Corrosion is one of the important elements that cause valve damage. Therefore, in valve protection, valve anti-corrosion is an important consideration. How to carry out valve anti-corrosion?
1. Select corrosion-resistant materials according to corrosion medium.
In production practice, the medium corrosion is very complex. Even if the valve material sample used in one medium is used, the concentration, temperature and pressure of the medium are different. And the medium corrosion to the material is also different. Therefore, the correct selection of valve materials should be based on the specific situation, analysis of various factors affecting corrosion, according to the relevant anti-corrosion manual selection of materials.
2. Non metallic materials.
As long as the temperature and pressure of the valve meet the requirements of non-metallic materials, it can not only solve the corrosion problem, but also save precious metals.
3. Metal surface treatment.
(1) Valve connection: the valve connection bolts are usually galvanize, chrome plated and oxidized (bluing) to improve the resistance to atmospheric and medium corrosion. In addition to the above methods, other fasteners are also treated with phosphating and other surface treatment according to the situation.
(2) Sealing surface and small diameter closure parts: surface technology such as nitriding and boronizing is often use to improve its corrosion resistance and wear resistance.
(3) Valve stem anti-corrosion: widely used nitriding, boronizing, chrome plating, nickel plating and other surface treatment processes to improve its corrosion resistance, corrosion resistance and abrasion resistance.
(4) small diameter valve body and hand wheel: often chrome plated to improve its corrosion resistance and decorate the valve.
4. Thermal spraying.
Most metals and their alloys, metal oxide ceramics, metal ceramic composites and hard metal compounds can coat on metal or non-metal substrates by one or several thermal spraying methods. Thermal spraying can improve the corrosion resistance, wear resistance and high temperature resistance of its surface, and prolong its service life.
5. Spray coating.
The coating is also a non-metallic material. Which is usually made up of synthetic resin, rubber slurry, vegetable oil, solvent, etc., covering the metal surface, isolating the medium and atmosphere, so as to achieve the purpose of anti-corrosion. Coating is mainly use in water, salt water, sea water, atmosphere and other less corrosive environment.
6. Adding corrosion inhibitor.
Adding corrosion inhibitor in the medium can slow down the corrosion of equipment and valves.
7. Electrochemical protection.
There are two kinds of electrochemical protection: anode protection and cathode protection. In the production practice, the anode protection is use less and the cathodic protection is used more. It is an economic, simple and effective method for large valves and important valves to adopt this cathodic protection method.
8. Control corrosion environment.
The operator shall clean and purge the valve regularly and add oil regularly according to the regulations in the operation regulations. Which is an effective measure to control environmental corrosion. Adopt open workshop or adopt ventilation and cooling measures to reduce environmental corrosion.
9. Improve processing technology and valve structure.
The anti-corrosion protection of valve is consider from the design. A valve product with reasonable structure design and correct process method will undoubtedly have a good effect on reducing the corrosion of valve.