Do you include the thickness of the convex surface when calculating the thickness of the flange and flange cover, as shown in the figure?
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0240550093.jpg When you calculate the thickness of flanges and flange covers, does the calculated thickness include the convex surface thickness? As shown in the figure, if the calculated thickness is 8mm, the convex surface thickness is 2mm, and the corrosion allowance is 0, then is the nominal thickness 8mm or 10mm?
Include it, the software seems to automatically get the value online, so give it more margin.
Please look at GB/T150.3 Table 5-9 No. 9, and you can clearly see where the effective thickness refers to.
The flange plate does not consider the thickness of the boss, regardless of its strength or stiffness calculation.； Non-surfacing flange cover considers boss thickness ； The cladding flange cover considers the difference between the thickness of the boss and the thickness of the cladding layer (such as RJ surface). In short, the flange cover considers the moment of inertia of the cross section. The contribution of the boss to the moment of inertia should be considered. If the surfacing layer does not participate in the strength calculation, the contribution of the surfacing layer will not be considered, so a conservative calculation can be made, although the surfacing layer must have contributed to the moment of inertia.
The effective thickness of the flange does not include the flange step. Please refer to Figure 7-1 in GB/T150.3. The effective thickness of the flat cover is the thickness of the section that bears bending stress, so the effective thickness of the flat cover should be the thickness within the sealing surface.