What are coating failures in pipelines, and how do they occur?
Pipelines are typically made of steel, which is primarily iron. Steel naturally corrodes over time when exposed to soil or water. To prevent corrosion, pipelines have an anti-corrosion coating on their outer surface. This coating acts as a barrier between the steel and its environment, reducing the risk of corrosion. Pipelines are also usually protected by a cathodic protection system that controls corrosion in the event of damage to the coating. There are a variety of coating failure modes. Coating failure occurs when the protective layer loses its adhesion or is damaged, exposing the underlying steel.1,2
What are the risks of coating failures in pipelines?
While not every coating failure immediately jeopardizes the integrity of the pipeline, as this is often compensated for by cathodic protection, problems arise when the coating detaches without visible damage. If a coating fails and cathodic protection cannot reach the exposed steel, the risk of corrosion increases significantly. In severe cases, stress corrosion may occur, which can compromise safety and reliability. Corrosion can weaken the pipeline’s structure, potentially leading to leaks or ruptures.2
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Source reference
- Managing Pipeline Threats, John Tiratsoo, 2019.
- The Encyclopedia of Pipeline Defects, ROSEN UK, Edition 3, 2017.