High-pressure Pipeline Research Articles

Study on physical explosion equivalent of large diameter and high pressure natural gas pipeline

High pressure natural gas pipelines are prone to material failure and explosion due to various reasons. Over the years, scholars have done in-depth research on the process of chemical explosion. In this paper, the energy components of high-pressure trunk natural gas pipeline under normal operation state were derived. Based on the assumption of adiabatic non isentropic, the pressure distribution in the pipeline within a period of time after the pipeline cracks was derived, and the energy released by the physical explosion of the pipeline was further derived. To verify the theoretical results, an original size pipe explosion experiment was organized, and the pressure distribution obtained from the experiment was found to be in good agreement with the theoretical calculation results. Through the crack propagation time and the duration of ground motion obtained from the experiment, the range of the duration of the pipeline burst crack impact was obtained, and the equivalent range of the pipeline explosion was further calculated. At the same time, through the regression analysis of ground motion, the equivalent of the pipe explosion in this experiment was about 177 kg TNT, which was consistent with the theoretical results. Further, the theoretical model and experimental results were verified by numerical simulation, and deeply studied the influence factors of buried depth on the explosion equivalent, as well as the relationship between the environment of the pipeline and the explosion damage mode and hazard range of the pipeline. The research results of this paper give the calculation method and magnitude range of physical explosion equivalent of high-pressure trunk natural gas pipeline. It provides a reference for the formulation of safety standards for high-pressure trunk natural gas pipelines and inert gas pressure vessels.

Influence of Phase Composition and Aging on Hydrogen Brittleness of High-Pressure Pipelines

Influence of Phase Composition and Aging on Hydrogen Brittleness of High-Pressure Pipelines

Research Progress and Prospects on Hydrogen Damage in Welds of Hydrogen-Blended Natural Gas Pipelines

Hydrogen energy represents a crucial pathway towards achieving carbon neutrality and is a pivotal facet of future strategic emerging industries. The safe and efficient transportation of hydrogen is a key link in the entire chain development of the hydrogen energy industry’s “production, storage, and transportation”. Mixing hydrogen into natural gas pipelines for transportation is the potential best way to achieve large-scale, long-distance, safe, and efficient hydrogen transportation. Welds are identified as the vulnerable points in natural gas pipelines, and compatibility between hydrogen-doped natural gas and existing pipeline welds is a critical technical challenge that affects the global-scale transportation of hydrogen energy. Therefore, this article systematically discusses the construction and weld characteristics of hydrogen-doped natural gas pipelines, the research status of hydrogen damage mechanism, and mechanical property strengthening methods of hydrogen-doped natural gas pipeline welds, and points out the future development direction of hydrogen damage mechanism research in hydrogen-doped natural gas pipeline welds. The research results show that: ① Currently, there is a need for comprehensive research on the degradation of mechanical properties in welds made from typical pipe materials on a global scale. It is imperative to systematically elucidate the mechanism of mechanical property degradation due to conventional and hydrogen-induced damage in welds of high-pressure hydrogen-doped natural gas pipelines worldwide. ② The deterioration of mechanical properties in welds of hydrogen-doped natural gas pipelines is influenced by various components, including hydrogen, carbon dioxide, and nitrogen. It is necessary to reveal the mechanism of mechanical property deterioration of pipeline welds under the joint participation of multiple damage mechanisms under multi-component gas conditions. ③ Establishing a fundamental database of mechanical properties for typical pipeline steel materials under hydrogen-doped natural gas conditions globally is imperative, to form a method for strengthening the mechanical properties of typical high-pressure hydrogen-doped natural gas pipeline welds. ④ It is essential to promptly develop relevant standards for hydrogen blending transportation, welding technology, as well as weld evaluation, testing, and repair procedures for natural gas pipelines.

Impact of hydrogen blended natural gas on linepack energy for existing high pressure pipelines

Impact of hydrogen blended natural gas on linepack energy for existing high pressure pipelines

Leakage analysis and prediction model of underground high-pressure natural gas pipeline considering box culvert protection

