Surface acoustic wave corrosion sensors for liquified natural gas tank monitoring

Abstract

The transportation of Liquified Natural Gas (LNG) is currently suffering from costly maintenance and the absence of a safe and robust monitoring system that will provide online information on the LNG tank status. Such a system is proposed, with the use of Surface Acoustic Wave (SAW) sensors. These sensors are passive, robust and suitable for harsh environment applications, meeting all the requirements set by this project. Here, the background of SAW technology is presented and the specifics of the project are discussed. The focus of this work is on the design and fabrication of SAW corrosion sensors and their implementation in a sensor system. These sensors feature SAW resonator structures on quartz and operate at frequencies inside the 433.92 MHz Industrial, Scientific and Medical (ISM) band. Following the successful fabrication of SAW resonators, a technique to obtain several resonators with tightly spaced frequencies is presented. Based on this, multi-resonance SAW transponder chips were developed, featuring five distinct resonances. The fabricated devices were used to explore corrosion sensing concepts. A transponder based corrosion sensor with sacrificial parts showed a detectable change in its response upon damage to the sacrificial parts. A mass loss based corrosion sensor showed a 28.4% reduction in its quality factor, upon damage to exposed parts. Progress was also reported in the materialization of a small-scale demonstrator of the proposed monitoring system. The results presented here demonstrate the feasibility of SAW corrosion sensors that can detect the onset of corrosion, as part of a complete, SAW resonator based, structural health monitoring system, for the detection of leaks in LNG tanks.

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Identifiers

ORCID for Dimitra Georgiadou: orcid.org/0000-0002-2620-3346

ORCID for Themis Prodromakis: orcid.org/0000-0002-6267-6909

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