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Corrosion type of plate heat exchanger
Source: Time: 2020-06-18 14:33:13 Hit:
In the use of plate heat exchanger units, the problem of failure due to corrosion and failure to complete heat exchange often occurs. Only by understanding the cause of corrosion can we better solve the problem. Yuanzhuo equipment will help you answer the plate heat exchanger corrosion.
1. Crevice corrosion:
A localized corrosion in the form of spots or ulcers caused by the effect of "occlusion battery corrosion". The main difference of the same pitting corrosion is that the corrosion occurs in the gaps of metal parts, which is caused by the electrochemical non-uniformity of the retention medium. For example, the corrosion at the groove bottom of the gasket or the outside of the corner hole gasket of the plate-type heat exchanger unit closed flow channel;2. Pitting:
A kind of local corrosion caused by the effect of "occlusion cell corrosion"-destroys the passive film on the local metal surface, forming a perforation or etch pit less than 1mm in size. For example, where the surface of the stainless steel plate is rusted or scaled (carbide, silica scale layer), corrosion due to poor thermal conductivity and reduced pH of the medium;
3. Stress corrosion cracking:
Under the combined action of static tensile stress and electrochemical medium, the local corrosion cracking or fracture of the metal caused by the cathodic dissolution process. For example, the plate-type heat exchanger unit will produce residual internal stress during press molding. If it contacts with halogen ions (such as Cl -, F-plasma) or H2S in the medium, it may cause stress corrosion cracking;
4. Intergranular corrosion:
Corrosion that originates from the metal surface and penetrates along the grain boundary to the inside can cause the loss of bonding force between the grains and greatly reduce the strength of the material. For example, the corrosion of stainless steel in the allergic temperature range (400℃~600℃);
5. Uniform corrosion:
The phenomenon that all or most of the metal surface in contact with the medium is corroded. For example, the plate material of the plate heat exchange unit is not selected properly, or the service life is too long, which exceeds the allowable service life;
6. Other corrosion failures:
There are mainly dew point corrosion, abrasion, microbial corrosion, etc. For example, hot steam containing acidic substances can contact the cold plate and cause dew point corrosion; the flow rate of the medium inlet corner of the plate and the diversion area is too high, or the fluid contains sand particles, which can cause abrasion; Algae, bacteria, and protists in seawater can cause microbial corrosion of the plates.
Knowing the type and cause of corrosion of the plate heat exchanger unit, we can take different measures to prevent or deal with the corrosion phenomenon for different reasons. Yojo is a heat exchanger supplier, launching a variety of plate heat exchanger types, we look forward to your arrival.
Tag: Yojo, heat exchanger supplier, Yuanzhuo equipment, plate heat exchanger type
