How to select pipe wall thickness based on the pressure rating of the pipe
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I would like to ask the experts: how is the wall thickness of a pipe determined based on its pressure-bearing capacity? What standards are used, and what are the steps involved in the selection and design process?
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When selecting the pipe wall thickness, you can follow these steps: 1. **Determine the operating pressure and temperature**: First, obtain the design operating pressure and temperature of the pipe, as these are crucial for calculating the wall thickness. 2. **Material Selection**: Choose an appropriate pipe material; properties such as compressive strength and corrosion resistance affect the calculation of the wall thickness. 3. **Refer to standards**: According to relevant industry standards such as ASME B31.3 (chemical process pipelines) and ASME B31.1 (power pipelines), determine the relationship between allowable wall thickness and pressure rating. 4. **Calculate wall thickness**: Use formulas for the calculation; for example, the wall thickness can be determined based on tension theory and internal pressure conditions: \ where t is the pipe wall thickness, P is the internal pressure, D is the outer diameter of the pipe, and S is the allowable stress of the material. 5. **Consider a safety factor**: Based on the calculated wall thickness, it is usually necessary to take into account a certain safety factor to account for unexpected loads or corrosion. 6. **Check other factors**: such as pipe support, connection methods, and local regulations, to ensure that the final choice meets the actual usage requirements. 7. **Conduct review and verification**: Finally, a comprehensive review of the selected wall thickness is carried out, along with verification using specialized software or manually, to ensure safety and reliability. By following the above steps, the wall thickness of the pipeline can be appropriately selected to meet the pressure resistance requirements. .
The “Chemical Process Design Manual” contains tables for selecting wall thicknesses for commonly used pressure pipelines.
Metal pipes can be calculated using the formula in GB 50316-2000 (2008 edition), the \"Code for Design of Industrial Metal Pipes\" (in Chapter 6).
The key is to choose the corrosion margin and pay attention to the machining thickness.
If higher wall thicknesses are used for the pipes, the effect of thermal stress must also be taken into account; generally, pipes with slightly thicker walls are less affected by thermal stress.
This is something done by the process engineering team in the design institute in accordance with the regulations, so there’s no need to worry unnecessarily.