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A tube sheet is a component that involves drilling holes in a steel plate with diameters matching those of the tubes, then inserting the tubes and welding them in place to achieve this function. Heat exchangers can be classified by their structural design into: fixed-tube-sheet heat exchangers and floating-head heat exchangers ； U-tube heat exchanger ； Gland-type heat exchanger. A fixed tube sheet heat exchanger consists of tube sheets at both ends and a shell. Due to its simple structure, it is widely used. A fixed-tube-sheet heat exchanger is an energy-saving device used for heat transfer between materials, and it is a process equipment widely employed in industries such as petroleum, chemicals, petrochemicals, metallurgy, power generation, light industry, and food processing. In oil refining and chemical plants, heat exchangers account for about 40% of the total number of equipment units, and represent 30%-45% of the total investment. In recent years, with the development of energy-saving technologies, its application areas have continued to expand, and the use of heat exchangers for the recovery of high- and low-temperature thermal energy has brought significant economic benefits. During the fabrication of shell and tube heat exchangers, the welding of the tube sheet to the tubes is generally carried out using manual arc welding. The welds suffer from various defects such as depressions, pores, and slag inclusions, and the stress distribution within the welds is also uneven. During use, the tube sheet portion is generally in contact with industrial cooling water, and the impurities, salts, gases, and microorganisms present in this water can cause corrosion to the tube sheet and welds. This is what we commonly refer to as electrochemical corrosion. Research shows that industrial water, whether freshwater or seawater, contains various ions and dissolved oxygen; changes in the concentrations of chloride ions and oxygen play an important role in determining the pattern of metal corrosion. Furthermore, the complexity of the metal structure also affects the corrosion pattern. Therefore, the corrosion of the tube sheet and tube sheet-to-tube welds is mainly pitting and crevice corrosion. Visually, the tube sheet surface is covered with numerous corrosion products and deposits, along with pits of varying sizes. When seawater is used as the medium, galvanic corrosion also occurs. Chemical corrosion refers to the corrosion caused by chemicals. The tube sheets of heat exchangers come into contact with various chemical substances, and as a result, they are subject to chemical corrosion. Additionally, a certain degree of bimetallic corrosion can also occur between the heat exchanger tube sheet and the heat exchange tubes. Some tube sheets are also constantly subjected to the erosion of corrosive media. Especially in fixed-tube-sheet heat exchangers, there are also temperature difference stresses; the joints between the tube sheet and the heat exchange tubes are prone to leakage, leading to the failure of the heat exchanger. In the calculations for fixed tube sheets, the axial stress of the shell, the axial stress of the heat exchange tubes, and the pulling force q between the heat exchange tubes and the tube sheet are determined under various operating conditions with temperature differences. If any of these values fails to meet the strength (or stability) requirements, it is necessary to install expansion joints. In the strength verification calculations for fixed tube sheets, once the thickness of the tube sheet is determined, if no expansion joints are used, the strength of the tube sheet may be insufficient; however, by installing expansion joints, the required thickness for the tube sheet can be achieved. Introduction to Cangzhou Shangtai Pipeline Co., Ltd