Behavior Of Pipelines Research Articles

Effect of Bacteria in Soil on Microbiologically Influenced Corrosion Behavior of Underground X65 Pipeline

Effect of Bacteria in Soil on Microbiologically Influenced Corrosion Behavior of Underground X65 Pipeline

Effect of Twin Gasket and Internal Fluid on the Dynamic Behavior of Pipeline with Flange Joint

Effect of Twin Gasket and Internal Fluid on the Dynamic Behavior of Pipeline with Flange Joint

Effect of thermal conduction on Kelvin-Helmholtz instability in straight pipe with different cross-sections

We investigate analytically the effect of thermal conduction on the Kelvin-Helmholtz instability (KHI) in a straight pipe with different cross-sections. The results show that the relative tangential velocity of the interface between the upper and lower fluid in the pipe first increases and then decreases with the increase of the wave number. Furthermore, the smaller coefficient of interfacial heat conduction causes the relative tangential velocity to decrease considerably with the increase of the wave number, which is different from the behavior of the straight pipeline with the same cross-section. In addition, the heat conduction increases the growth rate of KHI, which is in accordance with the scenario of straight pipeline with the same cross-section.

Synergistic Effect of Caco3 Scale Layer and Sulfate-Reducing Bacteria on the Corrosion Behavior of X80 Steel Pipelines

Synergistic Effect of Caco3 Scale Layer and Sulfate-Reducing Bacteria on the Corrosion Behavior of X80 Steel Pipelines

Mechanical Behavior of Buried Pipeline Crossing Thaw Settlement Zone

Abstract Thaw settlement is one of main reasons caused pipeline failure crossing cold region. The modeling method of mechanical response of pipeline crossing thaw settlement zone is proposed, the mechanical behavior of buried pipeline is investigated. Effects of pipeline and soil parameters on the buried pipeline were discussed. The results show that the high stress area and the maximum axial strain of the pipeline are at the edge of the thaw settlement zone. The upper surface of the pipeline is tensile strain while the lower surface is compressive strain. The maximum ovality of pipeline near the edge of thaw settlement zone tends to oval. The pipeline axial strain, ovality, and displacement decrease with the increasing of pipeline wall thickness while the change of high stress area is not obvious. The high stress area and ovality decrease with the increasing of pipeline diameter while the high stress area is expanded along the axial direction, but axial strain decreases slightly. The high stress area, axial strain, ovality, and displacement of pipeline decrease with the buried depth increases. With the internal pressure increases, the stress and axial strain of pipeline increase, but the ovality decreases. The soil's elasticity modulus has no obvious effect on pipelinès stress, axial strain, and displacement, but it can affect ovality slightly.

Experimental and numerical study of shallow‐buried high‐density polyethylene pipeline under collapse touchdown impact

AbstractThe debris from structures produced during the blasting demolition of engineered buildings (structures) may fall near buried pipelines, which threaten the integrity of the buried gas pipeline. In this paper, the dynamic response of nearby shallow‐buried high‐density polyethylene (HDPE) gas pipelines under collapse impact loads was investigated. The stress‐strain curve and material parameters of the HDPE pipe were obtained through uniaxial tensile tests. The strain distribution of buried pipelines under collapse loading was obtained. Subsequently, a 3D nonlinear finite element (FE) model of a buried HDPE pipeline impacted by a collapsed body was established. Finally, the effects of the impact velocity, touchdown angle, touchdown mode, offset distance, and pavement structure on the mechanical behavior of buried HDPE pipelines were analyzed in detail. The results show that, as the touchdown velocity and angle of the collapsed body increase, the von Mises stress of the pipeline is significantly affected. The pipe section close to the center of the impact zone tends to be damaged due to the von Mises stress reaching the maximum tensile strength. The maximum von Mises stress of the pipeline that is impacted by the edge of the collapsed body is the smallest, but the buried pipeline undergoes the largest displacement. The rigidity of the overlying pavement structure has a significant impact on the reliability of the buried HDPE gas pipeline. The stress concentration areas of buried pipelines mainly appear on the top, bottom, and the arches of the pipeline.

