The plate heat exchanger reduces the aggressiveness of the medium. It can control stress corrosion by removing dissolved oxygen and oxidants in the medium, reducing the mass concentration of Cl- in the medium, and strictly controlling the mass concentration of sulfur in the medium is also a useful method to control stress corrosion. Grasp the corrosion of the plate heat exchanger by the medium of the plate heat exchanger, which can extend the service life of the plate heat exchanger.
In order to prevent the retention of residual liquid and deposits, the structure of the plate heat exchanger needs to be perfected, so double-sided butt welding and continuous welding are used as much as possible when welding to prevent overlap welding and spot welding. 100% of welding wire should be added in the welding process to ensure the formation of the weld. Reducing the residual stress. According to practical experience, the stress that causes stress corrosion cracking of plate heat exchangers is mainly residual stress, and the residual stress is mainly composed of internal stress caused by cold working and welding.
Heat treatment of cold-worked and welded parts helps to eliminate residual stresses and then also helps prevent stress corrosion. Stress annealing heat treatment is often used to eliminate residual stress or other methods to eliminate residual stress, such as hydrostatic test, vibration aging and hammering. In the electrochemical protection method, stress corrosion cracking is the anodic dissolution process under stress. Therefore, it can be controlled by electrochemical protection.
The electrochemical protection method can not only prevent the stress corrosion cracking of the plate heat exchanger, but also can make it intermittently propagate even if a crack occurs under the condition that the protection parameters are selected properly. Optional sacrificial anode protection or surface spraying of corrosion-resistant metal methods. It participates in inhibitors, which prevent the stress corrosion cracking of stainless steel from occurring in the activation potential region. It is necessary to cover them with adsorption inhibitors.