Lessons from two field tests on pipeline damage detection using acceleration measurement (Invited Paper) Masanobu Shinozuka *a , Sungchil Lee a , Sehwan Kim a , and Pai H. Chou a a University of California, Irvine, CA USA 92697-2700 ABSTRACT Early detection of pipeline damages has been highlighted in water supply industry. Water pressure change in pipeline due to a sudden rupture causes pipe to vibrate and the pressure change propagates through the pipeline. From the measurement of pipe vibration the rupture can be detected. In this paper, the field test results and observations are provided for implementing next generation of SCADA system for pipeline rupture detection. Two field tests were performed on real buried plastic and metal pipelines for rupture detection. The rupture was simulated by introducing sudden water pressure drop caused by water blow-off and valve control. The measured acceleration data at the pipe surfaces were analyzed in both time and frequency domain. In time domain, the sudden narrow increase of acceleration amplitude was used as an indication of rupture event. For the frequency domain analysis, correlation function and the short time Fourier Transform technique were adopted to trace the dominant frequency shift. The success of rupture detection was found to be dependent on several factors. From the frequency analysis, the dominant frequency of metal water pipe was shifted by the water pressure drop, however, it was hard to identify from the plastic pipeline. Also the influence of existing facility such as airvac on pipe vibrations was observed. Finally, several critical lessons learned in the viewpoint of field measurement are discussed in this paper. Keywords: Pipeline, damage detection, acceleration measurement, correlation function 1. INTRODUCTION Vibration or acoustic signal measurement of water pipe to detect and locate damage or water leaks has been adopted in many research 1, 2 . The most widely used method for locating rupture is based on the correlation technique 3 . The technique is very straightforward. In this method a rupture or water leak acts as a signal source and two sensors as receivers. The delay time between two signals at the sensors attached on a pipeline network, computed from the cross correlation function, is used for locating water leak 3-5 . To enhance the detection performance signal processing techniques such as filtering and windowing are adopted during the procedure. In this method the signals are assumed to be stationary 5 . Though many correlation based techniques are widely used and reported to be successful to locate water leaks, several limits should be overcome to be applied to water supply systems which have a lot of water flow control units and may generate non-stationary flow and unexpected water flow changes. Moreover, the techniques should be verified for water pipe with large or varying diameters. In this paper, a more simple but robust method to detect rupture was applied to real water pipe with large diameter for the next generation of SCADA system. The fundamental idea of the new method is that change in water pressure induced by rupture produces a sharp peak in acceleration signal. So rupture can be identified directly from acceleration signal. To verify the new proposed method, it is applied to real buried plastic and metal pipes with large diameters. 2. DESCRIPTION OF FIELD TESTS 2.1 PVC pipe test A field test to verify the proposed method was performed by UC Irvine (UCI) and Santa Ana Watershed Project Authority (SAWPA) on May 17, 2010. The water pressure change was introduced by blowoff. From the several candidate locations, as seen in Figure 1, AV 0340 and BO 0335 were selected for the measurement and blowoff sites. The blowoff was carried out at BO 0335 location and the pipe vibration due to the blowoff was recorded at AV 0340 * shino@uci.edu ; phone 949 824 9379