Leak Detection in Pipelines using the Damping of Fluid Transients (original) (raw)
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Transient damping method for narrowing down leak location in pressurized pipelines
Hydrological Research Letters
Numerous leak detection methods have been developed for pipeline systems because of the shortage of water resources, increased water demand, and leak accidents. These methods have their advantages and disadvantages in terms of cost, labor, and accuracy; therefore, it is important to narrow down the location of a leak as easily, rapidly, and accurately as possible. This study applies the technologies based on the execution of a transient event (transient testbased technologies (TTBTs)), and a model is presented for representing the relation between the leak location and the damping of the pressure transient due to the leakage. The model is verified with laboratory experiments in which the leak location can be narrowed down to be less than 10% to 30% of the total pipe length. The model is found to be more effective if the leak location is nearer to the upstream end. In addition, the leak location found by the damping model varies with an approximate absolute error of 2% to 5% of the pipe length. It is suggested that the damping model is suitable for narrowing down and not for finding the leak location, and should be used in combination with other leak detection methods. KEYWORDS detection of water leakage; pipeline; water hammer; damping of pressure transient; narrowing down of leak location; stock management of infrastructure
Frequency Domain Analysis for Detecting Pipeline Leaks
Journal of Hydraulic Engineering-asce, 2005
This paper introduces leak detection methods that involve the injection of a fluid transient into the pipeline, with the resultant transient trace analyzed in the frequency domain. Two methods of leak detection using the frequency response of the pipeline are proposed. The inverse resonance method involves matching the modeled frequency responses to those observed to determine the leak parameters. The peak-sequencing method determines the region in which the leak is located by comparing the relative sizes between peaks in the frequency response diagram. It was found that a unique pattern was induced on the peaks of the frequency response for each specific location of the leak within the pipeline. The leak location can be determined by matching the observed pattern to patterns generated numerically within a lookup table. The procedure for extracting the linear frequency response diagram, including the optimum measurement position, the effect of unsteady friction, and the way in which the technique can be extended into pipeline networks, are also discussed within the paper.
Experimental verification of the frequency response method for pipeline leak detection
Journal of Hydraulic Research, 2006
This paper presents an experimental validation of the frequency response method for pipeline leak detection. The presence of a leak within the pipe imposes a periodic pattern on the resonant peaks of the frequency response diagram. This pattern can be used as an indicator of leaks without requiring the "no-leak" benchmark for comparison. In addition to the experimental verification of the technique, important issues, such as the procedure for frequency response extraction and methods for dealing with frequency-dependent friction are considered in this paper. In this study, transient signals are generated by a side-discharge solenoid valve. Non-linearity errors associated with large valve movements can be prevented by a change in the input parameter to the system. The optimum measuring and generating position for two different system boundary configurations-a symmetric and an antisymmetric system-are discussed in the paper and the analytical expression for the leak-induced pattern in these two cases is derived.
Journal of Loss Prevention in the Process Industries, 2019
Leakages in pipelines can cause serious consequences, such as economic loss, or fire and explosion. Hence, leak detection and location techniques are of crucial importance for pipeline maintenance, safety of industry facilities and environment. A modified transient-based method is proposed in this paper for leak detection and location in a reservoir-pipe-valve (RPV) system. The leak location model is based on the time when a pressure wave propagates from the valve to the leak location and back again. Furthermore, in the leak detection model, the onedimensional unsteady friction model is introduced into Method of Characteristics (MOC). Then, the governing equations are derived as a ternary system of equations, in which the unknown parameters, especially leak size coefficient, are obtained by analyzing the first transient pressure wave. To validate the method efficiency, both one leak and two leaks situations are taken into consideration in simulation. The simulated results show notable correlations between the model and real leak locations. Additionally, the errors between calculated and actual values of the parameters remain in acceptable ranges. Finally, the developed method is verified by experimental data, and the results demonstrate that it has high accuracy and shows a great performance in leak detection and location.
Locating leaks by using the step response of a pipeline
This paper presents a formal analysis of the pressure wave propagation along a pipeline to locate possible leaks. More specifically, this paper studies the step response of a pipeline when a downstream valve is closed to associate leaks' parameters (magnitude and position) with their effects on the pressure wave, such as the diversion and dissipation of the wave energy. The analysis starts with a matrix formulation (in the Laplace domain) to represent the behavior of a pipeline with a leak. Subsequently, boundary and initial conditions are imposed on the formulation in order to obtain the downstream pressure when a downstream valve is closed. Before converting the pressure response expression from the Laplace to the time domain, it is expanded into a series of exponential terms with negative exponents. The resulting transient expression is a sum of step functions with arguments that depend on time, the length of the pipeline, the wave speed and the leak position. From these arguments and the amplitude of the steps, the position and the magnitude of the leak can be determined.
