EMAT pipe inspection technique using higher mode torsional guided wave T(0,2)

Abstract

We developed a pitch-catch system based on electromagnetic acoustic transducers (EMATs) for pipe inspection, which moves inside the pipe in the axial direction. The first higher mode, T(0,2), of the torsional guided wave is transmitted and detected, and variations of amplitude and phase are measured while moving the EMATs. Several aluminum pipes containing dish-shaped defects are inspected, and the amplitude and phase show enough detection sensitivity. It is found that the phase measurement has better potential as a tool for quantitative inspection. The applicability of the technique for steel pipe is also confirmed.

Interaction of SH guided waves with wall thinning

“…Qualitative pipe inspection for corrosion at the high-frequency regime has been performed using circumferential SH guided waves [3,9] and torsional guided waves [26]. The basic concept consists of a screening system that transmits and receives the SH0 and SH1 modes using PPM EMATs.…”

Microwave-Based SAR Technique for Pipeline Inspection Using Autofocus Range-Doppler Algorithm

“…6, the SNR and IF of the images were computed for both the RDA and the ω − k algorithm. The SNR and the IF of the image are computed using SN R = 20log 10 µ pipe σ pipe…”

“…(MFL) [8] [9], and electromagnetic acoustic transducers [10]. While tremendous progress has been made on mainline piping systems, which are conventionally piggable, a key difficulty facing pipeline integrity personnel has been the ability to inspect and gather data on pipelines that are unpiggable or hard to navigate due to the smaller size of the pipes usually installed in the cities.…”

Signal Strength Enhancement of Magnetostrictive Patch Transducers for Guided Wave Inspection by Magnetic Circuit Optimization

“…Guided waves, which are ultrasonic waves restricted by the boundaries of the solid waveguide during propagation [1], have been applied in the inspection of many industrial structures, such as pipes [2,3], rods [4], plates [5][6][7] and rails [8][9][10] with the advantages of long distance, full coverage and low cost [11]. The conversions between the electrical energy and mechanical energy are mainly involved in guide wave inspection, which are accomplished by the transducers as the key parts in the inspection system.…”

“…transducers (PZT) and magnetostrictive transducers. The EMATs are able to work without contacting the waveguide using the Lorentz force [11,12] although their applications are limited due to the low conversion efficiency, inapplicability for non-metal waveguides and signal instability caused by the coil vibration. The laser can be used to generate guided waves in a contactless manner based on the thermoelastic effect.…”