Impact of Pre-Corrosion on Corrosion Inhibitor Performance: Can We Protect Aged Pipelines

摘要

The impact of pre-existing corrosion (pre-corrosion) on CI performance was evaluated in conditions unfavorable of protective scale formation. Results show that CI protectiveness was significantly reduced after a 3-day pre-corrosion period. Longer pre-corrosion durations further degraded inhibitor performance, acquiring a higher CI dosage to achieve adequate protection. These findings suggest that the effect of pre-corrosion should be considered in the lab qualification of CI for aged pipelines. Further studies indicate that the reduction of CI effectiveness was dominantly due to the enrichment of Fe_3C on the metal surface from corrosion, as opposed to being a result of the change in surface roughness. Corrosion inhibition was improved after removal of Fe_3C from the metal surface, also indicating the direct impact of Fe_3C on inhibitor performance after pre-corrosion. This suggests that for production environments which don't promote protective scale formation, it is necessary to maintain a clean pipe surface to ensure CI protectiveness during the operation.