Bolanle T. Abe

Pressure Management Strategies for Water Loss Reduction in Large-Scale Water Piping Networks: A Review

In water distribution networks (WDNs), water loss through leaking pipes is inevitable, as it constitutes a major threat to the operational services of water utilities. While water utilities are keen to providing an adequate supply of water to its end users, the undermined service quality, wasted energy resources and financial loss caused by leakages are major concerns. The financial loss, among others, associated with leaky pipes is increasingly growing at an alarming rate in recent years. Therefore, monitoring pipelines health through leakage control is crucial. Nevertheless, several methods for controlling leakages in WDNs have proposed. Research efforts conducted in the past acknowledged water pressure control as an effective method for reducing losses in water piping networks. Although, adequate pressure is required in the system to meet customer’s demands, it is a general agreement that reducing pressure will reduce the leakage flow rate as well as the possibility of pipe burst or crack. Several pressure management strategies have been proposed for leakage reduction in water distribution systems. In this work, we present an overview of the pressure management approaches proposed for reducing leakages in water distribution networks. Some previous and recent research efforts are outlined. Furthermore, information about leakage control, which may be useful for water utilities and pipeline engineers are provided.

Burst leakage-pressure dependency in water piping networks: Its impact on leak openings

In most water distribution systems, an appreciable volume of water is lost through leaking pipes, resulting in financial loss and environmental pollution among others. Thus, water loss constitutes a major challenge to utilities around the world. As water pressure is one of the causes of pipe burst resulting into leakages, pressure control could reduce the possibilities of pipe bursts. Thus, water utilities are keen on reducing the network pressure (to reduce leakages) while still maintaining the necessary pressure to fully satisfy customer demands. In this paper, the effect of pressure-bursts leakage dependency on leaks opening in water pipes using Torricelli mathematical model is investigated. Four different pipe leak openings of circular, rectangular, square and triangular geometries are simulated. Likewise, the probability of pipe breakage/burst due to pressure variations are investigated. The simulation results show that the effect of pressure variation is more pronounced on leak openings with rectangular geometry. Additionally, the characteristic nature of this leakage to pressure dependency is examined. The results also reveal the importance of pipe diameter inclusion in any leakage model. Small diameter pipes are more exposed to pipe burst as the pressure increases.

VARIATION IN PHASE SHIFT OF PHASE ARRANGEMENTS ON MAGNETIC FIELD UNDERNEATH OVERHEAD DOUBLE-CIRCUIT HVTLS: FIELD DISTRIBUTION AND POLARIZATION STUDY

The currents flowing through a transmission line produce a rotating magnetic field of vertical and horizontal components which are orthogonal in space and vary with time. Buried and aerial metallic pipelines that run parallel to or are placed in the vicinity of overhead AC high voltage transmission lines are affected by this field resulting in an induced voltage on the pipelines. Several related studies and safety standards dealing with this problem have been published. Nevertheless on a multi-circuit line, the issue of current phase shift variation has not been fully covered yet. This paper provides a detailed analysis of the effect of current phase shifts on the magnetic field distribution and polarization pattern around power lines using analytical approach from electromagnetic field theory. In this study, not only the variation of the filed distribution with phase arrangements and phase shifts is further established, but also the characteristic nature of the variation of the field distributions for six phase arrangements is examined in more detail. The results show that the magnetic field distribution at the ground level and the spatial distribution of the magnetic field polarization ratio vary significantly with the phase sequence arrangement as well as the current phase shifts between the two circuits. The field polarization differs at different locations. The information from the results can be useful for consideration in designing an effective AC mitigation technique and in placing pipelines in the utility corridor with power lines. Pipelines should be placed in a region of minimum field intensity within the right-of-way of the line, in order to have minimal induction on the pipeline in normal operating conditions of the line.

Variation in Phase Shift of Multi-Circuits HVTLs Phase Conductor Arrangements on the Induced Voltage on Buried Pipeline: a Theoretical Study

Alternating current interference from power transmission lines on nearby metallic pipelines has been a topic of research in the past years. Of particular interest is the induced voltage on metallic pipelines due to the time varying electromagnetic fields coupling from the transmission lines. Several related studies dealing with this problem have been published. Nevertheless, the issue of current phase shift variation and its effect on the voltage induced on metallic pipelines has not been fully covered yet. In view of this, we present the computation of the induced open circuit voltage on a buried metallic pipeline running in parallel with the power transmission lines in three Rand Water sites, South Africa. The computation was performed using Carson’s relations and power system concepts of mutual impedances between two circuits. The variation in current phase shift was considered for six different phase conductor arrangements. The overall simulation results yield useful information. The computations show that the induced open circuit voltage changes significantly with different phase arrangements and with variations in the current phase shift between the two circuits. In this work, the characteristic nature of the variation in the induced open circuit voltage for the six phase arrangements and phase shifts are examined in more detail. We concluded that in placing buried pipelines in the vicinity of AC double-circuits power lines, it is essential to consider the phase arrangement of the line and current phase shift between the two circuits. These, together with other line parameters, are vital in evaluating the induced voltage with the pipe position before installation and for the design of effective AC mitigation techniques.