Leak location in pipelines using the impulse response function
Current transient-based leak detection methods for pipeline systems often rely on a good understanding of the system—including unsteady friction, pipe roughness, precise geometry and micro considerations such as minor offtakes—in the absence of leaks. Such knowledge constitutes a very high hurdle and, even if known, may be impossible to include in the mathematical equations governing system behavior.An alternative is to test the leak-free system to find precise behavior, obviously a problem if the system is not known to be free of leaks. The leak-free response can be used as a benchmark to compare with behavior of the leaking system. As an alternative, this paper uses the impulse response function (IRF) as a means of leak detection. The IRF provides a unique a relationship between an injected transient event and a measured pressure response from a pipeline. This relationship is based on the physical characteristics of the system and is useful in determining its integrity. Transient responses of completely different shapes can be directly compared using the IRF. The IRF refines all system reflections to sharp pulses, thus promoting greater accuracy in leak location, and allowing leak reflections to be detected without a leak-free benchmark, even when complex signals such as pseudo-random binary signals are injected into the system. Additionally, the IRF approach can be used to improve existing leak detection methods. In experimental tests at the University of Adelaide the IRF approach was able to detect and locate leaks accurately.
Pipeline Leak Detection by Transient-Based Method Using MATLAB® Functions
This paper shows a method for pipeline leak detection using a transient-based method with MATLAB® functions. The simulation of a pipeline systems in the time domain are very complex. In the case of the dissipative model, transfer functions are hyperbolic Bessel functions. Simulating a pipeline system in the frequency domain using a dissipative model we could find an approximate transfer function with equal frequency domain response to in order get the pipeline system's time domain response. The method described in this paper can be used to detect, by comparison, to detect a leak in a pipeline system model.
Experimental Observation and Analysis of Inverse Transients for Pipeline Leak Detection
Journal of Water Resources Planning and Management, 2007
Fluid transients result in a substantial amount of data as pressure waves propagate throughout pipes. A new generation of leak detection and pipe roughness calibration techniques has arisen to exploit those data. Using the interactions of transient waves with leaks, the detection, location, and quantification of leakage using a combination of transient analysis and inverse mathematics is possible using inverse transient analysis ͑ITA͒. This paper presents further development of ITA and experimental observations for leak detection in a laboratory pipeline. The effects of data and model error on ITA results have been explored including strategies to minimize their effects using model error compensation techniques and ITA implementation approaches. The shape of the transient is important for successful application of ITA. A rapid input transient ͑which may be of small magnitude͒ contains maximum system response information, thus improving the uniqueness and quality of the ITA solution. The effect of using head measurements as boundary conditions for ITA has been shown to significantly reduce sensitivity, making both detection and quantification problematic. Model parsimony is used to limit the number of unknown leak candidates in ITA, thus reducing the minimization problem complexity. Experimental observations in a laboratory pipeline confirm the analysis and illustrate successful detection and quantification of both single and multiple leaks.
Detection and Location of a Partial Blockage in a Pipeline Using Damping of Fluid Transients
Journal of Water Resources Planning and Management-asce, 2005
A new blockage detection method using blockage-induced transient damping is developed based on a linear analytical solution for the transients in a pipeline with a blockage. The linear analysis indicates that pipe friction damping on a pipe transient is exactly exponential, while the blockage damping is exponential for each of the individual harmonic components. For each individual component, the blockage-induced damping depends on the blockage magnitude and position and is independent of measurement location and the transient event. The proposed blockage detection method is successful in detecting, locating and quantifying a pipe blockage based on the laboratory experiments.
Pipeline Leak Detection by Transient-Based Method Using MATLAB R Functions
This paper shows a method for pipeline leak detection using a transient-based method with MATLAB R functions. The simulation of a pipeline systems in the time domain are very complex. In the case of the dissipative model, transfer functions are hyperbolic Bessel functions. Simulating a pipeline system in the frequency domain using a dissipative model we could find an approximate transfer function with equal frequency domain response to in order get the pipeline system's time domain response. The method described in this paper can be used to detect, by comparison, to detect a leak in a pipeline system model.