Pipeline Operators employ two primary means of extemal corrosion monitoring on buried steel pipelines, Cathodic Protection (CP) Testing, and Corrosion In-line Inspection (Smart Pigs). CP testing has been used to directly assess the level of cathodic protection in accordance with
established criteria (NACE RP 016g). In-line inspection results have been traditionally used to determine integrity level by assessing remaining wall thickness and strength. In-line inspection results can also be used to indirectly assess the adequacy of Cathodic Protection by providing evidence that corrosion is active or not. A method has been developed to determine the presence of "Statistically Active Corrosion" based on a comparison of the moving average depth of wall loss features obtained by pig runs made in subsequent years. Evidence of
active corrosion is an indicator that CP may not be adequate. This paper describes the statistically active corrosion methodology, and discusses how it can be used in making pipeline corrosion monitoring and maintenance decisions.