Pipeline Condition Assessment Research Articles

Inverse Wave Reflectometry Method for Hydraulic Transient-Based Pipeline Condition Assessment

Established water distribution systems (WDSs) typically consist of pipelines buried underground that are aging and deteriorating, and as such, it is difficult to assess their condition for maintenance and replacement. This paper proposes a novel hydraulic transient-based inverse wave reflectometry method (IWRM) for condition assessment of water pipelines in WDSs. Instead of using the method of characteristics (MOC) for the transient modeling, a computationally high-efficiency wave reflectometry method (WRM) has been developed to simulate the transient response of a pipe system. Further efficiency improvement has been made by simplifying the friction term in the WRM. An IWRM has then been developed by combining the WRM with a differential evolution algorithm to calibrate the locations and magnitudes of the pipeline impedance changes (wall thickness changes and wave speed changes) caused by deterioration. The IWRM is able to concentrate on the major wave reflections caused by pipe impedance changes and minimize the effects from background noise and other interferences, such as background pressure fluctuations (i.e., those caused by pump operations, tank level fluctuations, and household water usage) and wave reflections by pipe fittings. The proposed method has a high efficiency due to its fast WRM simulation and its small number of optimization variables. Extensive numerical verifications have been conducted on reservoir-pipeline-valve systems with a uniform deteriorated pipe section, a nonuniform deteriorated section, and multiple deteriorated sections. The deteriorated sections in these case studies were all well detected even though the pressure signals were contaminated with strong noise. Experimental verification has also been conducted on a laboratory copper pipeline with one thinner-walled pipe section successfully identified.

Field evaluation of in-service buried pipeline using robust instrumentation

In-depth field instrumentation was undertaken on a section of a large diameter (660 mm) cast iron water pipe in Sydney, Australia to monitor the performance of a field pipeline under internal and external loads. This paper elaborates the instrumentation details and procedures adopted to capture various infield data to support the condition assessment of buried ageing pipelines under operational conditions including internal water pressure and external traffic loads. The adopted instrumentation realistically captured pipe strain, pipe joint displacement and rotation, soil pressure, temperature and moisture content. The results are discussed to evaluate the efficiency of the instrumentation for real-time monitoring which facilitates the understanding of the behaviour of a field pipeline. The pipe strains measured under various traffic conditions provide useful estimations for the evaluation of the condition of ageing pipelines. Fairly uniform strains were detected under internal water pressure loadings which showed a considerably larger impact on pipe performance than that due to other influential factors. The soil vertical and lateral pressures measured at various locations around the pipe revealed the relative magnitudes of ground stresses, facilitating new designs and the failure assessment of in-service buried pipelines. Soil moisture and temperature data showed variations directly related to atmospheric conditions. The robust field instrumentation adopted in this study is useful for the accurate monitoring of in-service pipes which may be highly vulnerable to catastrophic failure due to ageing-induced corrosion and severe operational loads.

Advances in Condition Assessment of Water Pipelines

Condition assessment forms an important component of prudent asset management. Information gained through condition assessment contributes to good decision making and optimizing asset life. Methodologies for inspecting pipelines are presented including screening techniques and more detailed techniques. Advances in technology have opened opportunities for new methods of inspection and evaluation of results. In some cases, the performance of an asset is just as important as its condition and sensors can be used to gain a good understanding of pipeline network performance and assist in optimizing maintenance scheduling to provide ongoing service to customers. Astute choice of condition assessment methodology can enhance asset life and achieve organizational targets.

