Journal of Pipeline Systems Engineering and Practice

The three-dimensional flow velocity components at the span shoulder, which is located at the junction of a submarine pipeline and the associated scour hole, are measured in unidirectional steady current in order to investigate the flow structure and mechanics of the lateral propagation of a three-dimensional pipeline-scour hole. A naturally formed three-dimensional scour hole around a modeled pipeline is immobilized using adhesive, giving a steady flow field around the fixed boundary. A three-dimensional down-looking acoustic Doppler velocimeter is then used to measure the flow velocities at several critical sections. Combined with the measured data and observations made in the study, the flow characteristics and other factors that affect propagation of the three-dimensional pipeline-scour hole in steady current are discussed.

The damage caused by the aging of sewage pipe systems has become one of the major rising problems in modern cities. The traditional method to search for damage points of sewage pipes is the use of cameras and human observation. However, the use of these methods to check all the sewage pipes in the city will require a great deal of time and money. In this paper, a quantitative analysis on sewage pipe damage is reported. This study utilized the results of the sewer investigation in Tokyo. Based on this analysis, a quantification theory type II is proposed to describe the relationship between various factors that contribute to the damage of sewage pipe systems. Thus, these factors, including pipe diameter, number of years since installation, type of road and foundation, overburden, and pipe slope, can be used to judge if the sewage pipe displays corrosion, cracks, or breakage. As a result, the diagnosis model can be used to determine the likely extent of damage to an existing sewage pipe system.

This paper presents the preliminary results of a research project that investigates the feasibility of continuous monitoring techniques using piezoelectric transducers (PZTs) permanently installed on steel pipes. The ultrasonic waves generated by PZTs are multimodal and dispersive. Therefore, it is difficult to detect changes created by the presence of damage, and it is even more difficult to differentiate changes produced by damage from benign changes produced by variation in environmental and operational conditions. In this paper, the results are reported of applying pattern recognition techniques to detect a mass scatterer (a proxy for damage) under ambient variations primarily due to varying internal pressure of a pipe. Using wavelet methods, 303 features are extracted, and adaptive boosting, modified adaptive boosting, and support vector machines for damage detection are employed. The performances of the three classifiers are evaluated over 41 trials with different combinations of training and testing data, resulting in the average accuracies of 85, 89, and 94%, respectively. Finally, the effectiveness of wavelet processing and features selected are discussed.

A primary concern of owners specifying trenchless installation and rehabilitation methods are surface movements during construction. Surface heave or settlement can occur as a result of contractor methodology, design, or geotechnical conditions. Performing quality assurance during and after construction provides owners with an understanding of what surface movements have occurred and if remedial action may be required. Traditional methods utilized to measure ground surface movements include surveying triangulation, geometric leveling, and global positioning system (GPS) surveying. This paper presents a procedure to utilize photogrammetry in the measuring of ground movements and examines its precision and accuracy in simulated field conditions. Utilizing consumer-grade digital single lens reflex (SLR) cameras, photogrammetry does not require highly trained personnel, takes less time, and costs less money than traditional methods. Accuracy is determined by comparing measurements taken with photogrammetry to those taken with traditional rod and level. The results are compiled and analyzed to determine the accuracy and precision of photogrammetry in measuring ground movements.

A number of different methods that use signal processing of fluid transients (water hammer waves) for fault detection in pipes have been proposed in the past two decades. However, most of them focus solely on the detection of discrete deterioration, such as leaks or discrete blockages. Few studies have been conducted on the detection of distributed deterioration, such as extended sections of corrosion and extended blockages. This is despite the fact that they commonly exist and can have a severe negative impact on the operation of pipelines. The research reported here proposes a method of detecting distributed deterioration by investigating the time-domain water hammer response trace from a single pipe with a deteriorated section. Through wave analysis using a step pressure input, a theoretical square-shaped perturbation is found to exist in the transient pressure trace as a result of distributed deterioration. The hydraulic impedance of this section can be derived from the magnitude of the reflected pressure perturbation, while the location and length of the corresponding deteriorated section can be determined by using the arrival time and duration of the perturbation. The proposed method has been validated by analyzing experimental data measured from a pipe with a section of wall thickness change.

Long-distance natural gas transmission pipelines are planned to pass through the mountain area of midwest China, portions of which are threatened by severe landslide hazards. Therefore, the protection plan and control scheme for pipelines traversing and/or exiting landslide areas are of increasing interest and importance. A typical landslide in western China was used as an example to implement the strategy and evaluate the safety for a typical underground pipeline crossing the landslide area. The investigation and resulting control measures are based on the engineering geological study, and the numerical (finite-difference) interactive model of the pipeline and landslide, including the effect of soil arching. The effect of key design factors, including the spacing of antisliding piles, is determined by three-dimensional finite-difference numerical modeling. This technique also calculates the stability coefficient by use of the strength reduction method and calculation of stress and displacement fields. The results show that the recommended deployment of the antisliding piles can dramatically improve stability by reducing the effect of the landslide, thereby maintaining the displacement and stress of the pipeline within acceptable limits.

