External Corrosion is generally considered the first threat to pipeline integrity, sometimes to the exclusion of the other classifications of pipeline threats. Mitigation began with coating the pipe as it was being lowered in. Installing impressed current systems for cathodic protection (CP) of pipelines became commonplace throughout the 1950s. By the end of the decade, CP was expected and was a common practice on all pipelines to stop or slow corrosion. Pipelines therefore have over forty years of managing external corrosion. Improvements in coating technology and impressed current systems through the years have continued to reduce reportable incidents to the point that annual numbers are usually second to third party damage.
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