Development of a Magnetic Eddy Current In-Line Inspection Tool

Abstract

Pipeline in-line inspections (ILI) are one of the primary methods used to assess the integrity of operating oil and gas pipelines. Conventional ILI technology is based on ultrasonic testing (UT) or magnetic flux leakage (MFL) sensors. Although these technologies are suitable for most pipeline inspections, there remains an opportunity to expand ILI technology and application. ExxonMobil and Innospection Ltd. are working to develop a new ILI sensor technology based on a combination of Magnetic Eddy Current (MEC) and multi-differential eddy current. This new technology provides the potential to detect small volumetric features, inspect heavy wall gas pipelines, and inspect pipelines with corrosion resistant alloy (CRA) or non-metallic liners. Initial feasibility trials were conducted with a prototype ILI MEC tool. Tests were conducted on an 8.625” (219 mm) X65 carbon steel pipe lined with 0.118” (3 mm) of Inconel 825 pipe. Four types of defects were machined into the pipe to represent natural defects anticipated in service: • Metal loss features from 3 to 24 mm in diameter on the external surface of the carbon steel base pipe • Erosion on the internal layer of the CRA liner • Internal girth weld crack-like defects • Metal loss defects at the interface of the CRA and carbon steel Over 80 pull tests were conducted to determine the detection capabilities and speed sensitivities of the tool. Defects were detected by the sensors including the very small (<10 mm) pinhole-type features. Signals were analyzed by a preliminary sizing algorithm to demonstrate proof of concept. Detection performance was not affected at speeds up to 0.75 m/s. Since detection capabilities exceeded expectations, future development will continue based on the current prototype.

Inspection and monitoring systems subsea pipelines: A review paper

“…The synergy with the eddy current system means that greater distances can be inspected for a lower energy cost. 77,78 Acoustics Ultrasound inspection. In the context of subsea pipeline inspection, ultrasound refers to the use of elastic waves to detect and quantify damage.…”

“…The synergy with the eddy current system means that greater distances can be inspected for a lower energy cost. 77,78…”

Research on Internal Shape Anomaly Inspection Technology for Pipeline Girth Welds Based on Alternating Excitation Detection

“…As the most common electromagnetic inspection method for conducting elements, Eddy current testing has been widely applied in detecting surface defects, subsurface corrosion, and coating characterization of conductive materials [13][14][15]. In 1879, British engineer David Hughes utilized the eddy current effect to achieve the sorting of metallic materials, marking the first practical application of eddy current theory in engineering [16].…”

“…This greatly improved the signalto-noise ratio of detection signals and further promoted the engineering applications of eddy current testing, laying the foundation for modern conventional eddy current testing. With the continuous development of eddy current testing theory, materials science, and digital signal processing technology, various techniques have been developed, including multi-frequency eddy current testing, remote field eddy current testing (RFEC), eddy current array (ECA) testing, and pulsed eddy current testing (PEC) [13]. Currently, mature eddy current internal inspection equipment abroad includes the RoCorr IEC eddy current internal detector by ROSEN, the RoMat DMG magnetic leakage and eddy current composite internal detector, and the See Snake remote field eddy current internal detector developed by Russell [18].…”

Crosspoint Localization of Spiral and Girth Welds of Spiral Steel Pipelines

“…It has a deeper penetration depth than radiographic inspection technology, but usually needs to apply coupling agent on the surface, and it is not suitable for the detection of rough surface. Eddy current inspection is based on electromagnetic induction, and uses the secondary eddy current generated by the pipe wall to detect pipeline defects and weld seams [17][18][19][20]. However, due to the skin effect of ferromagnetic materials, the penetration depth decreases with the increase of excitation coil frequency.…”