Gouge detection on dents below 1 depth with multiple data set technologies on an ILI tool

摘要

U.S. federal regulation 49 CFR192/195 requires repair of dents with depths greater than 6% of the pipeline's outer diameter, as well as any dent with metal loss. Pipeline failures have occurred from dents that pass these regulations. For example, dents with depths shallower than 3% may result in pipeline failure due to fatigue. Conversely, dents interacting with coincidental metal loss have been known to survive for extended service. Technology that records multiple data sets using a single in-line inspection device has shown capability in detecting low level mechanical damage interacting with dents less than 1%, with the results verified by dig feedback. The technology - which uses an oblique high field magnetizer, an axial high field magnetizer, an axial low field magnetizer, and a high-resolution geometry module - has also discriminated metal loss signatures indicative of gouging from corrosion and identified dents that have been re-rounded from those that are constrained. These factors are all important to integrity decision-making. This paper evaluates the multiple data set tool's detection and sizing accuracy against in-the-ditch NDE results. Specifically, it compares the capabilities of the tool versus NDE on dents below 1% depth with associated gouging or metal loss, and on constrained and re-rounded dents.