Abstract: A method of detecting leakage in a force main involves placing at least two spaced sensors on the force main. Liquid is pumped through the pipe by means of a pump. The pump is shut down for an interval of time, and during the period following pump shutdown while negative pressure is present in the pipe, signals are generated at the sensors due to noise or vibration resulting from fluid being drawn into the pipe. The position of a leak in the pipe is determined by correlating the leak noise signals generated while the pipe is under negative pressure. Alternatively, the invention can be applied to a pressurized pipe, in which case conditions of negative pressure can be deliberatively created for a period to draw in fluid from the outside.

Abstract: To perform a non-destructive condition assessment of a pipe carrying a fluid, an actual value representative of the propagation velocity of an acoustic disturbance propagating between two longitudinally separated points on the pipe is determined. A corresponding predicted value for the propagation velocity is computed as a function of at least one wall thickness parameter of the pipe by using a theoretical model for the propagation of acoustic waves in the pipe that assumes said pipe has a finite wall thickness with a predetermined circumferential thickness profile. The wall thickness parameter is then computed by matching the actual value with the predicted value, for example, by substituting the actual value in a formula predicting the theoretical value.

Abstract: A method of detecting leakage in a force main involves placing at least two spaced sensors on the force main. Liquid is pumped through the pipe by means of a pump. The pump is shut down for an interval of time, and during the period following pump shutdown while negative pressure is present in the pipe, signals are generated at the sensors due to noise or vibration resulting from fluid being drawn into the pipe. The position of a leak in the pipe is determined by correlating the leak noise signals generated while the pipe is under negative pressure. Alternatively, the invention can be applied to a pressurized pipe, in which case conditions of negative pressure can be deliberatively created for a period to draw in fluid from the outside.

Abstract: To perform a non-destructive condition assessment of a pipe carrying a fluid, an actual value representative of the propagation velocity of an acoustic disturbance propagating between two longitudinally separated points on the pipe is determined. A corresponding predicted value for the propagation velocity is computed as a function of at least one wall thickness parameter of the pipe by using a theoretical model for the propagation of acoustic waves in the pipe that assumes said pipe has a finite wall thickness with a predetermined circumferential thickness profile. The wall thickness parameter is then computed by matching the actual value with the predicted value, for example, by substituting the actual value in a formula predicting the theoretical value.

Abstract: To perform a non-destructive condition assessment of a pipe carrying a fluid, an actual value representative of the propagation velocity of an acoustic disturbance propagating between two longitudinally separated points on the pipe is determined. A corresponding predicted value for the propagation velocity is computed as a function of at least one wall thickness parameter of the pipe by using a theoretical model for the propagation of acoustic waves in the pipe that assumes said pipe has a finite wall thickness with a predetermined circumferential thickness profile. The wall thickness parameter is then computed by matching the actual value with the predicted value, for example, by substituting the actual value in a formula predicting the theoretical value.

Abstract: To perform a non-destructive condition assessment of a pipe carrying a fluid, an actual value representative of the propagation velocity of an acoustic disturbance propagating between two longitudinally separated points on the pipe is determined. A corresponding predicted value for the propagation velocity is computed as a function of at least one wall thickness parameter of the pipe by using a theoretical model for the propagation of acoustic waves in the pipe that assumes said pipe has a finite wall thickness with a predetermined circumferential thickness profile. The wall thickness parameter is then computed by matching the actual value with the predicted value, for example, by substituting the actual value in a formula predicting the theoretical value.

Abstract: The average wall thickness of a pipe carrying a fluid is determined by sensing disturbances in the pipe at two spaced locations, determining the propagation velocity of coupled propagation mode signals at low frequencies resulting from the disturbances, and calculating the average pipe wall thickness between the two locations from the propagation velocity and known constants for the pipe and fluid.

Abstract: This invention pertains to the detection of leaks in plastic water distribution pipes by processing the sound or vibration induced in the pipe by water escaping under pressure. Acoustic leak signals are measured at two (or more) contact points with the pipe, e.g., fire hydrants or valves, using vibration sensors or hydrophones. The signals are digitally recorded using the computer's soundcard. The leak is located using the difference in arrival times of two leak signals as determined from the cross-correlation function traditionally used in leak detection applications or an enhanced impulse response function. The enhanced impulse response function eliminates the need to filter leak signals before processing and hence avoids the uncertainty involved in selecting filter cutoff frequencies for non-experts. Listening to leak sound in plastic pipes is made possible in software by shifting their low-frequency content to an audible higher range.