A管 plate is an accessory that involves drilling holes in a circular steel plate. The tube plate is slightly larger in diameter than the tube, and the tube is then inserted and welded to secure it. In the calculation of tube plate fixation, if one of the following—shell axial stress, tube axial stress, or the tensile force between the heat exchanger tube and the tube plate—does not meet the strength (or stability) requirements under various working conditions, it is necessary to employ an expansion joint. In the strength calculation of fixed tube plates, if the tube plate thickness is determined without setting an expansion joint, the tube plate may not be strong enough. After installing the expansion joint, the tube plate thickness can meet the requirements. At this point, an expansion joint can also be set to make the tube plate thinner, but it must be determined through a comprehensive evaluation (material consumption, manufacturing difficulty, safety, and economic effects).