Leak detection by inverse transient analysis in an experimental PVC pipe system

Abstract

Leakage reduction in water supply systems and distribution networks has been an increasingly important issue in the water industry since leaks and ruptures result in major physical and economic losses. Hydraulic transient solvers can be used in the system operational diagnosis, namely for leak detection purposes, due to their capability to describe the dynamic behaviour of the systems and to provide substantial amounts of data. In this research work, the association of hydraulic transient analysis with an optimisation model, through inverse transient analysis (ITA), has been used for leak detection and its location in an experimental facility containing PVC pipes.Observed transient pressure data have been used for testing ITA. A key factor for the success of the leak detection technique used is the accurate calibration of the transient solver, namely adequate boundary conditions and the description of energy dissipation effects since PVC pipes are characterised by a viscoelastic mechanical response. Results have shown that leaks were located with an accuracy between 4-15% of the total length of the pipeline, depending on the discretisation of the system model. Key words 9 9 9 9 calibration, hydraulic transients, inverse models, leak detection, plastic pipes

Leak Size, Detectability and Test Conditions in Pressurized Pipe Systems

“…The effective area defines the hydraulic behavior of the leak completely and it is relevant for the practical applications. In fact, A E can be directly estimated by a leak detection technique and it is commonly used in the pressurized pipe system models within the steady and unsteady-state approach (e.g., Colombo et al 2009;Ferrante 2012;Gong et al 2013;Liggett and Chen 1994;Massari et al 2012Massari et al , 2013Pudar and Liggett 1992;Shamloo and Haghighi 2009;Soares et al 2011;Vítkovský et al 2000). The parameter l k has been also used to distinguish between leaks whose behavior is not affected by the shape (Brunone and Ferrante 2001) -defined as small leaks (l k ≤ 1/10) -and the others.…”

Transient vaporous cavitation in viscoelastic pipes

“…Even for identical discharge, the creep functions varied slightly from test to test; as successive transients were carried out, the pipe tended to relax not having sufficient time for complete recovery. In conclusion, calibrated creep functions may not represent the accurate rheological behaviour of an HDPE pipe wall, but the combination of mechanical behaviour of the pipe material in the system and of other damping effects (Soares et al 2008b(Soares et al , 2011.…”

“…A set of VE parameters was determined by an inverse model based on the two-step procedure, namely, the Genetic Algorithm and the LevenbergMarquardt search method (Soares et al 2011). The calculated elastic wave speed was 315 m/s and, according to the recommendation of Covas et al (2005) for HDPE pipes, three KelvinVoigt elements were determined via inverse calculations (τ 1 = 0.018 s, J 1 = 0.256 GPa −1 , τ 2 = 0.50 s, J 2 = 0.238 GPa −1 , and τ 3 = 3.0 s, J 3 = 0.211 GPa −1 for only VE; τ 1 = 0.018 s, J 1 = 0.256 GPa −1 , τ 2 = 0.50 s, J 2 = 0.210 GPa −1 , and τ 3 = 3.0 s, J 3 = 0.200 GPa −1 for VE + UF).…”

Optimal Selection and Monitoring of Nodes Aimed at Supporting Leakages Identification in WDS

“…Another set of methods is based on inverse transient analysis [11][12][13][14]. The principal concept of this methodology is the analysis of pressure data collected during the occurrence of transitory events by means of the minimization of the difference between the observed and calculated parameters [15].…”