Discussion on the area of the SW6 diaphragm groove
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The last edit to this post was made by jizhanwei22 on 2016-6-22 at 09:01. When using SW6 to calculate heat exchanger tube sheets, it is generally necessary to enter the \"separation groove area\"; of course, we use the Ad value specified in GB/T151-2014, which refers to the area at the layer separation point of the tube sheet. Personally, I think naming it SW6 (separator groove area) can cause confusion. Regardless of the difference in naming from GB/T151-2014, if partition grooves are also required on the tube sheet for the layering partitions of the shell, should the area of those partition grooves take into account the area of the partition grooves in the shell as well? (Question 1) If it needs to be taken into account, how should it be calculated? (Question 2) Personal understanding: Generally, the split diaphragm grooves in the shell side are located on the back side of the tube side. If the pipe stage was originally two stages, there is no need to consider it again. If there is one pass in the tube side and two passes in the shell side, the area of the partition groove can be calculated using the method applicable to the tube side. The above are personal interpretations. Welcome marine enthusiasts to discuss.
It is recommended that the original poster carefully read the sections of GB151 related to gasket plate calculations
:I don’t think it’s possible to have baffle grooves on both sides of the tube sheet at the same time. Although shell-side baffle grooves have not been seen yet, it is conceivable that such grooves might appear in U-tube heat exchangers where the tube sheet is integrated with the tube box. ;P
If you know it, say you know it; if you don’t know it, say you don’t know it. I didn’t oversee the plate calculations – how did I notice this problem? I post discussion threads so that everyone can share their opinions.
This post was last edited by jizhanwei22 on 2016-6-22 09:01. Generally, the partition grooves for the shell side are located on the back side of the tube side. If the pipe stage was originally two stages, there is no need to consider it again. If there is one pass in the tube side and two passes in the shell side, the area of the partition groove can be calculated using the method applicable to the tube side. The above are personal interpretations.
I haven’t seen it, but I can’t deny that such a structure exists; I have worked on structures of this kind before. There are 4 tubes in the tube side and 2 tubes in the shell side. When calculating the area of the partition grooves, it is the sum of the areas of the partition grooves on the tube side and those on the shell side.
This is related to the number of stages and the stage division structure of the two processes; if they are the same, only one side needs to be considered, eliminating the need for repetition. For example, if both sections are double-pipe sections with the partition at the same position on both sides, but if the positions are different, the values need to be added together and the duplicate parts removed.
This post was last edited by jizhanwei22 on 2016-6-22 09:31. It actually has nothing to do with the baffle grooves; it’s just that since the tube bank is divided into sections, baffles need to be installed. In GB/T151-2014, whenever there is a tube box partition, the tube sheet must have partition grooves. In fact, the definition of Ad is the area at the partition of the tube sheet, namely the area that is not supported by the heat exchange tubes. Imagine that if the tube bank has no stratification and only shell-stage separation, and the shells employ not only partition grooves on the tube sheet as a connection method, but also welding, bolted connections, etc., that is, without partition grooves. Can the Ad value be ignored in tube sheet calculations? Obviously not; therefore, the area of the partition groove entered for SW6 is not something that is entered only for partition grooves. There are no partition grooves, but they still need to be entered as long as there is stratification (for example, the longitudinal partitions of the shell layer can have grooves or not). The above is my personal understanding.
I fully agree with what this engineer said; once you understand the calculations, you will naturally comprehend the area of the partition grooves and the method for calculating it. The area of the baffle grooves is calculated in order to determine the piping area; piping is arranged outward from the center, deducting the area of the baffle grooves. The larger the area of the baffle grooves, the larger the area around the center where no piping is placed. Moreover, as the diameter of the piping increases, the stress at the edges of the tube sheet changes. Therefore, the area of this partition groove should strictly speaking be the area without pipes, which naturally includes the area occupied by the longitudinal partition on the back side, as well as the area occupied by the dummy pipes.
The calculation of the area of the tube sheet partition grooves consists of three parts: one is the area at the partition location, one is the area supported by the tie rods (a square has a central moment related to its side length, while a triangle or hexagon is related to its incircle), and one is the area that supports the heat exchange tubes (the content of this area is the same as that related to the tie rods)； In the areas where there are partition grooves, there will definitely be no rod or tube support, whether it’s a shell and tube design or not. Therefore, the actual area of the partition grooves, according to GB151, is not necessarily equal to the sum of the areas where the heat exchange tubes are supported; this also lays the foundation for more accurate calculations of the equivalent diameter later on. The piping area in question is then equal to the sum of these three areas. OK
This question is quite complicated. Read the book and its explanations carefully.