Journal of Pipeline Systems Engineering and Practice

Pigging technology is currently widely used in the oil and gas industry. The unstable movement of the pig in the pigging process after a water pressure test will not only affect the operation of pipes, but may even cause them to burst. In this paper, a transient hydraulic model of the pigging process after a water pressure test is established in a two-grid system. The model combines the mass and motion equations of the gas and liquid and then is solved by the method of characteristics. The combined method of computational fluid dynamics (CFD) software simulation and a semiempirical formula is used to study the gas-liquid flow pressure drop characteristics of T-abrupt and bend drain pipe. It is applied to the pig tracker and hydraulic pulse prediction to obtain the pig’s position and speed. Finally, the field data and the simulation results are basically consistent after comparison, which verifies that the established model is correct and the calculation results are reliable. Hence, we can provide a reliable and effective theoretical basis for the on-site pigging scheme.

With the increasing application of high-strength carbon steel pipes in oil and gas transport pipelines, a precise evaluation of such pipelines is of the utmost importance for the optimum and safe utilization of oil and gas resources. Gouge defects caused by external factors are among the major factors in reducing the strength of pipelines. Therefore, an accurate evaluation of gouged pipes is highly important for pipeline integrity management. This study used a semiempirical method to predict burst pressure in high-strength gouged pipelines. To this end, the nonlinear finite-element method was used to evaluate the effect of various factors, including material properties, strain hardening exponents, and pipe and gouge defect geometry on the remaining strength of high-strength carbon steel pipelines. Finally, a formula was provided to predict the remaining strength and burst pressure of the gouged pipelines. In order to validate the formula, full-scale burst pressure tests were used. The results of the predicted burst pressure using the developed formula were shown to be close to those of practical experiments and had a good correlation with the actual burst pressure.

Excavator-mounted hydraulic plate compactors have been used extensively for utility trench backfill compaction due to their efficiency. However, there is a need to study their effect on compaction and pipe performance in terms of loose lift thickness, backfill material, and compaction energy due to the lack of well-documented field studies. This paper presents the results of a field investigation to serve this need. Three different excavator-mounted hydraulic plate compactors with different compaction energy levels were used to compact two backfill soils: a well-graded 2A aggregate soil (gravel with sand), and a well-graded wash sand (sand with gravel). Three different loose lift thicknesses were used: 300, 450, and 600 mm (12, 18, and $24\mathrm{in.}$). The results showed that the compacted dry density achieved in the field was dependent on the loose lift thickness, impulse force of the compactor, and the backfill material used. High-energy compactors effectively achieved high dry densities in the field for the 2A aggregates even at $600\text{-}\mathrm{mm}$ lift thickness, whereas for the wash sand, they over-compacted the backfill, leading to lower densities. In contrast, low-energy compactors were effective in compacting the wash sand, achieving the target dry densities at $600\text{-}\mathrm{mm}$ lift thickness. The high-energy compactors resulted in high compaction-induced stresses in the backfill; however, compaction-induced strains in the pipes generally were similar irrespective of the compactor used.

The deflection of buried pipes depends on the exerted load and the embedment material. The portion of the exerted load transferred by the embedment material depends on the stiffness of the embedment material relative to that of the pipe. In the current study, four glass-reinforced polymer (GRP) pipes were buried in two different locations at the same depth under different geotechnical and installation conditions. For each of the test locations, two installation methods, namely controlled low-strength material (CLSM) and crushed rock, were used. The CLSM mixes were designed based on available native soil to satisfy the flow and strength criteria. Pipe deflection was meticulously measured at different stages of installation. In both cases, the behavior of the pipe showed the superior performance of CLSM as the backfill material. The behavior of the pipe was also evaluated by numerical modeling. The results of the numerical simulation were then compared with field test results, which showed a reasonable agreement. The pipe deflection was also predicted by a semiempirical equation and a numerical solution for the hardened CLSM. The effect of trench width on the vertical deformation was also evaluated through a parametric study.

Pipelines laid over long distances in harsh offshore environments may be affected by excessive strain, corrosion, scouring, icebergs, and other third-party damage. Small chronic leaks may cause severe safety and environmental effects if left undetected for a long time. A computational fluid dynamics (CFD) model of a subsea leaking pipeline is developed to predict the pressure and temperature profiles around the pipe’s leak surroundings. The developed CFD is used to study a pipeline section with a leak on top. In addition, a hydrodynamic model is used to evaluate the parameters of a full-scale model for a 150-km long-distance pipeline. This hydrodynamic model is developed to find the segment of the pipeline where it is difficult to detect the leak (e.g., segment with low temperature and pressure) in the long pipeline system. Furthermore, the hydrodynamic model provides the boundary conditions for the CFD model. The present study will help pipeline operators to select the most appropriate leak detection technology for the pipeline system. In particular, sensitivity analysis using the CFD model will assist pipeline operators to optimize direct sensing technologies including fiber optic cable distributed sensing solutions.

