A corrosion inhibitor is a chemical compound that is used to decrease the rate of corrosion in a metal or metal alloy. It is typically applied to the metal in small concentrations in a liquid or gaseous form. Inhibitors come in various types, each employing a different mechanism to reduce the rate of corrosion and prolong the service life of the component under consideration.
Trenchlesspedia Explains Inhibitor
Corrosion inhibitors reduce the rate of the corrosion process by one or more of the following mechanisms:
- Increasing anodic or cathodic polarization behavior
- Decreasing the emission of ions to the metallic surface
- Increasing the resistance of the metal surface
Inhibitors come in various types and are classified according to their main corrosion protection mechanism. The most common types of corrosion inhibitors are:
- Anodic inhibitors – These prevent corrosion by forming a thin protective oxide film on the metallic surface.
- Cathodic Inhibitors – These work by slowing down the cathodic reaction rate by limiting the diffusion of metal ions.
- Mixed inhibitors – These form a protective film that helps to reduce both cathodic and anodic reactions.
- Volatile Corrosion Inhibitors (VCI) – VCI’s work by slowly emitting a vaporized compound in a closed environment. The compound condenses and adsorbs to form a monomolecular protective layer.
Internal corrosion protection of pipelines during construction has often been overlooked in preference of exterior corrosion protection. Pipes are normally flushed and hydro-tested for leaks with untreated water and left in a dampened conditioned. This can eventually lead to corrosion if left untreated. Adding an inhibitor directly to the hydro-testing water can ensure that the interior of the pipe is protected during and after testing.