Issues with the dimensions of the tie rod holes in heat exchanger tube sheets
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Recently, while designing a fixed-tube-sheet heat exchanger, I encountered such a problem: the tube sheet that I designed was quite thin, around 30 mm thick. In accordance with the requirements specified in GB/T 151-2014, for heat exchange tubes with a diameter of 25 mm, I used rod holes with a nominal diameter of M16. Following the specifications in 151 P24, I designed the rod holes; however, the remaining thickness t of the tube sheet after drilling those holes turned out to be quite low – approximately 4 mm, as shown in the diagram below. Is this acceptable? Do I need to increase the thickness of the tube sheet? Also, what is a suitable value for this thickness t? Thank you.
One approach is to weld a gusset plate at the location of the tie rod.
The heat exchanger I’m designing now is quite small, around 400 in size. It’s possible to thicken the tube sheet slightly, but I’m not sure by how much would be appropriate; that’s why I’m seeking advice from everyone
Thank you, that’s a good idea. Are there any specific requirements regarding the dimensions of the gasket plates? How are they welded to the tube sheet – is a direct fillet weld sufficient?
Another option is for the poster to choose a rod with a smaller diameter. Then, follow the standard recommendations for the diameter and quantity of tie rods to calculate the supporting area, and from that, determine the number of tie rods with the smaller diameter you have chosen. Secondly, it is to appropriately increase the thickness of the tube sheet.
This post was last edited by sunhe0310 on 2015-11-17 at 16:57. I’ve learned something new; thank you. I’m a beginner in heat exchanger design; I hope to receive your guidance in the future. Just to ask further, what is a suitable minimum value for this t-value?
At the point where it is screwed into the tube sheet, a M12 thread is sufficient.
There is no specified requirement, but the minimum value must not be less than the outer diameter of the heat exchange tube or the minimum thickness of the tube sheet as required by standards. Personal experience
After designing it according to GB151, the current t-value is only 4 mm – is that a bit too small? What is the minimum value it should be increased to?
The design of this device is being developed rather urgently at the moment, so I can only wait online for everyone’s suggestions. Thank you all
What size should the tie rod be, and what is the diameter of the tube sheet? Given the thin thickness of the tube sheet as you described, aren’t you concerned about, or have you not considered, the deformation of the tube sheet during welding?