Concave-convex surface sealing for vertical fixed-tube-sheet heat exchangers
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Vertical fixed-tube-sheet heat exchangers use concave-convex surface sealing: the upper tube sheet is designed with a concave surface to match the seal, while the flange of the upper tube box has a convex surface; however, in many vertical heat exchangers, the tube sheet is made with a convex surface. Is a convex-shaped seal on the upper tube sheet not as good as a concave-shaped seal? If the medium handled by the pipeline is extremely hazardous, does it necessarily have to be designed with a convex upper part and a concave lower part? Can this be chosen simply based on the medium requirements?
The male and female surfaces are designed to fit together; it doesn’t matter whether the tube sheet flange or the tube box flange is made with a male surface or a female surface, as long as they match. As for the type of sealing surface to use, it depends on the pressure – at higher pressures, in order to ensure a good seal, flanges with male and female surfaces are certainly better than those with flat welds. Regarding the medium flowing through the system, the material of the gasket chosen depends on that medium. If you need it, I can provide you with some information on flanges; just send me an email
Does making the tube sheet concave mean it has become thinner? For the tube sheet with a bulged surface, it is sufficient to thin out the perimeter. Does a concave tube sheet require thicker material? I’m not sure if I misunderstood
You’ve misunderstood; the thickness of the tube sheet is calculated using formulas, it’s not something that’s determined arbitrarily.
If the tube sheet thickness is calculated to be 20 mm, and you want to make it a concave flange, does that require material that is thicker than 20 mm in order to achieve that? If the tube sheet is made as a raised-flange type, can it be created simply by trimming the edges of a 20 mm thick plate? What I mean is that when the concave and convex surfaces of the tube sheet are placed opposite to each other, there is a difference in the amount of material used
Among the fixed-tube-sheet heat exchangers I have encountered, I have really never seen a tube sheet that is concave. There is no need for the connection between the tube sheet and the flange to follow the principle of the upper part being concave and the lower part being convex, right? If what you say is correct, when calculating the tube sheet, how do you enter the value of \"the difference between the thickness of the tube sheet and that of the tube sheet flange\"?
I’ve never seen anyone make the tube sheet sealing surface concave...
Perhaps there is a problem; I think what the original poster said is different from what we are discussing. It’s weird too that a pit has to be made in the tube sheet’s concave surface.
Related to the difficulty of machining, deviations occur after processing the convex surfaces; these can be addressed by machining on the tube box, thereby reducing management risks.
This structure is indeed rare, so I’m not sure either. The medium is VCM; it is considered to have moderate hazard, but leakage due to sealing issues turns it into a highly hazardous substance. That’s why this issue is being considered. This statement is on 20660. Thank you all for your replies.