Our goal: to be a high-quality manufacturer of industrial control valves, gaining unanimous recognition from new and old customers
Our mission: To fully utilize the effectiveness of industrial control valves to achieve better results
Today's editor brings you information on how to choose and purchase valves with different functional materials, hoping to be helpful to you.
Many media have certain corrosivity; The corrosivity of the same medium varies with pressure, temperature, and concentration. Therefore, the valve suitable for this medium should be selected based on the corrosion resistance of the material.
1. Stainless steel valve
Stainless steel valves have excellent atmospheric resistance, are resistant to nitric acid and other oxidizing media, as well as corrosion by alkali, water, salt, organic acids, and other organic compounds. However, it is not resistant to corrosion by non oxidizing acids such as sulfuric acid and hydrochloric acid, nor is it resistant to dry hydrogen chloride, oxidizing chlorides, and organic acids such as oxalic acid and lactic acid. Stainless steel containing 2% to 4% molybdenum, such as Cr18Ni12Mo2Ti, has superior corrosion resistance compared to chromium nickel stainless steel. It has better acid resistance in non oxidizing acids, hot organic acids, and chlorides, as well as better resistance to pitting corrosion than chromium nickel stainless steel. Stainless steels containing titanium or niobium have a strong resistance to intergranular corrosion. Stainless steel with high chromium and nickel content has higher corrosion resistance than ordinary stainless steel, and can be used to treat sulfuric acid, sulfuric acid, mixed acid, sulfite, organic acid, alkali, salt solution, hydrogen sulfide, etc., even in high-temperature situations at certain concentrations. However, it is not resistant to corrosion by concentrated or hot hydrochloric acid, wet fluorine, chlorine, bromine, iodine, aqua regia, etc.
2. Cast Iron Valves
(1) Grey cast iron valve manufacturer
It is suitable for water, steam, petroleum products, and ammonia to work in the vast majority of low corrosive media such as alcohols, aldehydes, ethers, ketones, and lipids. It is not suitable for media such as hydrochloric acid, nitric acid, etc. However, it can be used in concentrated sulfuric acid because it can produce a passivation film on its metal surface. To prevent corrosion of cast iron by concentrated sulfuric acid.
(2) Ductile iron valve
Strong corrosion resistance, able to work in certain concentrations of sulfuric acid, nitric acid, sulfuric acid, and acid salts. However, it is not resistant to corrosion by fluoric acid, strong alkali, hydrochloric acid, and ferric chloride hot solutions. Avoid sudden heat and cold when using, otherwise it will crack.
(3) Nickel cast iron valve
Alkali resistance is stronger than gray cast iron and ductile iron valves; Nickel cast iron is an ideal valve material for use in dilute sulfuric acid, hydrochloric acid, and caustic soda.
3. Carbon Steel Valves
The corrosion resistance of carbon steel valves is similar to that of gray cast iron, but slightly inferior to that of gray cast iron.
4. Brass valve
Brass valves have good corrosion resistance to water, seawater, various salt solutions, and organic matter. It has good corrosion resistance to sulfuric acid, phosphoric acid, acetic acid, dilute hydrochloric acid, etc. that do not contain oxygen or oxidants, and has good resistance to alkali. However, it is not resistant to the corrosion of oxidizing acids such as nitric acid and concentrated sulfuric acid, as well as the corrosion of molten metals, sulfur, and sulfides. Avoid contact with ammonia, which can cause stress corrosion cracking of copper and copper alloys. When selecting, it should be noted that different grades of copper alloys have certain differences in their corrosion resistance.
