The finite element analysis software ANSYS Workbench is used to analyze the tube shell of shell-and-tube heat exchanger. According to the stress analysis standard JB 4732—1995, the stress intensity of tube sheet under four kinds of transient and steady-state operating conditions which may occur during normal operation, start-up and shutdown are analyzed. The results show that the maximum stress occurs at the junction of the heat exchange tube and the tube sheet and the joint between tube and tube sheet. The main influencing factor of the connection strength between the heat exchange tube and the tube sheet and the connection strength between tube and tube sheet is the pressure load.According to the strength check results, the design of the heat exchanger conforms to the standard of use.

A heat exchanger produced by a company. The tube medium of the heat exchanger is temperature-controlled water, and the shell medium is low-pressure steam. The heat exchange equipment suddenly leaked in less than half a year, causing the equipment to stop. During the maintenance inspection, cracks were found at the tube head of the heat exchange tube, and the cracks were circumferential cracks, and some tubes even broke. Therefore,the chemical composition, hardness, mechanical properties and metallographic structure of the heat transfer tubes were tested and analyzed. The micro-morphology of the crack was observed and analyzed by SEM, and the product of the heat exchange tube fracture was analyzed by EDS spectrometer. The results show that the inclusion is part of the cause of the cracking of heat exchange tube, and the corrosive medium in the heat exchange tube is an important cause of the failure of heat exchange tube. The excessive internal stress in the heat exchange tube is the root cause of the failure of the heat exchange tubes.