Abstract
Eddy current testing is a widely used NDT inspection technique for both ferrous and non-ferrous materials. This may explain why it was one of the very early techniques implemented on an inline inspection tool (ILI), alongside the development of Magnetic Flux Leakage (MFL) tools. Eddy current testing is primarily applied to accurately diagnose surface-breaking defects. The technology is highly mature and has been deployed in various applications, for instance for pipeline in-ditch inspection during validation activities.
The most common use of eddy current technology in ILI tools is a simple configuration for proximity measurement. This helps to discriminate between internal and external corrosion on a volumetric tool (MFL) or enhance caliper-based geometry measurements. The most advanced applications of eddy current testing target measurement of specific properties of the pipe wall such as material properties (pipe grade) or pipe stress due to external loading.
This paper will present the latest effort in developing eddy current for inline strain measurement in pipelines. The fundamental physical principles will be reviewed, and key parameters considered during the design. Internal validation steps and results will be highlighted. The technology developed is specifically targeting threats related to Geohazard. Working with IMU (Inertial Measurement Unit) and Geometry data, the combination of measurements, a Geohazard management application, is believed to offer the best dataset to detect and characterize Geohazards in pipelines.
With the collaboration and support of pipeline operators, the Geohazard tool is undergoing a validation campaign with the first results presented for a known and well-characterized geohazard event. Correlation to known events is key to validating new technology, and the site presented has extensive data available to fully understand and validate the Geohazard tool measurement. The authors will present the results of the validation activities completed in early 2023.
