This paper provides an overview of Pacific Gas and Electric Company's (PG&E) In-Line Inspection (ILI) process from start to finish. PG&E's integrity management program encounters numerous operational challenges as it expands its in-line inspection program to include more challenging pipelines than previously inspected. The company has addressed these challenges by developing a rigorous hydraulic feasibility study process that evaluates risks associated with a respective ILI run before making the decision to proceed with pipeline retrofits to accommodate in-line inspection tools. Several new operating methods have been developed to increase the number of pipelines hydraulically capable of in-line inspections, while reducing risk.
Two tools that PG&E has developed to analyze ILI system operations will be discussed. PG&E's Batch Analysis Tool (BAT) is used to conduct complex, multiple-scenario hydraulic analysis. Data results are then processed through an ILI BAT Results Tool, which summarizes BAT data into easily-viewed charts and tables. This allows engineers to consistently analyze and document predicted ILI run gas velocities and system response to varying operations during the inspection.
Once detailed analysis is conducted, preparation for the ILI is required. This paper will discuss upgrading pipelines to accommodate inspection tools, developing detailed operating plans, directing real-time operations, and preparing to respond to operational impacts due to anomalies identified on the line.
A case study of an ILI on Distribution Feeder Main (DFM) 0617-06 is presented to exemplify PG&E's ILI process from start to finish.