TITLE:
A Pipe Inspection Using a Circumferential SH-Mode Plate Wave Generated in a Pipe by an Electromagnetic Acoustic Transducer (EMAT)
AUTHORS:
Riichi Murayama, Hideo Nishino
KEYWORDS:
SH-Mode Plate Wave, EMAT, Pipe, Nondestructive Inspection, Resonance Method
JOURNAL NAME:
World Journal of Engineering and Technology,
Vol.6 No.3,
August
22,
2018
ABSTRACT: Inspection of a pipeline is essential for the safe use of such facilities. A trial sensor using an electromagnetic acoustic transducer (EMAT), which can generate the SH-mode plate wave propagating in the circumferential direction, has been developed to realize this objective. It consists of a circulating electromagnetic induction coil around the pipe and many permanent magnets arranged on the surface of the pipe in the circumferential direction. It is postulated that the intensity of the SH-mode plate wave propagating in the circumferential direction is dependent on any defects in the circumferential direction. A resonance method was then utilized to obtain a stronger received signal. As a result, it was confirmed that the resonance status can be detected. The relationship between the signal intensity and the pipe thickness was then evaluated. It was confirmed that the wall thickness of about 20% can be detected under a static condition. Finally, a moving test has been executed by using an axially traveling device manufactured by trial. The test pipes with different sizes of drilled holes were prepared. The change in the received signal intensity according to different sizes of the drilled holes was successfully detected.