【Weekly Technical Discussion Thread】Issues with threaded connections of thin tube sheet tie rods
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The last edit to this post was made by penryn on 2011-9-6 at 13:04, changing it from Yu Rou’s version. Let me start by explaining my situation: I’ve been working on a heat exchanger recently, and one of the issues involved the design of the tube sheet. The calculated thickness was 20, with the tube sheet also serving as a flange; however, in the end a thickness of 30 was chosen. The tie rods are connected using threads, and according to standards, the thread holes in the tube sheet should be 26 in diameter. Additionally, the drilling angle is close to 30 degrees, which means there’s a risk that the tube sheet might get punctured. I’m not sure how to resolve this issue
The threaded connection can be replaced with a welded one. ;P
I was wondering if you could send me the process conditions for the heat exchanger, so that I can do some calculations as well. The tube sheets with twenty-some tubes are too thin; it seems like I don’t have enough design experience – after all, one doesn’t gain much knowledge without seeing many examples
When we encounter this problem, we drill threaded holes in the tube sheet at intervals of 20 units to prevent penetration, or we thicken the tube sheet; the minimum thickness is 35 units
:o This little pull rod doesn’t necessarily have to be inserted into the tube sheet; it should work fine if welded to the outer surface of the tube sheet as well. . .
Reply to 5# yuri714: Those that are welded in also need to be inserted, but the depth should be shallow.
Reply to 6# penryn :lol Why? . . Give a reason first: hug:
Some are punctured; then the rod holes that have been punctured are welded shut
Reply to 7# yuri714: Well, that weld will crack easily then.
For the structure of thin tube sheets, the following approach can be adopted: if the tie rods are made of the same material as the tubes on the tube side, it is entirely possible to drill through the holes in the tie rods so that the tie rods are exposed, with fillet welds formed； If the tube is made of stainless steel and the tie rod is made of carbon steel, it is also possible to drill through the hole in the tie rod, but without exposing the tie rod itself, by performing a plug weld.
Reply: There are two types of pull rods specified in GB151 for 1# penryn. Tubesheets that are this thin are not suitable for threaded connections; it’s better to use welded pull rods. The specific dimensions and structure are clearly described in GB151.