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The Breech Lock Closure Type High Temperature, High Pressure Heat Exchanger was first developed jointly by the American company Chevron and the Japanese company Chiyoda. It is currently a widely used heat exchanger design in high-pressure hydrogenation units. This type of heat exchanger features an integrated tube-and-shell structure; at the ends of the tube sheet, a sealing disc with a flexible section is used to isolate the fluid from the outside environment, while the threaded lock rings are connected to the ends of the tube sheet via large trapezoidal threads. The sealing between the tubes and the shell side of the heat exchanger is achieved by tightening the inner ring bolts, which causes the flexible sealing disc to deform and press against the positioning ring, the inner sleeve, and the shell of the split-case structure, thereby compressing the gaskets on the tube side of the tube sheet; these gaskets prevent short-circuiting of the fluid flowing on the tube side. The inner ring bolts bear only the differential pressure between the tubes and the process side, as well as a small portion of the axial force exerted by the process fluid ； The sealing of the medium in the tube side of the heat exchanger is achieved by using outer ring bolts to compress the sealing disc, thereby deforming the gasket in the tube box. In addition to bearing the reaction force from the gasket, the outer ring bolts also only bear a portion of the axial force; as a result, the load on the inner and outer ring bolts of the heat exchanger is low, and their diameter is small as well. The axial force generated by the tube side medium is primarily borne by the flexible sealing disc, as well as the threaded locking ring and the tube box cover. All the axial forces generated by the medium between the tube and the shell, as well as the reaction forces from the gaskets, are transmitted to the tube sheet cylinder body through the large trapezoidal threads of the threaded locking ring.