Pipe wall thickness calculation
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This post was last edited by hao0923 on 2019-1-21 at 11:38. Calculation of steam pipe wall thickness: DN200, outer diameter of the pipe Φ219. Design temperature: 475°C, design pressure: 4.1 MPa; material: 12Cr1MoV (GB5310). Corrosion allowance: 1.5 mm; machining depth: 0.5 mm; negative deviation: 12.5%. Using GB50316 for the calculations, the resulting wall thickness is 7.69 mm. The actual wall thickness chosen is 9.0 mm; I’m not sure if this is reasonable. I would appreciate advice from those with more experience.
What size of pipe? We need to consider the actual standards
DN200, outer diameter 219. I’m not sure what is meant by considering the standard in practice
Please take into account the actual thickness of the corresponding size in the standards, unless it is a non-standard tube; otherwise, that’s another matter
If the pressure selected for calculating the wall thickness is 4.1, then the wall thickness might not be appropriate
What pressure should be chosen? Shouldn’t it be the design pressure that’s chosen?
Since flanges and valves are also required, these components have specific pressure ratings. Moreover, as the temperature rises, the allowable pressure decreases. In other words, the flanges and valves chosen should have a minimum pressure rating of PN63. The allowable stress at room temperature for 12Cr1MoV, multiplied by 4.1 MPa, gives 147/92*4.1 = 6.55 according to GB50316; according to GB/T32270-2015, it is 157/124*4.1 = 5.19
Selecting based on the table in the attachment should be no problem!
Based on the calculated values, the pressure class is determined; the wall thickness is then calculated using this pressure class. The adequacy of the wall thickness can be verified by checking against the allowable stress at the design temperature and the design pressure. Of course, if there are only pipes, then this calculation will work as well.
It’s different from what I calculated. My theoretical wall thickness is 6.1, while the calculated wall thickness is 9.3. Let’s check it again using the formula
The key to wall thickness calculation here is the selection of the allowable stress at 475 degrees. Under clause 475 of GB50316, the value is 72; at normal temperature it is 128. The calculated values are 9.35 respectively. The pressure testing situation also needs to be considered here. The pressure value is 11.09. The calculated wall thickness is 12.76; it can be rounded to 13 mm