DEVELOPMENT OF MEASUREMENT SYSTEM USING OPTICAL FIBER AE SENSORS FOR ACTUAL PIPING

摘要

AE monitoring for high-temperature components such as high energy steam pipings necessitates the use of waveguides to protect the sensor. However, this causes distortion of propagating waveforms and it is very difficult to quantitatively analyze AE using such modulated waveforms. From these backgrounds, recently CRIEPI has developed the optical fiber sensor that can be applied up to 600℃ and the measurement system. The aims of this study are to develop practical sensor installation techniques of the optical fiber sensors for high-temperature pipings and to investigate the suitable waveform analysis technique of optically detected AE signals. (1) Direct attachment of the sensor on piping surface using couplant and (2) attachment of the sensor on the end of a stud-welded waveguide were proposed for suitable sensor installation techniques. The wavelet-based signal processing has been applied to the detected signal by the optical fiber sensors to improve the accuracy of source location on steel pipings. It was demonstrated that loca-tional error of this technique was less than ±4% (direct attachment on the surface) or less than ±25% (attachment on the end of the waveguide).