PR-469-173823-R02 In-Line Inspection and Evaluation of Pinholes in Oil and Gas Pipelines - Phase II

Pinhole leaks have been reported as a significant cause of oil and gas pipeline failures in recent years. From 2010 to 2015, at least 131 significant incidents involving oil and gas pipelines in the United States (101 and 30, respectively) were attributed to pinhole leaks. The 9th European Gas Pipeline Incident Data Group Report states that as of 2013, the five-year moving average failure frequency for pinholes was equal to an approximate annual rate of 0.105 failures per 1,000 kilometers of pipeline. Pinholes may result from normal pipeline corrosion during routine operations, such as micro-biologically induced corrosion, or can be created by third-party activities, such as illegal tapping. These small leaks have become a major risk for many pipeline companies. Pinhole leaks are more likely to lead to serious consequences than larger leaks because they are difficult to discover through normal monitoring and patrolling. An undetected pinhole leak can lead to significant soil and groundwater pollution over time. The research objective of this phase is to improve the results based on the research of phase one. The major work of this phase are following. In response to the problems found in the pull test of phase one, a number of defects with different sizes have been designed, including pinhole, pitting and grooves, were added to further subdivide the detection boundary conditions. The NDT verification tool for pinhole defects was compared and selected, and the appropriate ultrasonic scanning system was selected as the NDT method for internal pinhole verification. According to the actual ILI report, two pinholes and three pittings were selected for dig verification, and the results were comprehensively compared and analyzed with the pull test.