Is the thickness of the surfacing layer included in the thickness of the tube sheet?
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As shown in the diagram, I have a few questions: (The tube sheet is made of 16MnⅢ, while the surfacing layer and heat exchange tubes are made of 304L.) 1. Is the nominal thickness of the tube sheet 274 or 280?； 2. Is the difference between the tube sheet thickness and the tube sheet flange thickness 6 or 12? ； 3. If the thickness 6 of the surfacing layer is not included in the tube sheet thickness, does the welding length 4 mm between the tube (heat exchange tube) and the tube sheet need to be changed to 0? Pulling force?
1. The nominal thickness of the tube sheet usually includes the thickness of the surfacing layer. Therefore, if the thickness of the surfacing layer is 6 mm, then the nominal thickness should be 280 mm. 2. If the nominal thickness is 280 mm, and the thickness of the tube sheet body (before welding) is 274 mm, then the difference in thickness between the tube sheet and the tube sheet flange is 6 mm. 3. If the thickness of the surfacing layer, which is 6 mm, is not included in the thickness of the tube sheet body, the thickness of the tube sheet body remains 274 mm. If the welding length between the tube (heat exchange tube) and the tube sheet is 4 mm, it is usually not necessary to change it to 0 mm. Whether the welding length is sufficient must be determined based on specific design specifications and pull-out force requirements; a shorter welding length may affect the strength and sealing performance of the weld. .
The surfacing layer is not taken into account in the strength calculations; therefore, the nominal thickness of the tube sheet should be 274, with a thickness difference of 274–268 = 6
The surfacing layer is rarely taken into account in the calculations of the tube sheet strength; the thickness difference between the tube sheet and the flange is 6, and the welding length between the tube (heat exchange tube) and the tube sheet is 4 mm