Journal of Pipeline Systems Engineering and Practice

Buried pipelines, such as water supply and power transmission systems, play a vital role in daily life. Seismic resistance of the pipeline systems is a very important research topic because of its tremendous impact during and after earthquake. This paper reviewed the investigations from the last several decades of the dynamic behavior of underground pipelines. Nine topics were included: theoretical evaluation of seismic response of buried pipelines, modeling for soil–structure interaction/fluid–soil–pipe interaction for buried pipelines, analysis of pipeline seismic response due to permanent ground deformation, seismic response of pipelines passing through liquefication areas, finite-element analysis of buried pipelines, experimental studies of seismic response of underground pipelines, seismic damage assessment, seismic behavior of pipeline networks, and seismic performance of joints and bend regions. It was found that more and more studies have been based on finite-element analysis considering that the computer technology has been well developed and finite-element analysis is much less expensive than experiments. Although common damages during earthquakes are caused by the wave propagation effect, the most severe damages are caused by permanent ground displacement, such as fault movement. The studies of pipelines subjected to fault movement were reviewed, but few seismic damage assessments were found that focused on the damage caused by fault movement.

Though often overlooked, the impact of seismic transient ground deformation on natural gas (NG) pipes can be highly adverse. Particularly, pipe elbows may undergo excessive in-plane bending demand and buckling. In this paper, a critical scenario of a pipe coupling two industrial structures typically found in an NG processing plant is studied. High strain and cross-sectional ovalization on the elbows are probable during an earthquake due to the out-of-phase oscillation of the two structures imposing asynchronous displacement demands at the two pipe ends. A parametric study was first performed to investigate various structure-pipe-structure configurations that increase seismic demands to pipe elbows. Simultaneous mobilization of divergent oscillation between two supporting structures at the low-frequency range, a lower pipe-structure stiffness ratio, a shorter length of straight pipe segments in the linking pipe element, and a higher pipe internal pressure have led to the onset of critical strain demands in pipe elbows. To validate this observation, an experimental campaign was developed in which a full-scale linking pipe element was physically tested by means of hybrid simulation (HS). The study shows that the seismic interaction of the structures coupled with the pipe is nonnegligible and can even be critical for the integrity of the coupling pipe. The finding depends on the structural system’s dynamic and geometrical properties as well the frequency content of the earthquake excitation.

The maximum axial force on a pipeline subjected to axial ground movement is commonly calculated using a design equation developed without proper consideration of soil-pipe interaction. The authors’ recent work revealed that soil-pipe interaction significantly contributes to the axial pullout load, particularly for flexible pipes. In this study, a three-dimensional finite element (FE) analysis is used to explore the pullout mechanism of a buried medium density polyethylene (MDPE) pipe to develop a rational method of calculating the pullout forces for the pipe. The FE model is developed through validation with experimental data available in the literature for MDPE pipes. The study reveals that axial elongation and diameter reduction occur during axial pullout of the MDPE pipe. The normal stress on the pipe surface from the ground is affected by the axial elongation and the diameter reduction, which also depends on the relative stiffness of the pipe to the surrounding soil and the shear strength parameters of the soil. A simplified method to calculate the normal force for MDPE pipe under various ground conditions is developed using FE analysis for rationally assessing the ground resistance to the pipeline.

The increasing storm frequency and severity due to climate change, and sewer system degradation due to aging and corrosion impose a greater risk of failure and overflooding to drainage systems. This paper proposes a new risk-informed framework in order to identify optimal strategies for drainage system rehabilitation under limited rehabilitation budgets. The proposed Hydraulics and Risk Combined Model (HRCM) dynamically couples the Storm Water Management Model (SWMM) and a risk model through a multiobjective optimization to maximize hydraulic performance while minimizing the risk of failure of the sewer system. The sensitivity analysis shows that with a small population size in a genetic algorithm the HRCM is capable of solving complex test cases. In addition, with increasing population size, the Pareto front converges with several rehabilitation strategies having the same objective function values. The model is examined in the context of several simple and complex scenarios, and the results demonstrate the model’s validity and robustness. The results also show that the proposed model is capable of identifying satisfactory rehabilitation strategies that can inform the optimal drainage system rehabilitation.

