Leak location in pipelines using the impulse response function

Abstract

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. RÉSUMÉLes méthodes courantes de détection de fuite, basées sur le transitoire, pour les systèmes de canalisation reposent souvent sur une bonne connaissance du système-incluant le frottement instationnaire, la rugosité des conduites, la géométrie précise et des micro considérations telles que les evacuations mineures-en l'absence de fuites. Une telle connaissance constitue un obstacle majeur et, même si on en disposait, elle serait impossible à inclure dans les équations mathématiques régissant le comportement du système. Une alternative est d'examiner le système étanche pour en trouver le comportement précis, évidemment un problème si le système n'est pas connu pour être exempt de fuites. La réponse étanche peut être employée comme test-repère pour comparer le comportement du système avec fuite. Comme alternative, cet article utilise la réponse impulsionnelle (IRF) comme un moyen de détection de fuite. L'IRF fournit une relation unique entre un événement transitoire injecté et une réponse mesurée de pression d'une canalisation. Cette relation est basée sur les caractéristiques physiques du système et est utile pour déterminer son intégrité. Des réponses transitoires de formes complètement différentes peuvent être directement comparées en utilisant l'IRF. L'IRF fait ressortir toutes les réflexions du système aux impulsions brusques, favorisant de ce fait une plus grande exactitude dans la localisation de la fuite, et permettant à des réflexions de fuite d'être détectées sans l...

Detection of Localized Deterioration Distributed along Single Pipelines by Reconstructive MOC Analysis

“…Several other transient-based leak detection techniques have also been proposed, either in the time domain (Brunone 1999;Lee et al 2007a) or in the frequency domain (Ferrante and Brunone 2003;Covas et al 2005;Lee et al 2005;Gong et al 2012). The transient analysis has also been used in detection of discrete blockages in pipelines (Wang et al 2005; Lee et al 2008a;Sattar et al 2008).…”

Frequency Response Diagram for Pipeline Leak Detection: Comparing the Odd and Even Harmonics

“…In the time domain, these reflections are observed as discontinuities in the pressure signal measured along the pipe (Lee et al 2007). In the frequency domain, the frequency response diagram (FRD) of the pipeline system may be distorted due to the reflected signals (Lee et al 2005a) (Silva et al 1996;Brunone 1999), impulse response techniques (Vítkovský et al 2003;Lee et al 2007) and inverse transient analysis (ITA) methods (Liggett and Chen 1994;Vítkovský et al 2007;Jung and Karney 2008). Frequency domain techniques are usually based on the analysis of a pipeline system's FRD, which describes the amplitude of the pressure response fluctuation corresponding to each frequency component in an input signal.…”

Detection of Distributed Deterioration in Single PipesUsing Transient Reflections

“…Transient-based methods are promising and attractive because they are non-invasive, simple to perform and can provide information about a lengthy section of pipe (hundreds to thousands of meters). While most transient-based fault detection methods focus on the detection of discrete elements, such as leaks (Wang et al 2002;Lee et al 2005;Lee et al 2007a) and discrete (partial) blockages (Vítkovský et al 2003;Lee et al 2008), the detection of distributed elements has not attracted much attention. However, distributed deterioration, such as extended corrosion or blockages (Arbon et al 2007), cement mortar lining spalling (Stephens et al 2008), and pipeline sections with a lower pressure rating (mistakenly installed), sometimes exist in real pipelines and impose negative impacts on the operation of fluid transmission.…”