Numerical Modeling of the Pipeline Uplift Mechanism in Clay

Abstract Buried pipelines are a vital infrastructure and are mainly used to transport energy carriers and other essential products. The pipes are generally buried in the upper layer of soil deposits and, therefore, are highly affected by different geo-environmental conditions. The various pathological cases recorded in the world are caused by the degradation of structures in contact with swelling soils, the fact that necessitates a full understanding and investigation of such a phenomenon. This paper presents a method for the pipeline behavior modeling based on the finite element analysis by using PLAXIS 3D software, aimed at the determination of the pipe bending moment, displacement over its length, and the evaluation of vertical stresses in soil under the pipe. A parametric study has been carried out to investigate the effect of the pipe burial depth and the soil cohesion. The finite-element results have been compared with experimental data from the literature. It was found that, unlike laboratory models, the numerical analysis can account for the internal pressure in the pipe and the depth of the pipe burial. The finite-element analysis showed that the presence of fluid pressure inside the pipe results in a decrease in the maximum swelling of the soil by about 95%. The displacement of the pipe is considerably affected by the burial depth. The vertical stress at one end of the pipe can be greater than that at the other end in the case of a pipe under internal pressure, while in the case of an empty pipe, the values are very close at both ends. The numerical analysis shows that an increase in the pipe internal pressure leads to a decrease in its vertical displacement.

Semianalytical Solution for Buried Pipeline Subjected to Horizontal Transverse Ground Deformation

For buried pipelines, it is not always possible to avoid active zones where there is a possibility of ground deformation either due to earthquake or topographical reasons, and hence it is necessary to understand the impact of ground deformation on buried pipelines. The present study derives a semianalytical solution for the case of a buried pipeline subjected to spatially distributed horizontal transverse ground deformation (HTGD). Governing differential equations are developed considering the pipe as a Timoshenko beam and surrounding soil as a two-parameter foundation. Firstly, the proposed semianalytical solution is validated with prior studies on the influence of HTGD on buried pipelines, and then a comprehensive parametric variation with various influential parameters such as peak ground deformation, pipe diameter, wall thickness of pipe, burial depth, backfill soil, width of HTGD zone, and type of HTGD pattern is studied to understand the effect on the behavior of buried pipelines. It is observed that the pipe stability increases with increasing the width of the HTGD zone and with decreasing peak ground deformation. Pipe responses significantly vary with the pattern of HTGD. Further, pipe failure against HTGD can be reduced by reducing pipe diameter or by increasing the pipe wall thickness and by providing loose backfill material. The present methodology will help to evaluate the displacement patterns of pipes and the qualitative behavior of an overall soil–pipe system subjected to spatially distributed HTGD without performing numerical analysis.

Dynamic behavior and failure of buried gas pipeline considering the pipe connection form subjected to blasting seismic waves

To ensure the safety of gas pipelines during tunnel blasting excavation, it is of vital significance to investigate the dynamic response of buried gas pipelines under blasting vibration. Based on a great number of engineering examples, a representative buried gas pipeline with a diameter of 1 m and a wall thickness of 10 cm in the urban area was taken as the research object, and a full-scale buried gas pipeline blasting experiment on basis of vibration monitoring and dynamic strain monitoring was designed and implemented Next, 3D numerical models were established to analyze the response characteristics of the buried gas pipeline based on the field experiment, and the reliability of the numerical model was verified by the field monitoring data. Considering the influence of pipeline connection form, the numerical calculation models of the buried gas pipelines with bolted flange joints were established under different blasting scaled distances to supplement the field experiment. The dynamic response characteristics of the pipeline without interface and pipeline with bolted flange joints were further analyzed, and the dynamic response characteristics of bolted flange joints were discussed emphatically. At last, based on the failure mode of pipeline connection and the results of dynamic strain analysis of pipeline in field experiment, the safety evaluation of pipeline with bolted flange joints and pipeline without interface was comprehensively proposed. By comparing the safety control vibration velocity of pipeline with bolted flange joints and pipeline without interface, it is concluded that the flange bolt connection is vulnerable to the harmful effect of blasting vibration and the safety evaluation of pipeline considering bolted flange connection is more reasonable.

