In-Line Inspection (ILI) surveys are widely employed to identify potential threats by capturing changes in pipe condition such as metal loss, caused by corrosion. The better the performance and interpretation of these survey data, the higher the reliability of being able to predict the actual condition of the pipe and required remediation. Each ILI survey has a certain level of conservatism from the assessment equations such as B31G and sensitivity to ILI performance for measurement uncertainty. Multiple levels of conservatism intended to limit the possibility of a non-conservative assessment can result in a significant economic penalty and excessive digs without improving safety. A study was undertaken to evaluate the reliability of responses to ILI corrosion features through multiple case studies examining the effects of failure criteria and data analysis parameters. This paper discusses the effect of validated ILI performance on safety, and addresses the risk of false acceptance of corrosion indications at a prescribed safety factor. The cost of unnecessary excavations due to falsely rejecting ILI predictions is also discussed.

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