Valve body corrosion prevention measures
Corrosion of valves, is usually understood as the valve materials in chemical or electrochemical under the destruction of the environment. Due to "corrosion" phenomenon appears in metal spontaneous interaction with the environment, how the metal and the surrounding environment are isolated or more using a non-metallic composite material, is the focus of corrosion.
Valve body (includes cover), occupying most of the weight of the valve, and is in regular contact with the media, so use valves, often starting from the valve body material.
Corrosion of the body in two forms, namely, chemical etching and electrochemical corrosion. Its corrosion rate depends on the medium temperatures, pressures, chemical properties and the corrosion resistance of the material of the valve body. Corrosion can be divided into six
1, totally corrosion: corrosion rate of less than 0.001 mm/year
2, extreme corrosion: corrosion rate of 0.001 to 0.01 mm/year
3, corrosion: corrosion rate of 0.01 to 0.1 mm/year
4, Shang Nai corrosion: corrosion rate of 0.1 to 1.0 mm/year
5, bad corrosion: corrosion rate of 1.0-10 mm/year
6, no corrosion: corrosion rate greater than 10 mm per year
Corrosion protection of the body, mainly is the correct choice of material. Although anti-corrosion of information is rich, but can selected have appropriate, also is not easy of things, because corrosion of problem is complex, for example sulfuric acid in concentration low Shi on steel has is big of corrosion sex, concentration high Shi is makes steel produced passivation film, can anti-corrosion; hydrogen only in high temperature high pressure Xia only displayed on steel of corrosion sex is strong, chlorine in dry state Shi corrosion performance and is unlikely to, and has must humidity Shi corrosion performance is strong, many material are cannot with. Select valve body material difficulties, also lies in not only the corrosion problems, and ability to endure pressure and temperature must be considered, rational, economical, and easy it is to buy, and other factors. So you must carefully.