Buried gas pipelines frequently experience failures as a consequence of adverse factors. The studies of gas leakage diffusion behavior and prediction of hazardous areas following pipeline failure hold profound significance in mitigating the risk of accidents. This paper exemplifies a specific segment of long-distance transportation gas pipeline in the "West-to-East Gas Transmission" project, employing the Soave-Redlich-Kwong (SRK) equation of state (EOS) to develop a numerical model for high-pressure gas leakage and diffusion, while considering box culvert protection. The characteristics of gas leakage diffusion and the effects of pressure, leakage diameter, and soil type on gas diffusion are presented. Furthermore, the prediction models for leakage rate, fastest hazardous time (FHT), fastest hazardous distance (FHD), and lateral hazardous distance (LHD) are introduced. The results show that the pressure and velocity at the beginning of the leakage manifest an annular diffusion centered on the leakage hole, stabilizing within 300 s. The gas primarily diffuses along the horizontal direction within the box culvert, and the peaks of gas concentration at the surface are situated at a distance of 2.35 m on either side of the pipeline. Variations in pressure and leakage diameter influence the gas concentration but do not alter the locations of the concentration peaks observed at the surface. The greater the viscous and inertial resistance of the soil, the shorter the overall diffusion distance becomes. However, backfilling the loam within the box culvert significantly elevates the concentration of gas that leaks to the surface. The leakage rate, FHT, FHD, and LHD can be well calculated by the prediction models proposed in this study.

Numerical study of the transient behaviors of vapour-liquid equilibrium state CO2 decompression

The vapor–liquid equilibrium (VLE) state of CO2 commonly appears in pipelines for its transport, refrigeration systems, and large-scale trans-critical cycle systems. However, the behavior of sudden leaks in such systems remains unclear, which poses a challenge in assessing the risk of leakage. This work is focused on the decompression behavior of VLE state CO2 with different volume fractions of vapor phases in high-pressure pipeline leakage, specifically with the development of a computational fluid dynamics (CFD) model with a nonequilibrium phase transition and the real gas model. The results suggest that the Peng-Robinson Equation of State (PR EoS) is more conservative in predicting the degree of superheat than that of Span-Wagner (S-W) EoS and GERG-2008 EoS. Moreover, it is found that the initial volume fraction of the vapor phase in VLE state CO2 plays a crucial role in determining the characteristics of sudden leakage, such as pressure, temperature, and decompression wave speed both inside and outside the pipe. However, the position of the Mach disk remains unaffected by the initial volume fraction of the vapor phase. The initial vapor volume fraction of 0.2 has the most significant impact on the transient behaviors of the leakage, that is, the speed of the initial decompression wave is approximately 1.46 times slower than that of pure liquid CO2, the pressure and temperature start to decrease approximately 0.46 ms after those of pure liquid CO2, which is about 5.1 times later. Additionally, the peak pressure of the near-field jet is 6.3% higher and the maximum velocity is 11.4% higher than that of pure liquid CO2. It hopes that this work will contribute to the improvement of research models that assess the consequences of potential high-pressure pipeline rupture scenarios.

Experimental investigation on the development characteristics of explosive overpressure induced by high-pressure hydrogen jet flame

Accidental release of high-pressure hydrogen can induce the self-ignition, and the spontaneously combusting flame can eventually induce a non-premixed jet flame or even explosion. In this study, the explosion overpressure characteristic of hydrogen jet flame outside the pipeline was investigated. Experiments were conducted on high-pressure hydrogen release pipelines with a diameter of 10 mm and pipeline lengths of 750, 1450 and 2200 mm, respectively, under different hydrogen release pressure. The impact of different initial conditions on the peak value of high-pressure hydrogen jet explosion was systematically investigated. The external pressure signals and flame images were completely collected. The results show that the external explosion overpressure decreased with the increase of axial distance away from the nozzle. When the length of the pipeline increased, the peak value of the overpressure was also gradually decreased. Meanwhile, as the high-pressure hydrogen burst pressure increased, the overpressure rose first and then decreased. With the increase of release pressure, when the hydrogen pressure exceeded 8 MPa, the hydrogen flow in the tube formed a blocked flow, so the increase of external explosion overpressure became slow. This topic can provide a reference for the safety development of the high-pressure hydrogen storage system.

