Discrete Blockage Detection in Pipelines Using the Frequency Response Diagram: Numerical Study

Abstract

This paper proposes the use of fluid transients as a noninvasive technique for locating blockages in transmission pipelines. By extracting the behavior of the system in the form of a frequency response diagram, discrete blockages within the pipeline were shown to induce an oscillatory pattern on the peaks of this response diagram. This pattern can be related to the location and size of the blockage. A simple analytical expression that can be used to detect, locate, and size discrete blockages is presented, and is shown able to cater for multiple blockages existing simultaneously within the system. The structure of the expression suggests that the proposed technique can be extended to situations where system parameters may not be known to a high accuracy and also to more complex network scenarios, although future studies may be required to verify these possibilities.Keywords: Frequency response; Linear systems; Transients; Water pipelines; Resonance; Numerical analysis. IntroductionThe increasing industrial reliance on pipeline systems for the transport of materials has led to the recent emphasis on technologies for the fast detection and location of faults within such systems. Amongst the types of problems that can occur in a pipeline system, the formation of blockages within the pipe poses a most elusive problem for existing fault detection technologies. Unlike leaks within piping systems, a blockage does not generate clear external indicators for its location such as the release and accumulation of fluids around the pipe. Often intrusive procedures, such as the insertion of a closedcircuit camera or a robotic pig, are required to determine the location of blockages. The creation of nonintrusive techniques for fault detection that gives a clear picture of the internal conditions of the pipeline is desirable, and the use of fluid transients for this purpose is a promising development.

Experimental verification of pipeline frequency response extraction and leak detection using the inverse repeat signal

“…In the last decade, the analysis of the FRF of pipeline systems under linear system theory has also been used in integrity monitoring of water pipelines, such as the detection of leaks (Covas, Ramos, & de Almeida, 2005;Duan, Lee, Ghidaoui, & Tung, 2011;, 2014Lee, Vítkovský, Lambert, Simpson, & Liggett, 2005a, 2005bMpesha, Gassman, & Chaudhry, 2001;, discrete blockages (Lee, Vítkovský, Lambert, Simpson, & Liggett, 2008;Sattar, Chaudhry, & Kassem, 2008), extended blockages (Duan, Lee, Ghidaoui, & Tung, 2012, 2013, and general parameter identification (Zecchin, White, Lambert, & Simpson, 2013).…”

Transient wave-blockage interaction and extended blockage detection in elastic water pipelines

“…(8) (12) in which the term (a) represents the wave propagation in a blockage-free pipeline while term (b) represents the effect of the extended blockage on the wave field. In particular, the presence of the Lee et al (2008 and and Sattar et al, (2008), where a blockage of a sufficiently short length can be approximated as a lumped local loss (discrete blockage), which changes the amplitude of the system resonant responses but not their frequencies. The quantity of this frequency shifting by the extended blockage is further analyzed in the next section.…”

“…Transient-based methods, where a transient signal is injected into the conduit and the response measured at specified locations, is a promising approach for detecting defects in pipes and have been used in the detection of discrete blockages, leaks, and assessment of pipe wall condition (Liggett and Chen, 1994, Brunone, 1999, Brunone and Ferrante, 2001, Vitkovsky et al, 2000, Wang et al, 2002, Wang et al, 2005, Ferrante and Brunone 2003, Covas et al, 2004, Mohapatra et al, 2006, Sattar et al, 2008, Lee et al, 2004, Lee et al, 2006, Lee et al, 2008, Stephens, 2008, Duan et al, 2011a, Duan et al, 2011b, Duan et al, 2012, Mohapatra and Chaudhry, 2011, Meniconi et al, 2009, Meniconi et al, 2011and Meniconi et al, 2013. The tenet of this approach is that a measured pressure wave signal in a conduit is modified by, and thus contains information on, the conduit properties.…”

“…Wang et al (2005) showed that a discrete blockage in a pipe system introduces a frequency dependent damping to the transient signal and developed a technique for locating and sizing discrete blockages based on this damping. Mohapatra et al (2006), Sattar et al (2008) and Lee et al (2008 and found the effect of the blockage in time translates to a pattern being imposed onto the amplitudes of the resonant responses from the system and this pattern can be used to detect and locate the discrete blockages in the frequency domain.…”

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

“…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). …”