Detecting thinner-walled pipe sections using a spark transient pressure wave generator

Research undertaken in the last two decades has demonstrated that hydraulic transient pressure waves, the phenomena behind water hammer, can be used as a tool for noninvasive and nondestructive condition assessment of long water transmission pipelines (in particular, detecting changes in the pipe wall properties). However, the spatial resolution of current transient-based technology is relatively low because the useful bandwidth of conventional valve-generated incident pressure waves is less than 100 Hz. This research develops a new transient pressure wave generator using controlled electrical sparks to provide high-frequency waves and improve the incident signal bandwidth. An electrical spark surrounded by water causes the development of a localized vapor cavity, the collapse of which induces an extremely sharp pressure pulse into the surrounding body of fluid. Experimental studies on a copper pipeline are conducted to investigate the usefulness of the pulse signals generated by the new spark generator for detecting thinner-walled pipe sections. Techniques are developed to analyze the wideband spark-induced pressure responses. The results show that the generated sharp pressure pulses have a useful frequency bandwidth up to 2 kHz. The success and accurate diagnosis of a thinner-walled section confirms that the dramatic improvement in bandwidth significantly enhances the spatial resolution of hydraulic transient-based pipe condition assessment.