Illegal connection detection in a viscoelastic pipeline using inverse transient analysis in the time domain (original) (raw)
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Mechanical Systems and Signal Processing, 2022
The widespread use of plastic pipes in different fluid conveyance systems has greatly driven the recent development and application of transient-based methods (TBMs) for leak detection in viscoelastic/polymeric pipelines. Current TBMs for viscoelastic pipe leak detection are usually achieved by a two-step procedure, namely viscoelastic parameters identification and leak detection, which requires the pre-knowledge of intact system states (i.e., non-leak) for comparative analysis. This paper presents an efficient single-step frequency domain inverse transient analysis (FDITA) method for simultaneous identifications of viscoelastic parameters and leaks in plastic pipes, so as to enhance the applicability and accuracy of TBMs. Both the single and branched polymeric pipe systems are applied for the method development and application. To this end, analytical solutions of single and branched systems from the transfer matrix method are firstly derived to represent the transient frequency responses of viscoelastic pipelines with leaks. A global optimized nonlinear curve fitting method is then employed to identify both viscoelastic parameters and potential leaks by knowing/measuring other system and flow conditions. Extensive experimental validations and numerical applications of both single and branched pipe systems demonstrate the very good efficiency and accuracy of the developed method for leak detection in different viscoelastic pipe systems. Furthermore, the mechanism of transient waveleak-viscoelasticity is analysed based on these application results and theoretical evidence. Finally, a sensitivity analysis is performed to quantify and discuss the advantages and potential limitations of the developed method in the paper.
Case study of leak detection based on Gaussian function in experimental viscoelastic water pipeline
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Leakage in transmission pipelines and water distribution networks causes water and energy loss and reduces water quality. The accuracy of leakage detection using transient-based methods depends on several factors. This study investigated the sensitivity of location and size of leaks in simple polyethylene transmission pipelines to dynamic parameters, flow regime, sample size, spatial-step increment, and leak size and location. For this purpose, a hydraulic transient solver was first developed to take into account the dynamic effects of unsteady friction, viscoelasticity of the pipe wall, and the leak. The leakage was assumed to function with a quasi-normal distribution around its real location to reduce problem dimensionality and unnecessary computations. This approach was evaluated based on experimental transient data in which leaks were simulated in different sizes and locations. Results revealed that the hydraulic transient model that includes only viscoelasticity effects could p...
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.
Determining the Internal Wall Condition of a Water Pipeline in the Field Using an Inverse Transient
The application of inverse transient analysis (ITA) to estimate the location and magnitude of lost lining and internal corrosion of metal pipelines is demonstrated for a field pipeline. The method uses a transient model and inverse search algorithm to analyze patterns of measured pressure reflections obtained after a transient pressure wave is induced in a pipeline. The method is applied in the field on a 6 km long section of a 750 mm nominal diameter steel pipeline with internal cement mortar lining. The equipment used for generating hydraulic transients and measuring pressure responses in the pipeline is described. Results of the field tests are analyzed to estimate the location and extent of internal wall damage along the pipeline. Extensive ultrasonic thickness survey results are used to corroborate the approximate location and magnitude of predicted pipeline wall damage.
Diagnosis of water pipeline systems by frequency domain analysis
2017
Inverse transient analysis is a tool for the diagnosis of water distribution systems based on the comparison of the results of analytical or numerical models with pressure signals acquired during transients. The needed numerical models can be derived in the time domain or in the frequency domain. The time-domain approach is the most followed and leads to the method of characteristics. The traditional models derived in the frequency domain as solutions to the linearized water hammer equations, namely the impulse response and the transfer matrix methods, are efficient in the simulation but are not suited for complex arbitrarily configured networks. An alternative frequencydomain formulation is the network admittance matrix method, where the equations are reorganized into a matrix form using graph-theoretic concepts. In this paper the network admittance matrix method is applied to assess its reliability in the diagnosis of water distribution systems. The unsteady-friction term is intro...
Water Supply, 2021
In this paper the results of an experimental validation of a technique for leak detection in polymeric pipes based on the inverse transient analysis (ITA) are presented. In the proposed ITA the Nelder–Mead algorithm is used as a calibration tool. Experimental tests have been carried out in an intact and leaky high-density polyethylene (HDPE) single pipe installed at the Water Engineering Laboratory (WEL) of the University of Perugia, Italy. Transients have been generated by the fast and complete closure of a valve placed at the downstream end section of the pipe. In the first phase of the calibration procedure, the proposed algorithm has been used to estimate both the viscoelastic parameters of a generalized Kelvin–Voigt model and the unsteady-state friction coefficient, by minimizing the difference between the numerical and experimental results. In the second phase of the procedure, the calibrated model allowed the evaluation of leak size and location with an acceptable accuracy. P...
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.
Application of hydraulic transients for leak detection in water supply systems
The current paper reports the investigation of two transient-based techniques for leak detection in water pipe systems using physical data collected in the laboratory and in quasi-field conditions. The first is the analysis of the leak reflected wave during a transient event and the second is inverse transient analysis (ITA). This was approached through the development of an inverse transient analysis tool and the collection of transient data for the testing and validation of this model. Two experimental programmes were carried out at Imperial College and in cooperation with Thames Water for the validation and testing of these techniques. Evaluation of the presence, location and size of leaks was carried out using the collected data. Transient-based techniques have been shown to be successful in the detection and location of leaks and leak location uncertainties depended on the leak size and location, flow regime and location where the transient event was generated. These leak detection methods are very promising for identifying the general area of the trunk main with leakage, and can be combined with other leak location techniques (e.g. acoustic equipment) to more precisely pinpoint the leak position. Transient-based techniques are particularly important for the diagnosis, monitoring and control of existing water supply systems, not only to detect leaks, but also to better understand the causes of pipe bursts and accidents, particularly when these are due to natural transient events.
Journal of Water Supply: Research and Technology-Aqua, 2012
A novel transient-based techniquethe direct backward transient analysis (DBTA)for leak location of single pressurized pipes is presented and tested using real-life data. A transient flow is generated in the pipe by closing the downstream end valve. The transient pressure signal is then measured only at the valve location. Using the method of characteristics and exploiting the measurements after full valve closure, the transient flow is backwardly analyzed by sweeping the pipe from the downstream to the upstream end. Knowing the upstream end heads, additional equations are developed to make the problem of leak detection determined and possible to be solved directly. A system of equations and unknown variables of leaks and flow specifications are then established and simultaneously solved together. Eventually, nodes with non-zero leak size are introduced as leaks. Finally, the method is applied to a real transmission pipeline, Lintrathen East Trunk Main Network at Scottish Water (Dundee, UK) and its abilities are investigated. The results show that the method is capable of dealing with real systems and is reliable, fast and easy to use.