A novel methodology to characterise the ductile-to-brittle transition behaviour of pipeline steels using the dynamic tensile tear test

Brittle fracture control strategies for high-pressure pipelines are essential to prevent catastrophic failures resulting in significant economic losses and environmental damage. Typically, this is achieved by operating the pipeline well above the ductile-to-brittle transition temperature (DBTT). In general, a series of lab-scale fracture tests, such as the Charpy V-Notch (CVN) or Drop Weight Tear Test (DWTT), are performed at different temperatures to construct the ductile-to-brittle transition curve and determine the DBTT. However, when applied to high-grade steels, correction factors or additional criteria are often necessary to obtain satisfactory results. As an alternative lab-scale testing methodology to characterise high-grade steels, the Dynamic Tensile Tear Test (DT3) has been introduced. Recently, an experimental campaign was conducted with the implementation of a liquid nitrogen spray cooling system to characterise the ductile-to-brittle transition behaviour of X70 grade steel using the DT3 system. In this work, tests were performed at temperatures ranging from −80 °C to 25 °C. The transition behaviour was analysed using measured data, and fractography was performed using Scanning Electron Microscopy (SEM). The DBTT for the considered X70 grade steel was determined, and the performance of the DT3 methodology was compared to CVN and DWTT testing methods. Additionally, numerical models were created using Finite Element (FE) modelling and results were compared to the obtained experimental data. By implementing a stress-strain cleavage criterion in combination with the MBW material model, the models considered both ductile damage and failure, as well as brittle failure and mixed ductile-brittle failure. It can be concluded that the DT3-based transition curve provided a satisfactory DBTT prediction. Furthermore, numerical results showed a good correlation with experimental observations and demonstrated a similar transition behaviour.

Experimental study of erosion behavior under fluctuating tensile loads

When studying the erosion behavior of fracturing pipelines, it is inevitable to consider the exacerbating effect of fluctuating internal pressure on pipeline erosion damage. Therefore, an erosion experimental apparatus capable of applying fluctuating tensile loads to specimens was developed to investigate the erosion rate of 35CrMo steel at different average tensile stresses (0–500 MPa), impact angles (15–90°), flow velocity (7.5–20 m/s), and experimental times (10–60 min), and to analyze the erosion damage mechanism under fluctuating loads by observing the microstructure within the erosion scars using scanning electron microscope. The results indicated that erosion rate increased up to 36.84% compared to that without loading under the same erosion condition. Erosion rate increased up to 822.00% when velocity increased from minimum to maximum. Under fluctuating loads, the deepest part of the erosion scar cracked first and the specimen eventually fractured completely along with its entire width, demonstrating that the newly established experimental conditions can well reproduce the sudden bursting phenomenon common to high-pressure pipelines that erode under harsh conditions. The fracture of the specimen shows laminar structure, which is a typical damage feature resulting from the combined effect of a great number of tensile stress cycles and erosion wear.

Coupling effect of multiple factors on the crater size of physical explosion in high-pressure natural pipelines

he physical explosion of high-pressure natural gas pipelines causes craters and shock waves, which pose a serious threat to the people and buildings in the surrounding area. This study utilized HyperMesh and LS-DYNA software to establish a physical explosion model for high-pressure natural gas pipelines. The physical explosion processes for pipe diameters of 813, 1016, 1219, and 1422 mm under six burial depths and three soil conditions were calculated. Based on the simulation results, the equations for the variation in crater size were fitted, and the curves of the relationships between crater size and influencing factors were fitted to analyze the coupling effect of multiple factors on the crater size variation. The results showed that the crater size was positively correlated with the pipe diameter. As the diameter of the pipe increased, the length, width, and depth of the crater increased by 64.2, 53.8, and 32.1 %, respectively. The larger the burial depth was, the smaller the crater length and width were. However, the crater depth first increased and then decreased as the burial depth increased. The crater depth was the highest at a burial depth of 3 m. These findings can provide a reference for the design and safety evaluation of high-pressure natural-gas pipelines in high-consequence areas.

Environmental impact assessment of an air-to-water heat pump through the expanded total equivalent warming impact index based on experimental data

The Total Equivalent Warming Impact (TEWI) index is conventionally used to evaluate emissions from heating, ventilation, air conditioning and refrigeration (HVAC&R) systems. However, a more comprehensive indicator, the Expanded Total Equivalent Warming Impact (ETEWI), has been proposed to overcome the limits of TEWI index and to consider additional environmental impacts such as the effects of urban heat island and the natural gas losses along high-pressure pipelines supplying gaseous fuel to natural gas-fired power plants. In this study, TEWI and ETEWI metrics are applied to an air-to-water electric heat pump (EHP) serving a university building in Benevento (Southern Italy). Real data on EHP electricity consumption have been derived from the entire building's electric load and compared to measured data. ETEWI index has been estimated in two scenarios, one considering the impact of refrigerant charge variation on the performance of the EHP and its environmental impact and the other disregarding it. Additionally, carbon dioxide emission factors for electricity production have been forecasted from 2021 to 2033 to determine the indirect term of ETEWI index. Over the lifetime of the EHP, ETEWI increases by 4.8% compared to TEWI when the variation of refrigerant charge level is not considered. However, this percentage growth is equal to 6.5% when the impact of refrigerant charge change is accounted too. In the latter scenario, the indirect term of ETEWI decreases from 22.7 tCO2 in 2015 to 12.0 tCO2 in 2033 when the forecast of the carbon dioxide emission factors for electricity production is taken into account.

