Inline-Inspection Crack Detection for Gas Pipelines Using a Novel Technology

Abstract

Gas transmission lines, especially those which were built from mid-20 century to the early 1980s are often affected by external SCC. A common methodology to manage this threat is to utilize EMAT based ILI tools to collect data to characterize the asset and flaws. It is common practice to utilize a transverse magnetic flux leakage tool (TFI) in addition to the EMAT inspection to enhance identification and characterization of EMAT signals. Furthermore, resolution and maximum wall thickness to operate those EMAT tools are limited as of today. NDT Global is developing an alternative technology which addresses crack detection, identification, and sizing in gas pipelines. It is based on directional gas coupled guided wave generation in the pipe wall which allows inspection of the asset without any contact of the sensors to the internal pipe wall. This paper presents the history of the development, starting with a gap analysis of existing solutions, some working hypothesizes to overcome those gaps followed by small scale lab test results and an outlook towards full-scale tests in a large Nitrogen filled pressure chamber in Norway, Europe, operated at different pressures. The solution combines newly developed gas coupled guided wave principles with several principles taken from the proven Eclipse UCx [1] technology operated in liquids.