Buried pipeline subjected to static pipe bursting underneath: a closed-form analytical solution

The present study proposes a closed-form analytical solution for investigating the behaviour of buried adjacent pipeline subjected to ground heave induced from static pipe bursting underneath. The governing differential equation of the adjacent pipe is derived based on the concept of a beam (both Euler–Bernoulli's and Timoshenko's beam) resting on a Pasternak foundation. A Fourier series is used to solve the governing differential equation. The proposed solution is validated with the results obtained from earlier full-scale experimental works and finite-element-based numerical study. Further, a parametric study is conducted to investigate the influence of relative pipe–soil stiffness and pipe–pipe intersection angles on the adjacent pipe response during the pipe bursting process. It is perceived that normalised maximum pipe deformation reduces and normalised maximum pipe bending moment increases as the value of the relative pipe–soil stiffness increases. Further, for the present case, the maximum pipe curvature is obtained at a 35° intersection angle. Hence, it is understood that a 90° intersection angle is not always the critical criterion. The study will be useful in the preliminary design stage for obtaining quick and relevant results without performing rigorous numerical or experimental study.

Effect of exposure time with SO2 as an impurity on the corrosion behaviour of pipeline steel in CCS transportation

ABSTRACT This study was aimed at evaluating the effects of exposure time and SO2 as one of the impurities on the corrosion behavior of steel pipeline transporting supercritical CO2 during carbon capture and storage. Steel coupons were exposed to supercritical CO2 with various concentrations of SO2 for durations up to 1512 hours. Weight loss measurements were performed to evaluate the steel corrosion behavior. The weight loss results revealed a decrease in corrosion rate with an increase in exposure time which was mainly attributed to the gradual increase of the mineral layer on the steel surface. The increase in SO2 concentration within supercritical CO2 increased the corrosion rate from 0.0109 mm/yr to the highest value of 1.396 mm/yr. X-ray diffraction analysis revealed that the mineral layer formed on the steel surface under pure supercritical CO2 mainly consisted of siderite while iron sulfite hydrate was observed under in the presence of SO2.

Ultimate strain capacity assessment of local buckling of pipelines with kinked dents subjected to bending loads

A dent is a typical defect found in oil and gas pipelines and poses a significant threat to their safety and integrity. In this study, the buckling behavior and limit strain capacity of pipelines with kinked dents under bending moment loads were investigated. First, four-point bending tests of full-scale pipelines with kinked dents were conducted in a laboratory, and the critical buckling load and strain response of the pipelines during buckling failure were tested. The test results revealed that the existence of kinked dents, specifically those with large depths, could weaken the bending resistance of the pipelines. During the buckling process of the pipeline, a considerable compressive strain was generated at the bottom center of the dent, which was considerably higher than the strain value at the corresponding position of the intact pipeline. However, the strain at both axial sides of the dent gradually changed from compressive strain at the initial bending stage to tensile strain after buckling failure. Then, nonlinear finite element (FE) models of buckling failure for pipelines with kinked dents under bending moment loads were developed, and the reliability of the FE models was verified through comparison with the test results. In addition, a parametric sensitivity study was conducted to determine the effect of parameters, such as dent depth, dent angle, diameter-to-thickness ratio of the pipe, and yield ratio of the pipe steel, on the compressive strain capacity of the pipeline. Finally, based on a large number of FE simulation results, a model for predicting the buckling compressive strain capacity of pipelines with kinked dents was developed, which can be used for evaluating buckling instability failure of pipelines with kinked dents subjected to bending moment loads.

