Third-party interference is widely documented as being a major cause of damage to buried pipelines. In addition to routine surveillance, maintaining a minimum depth of cover is recognized as a key means of mitigation against third-party interference. We know that the depth of cover over pipelines can change with time. Changes in depth of cover can also be an indication of thermal upheaval, frost heave or ground movement. Current techniques available for measuring depth of cover on buried pipes require significant effort to produce a high-resolution survey for an entire pipeline.
A UK Innovation project completed with National Grid Gas Transmission in 2017 successfully demonstrated a methodology for estimating pipeline depth of cover by combining ground elevation data with high-resolution inertial measurement unit (IMU) data collected during in-line inspection.
Since the end of the project, ROSEN has completed a further eight pipeline depth of cover inspections, with a total length exceeding 400 kilometers and including a range of pipe diameters.