Questions about tube sheet material substitution
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When designing a heat exchanger with a diameter of Φ3200 (refer to GB151-98), the final nominal thickness of the tube sheet is 100mm, and the initial tubesheet material is 16Mn IV. However, the equipment manufacturer reported that the minimum thickness of forgings with this diameter when forged with a 10t hydraulic press is 300mm, so it can only be reduced to 100mm by machining, resulting in a large waste of material. The manufacturer recommends using Q345R normalized plate instead of forgings. After comparing the strength and allowable stress of the two materials, there is not much difference. However, when I saw the recommendation of GB151, it said that "tube sheets with a thickness greater than 60mm should be forged.” ； “When the tube plate itself has convex shoulders and is connected to the cylinder (or head), forgings should be used." The tube plate meets the above two conditions. I wonder if it can be replaced by a steel plate? In addition, I don’t know much about the manufacturing of equipment. I ask the masters to clarify whether what the equipment manufacturer said is correct! ! Many thanks! !
The standards on 150 and 151 are too outdated and have not been updated in eleven years. The thickness of the current Q345R can reach 200mm. Below this thickness, forgings are used for plates with a thickness of more than 200. For example, our company has designed a 320mm tube plate that is a forging.
Yes, I heard that GB151 and GB150 seem to be updated. I don’t know if they will be corrected by then.
I personally think that as long as 100% testing is carried out and the steel plates used are free of defects, they can be used. 150 and 151 should actually be changed.
Thank you friends upstairs for your help. I just carefully read the standard interpretation of GB151-1999, and it says:: “The steel plates used to manufacture tube sheets and flat covers should be steel plates for pressure vessels that comply with the regulations of GB150-1998. When the design pressure is ≤1.6MPa and the design temperature is 0-350°C, GB151-1989 stipulates that 16Mn can be used to manufacture tube sheets and flat covers. Considering that the supply of 16MnR steel plates is good, the supply thickness of GB6654-1996 "Steel Plate for Pressure Vessels" can reach 120mm, and GB151-1989 also stipulates that re-inspection of 16Mn is very troublesome, so the provisions for 16Mn steel plates to be used as tube sheets and flat covers were canceled when this standard was revised." According to the above description, it should be understood that GB151-1998 cancels the provisions of steel plates used as tube sheets and flat covers, is it not allowed? It is still allowed, but the steel plates used as tube sheets are not re-inspected? This post was last edited by yakui on 2009-3-6 22:26 ]
It can be replaced by Q345R normalizing plate. GB151 is only recommended and not mandatory. We have designed many pressure vessels. The current dividing point is that forgings above 120mm are used, and 16MnR normalizing plates are used below.
personal understanding: Q345R can be used, but it only needs to be used in the normalizing state.
The standard is that forgings should be used. I don't know why the forging factory said that such forgings can only be forged to a thickness of 300mm. Is there really an insurmountable factor that causes it or something. It is not impossible in theory to use plates, but the internal structure of such thick plates is relatively loose, and the mechanical properties between the interior and the surface are quite different, so it is recommended to use forgings. If the board is reliable, I personally think it is usable.
I agree with Wen Bing's opinion. For tube sheets over 60mm thick, the standard uses "appropriate", which means that it is best to use forgings. However, if you strengthen the inspection and ensure the internal quality of the sheet, it does not mean that it cannot be used. However, when the tube sheet itself has convex shoulders and the cylinders are butt connected, forgings should be used.