Journal of Pipeline Systems Engineering and Practice

Monitoring and controlling construction productivity of pilot tube microtunneling (PTMT) are important in reducing delays of tunneling projects and in decreasing project costs. Collecting reliable and detailed productivity data in the field for effective PTMT productivity analysis, however, is challenging. Sensors attached to hydraulic devices of PTMT machines can automatically record time series of a boring machine’s hydraulic forces during operations. These time series show cyclic patterns corresponding to cyclic PTMT operations in three stages of PTMT: (1) pilot tube installation, (2) casing installation, and (3) product pipe installation. Analyzing these time series manually for detailed productivity analysis is possible, but such manual analysis becomes tedious and error-prone. This paper presents a knowledge-based and adaptive time series analysis approach that can automatically detect cycles of construction activities from time series data and thus achieve real-time PTMT productivity analyses. This approach can tolerate noises in time series data collected in real PTMT projects and thus can adaptively adjust its parameters according to the characteristics of input data. Such adaptive capability enables engineers to apply this method to various time series collected in different PTMT sessions. The testing results in a PTMT project in Wisconsin showed that the proposed approach achieves 95% or better precision and recall on data collected during seven different sessions of PTMT construction. These data covered three phases of PTMT that use three different machines and pipeline sections under different environmental conditions in order to validate the developed algorithms. Productivity analyses results revealed that productivities on some sections almost doubled those on others and that eliminating anomalous cycles could result in up to 40% improvement in overall productivity.

Reliable prediction of asset condition and its likelihood of failure is one of the core requirements for a utility to establish effective asset management strategies for optimized maintenance, rehabilitation, and replacement plans. Although there have been many research efforts in academia to predict the failure of pipe assets, many utilities across the United States still find it challenging to effectively predict the likelihood of failure (LOF) of their pipeline assets. Most of them still use subjective scales and rely on engineers’ anecdotal experience and judgments. This study developed a holistic procedural framework that utilities can follow to develop a data driven LOF prediction model of their pipeline assets. The unique contribution of this paper is that the framework addresses issues that a utility will encounter from data collection and data organization to LOF prediction model development, and discusses possible solutions as well. Historical performance records of sewer pipes from a major city were used to demonstrate and validate the framework. The procedural framework developed in this study is anticipated to facilitate and accelerate the practical use of advanced data-driven methods for underground pipeline asset management, which will result in more reliable and high-quality investment decisions. As a derivative of the case study, the study also found that different lengths of sewer pipes actually do change the expected life of a sewer pipe, which indicates that most of the previous deterioration models for sewer pipes without consideration of pipe length may be seriously flawed.

Rehabilitation of concrete structures by using synthetic resins such as epoxy is increasing worldwide. Understanding the structural behavior of the resultant composite structure and the interaction between the coating and concrete can be beneficial in predicting performance of the rehabilitated structure. However, knowledge of strength of the epoxy-coated concrete is very limited. This paper presents laboratory experiments designed to evaluate epoxy-coated concrete specimens under different load configurations with an emphasis on its strength characteristics. The studied load configurations included uniaxial compression for cylindrical specimens, three-point bending for beam specimens, and three-edge bearing for concrete pipe specimens. The concrete specimens used in the tests consisted of concrete specimens with and without epoxy coating. Finite-element modeling (FEM) was adopted to simulate the epoxy-coated concrete beams and pipes under three-point bending and three-edge bearing loads. The FEM models were verified by test results and simulated the behavior of epoxy-coated concrete under different load configurations.

Field instrumentation of an in-service cast iron gas pipe buried in a residential area is detailed in this paper. The aim of the study was to monitor the long-term pipe behavior to understand the mechanisms of pipe bending in relation to ground movement as a result of seasonal fluctuation of soil moisture content. Field data showed that variation of soil temperature, suction, and moisture content are closely related to the prevailing climate. Change of soil temperature is generally related to the ambient air temperature, with a variation of approximately $-3°\mathrm{C}$ per meter depth from the ground surface in summer (decrease with depth) and winter (increase with depth). Seasonal cyclic variation in moisture content was observed with maxima in February and March, and a minimum around September. The pipe top was under tensile strain during summer and subsequently subjected to compressive strain as soil swelling occurred as a result of increase in moisture content. The study suggests that downward pipe bending occurs in summer because of soil shrinkage, while upward pipe bending occurs in winter when the soil swells.

