The reason of corrosion phenomenon of plate heat exchanger and its maintenance

Corrosion is a complex chemical phenomenon, which is also the main reason of plate plate scrap. The corrosion phenomenon of plate heat exchanger is mostly caused by Cl- stress corrosion, which often occurs at the bottom of the seal groove and the bottom of the dirt. So what are the causes of corrosion phenomenon?

The main reason of corrosion phenomenon of plate heat exchanger

1, stainless steel heat transfer plate is composed of a mechanical stamping, inevitably a certain amount of residual surface residual stress, the stainless steel sheet does not contain molybdenum, eliminate the surface residual stress is very difficult, even is not feasible.

2, the harmful elements in the bottom of the sealing groove is often the binder in the Cl- due to the analysis of the temperature rise. Such as neoprene adhesive, compressed asbestos (containing CaCl2), often in the water and steam conditions, the precipitation of the enrichment of Cl- and H+ formation of HCl, so that the bottom of the slot at the crack stress cracking. Under the condition of surface residual stress, Cl- enrichment and temperature, the stress corrosion cracking may occur after a certain corrosion incubation period. In the process of material selection, installation and use of the plate heat exchanger, it is possible to prevent or delay the occurrence of corrosion, so that the equipment can run normally and safely. To this end, the correct selection of materials, regular scaling to destroy the formation of corrosion conditions and incubation period, the use of non chlorine elements of the adhesive, which can effectively prevent the stress corrosion to a certain extent.

3, the board after the formation of a multi slit structure, such as the contact between the plate, the bottom of the sealing groove and other parts. The gap is easy to cause the enrichment of Cl-, and the local enrichment is far more than the ability of stainless steel to resist stress corrosion.

4, when the surface of the surface of the dirt is serious, the medium of corrosive elements (Cl, S, etc.) may be attached to a large number of dirt, and at the bottom of the scale gap enrichment.