Anti-Corrosion Measures for Valves

I. Internal Anti-Corrosion of Valves

Internal anti-corrosion focuses on protecting the inner surfaces of the valve cavity that come into contact with the medium, preventing corrosion caused by the medium. Key measures include:
 

1. Material Selection Based on Media Characteristics: Select valve materials according to the corrosiveness, temperature, pressure, and other properties of the medium. For highly corrosive media, corrosion-resistant materials such as stainless steel or alloy steel are recommended.
2. Coating Protection: Apply anti-corrosion paint to the inner cavity to form a protective film, isolating direct contact between the medium and the valve interior. The choice of paint should align with the medium’s properties and operating environment.
3. Optimized Design: Improve valve structural design and manufacturing processes to minimize corrosion risks. For example, avoiding stress concentration points and reducing welding joints can lower susceptibility to corrosion.

 

II. External Anti-Corrosion of Valves

External anti-corrosion protects the valve’s exterior and connected components from environmental corrosion. Key measures include:
 

1. Surface Cleaning and Treatment:

   • Mechanical Rust Removal: Use sandpaper, wire brushes, or similar tools to remove rust and contaminants.
   • Sandblasting: Use compressed air to propel abrasives at high speed onto the valve surface, removing contaminants and oxidation layers while enhancing surface roughness and coating adhesion.

2. Coating Protection:

   • Anti-Corrosion Paint Spraying: Apply paint to form a protective barrier against oxygen and moisture. The paint type should match the valve material, environment, and corrosion resistance requirements.
   • Powder Coating: Spray plastic powder onto the valve surface, followed by high-temperature curing to create a dense, durable layer.
   • Electroplating: Coat the surface with corrosion-resistant metals like chromium or nickel.

3. Additional Protective Layers:

   • Install Protective Covers: Use plastic or rubber covers to isolate the valve from direct environmental exposure.
   • Wrap Anti-Corrosion Tapes: Apply polyethylene or fiberglass tapes to form an external protective layer.

4. Electrochemical Protection:

   • Anodic Protection: Apply an anodic current to form a passivation layer on the metal surface, inhibiting corrosion.
   • Cathodic Protection: Use an external current to make the valve act as a cathode in a corrosion cell, preventing oxidation. This method is particularly effective for buried or submerged valves.

5. Regular Maintenance:

   • Conduct periodic inspections to detect and address corrosion or wear. Clean surface contaminants and corrosion products to maintain smoothness and integrity.

6. Environmental Control:

   • Where feasible, mitigate corrosion by regulating environmental factors such as temperature, humidity, and oxygen levels. Examples include using open-air facilities or ventilation systems to reduce ambient temperature and moisture.