Leakage and diffusion of high-pressure gas pipeline in soil and atmosphere: experimental and numerical study

ABSTRACT Personal safety and environmental issues, such as fires and explosions, have climbed to the top of the list of concerns due to the rupture of a high-pressure gas pipeline. Analysis of the diffusion characteristics of methane leaks in soil and air is essential for engineering maintenance and the prevention of secondary mishaps. The primary contribution of this paper is the design and establishment of a full-scale experimental system to simulate small-hole leakage of high-pressure gas pipeline in order to observe the leakage and diffusion behavior of methane in soil and atmosphere under various leakage pore sizes and pressures. The results show that, near the leakage hole, the high-pressure jet dominates the action, whereas near the surface, lateral diffusion and accumulation dominate for an extended period of time. When the diffusion reaches a stable state, the vertical and horizontal diffusion distances are 0.76 m and 1.05 m, respectively, and the maximum temperature difference at the leakage hole is 8.7°C; Under the conditions of leakage holes of 0.5 mm, 1.0 mm, and 1.5 mm, the surface leakage radii are 0.4 m, 0.8 m, and 1.4 m, respectively. The leakage aperture is the main factor affecting the diffusion of methane in soil; A small hole leakage rate model for high-pressure gas pipelines was established based on experimental data, with an average error of 9%; The response time and steady time in the process of methane concentration growth have an exponential relationship with horizontal distance from the leakage hole and a power function relationship with vertical distance and leakage rate. The average relative errors of the calculation formula are 16% and 12%, respectively. This work can provide a basis for the hazard assessment of small hole leakage and diffusion in buried gas pipelines, and also provide data support for the theoretical and numerical models of high-pressure gas flow in soil and atmosphere.

Contact mechanical behavior and leakage prediction of metal lenticular gaskets in bolt flange joints of ultrahigh pressure pipelines

Metal lenticular gaskets have been widely applied in the bolt flange joints of high and ultrahigh pressure pipelines due to their semi-self-tightening sealing properties. However, research on the leakage prediction of the metal lenticular gaskets is still lacking, which limits their further optimal design and sealing performance improvement. In this paper, an elastoplastic contact mechanics analysis of a metal lenticular gasket used in the bolted flange joint of ultra-high pressure polyethylene pipelines was firstly carried out. The analytical formulas of contact stress and contact width were derived and compared with corresponding numerical results. Then, based on the surface topography measurement, a leakage model was established, in which the pipe surface was simplified to a smooth rigid flat surface, and the gasket surface was simplified to an equivalent rough surface composed of identical wedges. Finally, an analytical leakage prediction formula for the metal lenticular gasket was proposed. In addition, the effects of influence factors on leakage rate were discussed. It is shown that the analytical formulas can accurately calculate the contact stress and contact width in elastoplastic contact. The leakage rate increases with the decrease of the bolt load and the increase of internal pressure. For the ultrahigh pressure pipeline with internal pressure of 200 MPa, the minimum bolt load should be ensured to be higher than 120 kN in order to meet the T5 tightness level. In addition, the initial contact diameter is basically proportional to the leakage rate, while the change of gasket inclination angle has little effect on the leakage rate. Therefore, the contact diameter can be designed to be as small as possible within a reasonable range. This work can provide a theoretical basis for the sealing optimal design of metal lenticular gaskets.

Effects of shear strength variability on the peak and residual horizontal resistance of on-bottom subsea pipelines in clay