High-density polyethylene (HDPE) pipes have been widely adopted for municipal pipeline projects all over the world. HDPE pipe failures, including reduced flow capacity and wall buckling, have been reported extensively, and traffic loading is one of the major causes. Understanding bending moments in HDPE pipes is essential for pipe safety evaluation under traffic loading. However, existing methods cannot accurately estimate the bending moment in HDPE pipes due to neglecting the installation effect and the pipe-soil interaction under traffic loading. The installation of pipes generates an initial bending moment in the pipe, which should be included in the pipe bending moment calculation. The pipe-soil interaction dominates the load sharing between the pipe and the soil and thus influences the bending moment in the pipe under traffic loading. In this study, numerical modeling was used to investigate the bending moment in HDPE pipes caused by traffic loading. A field trial was firstly used to verify the effectiveness of the numerical modeling procedure. Subsequently, the effects of traffic load magnitude, soil cover thickness, pipe diameter, and pipe stiffness on the maximum bending moment were investigated. An empirical method was then proposed to predict the maximum bending moment in the HDPE pipe caused by the traffic loading based on the numerical results. Finally, a case history from the literature was used to validate the proposed method.

Sudden changes in operating conditions of a piping system induce a fluid hammer with cyclic pressure fluctuations that moves back and forth and finally dies out. Although one-dimensional continuity and momentum equations can predict the maximum pressure in a fluid hammer accurately, the simulated flow characteristic, viz., the pressure wave, deviates from the measured one, in subsequent cycles. In many instances, this deviation in the modeling is reduced by incorporating the concepts such as variable unsteady friction, artificial viscosity and diffusive terms, in the governing equations. The current study demonstrates that proper accounting of fluid-structure interaction (FSI) in the transient analysis in a three-dimensional computational fluid dynamics (CFD) model can predict the damping of a pressure wave with reasonable accuracy. The CFD-FSI model couples the Navier-Stokes equation with structural equations for axial, radial, flexural, and torsional motions, to represent the effect of FSI. Numerical simulations of three different problems from two different experimental setups were used for assessing the effect of FSI on the damping of the pressure wave. It is found that the incorporation of FSI into the three-dimensional (3D) CFD model leads to better prediction of the damping of the pressure wave in a quasi-rigid piping system. In contrast, such incorporation is not required for the prediction in a fully rigid system such as pipe buried in concrete.

The hydraulic capsule pipeline (HCP) is regarded as the third-generation pipeline, first and second generation being fluid and slurry pipelines, respectively. For increasing the performance of these pipelines, capsule numbers in the pipeline must be increased, thereby increasing solid throughput. In the present study, computational fluid dynamics (CFD) modeling of a three-dimensional (3D) concentric capsule train was carried out. The focus of this work was to study the effects of intercapsule spacing ($S$), diameter ratio ($k$), and aspect ratio ($a$) on the performance of the pipeline in amount of energy consumption. Results show that for $k=0.8$, $a=1.25$, and $S=0.75$ times of capsule length, the capsule train requires minimum power to move ahead. A detailed optimal cost analysis was also carried out, which revealed that total cost of the pipeline is first reduced then increased with the enlargement in pipeline diameter. Hence, optimizing the diameter of a hydraulic pipeline transporting capsule was the subject of this study.

The precise prediction of the driving force has significant meaning in preventing blockage accidents in oil and gas pipeline pigging engineering. In this paper, a novel prediction model is established for the typical bidirectional pig with the method of combing a theoretical model and finite-element (FE) simulations. The three-dimensional (3D) FE model of the pigging operation is established first, which is verified with a custom-built experiment from the literature. Then, friction characteristics such as deformation and contact area are analyzed based on the established model. The flexural-cantilever model and creep-Kelvin model are used to describe the bending and compression deformation, respectively, and a mechanical model, named the cantilever-Kelvin combination model, for presenting the stress state of the sealing disk, is built according to the simulation results. Finally, a prediction model of the driving force is established based on the cantilever-Kelvin combination model. The research results indicate that the bending deformation and contact area have a similar variation trend as the interference under different friction coefficients. A series of case analyses are conducted to verify the accuracy of the established prediction model, which is proven to satisfy the arbitrary interference and friction coefficient conditions.