Sewer Pipeline Fault Identification Using Anomaly Detection Algorithms on Video Sequences

Most existing sewer pipeline condition assessment methods determine the presence and types of faults via examination of videos, which is a time-consuming and labor-intensive process. A few automatic methods based on image processing techniques can be used to detect specific faults. However, these methods have limitations due to the presence of unpredictable sewer pipeline fault patterns. Deep learning methods have also been applied to sewer pipeline fault detection. However, these methods require a large amount of annotated data to obtain reliable results. In this paper, we propose a fault detection method that applies unsupervised machine learning based anomaly detection algorithms with feature extraction to videos recorded by new sewer pipeline visual inspection equipment. The recorded videos are regarded as sequence signals, which are converted into feature vectors, followed by application of an anomaly detection algorithm. Unlike existing methods, the proposed method is computationally efficient as it does not require an annotated fault sample database for training fault detection models. We evaluate various anomaly detection algorithms and feature combinations on real sewer pipeline data collected in Shenzhen, with an overall accuracy result of above 90%. The proposed method provides a new and fast technique for surveying urban sewer pipelines, and to facilitate further research in this area, we have made the code and data used in this paper publicly available.

Problems of simulating subsea pipeline condition on the arctic shelf under seismic impact

Introduction. The paper represents an approach to studying a model of interaction of a system ‘pipeline – soil’ under conditions of frost penetration and seismic impact. The given problem is connected with the reclamation of the shelf of the Russian sector of the Arctic. There is a feature of induced earthquakes connected with hydrocarbon production. These earthquakes occur in a few years after the beginning of field development and lead to the worst condition of the pipelines. The research aims to the development of a method for subsea pipeline strength assessment allowing for nonlinear properties of an elastic foundation under the seismic impact. Materials and methods. The research is based on mathematical models of structural strength assessment under seismic conditions in the Arctic. The results are empirically obtained from the safety assessment method for a subsea pipeline under the seismic impact. The work was performed by the procedure of the analysis of existing arctic offshore projects. Results. The paper develops suggestions on the analysis of subsea pipelines on a nonlinear elastic foundation under conditions of a seismic impact. The suggestions were submitted for consideration to the Russian Maritime Register of Shipping. Buried below the seabed, the subsea pipelines provide an efficient and safe mode of transporting energy resources. Issues of relations of the subsea pipelines with surrounding and frozen ground are considered, pipeline thermal operation modes and seismic risks resulting in damages to the pipelines are taken into account. Conclusions. Solving the problem of the subsea pipeline condition assessment under arctic conditions is of practical interest in developing energy resource transportation ways. Simulation of a subsea “hot” pipeline is considered allowing for the nonlinearity of elastic foundation properties and seismic impact.

Acceptance Sampling Plans for Pipeline Condition Assessment

AbstractPipeline condition data collection and assessment is the first step for strategic infrastructure asset management and planning. However, since condition data collection and assessment is a ...

Condition assessment of pipelines using a Bi-directional layer-peeling method and a dual-sensor configuration

Over the past two and a half decades, hydraulic transients have been proposed and also used to assess the condition of pipeline systems through detection of anomalies such as extended pipe wall corrosion and blockages. This paper proposes a new bi-directional layer-peeling method which is capable of reconstructing estimates of the spatial distribution of the pipe wall thickness section by section both in the upstream and the downstream direction from the measurement site. Effects of branched pipes connected to the main pipe are also incorporated into the developed approach. A dual-sensor (a pair of closely placed pressure transducers at one measurement site), instead of a single pressure transducer, is used to both measure the pressure traces and to separate the directional hydraulic transient waves. The layer-peeling method originally developed in the acoustics field has been adapted and further developed to allow bi-directional reconstruction for pressurized water pipes. Numerical verifications are performed on a pipeline with three deteriorated sections and a uniform branch. The deteriorated sections in the pipeline are successfully detected using the pressure traces simulated by the method of characteristics (MOC). Experimental verification is also conducted on a laboratory copper pipeline, and two sections of pipe with thinner wall thicknesses, located on both sides of the dual-sensor, are successfully detected.

