Physical Principles of Measurements with EMAT Transducers

Thompson, R. B.

doi:10.1016/b978-0-12-477919-8.50010-8

Cited by 213 publications

(108 citation statements)

References 15 publications

Supporting

Mentioning

107

Contrasting

Order By: Relevance

“…A value of 1 represents a normalized amplitude with minimal standoff. These measured results fit the predicted dependence for a meander line (ML) coil relatively well [8]. For a ML coil, the signal amplitude is expected to follow exp(-c G/D), where G is the coil standoff from the surface, D is the interline spacing for the meander coil, and c is a positive constant.…”

Section: Sensitivity To Standoff and Tiltsupporting

confidence: 54%

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

Aron¹,

Gore²,

Eaton³

et al. 2003

View full text Add to dashboard Cite

Abstract: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 reflection and transmission coefficients, beam width, standoff and tilt sensitivities. For most of the measurements the section presents analysis curves, such as reflection coefficient versus crack depth. Some notable results for the chosen modes are: that acceptable SNRs were generated in a pipe with magnetostrictive EMATs, that optimum bias for magnetostrictive transmitters and receivers is magnetic saturation, that crack reflection and transmission coefficients from crack interactions agree with 2 D simulations and seem workable for crack grading, and that the mouse has good waveform quality and so is ready for exhaustive measurement EMAT scans of SCC interactions. This section also reviews further coil optimisation and implementation requirements. These involve transmitter and receiver power, acquisition parameters, and magnetic configuration. At this time all these seem reasonable for an ILI tool.

show abstract

Section: Sensitivity To Standoff and Tiltsupporting

confidence: 54%

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

Aron¹,

Gore²,

Eaton³

et al. 2003

View full text Add to dashboard Cite

show abstract

“…It is also flagrant that the piezoelectromagnetic SH-waves can be produced by the electromagnetic acoustic transducers (EMATs) [62]. This non-contact method (EMAT) can offer a series of advantages in comparison with the traditional piezoelectric transducers [63] [64]. The results of this short report can be also useful for constitution of technical devices with a higher level of integration such as lab-on-a-chip, etc.…”

Section: Theory and Resultsmentioning

confidence: 95%

Investigation of SH-Wave Fundamental Modes in Piezoelectromagnetic Plate: Electrically Closed and Magnetically Closed Boundary Conditions

Zakharenko¹

2014

OJA

View full text Add to dashboard Cite

show abstract

“…Normally, there are two basic types of EMAT sensor structures [4]. One is a Lorentz force EMAT using a meander coil, and the other is a magnetostrictive force EMAT that employs a meander Fig.…”

Section: Design Of Sh Emat Sensormentioning

confidence: 99%

Feasibility Study on the Utilization of EMAT Technology for In-line Inspection of Gas Pipeline

Cho¹,

Yoo²,

Rho³

et al. 2011

Journal of Magnetics

View full text Add to dashboard Cite

If gas is leaking out of gas pipelines, it could cause a huge explosion. Accordingly, it is important to ensure the integrity of gas pipelines. Traditionally, over the years, gas-operating companies have used the ILI system, which is based on axial magnetic flux leakage (MFL), to inspect the gas pipelines. Relatively, there is a low probability of detection (POD) for the axial defects with the axial MFL-based ILI. To prevent the buried pipeline from corrosion, it requires a protective coating. In addition to the potential damage to the coating by environmental factors and external forces, there could be defects on the damaged coating area. Thus, it is essential that nondestructive evaluation methods for detecting axial defects (axial cracks, axial groove) and damaged coating be developed. In this study, an electromagnetic acoustic transducer (EMAT) sensor was designed and fabricated for detecting axial defects and coating disbondment. In order to validate the performances of the developed EMAT sensor, experiments were performed with specimens from axial cracks, axial grooves, and coating disbondment. The experimental results showed that the developed EMAT sensor could detect not only the axial cracks (minimum 5% depth of wall thickness) and axial grooves (minimum 10% depth of wall thickness), but also the coating disbondment.

show abstract

Physical Principles of Measurements with EMAT Transducers

Cited by 213 publications

References 15 publications

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

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

Investigation of SH-Wave Fundamental Modes in Piezoelectromagnetic Plate: Electrically Closed and Magnetically Closed Boundary Conditions

Feasibility Study on the Utilization of EMAT Technology for In-line Inspection of Gas Pipeline

Contact Info

Product

Resources

About