Steam pipe failure is a problem that may affect refinery production and personal safety. It has practical significance for engineers who need to find out how to prevent such failure. This paper reports on a pipe bursting accident in a steam network. An investigation to identify the root causes of the failed steam pipe was carried out by macro inspections, chemical composition analysis, metallographic microscopy, scanning electron microscope (SEM) images, and energy dispersive spectroscope (EDS) analysis. The results showed that the chemical composition and mechanical properties were within the related standards, a combination of the ratchet effect and material creep causing the pipe wall thinning was the major failure root, and spheroidization of pearlite in the material also contributed to the failure.

Local strain concentrations that develop where cured-in-place pipe liners span across perforations in the wall of the cast iron host pipe have been identified as a key limit state. However, difficulties measuring strain have resulted in minimal experimental support for existing theoretical findings. This paper reports on the use of distributed strain sensing with polyimide optical fibers to quantify strain profiles along the inside surface of a liner and the outside where the liner is exposed at a perforation through the pipe wall. Measured strains are compared to theoretical calculations to assess performance of the design model currently used for selecting liner thickness. Results obtained confirm that the peak axial strain location moves from the center of the perforation to the edge at perforation diameters above the limiting flat plate criterion. The measurements also support the use of current ASTM design rules for pressure pipe liners spanning across small sized perforations (up to 50-mm diameter in a 154-mm diameter pipe). However, ASTM design produces unconservative estimates for larger perforations.

Prior to the 2010–2011 Christchurch earthquake sequence in New Zealand, buried pipes were thought to be tested with respect to all expected significant loadings as specified by material standards, such as AS/NZS 1477 for PVC pipes. However, the amount of damage to pipe joints observed in the field led the authors to believe that adding an axial joint load to the tests already mandated would greatly enhance the seismic design of pipes. For this purpose, an experimental investigation was completed on diameter nominal (DN)225 mm PVC-U pipe joints to ascertain the serviceability and ultimate limit state allowable loads when a pipe joint is subjected to axial seismic-simulated actions. The experimental results were able to replicate reported pipe earthquake damage by incorporating forces simulating peak ground accelerations in both the horizontal and vertical directions in the testing and by subsequently deriving relevant formulae. This research suggests that the existing compliance pipe standards can be easily modified to better replicate the observed seismic pipe damage, and the derived formulae could be used to improve decision support system models used by buried infrastructure asset owners to provide better postdisaster functionality information on their pipelines. The formulae presented herein are first-order checks and do not account for ground strains, ground displacements, or tensile actions. However, the proposed approach allows simplistic multiscenario comparative analysis to be done with relative ease.

Microbiologically influenced corrosion (MIC) is a high-risk corrosion mechanism of oil refinery storage and transportation systems, and sand deposition is the necessary prerequisite for a corrosion environment under the scale. Based on a computational fluid dynamics (CFD) simulation, this paper analyzes and predicts the critical velocity of sand deposition. By comparing the field failure case data and experimental data, it is proved that there is good agreement between the data and the prediction results. The analysis also found that there is a critical angle that is prone to sand deposition in the refinery oil pipeline, and the critical velocity will jump after the critical angle. The sizes of the sand particles and the length of the inclined pipe section also influence the sand deposition rate. According to this feature, a probability model of sand deposition is established to predict the risk of microbial corrosion.

Drainage networks are generally repaired after a failure occurs, and there is a lack of risk prevention and evaluation. To provide an effective evaluation method for the safe operation of drainage pipe networks, particularly in terms of pipeline failure and the severity of issues, this study classifies the adverse factors of safe operation and establishes an index evaluation system to determine the probability of pipeline failure. The system considers human, management, pipeline attribute, and environmental factors and is suitable for buried drainage pipelines. According to the index evaluation system, the analytic network process (ANP) method is used to consider the coupling relationship between various factors and obtain the weight of each factor. A fuzzy comprehensive evaluation is performed to obtain the final evaluation results. Finally, the established method is implemented on the drainage network of Suzhou Industrial Park, China. The results show that the evaluation results of this method are consistent with the daily cognition and field detection results. In addition, the index system established in this study can provide a reference for the establishment of accident databases and management of drainage networks.

