Requirements for drilling heat exchanger tube sheets and the purpose of expansion bonding
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Dear experts, I have two questions: First, regarding the expansion fitting of the heat exchange tubes at 151, it is mentioned that this is done to eliminate the gap between the tube and the hole. Are there any requirements regarding sealing as well as a certain pulling strength? If so, how can relevant requirements be specified during the design or manufacturing phase? Second, regarding the drilling of the tube sheet, only the requirements for the hole diameter are specified; are there any requirements regarding the surface roughness of the inner wall of the hole? If so, are level one and level two the same? Are bulging due to adhesion the same as bulging due to strength? What are the requirements for surface treatment of heat exchange tubes regarding bulging?
For gasketed expansion joints, there are no requirements regarding sealing or pull-out strength; these aspects are ensured by the strong welds between the tube sheets. If it is a strength expansion driven by pull-out strength requirements, strength expansion is generally also considered in conjunction with seal welding to address sealing issues.