What other effects does a heat exchange tube wall thickness that is less than the value specified in the process specifications have on the heat exchanger, aside from affecting its strength?
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For GB13296-2007, the wall thickness tolerance for heat exchange tubes is +20%; is it acceptable if the tolerance is -10%? If the wall thickness is smaller than the thickness specified by the process, what other effects will it have on the heat exchanger aside from strength issues? For example: shear forces, vibrations, and pulling forces. . .
Let me provide a starting point: for heat exchange, among pipes of the same specifications, the thinner the wall thickness, the better the heat exchange efficiency. But it is necessary to consider whether it can withstand the pipe side pressure.
The tube has become thinner; is the corrosion allowance still sufficient?
This post was last edited by percy_qi on 2011-7-15 at 14:46. Haha, one thing that can have an impact is definitely the lower cost. . . It should also have an impact on those forces, but the specifics are unclear. There’s one more thing I don’t understand: if it’s a pipe that meets GB13296 standards, why isn’t it in compliance? Hehe, I just checked the version 13296-91; the old standard was -10%.
Reply to 3# Waiter: GB13296 should refer to stainless steel, so corrosion might not need to be considered.
This post was last edited and replied to by percy_qi on 2011-7-15 at 14:47. Reply to 2# wangtianyi*ao: I’m thinking about your question regarding the fact that the thinner the heat exchange surface, the better. . . . Why not develop some thinner tubes for certain heat exchangers, such as 25X1.6? . . . Hehe, I took another look at the old standard for 13296, the version from 1991 – specifications like 25X1.5..1.2 can be used. . .
Reply to 1# WAWJ: Hehe, I’ll secretly give you a suggestive conclusion. . . With pipes that have a -10% deviation, there shouldn’t be any problems,… Because according to the old standard GB13296-91, the deviation is -10%. Before the release of 13296-2007, everyone used GB13296-91 for manufacturing heat exchangers, and no issues arose.
In addition to the strength issue, the heat transfer coefficient increases, while the pulling force on the tube sheet decreases; as a result, the calculated thickness of the tube sheet generally needs to be reduced accordingly.
For heat transfer, the thinner the tube, the greater the reduction in total thermal resistance, which is certainly advantageous. However, in terms of strength, the thinner the wall of the tube, the smaller the cross-sectional area of the tube’s inner wall. This not only directly affects the pulling force and axial force on the tube, but also impacts the reinforcement factor K (capital K), thereby reducing the tube’s ability to support the tube sheet, which may ultimately lead to insufficient strength of the tube sheet. It seems we never considered this issue during the design. Speaking of the corrosion of heat exchange tubes, according to the regulations in GB151, corrosion is not taken into account for these tubes ； But in reality, corrosion is inevitable. So, does the tube sheet lose sufficient strength after the tubes corrode? Or has the axial force on the pipe exceeded the limit? I don’t think so either