Deposit Analysis of Pipelines with Hydraulic Grade Lines Measured by Free-Floating, In-Line Tools

This paper demonstrates the methodology for calculating the hydraulic grade line from free-floating, in-line inspection tools and the subsequent deposit analysis of the hydraulic grade line. Neutrally buoyant, in-line inspection tools measure the pressure along the entire pipeline length under regular operating conditions. Deploying multiple tools with a short time delay allows for localized features to be distinguished from changes to the pipeline operation during the deployment. Identified operational changes during the deployment are corrected before calculating the hydraulic grade line using an elevation profile of the pipeline. The resulting hydraulic grade line represents the pressure-head loss due to friction along the pipeline; locations with steeper pressure-head loss indicate restrictions in the pipeline from the build-up of deposits. The gradient of the hydraulic grade line, pipeline specifications, and inspection flow rate are used with the Hazen–Williams equation to calculate the levels of deposits in several segments along the pipeline.