What causes corrosion of plates in plate heat exchangers?
Plate heat exchangers are widely used in various industries thanks to their inherent advantages. However, corrosion often occurs during operation. Haote Plate Cooler Company introduces the corrosion issues of plates in plate heat exchangers:
Stainless steel heat transfer plates are manufactured by mechanical stamping, inevitably leaving a certain amount of residual surface stress. For thin stainless steel plates without molybdenum, it is difficult or even impossible to eliminate such residual surface stress.
Harmful elements at the bottom of sealing grooves are usually chloride ions (Cl⁻) precipitated from adhesives as temperature rises. For example, neoprene adhesives and compressed asbestos will release concentrated Cl⁻ which combines with H⁺ to form HCl under water and steam working conditions. This leads to severe stress corrosion cracking at the crevices on the bottom of grooves. Stress corrosion cracking may occur after a certain corrosion incubation period. During material selection, installation and operation of plate heat exchangers, disrupting any of the above conditions can effectively prevent or delay corrosion and ensure safe and stable equipment operation.
Multiple crevice structures are formed after plate assembly, such as contact points between plates and the bottom of sealing grooves. Crevices tend to cause enrichment of Cl⁻, and the local concentration can far exceed the stress corrosion resistance of stainless steel.
When heavy fouling forms on plate surfaces, corrosive components in the medium may deposit massively on the scale and accumulate in the crevices beneath the fouling layer.
