Development of Ultrasonic Guided Wave Transducer for Monitoring of High Temperature Pipelines

Abstract

High-temperature (HT) ultrasonic transducers are of increasing interest for structural health monitoring (SHM) of structures operating in harsh environments. This article focuses on the development of an HT piezoelectric wafer active sensor (HT-PWAS) for SHM of HT pipelines using ultrasonic guided waves. The PWAS was fabricated using Y-cut gallium phosphate (GaPO4) to produce a torsional guided wave mode on pipes operating at temperatures up to 600 °C. A number of confidence-building tests on the PWAS were carried out. HT electromechanical impedance (EMI) spectroscopy was performed to characterise piezoelectric properties at elevated temperatures and over long periods of time (>1000 h). Laser Doppler vibrometry (LDV) was used to verify the modes of vibration. A finite element model of GaPO4 PWAS was developed to model the electromechanical behaviour of the PWAS and the effect of increasing temperatures, and it was validated using EMI and LDV experimental data. This study demonstrates the application of GaPO4 for guided-wave SHM of pipelines and presents a model that can be used to evaluate different transducer designs for HT applications.

High Temperature Ultrasonic Transducers: A Review

“…The variation in the properties for the estimation of the transducer figure of merits was monitored at 600 °C for 1000 h, while the electromechanical coupling factor and elastic constants remained almost the same with variations of less than 1% and 1.5%, respectively. Thermal aging experiments and a stable thickness-shear mode response showed that this ultrasonic transducer could be used at high temperatures up to 600 °C for ultrasonic guided wave applications to superheated steam lines [ 86 ].…”

Sensors for Ultrasonic Nondestructive Testing (NDT) in Harsh Environments

“…The first paper by Dhutti et al [1] from Brunel University UK, focuses on the on-line integrity monitoring of high temperature piping systems, by the use of a piezoelectric wafer active sensor to generate torsional guided waves. As piping temperatures reach up to 600 • C, a gallium phosphate (GaPO 4 ) piezoelectric element was selected, which will resist depoling over extended time periods.…”

Design and analysis of sensor structure based on ultrasonic temperature measurement

“…With the development of technology, temperature measurement has gradually played an important role, especially in the aerospace field. Compared with traditional thermistors or strain gauges, ultrasonic temperature measurement has the characteristics of lightweight, small volume, high sensitivity, and being unaffected by electromagnetic fields [1][2].…”