3. Metal surface treatment
At the connection point of the aerodynamic ball valve, the valve connection screw is usually galvanized, chromium-plated, and oxidized (blue) to improve the ability to resist atmospheric and medium corrosion. Other fasteners are treated according to the situation in addition to the above methods. Surface treatment such as phosphating.
Sealing surface and closing parts with small diameter often adopt surface technology such as nitriding and boronizing to improve its corrosion resistance and wear resistance. For the valve flap made of 38CrMoAlA, the nitriding layer is ≥0.4mm. Valve stem anticorrosion widely adopts surface treatment processes such as nitriding, boronizing, chromium plating, nickel plating, etc. to improve its corrosion resistance, corrosion resistance and wear resistance. Different surface treatments should be suitable for different valve stem materials and working environments.The valve stem in the atmosphere, water vapor medium and asbestos packing can be hard chromium plated, gas nitriding process (ion nitriding process is not suitable for stainless steel); The valve in the atmosphere of hydrogen sulfide adopts electroplated high-phosphorous nickel coating to have better protection performance;

Cast Steel Ball Valve

Sealing surface and closing parts with small diameter often adopt surface technology such as nitriding and boronizing to improve its corrosion resistance and wear resistance. For the valve flap made of 38CrMoAlA, the nitriding layer is ≥0.4mm. Valve stem anticorrosion widely adopts surface treatment processes such as nitriding, boronizing, chromium plating, nickel plating, etc. to improve its corrosion resistance, corrosion resistance and wear resistance. Different surface treatments should be suitable for different valve stem materials and working environments.The valve stem in the atmosphere, water vapor medium and asbestos packing can be hard chromium plated, gas nitriding process (ion nitriding process is not suitable for stainless steel); The valve in the atmosphere of hydrogen sulfide adopts electroplated high-phosphorous nickel coating to have better protection performance;
38CrMoAlA adopts ion and gas nitriding to resist corrosion, but hard chromium coating is not suitable; 2Cr13 can be resistant to ammonia gas after tempering, and carbon steel using gas nitriding can also resist ammonia corrosion, and all phosphorus nickel coatings are not resistant to ammonia Corrosion; 38CrMoAlA material after gas nitriding has excellent corrosion resistance and comprehensive performance, and it is mostly used to make valve stems. Small-bore valve bodies and hand wheels are also often chrome-plated to improve their corrosion resistance. Decorative cast steel ball valves.
4. Choose corrosion-resistant materials according to the corrosive medium
In the actual production, the corrosion of the medium is very complicated. Even if the valve material used in a medium is the same, the concentration, temperature, and pressure of the medium are different, and the medium corrodes the material. The temperature of the medium is increased by 10 ℃ every time , Corrosion rate increases about 1-3 times.
The medium concentration has a great influence on the corrosion of valve materials. For example, lead is in sulfuric acid with a small concentration, and the corrosion is very small. When the concentration exceeds 96%, the corrosion rises sharply. On the contrary, carbon steel has a serious corrosion when the sulfuric acid concentration is about 50%. When the concentration increases to more than 6%, the corrosion decreases sharply.
For example, aluminum is very corrosive in concentrated nitric acid with a concentration of more than 80%, but it is more serious in medium and low concentrations of nitric acid. Although stainless steel has strong corrosion resistance to dilute nitric acid, it is corroded in more than 95% of concentrated nitric acid. Instead, heavier.
It can be seen from the above examples that the correct selection of valve materials should be based on specific conditions, analyze various factors affecting corrosion, and select materials according to the relevant anti-corrosion manuals.
5. Spray paint
Paint is a widely used anti-corrosion method, and it is an indispensable anti-corrosion material and identification mark on valve products.
The coating is also a non-metallic material. It is usually made of synthetic resin, rubber slurry, vegetable oil, solvent, etc., covering the metal surface, isolating the medium and the atmosphere, to achieve the purpose of anticorrosion.
Coatings are mainly used in water, salt water, sea water, atmosphere and other less corrosive environments. Gost ball valves inner cavity is often painted with anti-corrosion paint to prevent water, air and other media from corroding the valve. The paint is mixed with different colors to indicate the materials used by Farn. The valve spray paint is generally from half a year to once a year.