The thickness calculation for the tube sheet, which also serves as a flange, takes into account the reduction resulting from the grooved areas
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Dear teachers, regarding the tube sheet structure of the heat exchanger shown in Figure 1, in cases where hc > h1 + h2, should m1 or m2 be used when calculating the thickness of the extended portion of the tube sheet that also serves as a flange? – When deducting the groove depth, should it be hc or (h1 + h2) that is deducted? ——Is the determination based on whether the slotting position starts with “” and lies within the range of the combined flange width d=(Df-Di)/2? ——When calculating the flange thickness, the groove depth and cut depth within the range of d=(Df-Di)/2 need to be deducted; whereas grooves outside this range do not require such deduction? Specifically, as shown in Figure 2, the tube sheet is divided by Di; the annular region from Di to Df constitutes the combined flange portion, while the area up to Di belongs to the tube sheet portion. Therefore, the strength verification for the combined flange is carried out only for the annular region from Di to Df. Thus, the calculation of the thickness of the combined flange depends solely on the grooves and steps within this annular region; the grooves in the area up to Di have no impact on the calculated thickness of the combined flange. Is that correct?
When calculating the thickness of the tube sheet extension that also serves as a flange, m1 should be used as the thickness. To subtract the grooving depth, (h1+h2) should be deducted. The decision on whether to subtract the grooving depth is determined by whether the grooving position falls within the range of the combined flange width d = (Df – Di)/2. When calculating the flange thickness, only the groove depth and cut depth within the range of d=(Df-Di)/2 need to be deducted; grooves outside this range do not require such deduction. Your understanding is correct; the strength verification for the combined flange is performed only on the annular section from Di to Df, and the grooving in the tube sheet has no impact on the thickness calculated for the combined flange. .
The split diaphragm groove is level with the sealing surface
It’s actually flush. The assumption in the question that hc > h1 + h2 is merely to discuss whether, for a tube sheet that also serves as a flange, the groove depth should be reduced beyond the range of d = (Df – Di)/2; in reality, the position where the gasket is installed is such that hc = h1 + h2.
This post was last edited by wanlirn on 2024-5-8 at 16:37. It refers to the minimum thickness of the tube sheet flange; it’s not as complicated as you think. GB150 is based on an empirical approach – you can’t calculate things like the 3mm thickness of the sealing surface, or determine where the stress levels decrease. Therefore, the minimum thickness is used as a guideline. Of course, this doesn’t include stress grooves, which have nothing to do with tube sheet flanges