Overview of Condition Monitoring Methodologies for Integrity Assessment of Natural Gas Pipelines

Abstract In 2015, the National Transportation Safety Board conducted a study1, revealing that while Pipeline and Hazardous Materials Safety Administration (PHMSA) gas integrity management measures effectively address corrosion and material failures in pipes and welds, there is an observed lack of reduction in incidents within High Consequence Areas of gas transmission pipelines. The findings from the study are of value to all pipeline operators and not only PHMSA-regulated pipelines to improve their integrity management program. The paper will focus on how a pipeline operator assesses hazards on pipelines that were identified as difficult to pig lines. The paper will delve into the utilization of recent advancements in robotics and tethered inline inspection (ILI) tools for cleaning and inspecting buried natural gas transmission steel pipelines, formerly considered difficult to inspect. The author will provide case study on condition monitoring of natural gas transmission steel pipelines using direct assessment (DA) and ILI. The paper will share insights into common retrofits needed and examples of retrofits completed to make pipelines piggable. The paper will discuss on advancements needed in DA. Finally, it will compare hazards assessable through ILI and DA, offering an overview of their respective capabilities.