Pipe Corrosion Types And How To Prevent Them

Pipeline corrosion is very common in the real working process. Then how much do you know about it? What should you do to prevent it? This article talks about 10 types of pipe corrosion and tells the prevention way for each of them.

1. Electrochemical corrosion
   Reason: metal and electrolyte contact REDOX reaction.
   
   Prevention methods:
   Cathodic protection (sacrificial anode or impressed current).
   Use anti-corrosion coatings (e.g., epoxy resin, polyethylene coating).

2. Chemical corrosion
   Reason: Metals react directly with chemicals such as strong acids and bases.
   
   Prevention method:
   Choose corrosion resistant materials (such as titanium alloy, Hastelloy).
   Control the composition of the medium (e.g., adjust pH to reduce corrosive substances).

3. Pitting (pitting)
   Cause: Local chloride ions or sulfides cause small holes to form on the metal surface.
   
   Prevention methods:
   Use pitting resistant materials (such as 316L stainless steel, duplex steel).
   Add corrosion inhibitors (such as molybdate, nitrate).

4. Microbial Corrosion (MIC)
   Reason: sulfate-reducing bacteria and other microorganisms metabolize acid or sulfide.
   
   Prevention methods:
   Clean pipes regularly and use fungicides or bioinhibitors.
   Keep the pipe dry or control the temperature to inhibit microbial growth.

5. Stress Corrosion Cracking (SCC)
   Cause: Tensile stress and corrosive environment (such as chloride ions, high temperature).
   
   Prevention methods:
   Remove residual stress (annealing treatment).
   Avoid using sensitive materials (such as austenitic stainless steel in chlorine environments).

6. Uniform corrosion
   Reason: The surface of the metal is uniformly eroded by the corrosive medium.
   
   Prevention methods:
   Increase wall thickness to reserve corrosion margin.
   Use a coating or lining (such as a rubber lining).

7. Crack corrosion
   Reason: The concentration battery is formed by the retained corrosion medium in the gap of the pipeline.
   
   Prevention methods:
   Optimized design to avoid gaps (e.g. welded instead of bolted).
   Fill gaps with sealant.

8. Hydrogen brittle
   Cause: Hydrogen atoms penetrate into the metal causing brittle fracture.
   
   Prevention methods:
   Control the hydrogen sulfide content in the medium.
   Low strength steel or hydrogen trap alloy.

9. Erosion corrosion
   Cause: high-speed fluid impact damage the surface protective film.
   
   Prevention methods:
   Reduce flow rate or change direction design.
   Use wear-resistant materials (such as silicon carbide coatings).

10. Stray current corrosion
    Cause: An external current (such as a tram track) triggers an electrolytic reaction.
    
    Prevention methods:
    Install drain device or insulation flange.
    Strengthen insulation protection between pipeline and soil.