An acoustic technique for tracing plastic pipe

Many gas distribution company operation and maintenance activities require precise knowledge of the location of buried plastic piping. Under sponsorship of the Southern California Gas Company, IGT successfully demonstrated an acoustic plastic pipe location technique and is developing that technique into a practical field instrument. An acoustic signal is injected into the plastic pipe such that it propagates through the pipe. As the acoustic wave travels along the pipe, some of the sound radiates from the pipe to the surface of the ground. An array of sensors on the surface of the ground perpendicular to the pipe detects the acoustic signal, thereby locating the pipe. Two different acoustic measurements are used. The first measurement locates the pipe to within + 1.2 m (+ 4.0 ft). The second technique then determines the location of the pipe to within + 15 cm (+ 6 in.) and gives an estimate of pipe depth.