Broken prestressing wire wraps are the main cause of failure in prestressed concrete cylinder pipes (PCCP). The effect of the number and location of broken wire wraps on the structural performance of PCCP is investigated using advanced numerical modeling that considers full interaction between the spigot and bell ends of adjacent pipes. The stresses and strains in the various components of PCCP are evaluated with increasing internal pressure. A sensitivity analysis is performed to understand how manipulating the severity of the damage through varying the number of broken wire wraps affects the internal fluid pressure that causes failure. A 244-cm (96-in.) embedded cylinder pipe (ECP) is modeled with 5, 35, 70, and 100 broken wire wraps. The results obtained show that the internal fluid pressure required to cause failure can be as much as 14% lower when the damage is at the joint, and that the internal pressure that causes yielding of the wire wraps decreases approximately 65% as the severity of the damage increases from 5 to 100 broken wires.

With the increase in pipeline operating depth, research on pipeline global buckling during the process of oil and gas transport is drawing considerable attention. Numerical simulation is an important method that is used to analyze pipeline buckling, which is immediately caused by the combined action of high temperature and high pressure. Two important problems must be solved before simulating submarine pipeline global buckling. Because the finite-element (FE) model length greatly affects analysis of the buckling results, finding a reasonable model length is the first problem in finite-element analysis (FEA). The second is how to trigger global buckling in the pipeline because the ideal pipeline would not buckle in FEA. Previous studies only state that geometric initial imperfection and interference force could trigger pipeline global buckling. Therefore, simulating pipeline global buckling in FEA becomes a problem. In this paper, an effective method for calculating the reasonable model length (also called the virtual anchor spacing, or VAS) has been put forward based on the limit equilibrium theory of the analytical solution method. Two different methods, i.e., imperfection and interference force, have been used to simulate pipeline global buckling. Based on the VAS model with perfect length, a series of analyses on lateral buckling triggered by geometric initial imperfection and interference force are given. The research shows that no direct relation exists between the triggering methods and that their analytical results significantly differ.

Water mains are the essential component of a water supply system (WSS) buried underground, and they account for 80% of total system expenditures. Deterioration of this asset, as a result of an aggressive soil environment, is inevitable over a pipe’s service life. Although an increasing number of studies have estimated the remaining service life (RSL) of metallic pipes, most of them either are data intensive or consider limited soil and pipe parameters. In this paper, a Bayesian belief network (BBN) model is proposed to handle the problem of varying data availability and the dependency between parameters. First the proposed approach uses a combination of empirical data, experimental data, expert opinion, and a mathematical model to predict soil corrosivity and pit depth. Then a simple programming logic is used to predict RSL. Finally, the performance of the model is evaluated using a BBN sensitivity analysis. Monte Carlo simulations (MCSs) are performed using randomly generated input from measured statistical parameters (i.e., mean and standard deviation) to indicate the effect of input parameters on metallic pipe RSL and safety index (SI).

In-service conditions of a corrugated high density polyethylene (HDPE) pipeline network embedded within a bioleaching pad in the Atacama Desert in Chile were assessed. The pipes provided air for the copper extraction process and were subjected to large overburden stresses generated by the ore heap pile. A pipe crawling device was developed for the study. The field data collected revealed that the pipes were suffering from excessive deflections, circumferential shortening, and flexural bending. Wall buckling was observed in some sections. The flexural bending affected the pipe joint integrity. Field data also revealed localized punctures at some locations because of ore rocks pressing against the pipes. A few sections showed reversed curvature and joint failure. These conditions can generate a loss of functionality for the pipeline system. After a review of the construction record, it was determined the distresses were a result of using inappropriate backfill material and a poor installation procedure.

For transporting a large quantity of water over a long distance, large pipes are used. In most cases, water is transported by pumping. Installation of break pressure tanks (BPTs) at proper locations on such pipelines provides a good solution to control water hammer pressure in the pipeline. In some cases, the pipeline on the downstream side of the BPT may be in the form of an inverted siphon. Because of the stagnant water in the inverted portion of the pipeline, water level in the BPT will rise and then fall to some extent, until the velocity increases from zero to a steady-state value. The maximum value to which this water level rises depends on cross-sectional areas of the BPT. This paper develops a method based on analysis of unsteady flow in the pipeline to determine the relationship between the area of the BPT provided and the maximum level to which the water in the BPT will rise.