

3. The thickness of the casing pipe steel plate should be calculated according to factors such as design wall thickness, injection pressure, annulus settlement and reinforcement materials.

4. The formulation of casing pipe specifications should be based on the minimum inner diameter and maximum outer diameter of the casing pipe to ensure product quality and use effect.

How to choose the appropriate steel casing pipe wall thickness

Correctly selecting the appropriate steel casing pipe wall thickness is the key to ensuring its service life and pressure bearing capacity. When choosing, it is necessary to judge based on the following points:

1. Determine the pipe diameter and pressure level

First, it is necessary to determine the diameter and pressure level of the connecting pipe. This can help choose the appropriate wall thickness range (which can be queried according to national standards).

2. Consider the purpose and working conditions of the pipeline

Different pipeline purposes and working conditions have different requirements for pressure bearing capacity. For example, pipelines in the chemical industry require higher corrosion resistance, so special materials and larger wall thicknesses need to be selected. Therefore, when selecting, it is necessary to fully consider the purpose and working conditions of the pipeline.

3. Adjust according to actual conditions

In addition to national standards, adjustments need to be made according to actual conditions. For example, in special projects, according to engineering design requirements and construction drawings, it is sometimes necessary to adjust the wall thickness of the steel casing pipe to meet the corresponding pressure bearing capacity requirements.

Summary

In short, when selecting the wall thickness of the steel casing pipe, it is necessary to fully consider the diameter and pressure level of the connecting pipeline, the purpose and working conditions of the pipeline, and the actual situation, and constantly adjust and correct to ensure that the appropriate wall thickness of the steel casing pipe is selected to meet actual needs.

Read more: How To Choose The Size of Steel Casing Pipe?