Compensation of sound velocity variation based on resampling algorithm for natural gas pipeline safety monitoring

Abstract An active acoustic excitation method based on pulse-compression and envelope subtraction is used for natural gas pipeline safety monitoring. However, when sound velocity changes with ambient temperature, signal-to-noise ratio (SNR) of subtraction result will decrease and severe location error may occur. Therefore, resampling algorithm is utilized to compensate the detection signal drift caused by sound velocity variation. Experiment results demonstrate that the drift of both reflected signal and envelope can be corrected completely after resampling. The SNR of subtraction results are significantly improved to 8.3 dB and 7.34 dB in hydrate plugging and leak detection respectively. The relative location errors of hydrate plugging and leak are respectively reduced from 0.3110% and 0.3494% to 0.0303% and 0.0186%. Besides, the standard deviation of 27 leak location results is 0.0014 m which verifies the repeated location accuracy. The novel method has considerable application prospect in natural gas pipeline safety online monitoring.