Papadopoulou K., Glover D., Lennox B., McKay D., Taylor A., Turner J.

Acoustic waves are sensitive to changes in the properties of the fluid medium1, 2, 6. Consequently, any leakage or blockage in a pipe will cause some of the incident acoustic energy to be reflected2, 6. This principle enables the integrity of the pipeline to be monitored using acoustic reflectometry2, 3, 4, 5. The maximum interrogation length will be determined by the signal to noise ratio. Thus, all acoustic methods are limited by the penetration of the acoustic signal through the fluid, which depends on the attenuation and reflections e.g. at welds, T-pieces. Acoustic time histories have been collected in air-filled pipelines up to 305 mm diameter. The waveform and frequency content of the plane waves generated by a loudspeaker were varied systematically. Successive reflections then yielded the attenuation of the acoustic signal due to wall friction and the transmission parameters of individual pipe features. [Similar measurements have also been made in a water flow rig]. Significant differences have been found between the measured values and those quoted in the standard literature1. Preliminary calculations suggest that an interrogation length in excess of 1 km is achievable. References 1. Kinsler, 1999, 'Fundamentals of Acoustics', Wiley. 2. Morgan, 1979, 'Experience with the Acoustic Ranger', ASNT/CSNDT Conf., Niagara Falls. 3. Papadopoulou et al., 2005, 'A novel acoustic technique etc.', Chem. Eng. World Cong., UK. 4. Shamout et al., 2001, 'Remote pipeline leakage detection', UK Pat. App. 0128704.4. 5. Shamout, 2002, 'Remote leakage detection etc.', PhD thesis, Univ. Manchester. 6. Sharp, 1996, 'Acoustic pulse reflectometry etc.', Ph.D. thesis, Univ. Edinburgh.