Journal of Pipeline Systems Engineering and Practice

Analytical ratchet limits of cylindrical pipelines subjected to several typical cyclic nonproportional loading combinations, such as internal pressure, tension, compression, moment, torsion, and thermal loading in practical engineering, were deduced theoretically according to the noncyclic method. The effects of the axial compression stress and radius ratio on the ratchet limit of structures were investigated intensively. Results revealed that the ratchet limit reduces significantly when axial compression stress is applied, while it clearly increases with the increment of radius ratio. Moreover, several Bree-like diagrams under the corresponding loading conditions of this paper were obtained, which can be used to conveniently estimate the ratchet limit of cylindrical pressure vessels and piping for engineering design.

Long-distance natural gas pipelines often pass through unfavorable geological areas. Pipelines are prone to suspension due to geological disasters like earthquakes. The stress of the suspended segment is likely to exceed allowable values, causing the pipeline to rupture. Therefore, it is necessary to analyze the stress on a suspended gas pipeline and determine the ultimate length of the suspended segment. Constraint and boundary conditions can be determined for the mechanical model of the suspended pipeline and pipeline beam. A numerical simulation of a suspended pipeline was conducted. The result was compared with existing data in order to verify the reliability of the simulation. The analysis of the factors that influence the suspended pipeline, including internal pressure, soil overburden compaction multiplier (OCM), buried depth, and diameter-thickness ratio, indicates that (1) it is imperative to check peak stress during inspection of the suspended gas pipeline; (2) because of the pipeline’s flexibility, a slight drop in stress is observed from the middle point of the suspended segment toward the junction of the covered segment and the suspended segment; (3) with increases in pipeline pressure or buried depth, maximum peak stress increases for pipelines with the same suspended segment length; (4) when the length of the suspended segment increases, changes in OCM-Stress show different behaviors; and (5) with increases in the length of the suspended segment, the stress tends to increase as the diameter-thickness ratio becomes more and more pronounced.

This paper studies flow resistance characteristics of corrugated circular drainage pipes through experimental measurements and numerical calculations under turbulent uniform open-channel flow conditions. The Manning roughness coefficient $n$ is determined for corrugated pipes where semicircular ribs are placed on the inner surface of the pipe periodically with different height-to-pitch ratios. Numerical simulations are conducted for circular pipes having diameters of 0.6, 0.8, 1.2, 1.6, and 2.2 m and a slope of 7% with discharges varying between 0.1 and $2.5{\mathrm{m}}^3/\mathrm{s}$. Results of the numerical calculations are validated in terms of Manning’s $n$ by full-scale experiments. In this way, experiments are conducted for smooth and corrugated pipes of 0.8 m diameter, where two distinct inner corrugation profiles and various flow rates are employed. It is found that the Manning roughness coefficient can be increased significantly, which is a favorable outcome with regard to reducing the abrasive effect of water by lowering its velocity to more plausible values for steep slopes in an underground pipe network. Considering the numerical results, a new correlation between Manning’s $n$ and the height-to-pitch ratio of corrugation is proposed.

One of the latest products available for stormwater drainage and storage purposes is the underground chamber. These structures are typically shaped semicircular or semielliptical with flat outward flanges at the end of their legs. Despite the fact that several different chamber products are currently on the market and their applications are growing rapidly, there has been a total lack of even a simple analysis made available to the practicing engineers. In this paper, the author presents his first attempt in developing an analytical tool for the buried chamber structure. The end results are deflection and vertical pressure formulas that are based on observations made by the author during field load tests and computer simulations. A parametric study is carried out, with the equations derived to gain some insights into how these chamber structures behave in the ground.

Generally, pipelines in the deep ocean are laid without artificial embedded depth, but they penetrate into the sea floor under their own weight and the influence of the installation. Under this condition, pipelines easily experience lateral buckling. The pipe-soil interaction plays a critical role in the thermal buckling of a pipeline. In this study, a pipe segment with a 16-cm outer diameter and 1-m length is considered the object. Pipe-soil interaction model tests of lateral movement under different pipe segment weights within the scope of 0.05 to $0.65\mathrm{kN}/\mathrm{m}$ are implemented in sand. The maximal lateral resistance, the trajectories of the pipe segment, and the large deformation behavior of the seabed are investigated. In the foundation of the test analysis, an upper-bound mechanism that consists of two isosceles triangles and a logarithmic spiral is proposed. The formula to calculate the maximal lateral resistance is proposed on the basis of the upper-bound mechanism. The maximal lateral resistance can be obtained by knowing only the pipe weight, the internal friction angle, and the density of sand. Compared with the existing calculation methods, the result of this paper is much closer to the real situations when the weight of a pipe segment is within the range of $0.15–0.45\mathrm{kN}/\mathrm{m}$.

This paper explores the potential savings that can be realized through the identification of optimal asset management business policies for small-diameter (25–50 mm) water communication pipes, which are installed between the customer’s property boundary and the distribution main. The outputs from a geospatial mapping tool are used alongside a set of calibrated Weibull deterioration curves to drive a whole-life cost and performance analysis. Against this improved understanding of whole-life costs, an optimization algorithm is used to evaluate the trade-off between total expenditure (totex) and the prevention of future asset failures (serviceability) to identify the optimized investment policy according to the decision maker’s priorities. Despite attracting an estimated yearly expenditure from water utilities operating across the developed world in excess of £4.42 billion per annum, the authors believe this is the first instance of optimizing communication pipe maintenance policies at the asset level in the industry. A case study is used to demonstrate the development and deployment of this methodology for South West Water (U.K.), whereby £8.5 million in savings and the prevention of up to 1,320 failures have been identified over a 25-year planning horizon.

Pipe jacking plays a vital role in project execution by providing an economical, practical, and environmentally responsible approach to installing buried pipeline systems. Effectively calculating ground movement is an important preconstruction consideration and can present a challenge to the pipe-jacking industry. Four main factors that contribute to potential ground movement during pipe jacking are discussed in this paper: (1) soil loss; (2) fluid pressure; (3) friction between the pipe and soil; and (4) jacking force at the cutting head. A new model based on the Mindlin Solution and considering these four factors is presented. In the model, a new solution for predicting ground movement caused by soil loss is proposed and a theoretical solution of ground movement caused by fluid pressure is demonstrated. Data from the Guan River Pipe Jacking project in Jiangsu Province, China were used for comparison with established predictive models. The research results show that surface movement is not uniform along the length of an installation. The model developed in this paper effectively predicts surface movement during pipe jacking and more-accurately reflects field data than existing models.

The acoustic emission (AE) method is becoming popular for detecting leaks in municipal water mains where leaks are identified and the locations are determined through the interpretation of measured acoustic signals without excavation or disruption of services. For the interpretation of signals, several parameters, such as the frequency band of signals, coherence between signals, and cross correlation between signals, are used. However, studies published in the literature lack data on the applicability of the AE method under various field conditions. This paper presents a number of case studies on the field application of the AE method performed by measuring acoustic noises at two points bracketing a leak along the pipe length. Relevant parameters for successful leak detection in ductile iron and copper water distribution pipes are identified. In the case studies presented, leaks were successfully determined for an estimated leak rate of $1.6\mathrm{L}/\mathrm{s}$ and with a sensor distance of up to 176 m. Acoustic signal frequency corresponding to the leak noise was found to vary from approximately 220 Hz to around 1,400 Hz. The magnitudes of coherence between the signals from two sensors were higher than 0.5.