Calculation of flange bolts for high-pressure lens pads
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For high-pressure threaded flanges used for sealing lens gaskets, as specified in HG/T20582-2011, when calculating the bolt loads under operating conditions, it was found that the bolts used in ZH-300 flanges and those specified in HG/T20256 standards cannot meet the requirements of the calculation formulas in HG/T20582-2011: https://attach01.hcbbs.com/forum/201409/22/182722s6ymey99eyvqdo1e.jpg Is there something wrong with these formulas? Are they much more stringent than those in the older standards? Operating conditions: 22 MPa; bolts made of 35CrMoA; threaded flanges used, PN260 DN175.
You can try using ASME calculations as a reference; all standards in our country are based on ASME, so there is at least an influence from ASME.
I tried to look for it but couldn’t find it:dizzy:. I only found flat shims; I’m not familiar with ASME standards
There is an issue with this formula; originally it was \(-0.0404\) squared of 315394, but now it’s \(-0.0404\) squared of the design pressure multiplied by the coefficient mentioned earlier. The value obtained in this way is extremely large, and according to current standards, the previous calculation methods were incorrect.
Yes, the value calculated for this part is larger than that resulting from the internal pressure mentioned earlier. What formula are you using for the calculations now?
The new standard should be correct; the minimum bolt load Wp = F + Fp, where F is the axial force caused by internal pressure and Fp is the minimum gasket compression force required under operating conditions. If it is not -0.0404 times the design pressure, then the units will not be consistent. The previous formula was problematic. Calculate using the current formula.
Using the current formula, the bending stress of a standard PN260 flange at 22 MPa cannot be met, and the bolts are not large enough either.
It’s normal for standard flanges to fail the calculations; if you’re interested in giving it a try, not only this flange will fail the checks – many others will as well. I heard experts discuss this issue before. Just choose the one you like.
Also struggling with this; using this formula is terrible – basically, all the results are unsatisfactory.