Under high thermal stress, buckling of submarine pipelines may occur to release the stresses accumulated in the walls of the pipelines. The likelihood that buckling occurs is largely determined by the capability of the soil to resist pipeline movements. Therefore, it is very important to determine the soil resistance in upheaval buckling when designing submarine pipelines. A series of large-scale model tests were carried out with soft clay chosen as the supporting medium in view of Bohai Sea geotechnical conditions. Pipe segments with diameters of 30, 50, and 80 mm were used. The pipes were buried in different depth-to-diameter ratios between 1 and 9. The uplift, lateral, and axial resistances were recorded during the tests. The test results have shown that the soil resistance depends on the pipe’s diameter and cover depth. According to the uplift test results, the load-displacement relationships with smaller depth of cover differ greatly from those with larger depth of cover. The results of the lateral sliding and axial pull-out tests have shown that the soil resistance initially increases before a peak value is reached. However, once the peak value is reached, the soil resistance will remain at approximately the same level. For the same cover depth, the lateral soil resistance is more than twice as much as that of the uplift. The observed data were compared with existing formulae, among which the best fit is selected. Meanwhile, the coefficients for the chosen formula were determined. These formulae and coefficients can be used in calculating the soil resistance in the Bohai Gulf.

In modern civilization, water distribution network has a substantial role in preserving the desired living standard. It has different components such as pipe, pump, and control valve to convey water from the supply source to the consumer withdrawal points. Among these elements, optimal sizing of pipes has great importance because more than 70% of the project cost is incurred on it. Unfortunately, optimal pipe sizing falls in the category of nonlinear polynomial time hard (NP-hard) problems. Hence, solid research activities march on because of two facts, namely, importance and complexity of the problem. The literature revealed that the stochastic optimization algorithms are successful in exploring the combination of least-cost pipe diameters from the commercially available discrete diameter set, but with the expense of significant computational effort. The hybrid model PSO-GA, presented in this paper aimed to effectively utilize local and global search capabilities of particle swarm optimization (PSO) and genetic algorithm (GA), respectively, to reduce the computational burden. The analyses on different water distribution networks uncover that the proposed hybrid model is capable of exploring the optimal combination of pipe diameters with minimal computational effort.

This paper presents results and analysis of pressure tests performed on carbon steel pipes with external defects repaired using composite materials. These results are part of a broader study on the structural health monitoring of the use of composite repairs to rehabilitate damaged carbon steel pipework. The surface of pipe that contains the arc-shaped defects was appropriately prepared prior to installation of the composite repair, and monitoring of the performance was achieved through strain gauges. Rectangular strain gauge rosettes were installed beneath and on the outer surface of the composite repair, and the output strain data were acquired using the real-time Labview software and a Compact Rio system. The hoop and axial strains measured by each of these gauges showed a consistency in the strain distribution through the composite repair and demonstrated that the load was transferred from the steel pipe into the composite material.

Large crater-forming pipeline explosive ruptures in the past 25 years are briefly reviewed in this paper. The National Transportation Safety Board reports on these accidents have found the mechanical failure of damaged or defective pipe to be the rupture cause. An alternative cause explored and discussed here is the explosive ignition of accumulated gas leaks from pipeline defects into surrounding air spaces. Remedial actions augmented to address the added risks associated with pipeline leaks and nearby air spaces could improve public safety.

The main goal of this study is to assess the Morgan-Morgan-Finney (MMF) and the universal soil loss equation (USLE) erosion models in the prediction of soil degradation along the corridor of oil and gas pipelines. In the comparative analysis, the MMF model revealed a larger coefficient of variation (COV) in predicted soil loss rates. Based on the pair-sample $t$-test, the predictions of the two models were significantly different in the spatial distribution of soil loss along the rights-of-way (RoW) of the pipelines. Sensitivity of the MMF and USLE models to terrain morphometric elements was also assessed. Slope gradient was one of the controlling factors of erosion processes, but not of the soil loss rates. The MMF and USLE models did not reveal any sensitivity to slope aspects. In terms of elevation, the MMF model revealed higher soil loss rates in the lower elevations than with the USLE model, leading to the conclusion that the USLE model is more sensitive to elevation change than the MMF model. The USLE model revealed higher sensitivity to the terrain curvature than the MMF model because it had larger variations within concave and flat terrain curvature types. Both models were sensitive to increasing vegetation cover (VC) percentage. Both models revealed different sensitivities; therefore, better understanding of these sensitivities may contribute to the selection of the most suitable model, depending on the terrain, to yield the highest soil loss prediction accuracy. Qualitative validation of the spatial distribution of USLE- and MMF-predicted erosion-prone areas was performed using 6 years of ongoing surveillance and measurement of erosion occurrences. Quantitative validation of the predicted soil loss was performed using 3 years of monitoring of field erosion plots. The USLE model performed better than the MMF model in terms of the frequency ratio of erosion occurrences within the critical erosion classes (soil loss $>10\mathrm{t}/\mathrm{ha}$). The USLE-predicted soil loss rates were more reliable than the MMF rates not only in terms of spatial distributions of critical erosion classes, but also in quantitative terms of soil loss rates because of the high correlation with the soil loss measurements of field erosion plots. The number of erosion-prone pipeline segments realistically predicted by the USLE model, e.g., soil loss more than $10\mathrm{t}/\mathrm{ha}$, was 88, whereas the MMF model predicted only 76 erosion-prone pipeline segments. The regression analysis between the total of 354 USLE and MMF erosion-prone segments revealed an $R^2$ equal to 0.33, which means that the predictions by the USLE and MMF erosion models are significantly different on the level of pipeline segments.