Improvement of ILI Sizing Accuracy for Problematic Corrosion Profiles: A PRCI/PHMSA Project

Abstract In March 2019, the United States Pipeline and Hazardous Materials Safety Administration (PHMSA) issued a Research Announcement to improve the detection capability and sizing accuracy of In-Line Inspection (ILI) systems for various types of anomalies. The objective is to focus on those anomalies that represent the most significant risk threats to the safe operation of pipeline systems and also reduce the number of excavations required for integrity management. Pipeline Research Council International (PRCI) Project NDE-4-19 was created in December 2019 as part of this initiative. The multi-phased PHMSA-PRCI-Blade Energy project aimed to conduct a collaborative study involving pipeline operators, ILI Technology Providers (TPs), subject matter experts, and consultants to quantitatively measure and improve the detection and sizing capabilities of current ILI systems for challenging and problematic corrosion features. A data-driven approach was devised, which factually identified problematic corrosion shapes and profiles by reviewing recent Root-Cause-Analysis (RCA) reports of corrosion-related pipeline failures that had previously been inline inspected. This information was used to design and construct an ILI corrosion test string containing complex features with similar profiles. All such profiles were then documented using the best possible Non-Destructive Evaluation (NDE) techniques. Three participating ILI TPs proposed appropriate inspection tools based on their knowledge of the string containing complex corrosion features. A series of blind pull-through tests of the ILI systems were conducted, and the participating ILI TPs delivered standard ILI reports for performance evaluation. The ILI TPs received detailed feedback identifying the detection and sizing gaps. They were given a limited subset sample of detailed 3D corrosion profile data to identify potential sources of detection and sizing improvement. A second series of ILI tests were performed, and the changes in detection capability and sizing accuracy were analyzed and quantified for each problematic corrosion profile, identifying the improvements and the remaining gaps. The results and findings of this 3.5-year-long project are presented in this article.