Considering the difference in hardness, what materials can be used for the heat exchange tubes 304 and the tube sheet for expansion jointing?
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Considering the difference in hardness, for heat exchange tubes made of 304 steel, expansion joints are used to connect the tube sheet to the tubes. What materials can be used for the tube sheet? Is 16MnR suitable? And is the Q235 series appropriate? This post was last edited by weilegongzuo on 2009-3-31 at 14:07
I don’t know the specific hardness values, but 1.2mm thick 304 pipes with diameters of 19, 25, and 32 can be used together with 16MnR and Q235-B without any issues regarding strength, as we have used them all before.
The heat exchange tubes are made of stainless steel; why then is the tube sheet made of ordinary carbon steel? It would be better if it were also made of stainless steel.
I would like to ask what the expansion joining process is. Is welding required after expansion joining? Is expansion joining only used in situations where pressure is not high? Please advise
Stainless steel is used for the heat exchange tubes only due to considerations related to the medium; if it is difficult to clean the tube bundle, stainless steel is employed. For the specific scope of application of expansion jointing, refer to the contents of GB151.
Q235 cannot be used for compression components; the requirements for tube sheets are higher than those for tubes. Depending on whether the fluid is corrosive, tube sheets are generally made from forgings.
For stainless steel pipes, use 16MnR; Q235 is not suitable as its hardness is insufficient
The tube sheet is selected based on operating parameters and the properties of the medium. If there is a mismatch in hardness between the tube sheet and the tubes due to expansion bonding, the tube ends can be heat-treated. If a non-stainless steel tube sheet is used, a stainless steel layer can be welded onto its surface.