Pipelines transporting oil and natural gas may experience upheaval buckling due to substantial compressive forces induced by high temperature and pressure of the fluid content. Such upheaval buckling may pose a major threat to the structural integrity, safety, and operability of pipelines. This study presents results from a series of scaled physical model tests conducted to investigate the uplift behavior and upheaval buckling of buried pipelines. The first set of experiments investigated the resistance force during vertical pullout for different pipe geometries, embedment depths, and relative densities of sand. The second set of experiments investigated the development of global upheaval buckling due to high axial compression of a buried pipe. The study examined the effect of embedment depth on the buckling characteristics and the postbuckling behavior of the pipe. Numerical analyses simulated the experiments and validated the numerical models. A parametric investigation based on rigorous numerical simulations examined the effect of trench-base initial imperfection, internal pressure, and soil strength on the upheaval buckling resistance. The results showed that as the geometric imperfection amplitude increased and its distribution length decreased, the upheaval buckling resistance substantially decreased. Similarly, an increase of the internal pressure of the pipeline may significantly decrease upheaval buckling resistance.

Pipelines are widely used as an economical transmission mode in petroleum transportation, ocean engineering, aerospace engineering, and nuclear industry. However, pipelines are potentially susceptible to vibration in horizontal and vertical directions under external excitation, which leads to a significant reduction in the service life of pipelines, or even the damage of pipelines. In this paper, a novel multidimensional vibration isolation and mitigation device (MVIMD) is proposed and optimized to mitigate the multidimensional vibration of pipelines. First, the dynamic characteristics and responses of pipelines with and without the devices are compared based on the modified equivalent standard solid model. Then the MVIMD is attached to a pipeline to verify its vibration mitigation effect in horizontal and vertical directions. Finally, the genetic algorithm (GA) is adopted to optimize the parameters of MVIMD. The numerical analysis results show that the novel MVIMD with parameters optimized by the genetic algorithm has better effects for controlling both horizontal and vertical vibration responses of pipelines.

This paper investigates the effect of the viscosity of crude oil and stress acting on buried oil pipelines inside dune sand. Due to the increase in energy demand, transportation of all hydrocarbons is obligatory. However, transportation of this oil is very tedious, owing to its viscosity. Thereby, the reduction of viscosity of oil is mandatory before transportation. This paper investigates the blending and emulsification method in the reduction of viscosity. The addition of blends naphtha and kerosene with silica nanoparticles decreases the viscosity of heavy crude oil by 80%–90%. Moreover, the introduction of the surfactant also decreases the viscosity of the oil significantly. Adding to the preceding, the problem faced by the petroleum pipelines under the ground overload is discussed in this study. The estimation of ground overload is imperative to ensure the safe operation of oil pipelines. Provided that when the ground load is raised, the stress on the pipeline enlarges considerably. On the one hand, parameters such as the Von Mises stress, plastic strain, and ovality also increased subject to a higher ground load. On the other hand, the pipe reacted to all stages and deformed to the original position due to the removal of the loads.

Improper asset management practices increase the probability of water main failures due to inactive intervention actions. The annual number of breaks of each pipe segment is known as one of the most important criteria for the condition assessment of water pipelines. This metric is also considered one of the major performance measures in levels of service (LoS) studies. In an effort to maximize the benefits of historical data, this research utilized the evolutionary polynomial regression (EPR) method in determining the best mathematical expression for predicting water pipeline failures. The prediction model was trained and tested on the city of Montreal water network. After determining the best independent variables through the best subset regression, pipelines were clustered based on their attributes (length, diameter, age, and material). The majority of the models provided high $R^2$ values, but the highest performing model’s $R^2$ was 89.35%. Further, a sensitivity analysis was also performed and showed that the most sensitive parameter was the diameter, and the most sensitive material type to age was ferrous material. The tools and stages performed in this research showed promising results in predicting the expected water main failures using four different asset attributes. Therefore, this research can be implemented in asset management best practices and in LoS performance measures to predict the number of water pipeline failures. To further improve the prediction model, additional explanatory variables could be considered along with leveraging multiple artificial intelligence tools.