Effect of nonlinear pipe-soil interaction on lateral buckling of subsea pipelines triggered by a distributed buoyancy section

A distributed buoyancy section is one of the main buckle initiation techniques to trigger a pipeline to buckle laterally to release the high axial force induced by the high temperature of the transported fluid. A key design parameter governing the initiation of the lateral buckle is the breakout resistance. In this study, a nonlinear pipe-soil interaction model is incorporated into the mathematical model to study the lateral buckling behaviour of the subsea pipeline triggered by a distributed buoyancy section. The numerical solution is compared with test results and analytical results in the literature to validate the mathematical model. A parametric discussion is carried out to investigate the breakout resistance, residual resistance and parameters of the distributed buoyancy section on lateral buckling behaviour. The results show that the breakout resistance has a great effect on the minimum critical temperature difference. The influence of breakout resistance on the buckling behaviour is much smaller than the influence of residual resistance. Moreover, the most optimal length of distributed buoyancy section should be equal to the length of the buckled section. Thus, the largest length of the buckled section during design should be estimated first to determine the optimal length of distributed buoyancy section.

Influence of the topographic effect on the seismic response of buried pipelines

Detailed study of the response of pipelines during seismic excitation can help reduce physical and financial losses during and after an earthquake. The current research investigated the seismic behavior of pipelines passing through variations in topography using two-dimensional and three-dimensional modeling. Their behavior has been modeled at the crest and toe of a slope and during longitudinal passage through the topography. The effects of the soil stiffness, diameter-to-thickness ratio of the pipeline, height-to-half-width ratio (shape factor), and input wave characteristics on the performance of the pipeline have been investigated. The results indicate that topographic effects can increase the strain on pipelines and the factors studied are crucial to accommodating this potential hazard.

Effect of weld geometry parameters on dynamic behavior of buried X70 steel pipeline under subsurface detonation

Although a significant amount of research has been conducted to investigate the deformation and failure of buried pipelines subjected to load disturbance, scarce information is available about the effect of weld geometry parameters on the dynamic behavior of buried pipelines under blast loads. In the present study, numerical method and range analysis method were conducted to investigate the effect of weld geometry parameters including bevel angle, residual weld height, weld root opening, and thickness of root face on the dynamic performance of welded X70 steel pipelines under subsurface detonation. The results showed that the deformation of explosion-front surface is larger than that of explosion-back surface of the buried pipeline. The bevel angle, residual weld height, and thickness of root face have different effects on the dynamic comparison index of the welded pipes including peak vibration velocity, peak equivalent stress, peak equivalent strain, and peak displacement. Reasonable configuration should be adopted to properly select the geometry and dimensions of welding groove due to the complex influence of the weld geometry parameters. Combined the present results with the designing practice and current standards, the suggested weld geometry parameters to decrease their effects on the dynamic behavior of the welded X70 steel pipeline are as follows: the bevel angle (25 ± 5°), residual weld height (less than 1 mm), weld root opening (3.5 ± 0.5 mm), and thickness of root face (1.6 ± 0.6 mm).

Comparison of 3D Solid and Beam–Spring FE Modeling Approaches in the Evaluation of Buried Pipeline Behavior at a Strike-Slip Fault Crossing

Validated 3D solid finite element (FE) models offer an accurate performance of buried pipelines at earthquake faults. However, it is common to use a beam–spring model for the design of buried pipelines, and all the design guidelines are fitted to this modeling approach. Therefore, this study has focused on (1) the improvement of modeling techniques in the beam–spring FE modeling approach for the reproduction of the realistic performance of buried pipelines, and (2) the determination of an appropriate damage criterion for buried pipelines in beam–spring FE models. For this paper, after the verification of FE models by pull-out and lateral sliding tests, buried pipeline performance was evaluated at a strike-slip fault crossing using nonlinear beam–spring FE models and nonlinear 3D solid FE models. Material nonlinearity, contact nonlinearity, and geometrical nonlinearity effects were considered in all analyses. Based on the results, pressure and shear forces caused by fault movement and pipeline deformation around the high curvature zone cause local confinement of the soil, and soil stiffness around the high curvature zone locally increases. This increases the soil–pipe interaction forces on pipelines in high curvature zones. The beam–spring models and design guidelines, because of the uniform assumption of the soil spring stiffness along the pipe, do not consider this phenomenon. Therefore, to prevent the underestimation of forces on the pipeline, it is recommended to consider local increases in soil spring stiffness around the high curvature zone in beam–spring models. Moreover, drastic increases in the strain responses of the pipeline in the beam–spring model is a good criterion for a damage evaluation of the pipeline.