Sensor Placement Strategy for Pipeline Condition Assessment Using Inverse Transient Analysis

Inverse transient analysis (ITA) has been recognized as a useful technique for pipeline condition assessment, such as leak detection and pipe wall thickness estimation. The effectiveness and accuracy of the inverse analysis are dependent on the sensor placement design; however, previous research on this topic is limited. This paper investigates how the number and location of pressure sensors affects the identifiability of pipeline parameters in the ITA approach. An analytical analysis demonstrates that infinite pipe parameter combinations can produce almost the same pressure responses at specific observation locations, which means that the identifiability of the pipe parameters will be poor if sensors are installed at these locations. Numerical sensitivity studies and multiple ITA case studies are conducted to investigate the relationship between the sensor locations and the parameter identifiability. It is found that at least three sensors are needed, and given the first two sensors are N reaches apart (i.e. N pipe segments in the inverse model), the third sensor should not be placed at nodes that are separated from any of the first two sensors by an integer multiple of N reaches.

Nonlinear Bayesian inversion for estimating water pipeline dimensional and material parameters using acoustic wave dispersion

Monitoring pipeline thinning and material degeneration is becoming important for water-filled pipeline condition assessment. In this paper, an inverse method is proposed for estimating a pipeline's dimensional and material parameters using the dispersion characteristics of its modal wavenumbers. The inverse method is established by matching observed wavenumber dispersion characteristics of the water-filled pipeline with forward model predictions, where pipeline inner radius, thickness and density, and longitudinal and transverse wave speeds of the pipeline wall material are taken as unknown parameters. To account for the strong nonlinearity of the inverse problem and improve inversion efficiency, a Bayesian inversion scheme is formulated using a parallel-tempering Markov chain Monte Carlo approach. The characteristics and the performance of the proposed inverse method are investigated by systematic simulations which cover the impact of the number of modes utilized, dispersion frequency interval and observation errors. Laboratory experiments are utilized to validate the inversion method using wavenumber dispersion observations (below 50 kHz) from three metallic pipelines all with the same outer radius but different wall thicknesses and materials. The uncertainties of the estimated dimensional parameters are found to be lower than 0.2 mm and different materials are successfully distinguished and identified for the three pipelines.

Review on Computer Aided Sewer Pipeline Defect Detection and Condition Assessment

Physical and operational inspection of sewer pipelines is critical to sustaining an acceptable level of system serviceability. Emerging inspection tools in addition to developments in sensor and lens technologies have facilitated sewer condition assessment and increased the quality and consistency of provided data. Meanwhile, sewer networks are too vast to be adequately investigated manually so the development of innovative computer vision techniques for automation applications has become an interest point of recent studies. This review paper presents the current state of inspection technology practices in sewer pipelines. An overall inspection tool comparison was conducted and the advantages and disadvantages of each method were discussed. This was followed by a comprehensive review of recent studies on visual inspection automation using computer vision and machine learning techniques. Finally, current achievements and limitations of existing automation methods were debated to outline open challenges and future research for both infrastructure management and computer science researchers.

Wave separation and pipeline condition assessment using in-pipe fibre optic pressure sensors

Abstract The use of two pressure transducers in close proximity can enable the separation of the directional travelling pressure waves in pipelines. However, the implementation of this measurement strategy in real water pipes is difficult due to the lack of closely located access points. This paper reports the use of a customised in-pipe fibre optic pressure sensor array for hydraulic transient wave separation and pipeline condition assessment. The fibre optic pressure sensor array can be inserted into a pressurised pipeline through a single access point. The array consists of multiple fibre Bragg grating (FBG)-based pressure sensors in close proximity (∼0.5 m apart). A previously developed wave separation algorithm is adapted to analyse the transient pressure measurement from the FBG sensors. The resultant directional pressure waves are then used to detect pipe sections with a thinner wall thickness. A challenge is the influence of the in-pipe fibre optic sensing cable on the transient pressure measurement. The impact is analysed and adjustments to the pipeline condition assessment algorithm are undertaken to resolve the issue. The successful experimental application verifies the usefulness of the in-pipe fibre optic sensor array, which can facilitate transient-based pipeline condition assessment for buried water pipes with limited access points.

