Metal valves can be said to be the most susceptible key component structure to corrosion failure in engineering equipment. Usually, the sealing surfaces, valve stems, diaphragms, small springs, and other valve components of metal valves are made of first-class materials. The valve body, valve cover, etc. are made of secondary or tertiary materials. Valves used for high-pressure, highly toxic, flammable, explosive, and radioactive media should be made of materials with minimal corrosion. Metal valves constantly undergo uniform corrosion on the metal surface under complex working conditions such as atmosphere or solution.  

Corrosion prevention measures for metal valves

1. Select corrosion-resistant materials based on corrosive media

The correct selection of valve materials should be based on specific situations, analyze various factors that affect corrosion, and select materials according to relevant anti-corrosion manuals.

2. Using non-metallic materials

The corrosion resistance of non-metals is excellent. As long as the temperature and pressure of the valve meet the requirements of non-metallic materials, it can not only solve the problem of corrosion, but also save precious metals.

3. Metal surface treatment

Valve connection: Valve connection bolts are commonly treated with zinc plating, chromium plating, and oxidation (bluing) to improve their resistance to atmospheric and medium corrosion. In addition to using the above methods for treatment, other fasteners also undergo surface treatment such as phosphating according to the situation.

Sealing surfaces and small diameter closure parts: Surface processes such as nitriding and boronizing are often used to improve their corrosion resistance and wear resistance.

Valve stem anti-corrosion: Surface treatment processes such as nitriding, boronizing, chrome plating, and nickel plating are widely used to improve its corrosion resistance, corrosion resistance, and abrasion resistance.

Small diameter valve bodies and handwheels are often chrome plated to improve their corrosion resistance and decorate the valve.

4. Thermal spraying

Thermal spraying is a kind of process block for preparing coatings, and has become one of the new technologies for surface protection of materials. Thermal spraying can improve its surface corrosion resistance, wear resistance, high temperature resistance and other properties, and extend its service life.  

5. Spray coating

Coating is the most widely used anti-corrosion method, and it is also a anti-corrosion material and identification mark on valve products. Coatings are also non-metallic materials, usually formulated from synthetic resins, rubber slurries, vegetable oils, solvents, etc., which cover the metal surface, isolate the medium and atmosphere, and achieve anti-corrosion purposes.

6. Adding corrosion inhibitors

The mechanism by which corrosion inhibitors control corrosion is that they promote the polarization of the battery. Corrosion inhibitors are mainly used in media and fillers.

7. Electrochemical protection

There are two types of electrochemical protection: anodic protection and cathodic protection.

8. Control of corrosive environment

The so-called environment has two broad and narrow senses. The general environment refers to the environment around the valve installation site and its internal flow medium. Narrowly defined environment refers to the conditions around the valve installation site.

9. Improve processing technology and valve structure form

The anti-corrosion protection of valves is an issue that has been considered from the beginning of design. A valve product with a reasonable structural design and correct process method undoubtedly has a good effect on reducing valve corrosion.

Therefore, the design and manufacturing departments should improve the components that have unreasonable structural design, incorrect process methods, and are prone to corrosion to meet the requirements of various working conditions.