Electromagnetic imaging for internal and external inspection of metallic pipes

Electromagnetic induction tomography (EMT), also known as magnetic induction tomography (MIT), is a new and emerging tomographic imaging technique with potential applications in industrial process tomography. In this paper, the EMT method is proposed as a novel non-invasive inspection tool for metallic pipes. The traditional EMT image reconstruction method offers limited resolution, which may not be suitable for pipeline inspection. A limited region tomography algorithm using a narrowband pass filtering method (NPFM) was developed, resulting in a significant improvement in the resolution of the EMT system for the pipe inspection process. The proposed technique was tested on both aluminium and steel pipes. Damage was created by removing metal sections from the inside or outside of the pipes. Experimental validation of the pipe inspection using an eight-channel EMT system is shown.