J-lay is currently the most appropriate technique for pipeline installations in deep and ultradeep waters. Pipelay parameters can significantly influence the dynamic behavior of deepwater J-lay systems. This study proposed a fully coupled finite-element model (FEM) for deepwater J-lay systems using the software OrcaFlex to predict the dynamic responses of the pipeline and the seabed caused primarily by hydrodynamic loads and vessel motions. Meanwhile, an advanced hysteretic soil model and a bilinear Coulomb friction model were employed to simulate the vertical and lateral pipe-seabed interactions, respectively. The influences of some important pipelay parameters, such as the water depth, departure angle, submerged weight and outer diameter of the pipe, J-lay tower location on the dynamic behavior of the whole pipeline, and the seabed in the touchdown zone (TDZ), were estimated quantitatively. Then, the dynamic laying effects of the pipelines on aspects of the effective tension, bending moment, equivalent stress and strain, pipeline embedment, and seabed resistance were systematically identified. The significant findings provide a comparatively good work basis for the pipelay parameter optimization design of deepwater J-lay systems.

Collapse bucking is a typical failure mode of flexible pipes during deepwater service. It is essential to investigate the failure characteristics and obtain the accurate critical collapse pressure to improve the design of flexible pipes and make them more durable in a deepwater environment. Firstly, an equivalent layer method based equivalent hoop stiffness is presented in the paper. Then, the proposed method is verified by corresponding comparative analysis. Next, two-dimensional (2D) collapse numerical models are created based on the verified method. Finally, the parametric analysis of collapse influence factors is carried out by the arc-length method. The results show that the equivalent method is valid and convenient for obtaining the equivalent thickness of the carcass layer. The parametric analysis results under different collapse influence factors can provide some useful advice for collapse-resistant design of flexible pipes.

Fresh mud (uncontaminated by soil or rock cuttings) plays important roles during borehole drilling, and its rheology has been studied for years in the oil and gas drilling industry. However, mud properties in those areas of application are different from mud used during horizontal directional drilling (HDD), one of the important trenchless technologies used for pipe installation. Specialists usually follow their experience or recommendations from mud suppliers when preparing mud for HDD because few documents have discussed the rheology of fresh mud and its related properties with different recipes. This paper focuses on the rheology of fresh mud with different bentonite and soda ash contents and the effect of time on those properties. In addition, the properties of filter cake are also examined such as its thickness and hydraulic conductivities as influenced by the mud recipe, fluid pressure, and time. The work quantifies how rheological properties change with different bentonite or soda ash contents and hydration times and how filter cake thicknesses increase with increased testing time. Decreases in the hydraulic conductivity of filter cakes are also quantified for increases in mud pressure. These data could help specialists quantify the rheology of muds with a range of different bentonite and soda ash contents considering the time effect and properties of filter cakes. The information could be valuable for engineers and researchers choosing their own recipes in practice.

Work in this paper investigates the efficacy of mitigation measures to minimize the contaminant ingress into subsurface concrete pipes. The 3D study model of the concrete pipe and the soil domain are implemented in Visual MODFLOW version 6.1. The site parameters are developed from data for a site in Jacksonville, North Carolina, at which subsurface contamination occurred in the presence of subsurface concrete drainage pipe. Modeling results indicate that after 20 years, the installation of a clay barrier reduces the concentration of benzene within the pipe by 22% compared to no clay barrier case. In comparison, the use of flowable fill leads to a 99.9% reduction in the concentration of benzene breaking through the pipe, and the use of an antiseep collar leads to a 60% reduction in the concentration of benzene. The natural hydraulic gradient of the site affects the level of contamination breaking through the pipe with a smaller breakthrough mass with lower site hydraulic gradients. Additional research is needed to obtain data on the efficacy of the studied mitigation measures through field implementation and performance monitoring with time. Such field implementation and monitoring studies are needed on concrete pipes and mitigation measures installed in saturated and unsaturated subsurface soil profiles.

The French standard for the design of liners for gravity pipe application offers a fully analytical approach for the design of circular and noncircular liners under groundwater pressure. Liners’ geometrical imperfections, which dramatically decrease the resistance of the lining to groundwater pressure, are treated using single or combined analytical correction factors that apply to quantities (buckling pressure, deflection, hoop force, and bending moment) calculated based on the perfect profile. This paper presents analytical calculations that establish correction factors for close-fit liners encased in fractured rigid circular and noncircular host pipes. An approximate solution is generated by assuming an allowable displacement function and minimizing the potential energy. It is shown that the effect of fractures on liners’ resistance to buckling is governed by the rotation angle of the hinge formed by the fracture, which imposes an angular step to the liner. Finite-element simulations of liners encased in fractured rigid circular, elliptical, and egg-shaped pipes are presented, and showed good agreement with the analytical solution.

