During the production process of stainless steel heat exchange tubes, cracks appear on the surface. The reasons may be as follows:
1. Contact with chloride
Stress corrosion occurs when stainless steel heat exchange tubes come into contact with various chlorides or chloride-containing solutions, nitric acid, nitrate, hydroxide, hydrofluoric acid, hydrogen sulfide aqueous solution, polythionic acid, sulfuric acid, sulfurous acid, etc. cause surface cracking.
2. Residual stress
The residual stress of the material produced by the stainless steel heat exchange tube during welding, heat treatment, and thermal processing, as well as the assembly stress during installation, and the pressure difference and temperature difference inside the tube during operation will cause mechanical stress and thermal stress, thereby causing the steel tube to produce tension. stress. The greater the residual stress, the more prone to stress corrosion cracking of stainless steel heat exchange tubes.
The method to solve the cracking of stainless steel heat exchange tubes should be analyzed from the stress, transportation medium and working conditions.
1) Stress concentration and gap generation should be avoided, and the welding process should be improved.
2) Strictly control the water quality conditions. When the Cl- concentration and oxygen content increase and cannot be reduced within a few hours, the equipment should be stopped immediately.