Study On Expansion Technology Of Tube To Tube-sheet For Heat Exchangers Of Nuclear Power Auxiliary System

Heat exchanger is very important for nuclear power station auxiliary system, leakage accidents often occur with serious consequences on the safety and reliability of the nuclear facility. The stress corrosion crack of tube to tube-sheet joints is the main cause of leakage accidents due to the residual stress produced during manufacturing process. Therefore it has very important significance to study the residual stress level of the tube to tube-sheet after manufacturing process to improve manufacturing process and prevent leakage accidents.On the basis of present research achievements, through reasonably simplifying calculation model and using the material elastic-plastic theory, the theoretical calculation formula of residual contact stress is deduced under certain expansion pressure in this paper. The comparison of calculation results and simulation results verify the accuracy of the formula. Then through the numerical simulation and stress corrosion test, we have a deep understanding of the stress distribution of the inner and outside surface of the tube, the results of the theoretical calculation are in accord with the experimental data.This paper can not only be used as a theoretical basis of choosing the expanding pressure, and predicting the residual stress levels reasonably after expanding but also has an important theoretical scientific value and clinical significance to choose the best expansion parameters and prevent the stress corrosion of the expansion joint.