On the design calculations for flanged flanges
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I need to design a high-pressure vessel with a design pressure of 14.4 Mpa. The upper end of the spherical head is required to be connected using a flanged fitting. While performing the calculations in accordance with HG/T20582, I noticed that older versions of this standard did not specify any pressure range limits, whereas the newer version HG/T20582-2011 stipulates that the calculation pressure should not exceed 5 Mpa. I’m confused about this – all the previous calculation sheets were prepared based on HG20582, but how should I carry out the calculations now? Should we still refer to HG20582? I found a new GB150 standard, but it doesn’t contain any calculations or checks related to flanged connections. Please help me out, experts!
As explained on page 394 of HG/T20582, calculations can be carried out in accordance with this method; however, the results obtained will be conservative.
What you mentioned is the explanation regarding the calculations for flanged flanges as specified in HG/T 20582-2011; this explanation clearly states the reasons for the specified pressure range. So, can the flanged flanges of my current equipment be calculated in accordance with HG20582-2011? I asked our senior engineer today, and she also said she had doubts and was quite conflicted
HG/T 20582-2011 uses the calculation formulas for slip-on flanges as specified in GB150 for the calculation of flanged connections; it does not take into account the reinforcing effect of end caps. In cases where high pressures are involved, this approach is rather conservative, and analytical design is recommended.
Since the calculation results are relatively conservative, it may not be necessary to address the issue using analytical design methods.
When the pressure is high, there is a significant deviation from the calculation model; the calculated flange thickness is too large, and it is not appropriate to use this calculation method. In this method, the local stresses at the junction between the head and the flange are not checked, and at high pressures, when the head is thick, higher bending stresses occur at this junction, so a more reliable design approach should be adopted.
Is it necessary to have relevant qualifications to conduct stress analysis? Are there any other design methods to solve this design problem?