Development of an EMAT in-Line Inspection System for Detection, Discrimination, and Grading of Stress Corrosion Cracking in Pipelines Progress Report (open access)

Development of an EMAT in-Line Inspection System for Detection, Discrimination, and Grading of Stress Corrosion Cracking in Pipelines Progress Report

This report describes progress, experiments, and results for a project to develop a pipeline inline inspection tool that uses electromagnetic acoustic transducers (EMATs) to detect and grade stress corrosion cracking (SCC). There is a brief introduction that gives background material about EMATs and relevant previous Tuboscope work toward a tool. This work left various choices about the modes and transducers for this project. The experimental section then describes the lab systems, improvements to these systems, and setups and techniques to narrow the choices. Improvements, which involved transducer matching networks, better magnetic biasing, and lower noise electronics, led to improved signal to noise (SNR) levels. The setups permitted transducer characterizations and interaction measurements in plates with man-made cracks, pipeline sections with SCC, and a full pipe with SCC. The latter were done with a moveable and compact EMAT setup, called a lab mouse, which is detailed. Next, the results section justifies the mode and transducer choices. These were for magnetostrictive EMATs and the use of EMAT launched modes: SH0 (at 2.1 MHz-mm) and SV1 (at 3.9 MHz-mm). This section then gives details of measurements on these modes. The measurements consisted of signal to noise ratio, insertion loss, magnetic biasing sensitivities crack …
Date: July 1, 2003
Creator: Aron, Jeff; Jon Gore, Roger Dalton; Eaton, Stuart; Bowles, Adrian; Thomas, Owen & Jarman, Tim
System: The UNT Digital Library