Impedance Estimation along Pipelines by Generalized Reconstructive Method of Characteristics for Pipeline Condition Assessment

AbstractReliable and efficient pipeline condition assessment in water transmission mains is required to locate deteriorated sections, such that water authorities can rehabilitate or replace vulnera...

How much data is enough? Financial optimisation of condition assessment spending to support pipeline replacement decisions

Abstract When facing pipeline replacement decisions, asset managers face a dilemma. Factual information about the condition of the pipelines allows better replacement decisions and capital efficiency gains. On the other hand, gathering this information is costly. Performing a cost-benefit analysis is also challenging, as the benefits are difficult to project. This paper models the financial impact of pipeline condition assessment by considering the financial risk associated with decision making errors. An economic optimization equation using the model is presented. This equation yields the Economic Assessment Level: the amount of condition information needed to minimize the total combined spending on information gathering and incorrect decisions. Case studies and examples of the impact of different levels of information gathering are presented. The results of these programs are compared with the predictions of the model, illustrating how the calculations can be used to improve capital improvement program efficiency real world situations.

Mesoscopic-based finite volume solutions for waterhammer flows

ABSTRACTIt is becoming evident that high resolution finite volume (FV) numerical schemes for multi-dimensional waterhammer problems are needed for the development of an accurate transient-based condition assessment of pipelines. As a prerequisite, FV methods for one-dimensional waterhammer flows need to be developed. Such models can then be applied to multi-dimensional problems via directional splitting. In this paper, two FV schemes (one uses Bhatnagar–Gross–Krook Boltzmann (BGK) and the other uses kinetic flux vector splitting (KFVS) in the flux approximation) for one-dimensional waterhammer problems are formulated and applied. It is found that the KFVS and BGK schemes correctly capture discontinuity fronts in a classical reservoir-pipe-valve system. An oscillation-free collision time formulation has been proposed, tested and found to be robust. The stability of the proposed schemes is guaranteed when . Comparison between the BGK, KFVS, fixed-grid MOC, and first and second order Godunov schemes reveals that the second-order Godunov performs best, followed closely by the BGK scheme. However, the BGK should not be quickly dismissed since it is known that its real power becomes evident when dealing with complex physics, multi-scale and multi-dimensional problems.

Guided acoustic wave interaction with flanged junctions in water-filled steel pipelines.

The interactions of guided acoustic waves with pipelines and associated components has become a topic of interest due to their application in water pipeline condition assessment. In this paper, guided acoustic wave interactions with flanged junctions in a water-filled pipeline are investigated by an analytical model and experimental measurements. In the model, axial wavenumbers, displacement, and stress profiles of the main pipeline and flange junction components are calculated by an existing cylindrical waveguide analytical model. These components are then concatenated together using mode matching to determine the overall theoretical characteristics. Experiments with a flanged water-filled steel pipeline are carried out to verify model predictions. Transmitted signals are acquired using acoustic transducers uniformly spaced along the pipeline axis to separate individual modes and extract mode amplitudes. Transmission losses are estimated by comparing the extracted amplitudes in a pipeline with and without the flanged junction. Both theoretical predictions and experimental results indicate that the flanged junction interacts with pipeline wall dominant modes by transforming them into waterborne modes and as a result guides acoustic power into the water medium. The flange is shown to cause a small transmission loss in waterborne modes as compared to the pipeline without flanges.

