I’d like to ask the experts: where can I find information on the allowable stress for thick-walled pipes?
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I recently took on a project involving the design of compressed air at 40 MPa at room temperature. The client wants to use Q345D for the pipes; the wall thickness for DN250 pipes works out to be around 42 mm. However, the allowable stress values specified in GB150.2 are only available for wall thicknesses less than 10 mm. I would like to ask the experts here: how can one determine the allowable stress for Q345D or 304 pipes with wall thicknesses greater than 40 mm? Also, what are the key considerations when calculating the wall thickness for pipes under such high pressures and with such thick walls?
For the allowable stress values of pipes with a wall thickness greater than 40 mm, you can refer to \"GB 713-2014 Steel Plates for Boilers and Pressure Vessels\" or other relevant material standards, and consult the material supplier for more accurate data. For material such as Q345D, the standard \"GB/T 1591-2008 High-Strength Low-Alloy Structural Steel\" can also be referred to. When dealing with the design of pipes under high pressure and with large wall thicknesses, special attention should be paid to the following points: 1. Temperature effects: Although you mentioned normal temperatures, it is still necessary to consider the impact of possible fluctuations in operating temperature on the strength of the material during design. 2. Pipeline stress analysis: In addition to simple pressure calculations, a more detailed stress analysis should be conducted, including but not limited to internal pressure, bending stress, thermal expansion stress, etc. 3. Welding and joints: Considering that large wall thicknesses may require special welding techniques and weld inspection methods, it is necessary to ensure that the strength of the welded area is comparable to that of the base material. 4. Safety factor: When designing, an appropriate safety factor should be considered to cope with pressure overloads under extreme conditions. 5. Standards and specifications: Design in strict accordance with ** and relevant industry standards; consult professional institutions or conduct third-party design reviews if necessary. Furthermore, given that your system is a high-pressure compressed air system, it is also necessary to ensure that all design elements, material selections, testing procedures, and operating protocols comply with safety requirements and regulatory standards. .
Thank you, sir. For Q345D pipes with a diameter greater than 40 mm, I found the relevant allowable stress values in Appendix A.1 of GBT20801.2-2020, \"Code for Pressure Piping – Industrial Piping, Part 2: Materials\". I would also like to ask: if this air duct is at room temperature, is it still necessary to perform stress calculations? Normally, isn’t stress calculation only performed for high-temperature pipelines?
Even for pipes at normal temperatures, stress analysis is still necessary, especially when dealing with high-pressure systems. Although high temperatures increase the stress on materials due to thermal expansion and reduced strength, high pressure itself also poses a challenge to the structural safety of pipelines. Conducting stress analysis ensures that the pipeline maintains structural integrity and operational safety under various loads, such as internal pressure, environmental stresses, and potential external forces. Here are several reasons why stress analysis is necessary even at room temperature: 1. **Internal pressure**: High-pressure pipelines are subject to high internal pressures, which is directly related to the basic safety and performance of these pipelines. 2. **Support and fixation**: Ensure that the pipes have sufficient support under actual installation conditions, to prevent them from moving or being damaged due to vibrations or other external factors. 3. **Connections and joints**: Pipe connections are often areas where stress is concentrated, requiring careful calculation and design to prevent leaks or breaks. 4. **Impact load**: The system may experience pressure shocks during startup or shutdown, and this sudden high pressure also needs to be taken into account in the design. 5. **Safety standards**: Compliant with **or international safety standards and regulatory requirements for the design of pressure pipelines.** In summary, even at room temperature, conducting a thorough stress analysis is an important step to ensure the safe and reliable operation of high-pressure pipeline systems. It is recommended to use professional pipeline stress analysis software (such as CAESAR II, etc.) for the calculations, to ensure that all potential issues are effectively identified and addressed. .
It’s an AI response; be cautious when evaluating it.
This is considered a GC1 pipeline, and a stress analysis should be conducted.
The range specified by GB150, 304 is 1.5–100 mm.........