Regarding the calculation data error of SW6 medium-B flange
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I was making a non-standard flange today. I originally wanted to refer to the data of Type B flange, but I accidentally discovered an error in the calculation of Type B flange of SW6. Regarding the shear plane height, the data given in SW6 is inconsistent with the calculation of GB150.3, see the screenshot.: SW6 is based on the length of full penetration, and the actual shear surface length of Type B flange should be l, that is to say, it should be 20 here, not 84. Therefore, if you use Type B flange and need to calculate it (for example, using stainless steel material), you need to pay attention to the correctness of the data when calculating SW6.
This post was last edited by zjq1962 on 2018-12-20 15:50. This is to calculate the Type B flange as an integral flange. If it is calculated as an arbitrary flange, it will be the same as hijk in GB150.3. The Type B flange in the flange standard does not have full thickness penetration, so the software is not wrong.
This post was finally edited and marked by yechao25038 on 2018-12-20 16:04, waiting for everyone to discuss the results: lol. I have never used Type B flange. Under what circumstances would I consider using Type B flange?
This also leads to a question. If the Type B flange is calculated according to the arbitrary flange, it will be no different from the calculation of the Type A flange. The influence of the barrel section on the flange calculation is not used in the calculation. This is just a simple calculation. So I think the most reasonable calculation should be based on the integral flange (1) in SW6. Article 7.4.4 in GB/T150.3 also states that if the calculation is based on the integral flange, it should be calculated according to Table 7-5.
This is relatively easy to identify. The software automatically classifies the B-type flange to the integral flange, and the screenshot shows an arbitrary flange, which means that the two l values are destined to be different. If the cylinder remains unchanged, the thickness of the flange ring may need to be adjusted.
The software is indeed calculated based on the integral flange. There is no problem in calculating based on the integral flange. GB150.3 also said that this kind of structure is calculated based on the integral flange, but the calculation method is based on the entire body. However, the value of the shear plane calculation height l here is not reasonable based on the l value of the integral flange.
I didn't question that the calculation based on the integral flange was incorrect, but I had doubts about the value of the shear plane height. Do you think the value of the calculated height l of the shear plane should be based on the value of l of the overall flange, is it reasonable?
This post was last edited by zjq1962 on 2018-12-21 08:35. The SW6 software indeed automatically selects the flange calculation mode shown by the original poster, which is the same as the g diagram in Figure 7-1 of GB150.3. Type B flange is an arbitrary flange. According to the data given in the standard, it does not meet the conditions for simple calculation as a loop flange (δ0≥16), so it is calculated as a whole flange, and its structure is closest to the g diagram in Figure 7-1 of GB150.3. The view section and the flange ring are jointly stressed.
My question is, the height in the calculation only includes the weld. Why does the flange standard specify the height of the barrel section?
150.3 stipulates that arbitrary flanges are calculated as integral flanges, but the shear plane height should be selected according to the respective flanges, right? The picture shows an example of Type B flange in the "Pressure Vessel Engineer Design Guide". The calculation results show that the effective thickness of the flange is 195mm.
This calculation example is not calculated based on the shear surface length of the integral flange of the full welding head, but the length of 80 is not the same as the length of l in the structural form given in NB/T47022.