Prestressed concrete cylinder pipes (PCCPs) are widely used for water mains and wastewater lines that serve almost every major city in Morocco. By all accounts, PCCPs have performed relatively well over the years. However, in 2016, the Agadir Authority found failures due to widespread corrosion of the prestressing wires and water hammer damage. The failure rates were particularly severe in the case of the water transmission pipeline P3. Therefore, the objective of this study is to establish the main causes of the severe deterioration of the PCCPs used for the P3 pipeline project. To achieve this objective, a diagnostic study, both in situ and laboratory tests, were carried out to locate and visually inspect the damaged areas as well as to characterize the damaged PCCPs and the soil. The findings indicate that chloride-induced corrosion of the prestressing wires is the main cause of the PCCP failures. The high concentration of chloride ions in the mortar coating capillary system is found to originate from the soil and contamination of the PCCP mortar coatings. It is also found that the cyclical wetting and drying conditions coupled with the presence of high sulfate ions in the soil played a significant role in increasing the rate of corrosion. The low soil resistivity in areas between ${\mathrm{SP}}_2$ and Bouargane tanks tends to confirm that the PCCPs were damaged by the water hammer effect. Manufacturing defects (such as irregular mortar coating thickness, inconsistent prestressing wire spacing, and low quality of mortar) also significantly affect the performance of PCCPs. Based on the results obtained, the durability exposure class for the Greater Agadir was identified both as XA2 (i.e., moderately aggressive chemical environment) and XD3 (i.e., corrosion induced by chlorides other than from seawater) based on NM 10.1.008 and EN 206-1. In such exposure conditions, it is essential to use chloride or sulfate-resisting cement. However, the mortar coatings evaluated were neither sulfate resistant nor chloride resistant, therefore, the study concludes that the PCCPs installed were not adequately designed for the hazardous exposure conditions in the Greater Agadir region.

This paper describes the most important results of investigations conducted to determine the causes of the degradation of underground prestressed concrete cylinder pipes (PCCPs) used for the drinking water supply in the Tafilalet region of Morocco. Diagnostic, laboratory, and in situ studies were conducted to locate and visually inspect the damaged areas as well as characterize the damaged PCCP, soil, and groundwater. The results obtained show that chloride-induced corrosion of the prestressing wires is the main cause of the deterioration of the PCCP pipes. The high concentration of chloride ions in the mortar coatings’ capillary system is found to originate from the soil and groundwater surrounding the damaged pipes. This is because the soil and groundwater in the damaged areas were found to be highly corrosive. The presence of high amounts of sulfate ions in the mortar coatings, soil, and groundwater further accelerated the corrosion process. The rapid corrosion attack on the PCCPs is also partly attributed to the cyclical wetting and drying exposure conditions in the region, which tends to increase the chloride and sulfate concentrations in the capillary system of the PCCP mortar coating and thus initiate corrosion on the prestressing wires. Improper design and manufacturing defects (such as irregular mortar coating thickness, inconsistent prestressed wire spacing, and low quality of mortar coating) also significantly affected the durability of the PCCPs. Operational factors, however, had a minimal impact on the performance of the PCCP pipes. Based on the results obtained, the durability exposure class for the Tafilalet region was identified as XA3 (i.e., highly aggressive chemical environment) according to international standards. In such circumstances, it is essential to use sulfate-resisting cement. However, the mortar coatings evaluated were neither sulfate resistant nor chloride resistant; therefore, the study concludes that the PCCPs installed were not adequately designed for the exposure conditions in the Tafilalet region.

The majority of hydrocarbon reservoirs discovered in recent years contain considerable corrosive hydrogen sulfide. The pipeline material for this application needs to be resistant to hydrogen-induced defects. API 5L PSL2 X60MS is one of the most common material grades for use in sour service applications. However, due to the complexity of affecting parameters, the fabrication of this type of material is still challenging. This study investigates the effect of the cooling rate during the steel-making process on the corrosion resistance of API 5L X60MS grade. Dozens of mechanical and corrosion resistance tests were performed to investigate the susceptibility of the material for hydrogen-induced cracking (HIC) and sulfide stress cracking (SSC) failure mechanisms. They found that the cooling rate is the most influential factor in the HIC/SSC performance of the samples. The slab cooling rate dictates the final hydrogen content of the plates; in slow cooling rate regimes, the atomic hydrogen finds more chances to escape from the steel. This study experimentally revealed how the arrangement of the slabs in bundles during the slow cooling process can affect the HIC and SSC test results. This study also indicated that altering the arrangement of the slabs enhanced the HIC/SSC performance of the plate samples.