This paper investigates the influence of a fiber optic cable inserted into a straight steel pipeline on pressure oscillations occurring during the rapid water hammer phenomenon. In order to numerically simulate water hammer in the pipeline with an inserted cable, a one-dimensional model with variable pressure wave speeds was used. The required smoothing of the pressure wave was obtained by introducing a diffusion coefficient into the momentum equation. Transient equations were solved using a modified finite-element method. The numerical model was calibrated with the dissipation coefficient based on the results of our own experimental tests. In the experimental study, four different types of cables and three values of initial flow rates have been considered. The obtained values of the calibrated dissipation coefficient are directly proportional to the initial water flow velocity. The results demonstrate that this approach allows one to reproduce the damping of pressure oscillations accurately and to obtain satisfactory results compared to experimental data for a given range of volumetric flow rates.

Fourth generation district heating networks (4GDH) must be designed for future energy systems, integrating renewable volatile energy sources, with lower operation temperatures, and consequent reduction of heat losses and increased energy efficiency. The lower levels of operating temperature and the greater amount of cyclic loading, influence aging, and the service life of 4GDH pipelines, differently from traditional district heating (DH) networks, and thus require proper investigation of the system response at the cross-sectional level. To evaluate the material durability of 4GDH pipelines, we have analyzed the behavior of the service steel pipe, the insulation foam, and their adhesive interaction, using an innovative analytical and experimental procedure. This paper describes the influence of traditional and future operational loading conditions on the performance of preinsulated bonded single-pipe systems, representing the majority of currently operating DH pipelines. The performed fatigue analysis of the steel service pipe showed that the lifetime of 4GDH pipelines is expected to increase because of the lower operating temperature, and the low impact of thermal loading volatility in the network, compared to conventional DH. The accelerated aging tests of DN $50/160$ pipes demonstrated that the combined effect of cyclic mechanical loading and thermal aging accelerates the rate of chemical degradation of the PUR foam, leading to a faster deterioration of the mechanical adhesion strength. The shear strength tests of naturally aged DH pipes revealed that, besides the initial pipe system characteristics and aging period, the residual shear strength of the polyurethane (PUR) foam depends on the temperature history, decreasing with the level of operating temperature and amount of fluctuation. The obtained results give a better understanding of the performance of traditional and 4GDH pipelines in operation that need to be appropriately considered in the engineering design standards of DH networks toward a more sustainable and energy-efficient infrastructure.

Water utilities are often required to continue building and improving their water infrastructure assets to meet increasing demands. Innovative project delivery methods, such as design–build (DB), integrate the design and construction phases and are implemented by water utilities to further advance the delivery of their water transmission pipeline projects. The objective of this study was to present effective DB project administration practices specifically for the water industry. An elaborate interview protocol was developed to collect information from utilities that have extensive experience delivering DB water projects. Interviews were conducted with 10 utilities in the United States and Canada. DB practices were examined under seven key DB project administration categories. A selection of effective DB project administration practices revealed by this study include (1) using a guaranteed maximum price (GMP) and finalizing it later in the design process; (2) providing the risk register to the design–builder to maintain during the design and construction process; and (3) using qualification-based procurement. This study contributes to the literature by identifying a wide selection of effective DB project administration practices that may support utilities in the delivery of their water infrastructure projects.

Pipeline systems are vital but are often damaged severely under earthquake actions. Because a well-designed bellow joint has a high deformation capacity and low stiffness, it can be used as a connector to protect pipes. In this work, a pipe with a bellow joint was buried in a steel box filled with soil. The pipe was fixed at one end, and an axial cyclic displacement was applied at the other end. Strain, axial force, and deformation along the pipe were collected. Results indicate that all the deformation was concentrated at the joint, while the pipe experienced no damage and was fully functional after the test. A finite-element (FE) model respectively with and without a bellow joint was then developed to comparatively study the effectiveness of the joint. The results obtained from both experiments and FE analysis show that the bellow joint can efficiently reduce the axial force and increase the deformation capacity.

This study investigates the solid particle erosion in an elbow of a slurry conveying circuit by using a commercial computational fluid dynamics (CFD) code FLUENT. Erosion wear was predicted by using the Euler-Lagrange model applied with a turbulence scheme of standard $k\text{-}\epsilon$. In the present study, the effect of various design parameters, namely radius of bend-to-pipe diameter ($r/D$) ratio, pipe diameter ($D$), bend curvature angle, and bend radius angle, was studied. The radius of the $r/D$ ratio varied from 1.4 to 1.7. The flow velocity varied between 2 and $5\mathrm{m}/\mathrm{s}$ and the solid concentration was kept constant, i.e., 10 vol.%. The mean size fraction of bottom ash varied from 102 to $300\mathrm{\mu m}$. Numerical simulation results show that erosion rate increases with velocity, particle size, and pipe diameter. The optimum value of the $r/D$ ratio was between 1.5 and 1.6. Lower erosion wear occurred near the entrance of the elbow and reached the maximum near 60° of the bend curvature. The particle size range of $162–230\mathrm{\mu m}$ was found critical for high erosion wear.

