Assessment Models for Residual Stresses and Sealing Integrity of Rolled Joints in Copper Pipes of Heat Exchangers

Methods for predicting the sealing integrity of “tube-to-tube sheet” rolled joints in heat exchanger systems are explored, the mechanisms of elastoplastic deformation during the formation of rolled joints are investigated, and the main parameters of the mechanical processes of tube expansion that determine the sealing integrity and reliability of the joint components are established. It is demonstrated that the functionality and sealing of the connections formed by mechanical rolling are conditioned by the level of contact stresses in the zone of plastic deformation of the elements. Finite element modeling of the tube rolling process into tube sheet holes with two annular grooves was performed, providing an analysis of the stress–strain state of the interaction zone after contact formation and under operational loads. The key adverse factors affecting the sealing and strength of the rolled joint were identified.