Research on Effect Factors of Mechanical Response of Cross-Fault Buried Gas Pipeline Based on Fluid–Structure Interaction

Abstract Long-distance buried pipelines inescapably go through seismic fracture zones which makes the buried pipelines be easily influenced by the diastrophism. A strong and resilient pipe can withstand a certain degree of seismic oscillation. However, it is really difficult for buried pipelines to resist the permanent ground displacement caused by faulting and surface damage. Most of the existing studies only focus on the two-phase contact between pipeline and soil, and the mechanical behavior of the cross-fault pipeline under transportation condition has not been studied. In this article, ADINA finite element software is used to establish a pipe-soil-fluid three-phase coupling model based on fluid–structure interaction (FSI), and the influence of the parameters of pipe, fluid and fault on the mechanical properties of cross-fault buried gas pipeline is studied. The model considering the effect of fluid–structure interaction can effectively simulate the mechanical response of pipelines in the actual working condition. The work presented in this article can provide a reference for the design and safety of cross-fault buried pipeline conveying fluid.

Buckling analysis of subsea pipeline with idealized corrosion defects using homotopy analysis method

Comprehension on the bucking failure of corroded subsea pipelines is important. Those corrosion defects usually exhibit complex geometries and will complicate the buckling failure behavior of subsea pipeline under external pressure. In this paper, a semi-analytical approach named homotopy analysis method (HAM) is introduced to investigate the buckling failure of subsea pipeline with three idealized corrosion defects. The proposed solutions are proven to be capable of giving accurate and efficient predictions in comparison with finite element result as well as analytical results. Numerical examples indicate that corrosion shapes have pronounced effect on the buckling pressure as well as buckling mode of pipeline with severe corrosion defects and those cases should be carefully concerned in the structural integrity assessment of subsea pipelines.

Mechanical behavior analysis of gas pipeline with defects under lateral landslide

Landslide is the main factor threatening the operation safety of long-distance gas pipeline, and the internal corrosion of pipeline will also seriously affect its reliability. Using LS-DYNA software, considering the interaction between pipeline and soil, a model of pipeline with defects crossing landslide is established based on the coupling of smoothed particle hydrodynamics and finite element method (SPH-FEM). The effect of the depth, number and spacing of pipeline defects and gas pressure on the mechanical behavior of pipeline is analyzed. The results show that the corrosion defects and gas pressure have little effect on the deformation of the pipeline. It is also found that when the gas pressure of the pipeline increases gradually from zero, the residual strength of the pipeline has a maximum value. Additionally, for the single corrosion defect, the maximum plastic deformation appears in the center of the corrosion defect, but for the double corrosion defect, it appears in junction of the corrosion defects. Furthermore, with the increase of landslide displacement, the plastic strain zone gradually extends along the circumference of the pipeline in these two kinds of defective pipelines. At the same time, the interaction between adjacent corrosion defects is found. The interaction is related to the defect spacing: within a certain range, the interaction increases with the increase of the defect spacing, the maximum equivalent stress appears at the junction of defects, and the stress concentration area expands along the circumferential direction. With the further increase of the spacing, the interaction disappears.

Seismic Behavior of Steel Pipeline Embedded in Controlled Low-Strength Material Subject to Reverse Slip Fault

AbstractControlled low-strength material (CLSM) has been widely used for pipe backfilling applications with several advantages, as described in detail in numerous documents. Our previous study indi...