Effect of increasing energy demand on the corrosion rate of buried pipelines in the vicinity of high voltage overhead transmission lines

There are continuous cases of pipelines sharing corridor with high voltage overhead transmission lines (HVTLs) both in rural and urban areas due to economic reasons, increasing energy demand, environmental factors and land use regulations. There is induction of voltage on the pipes due to inductive, capacitive and resistive coupling between the pipelines and the HVTLs, which accelerate corrosion of pipes. In this work, we present the effect of increase in energy demand on the corrosion rate of buried steel pipelines in the vicinity of HVTLs. The corrosion penetration rate of a buried pipeline with variations in the line current of a nearby overhead single circuit transmission line of vertical geometry was computed using existing relations from literature. The results obtained showed that increase in line current increases the corrosion rate of the pipeline. It can therefore be inferred from the results that a pipeline sharing corridor with transmission lines in urban cities and industrial areas where the energy demand is high will experience greater corrosion than those in rural areas where load demand is less, assuming the same condition of soil resistivity and its composition. Also, AC corrosion mitigation system and cathodic protection criteria need to be reviewed from time to time to meet the trend in energy demand.

Assessment model for monitoring AC induced interference corrosion of buried pipelines from HVTLs

Alternating current (AC) induced interference corrosion has been a major threat to pipeline sharing right of ways with AC high voltage transmission lines (HVTL). Defects occur on these pipelines due to the dielectric breakdown of the pipe coating as a result of appreciable voltage being induced on the pipe from the nearby transmission lines. These defects cannot be easily assessed by inspection of the pipes surface as the pipeline of interest is buried below the soil surface. The value of AC current density through these coating defects has to be monitored not to exceed the threshold value that can cause corrosion damage to the pipe. In view of this, we present an assessment model given input data from field measurement, for monitoring of AC induced corrosion of an underground pipeline co-located with four single circuits HVTL of horizontal geometry. The results obtained showed that the pipeline is exposed to corrosion damage for soil with low electrical resistivity. AC current densities increase as the magnitude of the induced voltage on the pipe increases. The results also showed that the relative risk of corrosion damage also high at that area. We also provide a user friendly MATLAB-based graphical user interface to facilitate easy usage of the developed assessment model.

A spreadsheet tool for the analysis of flows in small-scale water piping networks

The analysis of water piping system has been presented by several authors in the past and in recent years proposing several solution algorithms. Among the notable methods are the Hardy cross method, linear approximation method, Newton Raphson method and the hybrid method to mention but a few, to solve a system of partly linear, and partly non-linear hydraulic equations. In this paper, the authors demonstrate the use of Excel solver to verify the Hardy Cross method for the analysis of flow in water piping networks. A single-loop water network derived from real situation was used as numerical example and case study. Detailed numerical data are presented to explain the results of the studied network.

Assessment of AC interference caused by transmission lines on buried metallic pipelines using F.E.M.

The focus of this paper is on the implementation and subsequent improvement of a technique for computing AC interference on buried metallic pipelines due to nearby power transmission lines. In order to perform this task, the finite element method (F.E.M.) is employed. After performing a description of the implementation of the classic F.E.M. approach, a hybrid technique designed to reduce the size of the mesh and therefore the computational time is presented. The results obtained with the two approaches are finally compared.

Influence of AC interference on the cathodic protection potentials of pipelines: Towards a comprehensive picture

AC interference on metallic structures has been a major challenge to the operational services of utilities around the world. As a result of frequent installation of metallic pipelines in the energy utility corridor of transmission lines, AC interference problem is prominent. A major research area is the development of an optimum cathodic protection (CP) potential for protecting the pipeline in the presence of AC. In this study, an investigation on the influence of AC potential variation on the stability nature of some CP potentials was conducted using a small experimental test beds derived from the real situation of pipeline-power line right of way. A promising result was observed when a CP of −1150 mV is applied to the steel pipe specimen. At this CP potential, a better stability is observed, among other potentials, under the presence of the same varying AC voltages. Detailed graph is presented herein which could be useful for utility engineers.

Effects of soil properties on corrosion of buried steel pipeline: A case study of rand water pipeline, South Africa

Pipeline corrosion is a worldly recognized problem and has been a major concern for owners of pipeline in the past decades. Previous researches have established factors that influence the corrosion of buried pipelines in soil environment. In this work, we focus on analyzing some soil properties such as moisture content, soil pH, plasticity index, soil organic content, soil resistivity, and percentage composition of soil corrosive elements, as it affects underground pipeline. The pipeline of interest is a steel pipeline conveying water and was buried 1m beneath the soil surface. Soil samples were taken around this pipeline at four different sites; mine damp area, vicinity of power lines, an open field of clay soil, and vicinity of a railway line. These soil samples were taken to the laboratory for test and analysis. The results obtained showed that the soil samples from the mine damp area and railway line area are very corrosive to the pipeline while soil sample from the clay soil area is less corrosive. The result of these parameters also showed that soil sample from the power line area is not corrosive to the pipe. Hence, the pipeline which was exposed to soil in the mine damp area and railway line area need to be properly protected to avoid corrosion damage to the pipe.