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Plate heat exchangers are an important component in heat exchange technology for process industry equipment. The elastic gasket used to seal between the various fin plates is a wear part, and it is also prone to aging under natural conditions. Its service life has a significant impact on the service life of plate heat exchangers. If these seals heat-harden and lose their original elasticity, it can prevent the heat exchanger from functioning properly. The following factors have a significant impact on the service life of elastic gaskets: 1. The operating mode of the heat exchanger (continuous or intermittent) ； 2. The heat dissipation medium and the corrosivity of the cleaning agents used ； 3. Maximum operating temperature ； 4. Maximum operating pressure ； 5. The elastic gasket is subjected to high stress due to excessive pressure and uneven pressure distribution ； 6. Natural aging. The softening of elastic gaskets is related to pressure and temperature; when the gaskets lose their elasticity, leakage occurs in the heat exchanger. In some products, in order to address leakage caused by the aging of gaskets, it is possible to adjust the sealing performance of the heat exchangers – that is, to tighten the bolts of the modular plate heat exchangers again and adjust the compression force of the elastic gaskets between the various heat exchangers, thereby resolving the leakage issue. On the nameplate of heat exchangers equipped with this function, the allowable maximum and minimum stresses are generally specified. For new heat exchanger packings, they should be connected and secured using the minimum allowable stress. Depending on the number of heat exchanger fins in each group, the tightening force of the heat exchanger can be adjusted once or multiple times. Each time it is tightened, the nut can be turned in by 3 mm, and attention must always be paid to the stress levels of the fins during the tightening process. Additionally, adjustments to the tightening force are only allowed for heat exchangers that are not under pressure, and this should be done at room temperature in order to prevent leaks. For plate heat exchangers for which the stress adjustment range is not specified on the nameplate, the stress values are generally given in the part drawings. When tightening such plate heat exchangers, the tightening torque must in any case not be lower than the value specified in the drawings, as it is related to the assembly quality and deformation of the plate heat exchanger. When the tightening torque meets the specified value, the elastic gasket can be replaced in a planned manner. For plate heat exchangers used in critical production equipment and in corrosive media, it is recommended to have a set of spare seals. At a warehouse temperature of 18°C, in transparent plastic packaging, the seals of plate heat exchangers can be preserved for about 3 years. In principle, the fixation of seals is divided into two main categories: adhesive fixation and non-adhesive fixation. The shape of the gasket should match the shape of the sealing area in the plate heat exchanger. It must be noted that the adhesive fixing method has no effect on the sealing function. 1. Non-adhesive sealing: (1) Alignment: Place the seal ring in position. (2) Insertion: Guide the seal ring into the sealing groove properly. (3) Compression: The sealing groove has a cross-sectional shape that tapers, which helps to ensure the proper positioning of the seal ring. 2. Adhesive sealing: Depending on the intended use of the gasket and the required quality of sealing, either mixed-type or non-mixed-type adhesives from different manufacturers can be used. Before bonding, the adhesive residue and remaining gaskets on the bonding surfaces should be thoroughly removed using a steam stream. For bonding with harmonious sealants, it is necessary to burn off any remaining adhesive and residual gaskets on the mating surfaces of the plate heat exchanger. When bonding on a large scale, a liquid nitrogen tank for freezing the seals should be prepared, as well as a heating furnace for drying the plate heat exchangers equipped with gaskets. The heating temperature should reach 160°C; if possible, the plate heat exchangers should be chemically cleaned to ensure that any residual gaskets from the bonding materials are completely removed from the joints between the plates. It is possible to determine whether the gasket is installed correctly by observing the cells of the plate heat exchanger. The above content has been compiled based on the problems encountered by trainees in their actual work, for reference only. If you have any issues, please feel free to communicate and provide feedback promptly.