Transportation of fluids such as crude oil and natural gases through pipelines is crucial with utmost precaution needed to be taken to avoid leakage or burst of these pipelines. In this paper, a hardware-based novel method is proposed to detect the leakage in the pipeline. Aluminum strips consisting of parallel plates are used to predict the length at which the discontinuity is witnessed. These strips are inscribed on the surface of the pipeline. The self-capacitance of the strip is directly proportional to the length. The reduction in length reports a reduction in the value of self-capacitance. The value of self-capacitance increases with temperature; however, it still remains a function of length only. Application of load uniformly over the strip releases the trapped air. As a result, self-capacitance increases until all the trapped air is removed, after which register no change in self-capacitance with increased load. For a strip breadth of $0.001\mathrm{m}$, the reported accuracy for detection of discontinuity is $\pm 0.04\mathrm{m}$.

Pipeline systems are a safe method of transporting oil and gas from one place to another, although they suffer from leaks due to external and internal factors and fail to deliver the required products to customers. Many methods have been researched and implemented for gas leakage detection and localization. However, larger leakages can be easily detected while small leakages may not be detected for some time, especially when a pipeline is buried in remote places or under ice. Therefore, lacking real-time small and larger gas leakage wireless sensor detection systems causes financial, environmental, and health problems. In this paper, an experimental study has been conducted for real-time natural gas leakage detection and localization based on acoustic waves. Surface acoustic sensor technology and Hilbert–Huang transform (HHT) processing algorithm were successfully studied both experimentally and numerically to discover their efficiency on leakage detection and localization, and they are proposed and established as the best method for gas pipeline leak detection. A small gas pipe section with 40-m length, $20\text{-}\mathrm{mm}$ internal diameter, and two valves as the artificial leaks was used. First, the leakage detection and location method based on an acoustic wave with an improved HHT method and the propagation model were suggested and designed. When the two key points were established, the experiential equipment was constructed on a laboratory scale and the experiments were conducted. The time difference (TD) was calculated, and the propagation model and the leakage localization methods were also verified. Finally, the results of the experiments are discussed and analyses indicate the improved HHT method and the HHT method yield different experimental leak location error maximum absolute values of 0.58% and 13.66%, respectively, showing that an improved HHT method is better than the HHT method for calculating the TD of leakage location; the method based on the amplitude propagation model can be achieved without TD calculation. Therefore, it is concluded that the new method is efficient and can protect and monitor natural gas pipelines.

Extended high fluctuations of internal water pressure have often been causally linked to pipeline failures in water distribution systems, especially when this exposure has continued over many years. However, as yet, there is little solid quantitative evidence to support this in real water systems. This paper examines the impact of internal pressure and other critical parameters on the integrity of water pipelines in five districts operated by a California water utility. Eight years of data from the utility’s Annual Pressure Survey and $25\mathrm{years}$ of water pipeline failure data were collectively analyzed using spatiotemporal clustering tools and a Poisson regression model. The analytical procedures and results presented in this paper are designed to support both the water utility’s short-term operations and its long-term programmatic drinking water pipeline planning and management practices.

This paper proposes a systemic framework for dynamic safety risk analysis for natural gas pipeline leakage in a utility tunnel, which merges the bow-tie model (BT), Bayesian network (BN), and fuzzy set theory (FST) combined with monitoring data. Firstly, the hazard factors that cause natural gas leakage in a utility tunnel are identified to establish a BT model for simulating the causal relationship under specific accident scenes. Subsequently, the BT model is mapped to the BN model via a logic relationship for probabilistic reasoning, in which the prior probability of basic event is obtained through multiexpert scoring and FST. Then, the critical events can be obtained by using sensitivity analysis. Finally, combined with the monitoring data, the prior probabilities are updated to obtain the dynamic analysis result. A case study relating to safety risk analysis of overhead natural gas pipelines in a utility tunnel in the city of Liupanshui, China, is used to verify the feasibility of the approach as well as its application potential. The proposed method not only reduces the subjectivity of expert estimations, but also provides dynamic guidance for the risk analysis of utility tunnel gas pipelines.