Multi-stage parameter-constraining inverse transient analysis for pipeline condition assessment

Abstract Fault detection in water distribution systems is of critical importance for water authorities to maintain pipeline assets effectively. This paper develops an improved inverse transient analysis (ITA) method for the condition assessment of water transmission pipelines. For long transmission pipelines ITA approaches involve models using hundreds of discretized pipe reaches (therefore hundreds of model parameters). As such, these methods struggle to accurately and uniquely determine the many parameter values, despite achieving a very good fit between the model predictions and measured pressure responses. In order to improve the parameter estimation accuracy of ITA applied to these high dimensional problems, a multi-stage parameter-constraining ITA approach for pipeline condition assessment is proposed. The proposed algorithm involves the staged constraining of the parameter search-space to focus the inverse analysis on pipeline sections that have a higher likelihood of being in an anomalous state. The proposed method is verified by numerical simulations, where the results confirm that the parameters estimated by the proposed method are more accurate than the conventional ITA. The proposed method is also verified by a field case study. Results show that anomalies detected by the proposed methods are generally consistent with anomalies detected by ultrasonic measurement of pipe wall thickness.

Faster Inverse Transient Analysis with a Head-Based Method of Characteristics and a Flexible Computational Grid for Pipeline Condition Assessment

AbstractTargeted and proactive pipeline condition assessment is critical for cost-effective maintenance of aging water transmission and distribution systems. The current research proposes a fast in...

Water Pipe Condition Assessment Using Submersible Quasi-distributed Optical Fibre based Pressure Transducers

Transient based technique is known as one of the most economical ways for pipeline condition assessment. This technique involves monitoring and analysing pressure transient profiles at multiple points in a distributed system. Its application is restricted due to its low spatial resolution (10 m). It is hypothesised that by increasing the number of pressure transducers and reducing the gauge length (distance between the transducers), the spatial resolution of the measurements would highly be improved. However, the deployment of pressure transducers is restricted to the location of the hydrants. In this paper, a submersible quasi-distributed optical fibre based pressure sensors were proposed, constructed and tested in laboratory to verify this concept. For this context, this paper describes the proposed optical device and presents some preliminary analysis and results obtained from a set of experiments. The experimental results show that using the quasi-distributed optical fibre based pressure transducers for pressure transient analysis can potentially detect small anomalies (200 mm) and measure the growth of the anomalies along a water pipe.

Decoupling pipeline influences in soil resistivity measurements with finite element techniques

Periodic inspection of pipeline conditions is an important asset management strategy conducted by water and sewer utilities for efficient and economical operations of their assets in field. The Level 1 pipeline condition assessment involving resistivity profiling along the pipeline right-of-way is a common technique for delineating pipe sections that might be installed in highly corrosive soil environment. However, the technique can suffer from significant perturbations arising from the buried pipe itself, resulting in errors in native soil characterisation. To address this problem, a finite element model was developed to investigate the degree to which pipes of different a) diameters, b) burial depths, and c) surface conditions (bare or coated) can influence in-situ soil resistivity measurements using Wenner methods. It was found that the greatest errors can arise when conducting measurements over a bare pipe with the array aligned parallel to the pipe. Depending upon the pipe surface conditions, in-situ resistivity measurements can either be underestimated or overestimated from true soil resistivities. Following results based on simulations and decoupling equations, a guiding framework for removing pipe influences in soil resistivity measurements were developed that can be easily used to perform corrections on measurements. The equations require simple a-prior information on the pipe diameter, burial depth, surface condition, and the array length and orientation used. Findings from this study have immediate application and is envisaged to be useful for critical civil infrastructure monitoring and assessment.

Piezoelectric wave generation system for condition assessment of field water pipelines

ABSTRACTThe condition assessment of pipelines is central to the management of water systems but is only conducted sporadically due to the limited range and practical constraints of current technologies. This paper describes the successful international field trial of a new condition assessment approach that was tested in live water pipeline networks of large cities during peak water demand and traffic conditions. The system, referred to as PIPE SONAR (PCT/EP2015/059540), uses a piezoelectric actuator capable of generating customized, small amplitude (<0.4 m) pressure signals. The field trial involved 1600 individual field tests covering 31 sites of water networks in New Zealand and China, across nine different pipe materials and pipe diameters ranging from 100 mm to 600 mm. The results of the condition assessment were independently confirmed using hydrant tests, low frequency transient tests, and direct inspection through excavation.