Industrial Valve Materials Selection for Corrosive Environments

 
In the operation of chemical equipment, the selection of industrial valve materials is a crucial aspect. Especially in corrosive environments, the choice of industrial valve materials directly impacts the performance, safety, and lifespan of the equipment. This article will delve into the analysis of several common chemical media, providing corresponding industrial valve material recommendations to ensure reliable operation of the equipment under various conditions.
 
1. Sulfuric Acid Media

Sulfuric acid is a strong corrosive medium, and the degree of material corrosion is greatly affected by concentration and temperature. Although carbon steel and cast iron exhibit some corrosion resistance to concentrated sulfuric acid with a concentration above 80% and a temperature below 80°C, they are not suitable for high-speed flowing sulfuric acid. Generally, stainless steels such as 304 and 316 have limited suitability for sulfuric acid media, while high-silicon cast iron and high-alloy stainless steel are more suitable for pumps and valves transporting sulfuric acid. Fluoroplastic-lined pumps and valves are more economical for transporting sulfuric acid.
 
2. Hydrochloric Acid Media

Most metal materials have poor corrosion resistance to hydrochloric acid, while most non-metal materials exhibit good corrosion resistance to hydrochloric acid. Therefore, rubber-lined or plastic-lined pumps and valves are the best choice for transporting hydrochloric acid.
 
3. Nitric Acid Media

Nitric acid has strong corrosive properties to most metals, but stainless steel is the most commonly used material resistant to nitric acid. Titanium and titanium alloys are typically selected for high-temperature nitric acid conditions.
 
4. Acetic Acid Media

Acetic acid is one of the most corrosive organic acids. Stainless steel, especially molybdenum-containing 316 stainless steel, is a good material resistant to acetic acid, even in high-temperature acetic acid steam. For high-temperature and high-concentration acetic acid or requirements involving other corrosive media, high-alloy stainless steel or fluoroplastic pumps are preferred.
 
5. Alkali (Sodium Hydroxide)

Steel is typically used in low-concentration and low-temperature sodium hydroxide solutions, but it is prone to corrosion under high-concentration and high-temperature conditions. Titanium and titanium alloys or high-alloy stainless steel are usually more suitable for high-temperature alkali solutions.
 
6. Ammonia (Ammonium Hydroxide)

Most metals and non-metals have minimal corrosion in liquid ammonia and ammonium hydroxide, except for copper and copper alloys, which are not suitable.
 
7. Saltwater (Seawater)

Generally, steel has a low corrosion rate in sodium chloride solutions and seawater, but it often requires coating protection. Various types of stainless steel have low uniform corrosion rates, but localized corrosion may occur due to chloride ions, making 316 stainless steel more suitable.
 
In summary, the corrosion resistance of valves in chemical equipment is one of the key factors in ensuring production safety and stable equipment operation. Choosing the appropriate valve materials is crucial for different chemical media. With the continuous advancement of technology, the emergence of new materials will provide more choices for chemical equipment. Therefore, we need to closely monitor the development of material science and continuously optimize material selection to enhance the corrosion resistance of chemical equipment, ensuring the sustainable safety and stability of industrial production.