Subsea production pipelines in deep water oil and gas fields are susceptible to a phenomenon called lateral buckling which is a major pipeline design concern. Accurate estimation of lateral buckle formation and the additional stresses generated are of particular importance for High-Temperature High-Pressure (HTHP) pipelines resting on soft clay and is the subject of pipe-soil interaction studies (PSI). Variability in pipe embedment and soil resistances constitute the largest uncertainty in PSI analyses. Best practice methods for PSI studies constitute multi-step strategies that involve finding solutions to nonlinear and implicit equations. In the present study, the impact of soil strength variability on embedment and subsequently peak (Hpeak/V) and residual (Hres/V) lateral friction factors are evaluated. An R code, PSI-Lateral, is developed and verified against published case studies. It is used to calculate the pipeline embedment and horizontal resistances mobilized in a parametric study on three pipe diameters (0.6, 0.8 m and 1.0 m) with three different wall thicknesses. For each pipe diameter-weight combination, embedment and lateral friction factors (peak and residual) are calculated for a series of mean shear strengths ranging from 2 kPa to 8 kPa and COV ranging from 5% to 37.5%. The high estimate and low estimate shear strengths, suHE and suLE, correspond to values that are +/- two standard deviations from the mean. Hence, the range of strengths encompassed between these two extremes represents approximately 95% of the shear strength distribution. The results of the parametric runs conducted are presented in the form of graphical charts where high and low embedment and lateral friction factors can be read-off for any selected pair of mean shear strength and COV. Similar trends are observed in the charts for all pipelines evaluated. It is found that the range of normalized embedment, z/D, increases with increasing COV and decreases with increasing mean shear strength for all pipelines tested. A similar trend is observed for the residual horizontal resistance. The expected range of peak horizontal resistance Hpeak/V shows the same trend but only for soils with mean strengths less than 4 kPa. For soils with higher mean strengths, the range of Hpeak/V is found to be mostly insensitive to variations in COV and further increases in the mean strength.

Mechanical and microstructural characterization of Nimonic 263 superalloy after constrained groove pressing at elevated temperatures

Nimonic 263 superalloy is primarily being used in gas turbines, high-pressure pipelines, steam heaters, etc. due to its capability to withstand high temperatures and pressure for a longer duration. In this work, an experimental investigation on Nimonic 263 alloy has been carried out to improve its mechanical and microstructural properties using constrained groove pressing (CGP) at various temperatures. CGPed specimens have been characterized through mechanical tests (tensile test and hardness test) and microstructural studies (XRD, SEM fractography, and optical microscope). The results demonstrated that the CGP process had a significant impact on the alloy's properties. Compared to the as-received material, the CGPed specimens exhibited substantial improvements in yield strength (YS), ultimate tensile strength (UTS), and micro hardness, with average values of 234.58%, 43.79%, and 110.31%, respectively. The average grain size gets reduced due to CGP from 220.70 μm for the as-received material to 106.02 μm, 117.09 μm and 94.01 μm for CGP at room temperature, 250o C, and 450o C, respectively. An increase in the peak intensity is observed in the XRD after the CGP process due to a decrease in crystal size and an improvement in dislocation density with an average value of 31.68%. Fractography studies have revealed a mixed-mode (ductile and brittle) failure for the CGPed specimens compared to the ductile failure mode in the as-received material. Using Abaqus 6.14 software, the finite element analysis of the CGP process has been performed and the results have been found in good agreement with the analytical results. Thus, the CGP process can effectively improve the mechanical and microstructural properties of Nimonic 263 alloy for high-temperature applications.

Study on the erosion performance of high-pressure double elbow based on experiment and numerical simulation

Fluctuating stress of material strongly influences erosion to some extent, especially for high-pressure pipelines. However, this important influence is usually ignored due to strict experimental conditions. Therefore, erosion experiments under fluctuating stresses were conducted in this study, and the damage mechanism was observed by scanning electron microscopy. According to erosion data, a novel prediction equation involving fluctuating stresses and high concentrations was developed, which was adopted to simulate erosion of double elbow by sand-carrying fluid at different velocities, internal pressures, particle sizes and concentrations. The results indicated that the increase in fluctuating stress levels increased the erosion ratio, and that the effect of erosion factors on the second elbow was far more complex than that on the first elbow.

Effect of high pressure on severe slugging and multiphase flow pattern transition in a long pipeline-riser system

Severe slugging poses an enormous threat to the safe operation of high-pressure long petroleum pipelines. However, most published studies are conducted in short pipelines under atmospheric pressure. In this work, the gas–liquid two-phase flow experiment is conducted in the pipeline-riser system of 380 m long and 75 mm inner diameter under the separator pressure from atmospheric pressure to high pressure (10 MPa), and flow pattern maps are established. Under high-pressure conditions, liquid fallback and second blowout of severe slugging disappear. In the flow pattern maps, flow pattern types reduce, and severe slugging region shrinks. The boundary between stable flow and severe slugging appears on the left side of the flow pattern map and moves in the direction of higher superficial gas velocity. Increasing separator pressure leads to the increase in the severe slugging period. A correlation equation applicable to predicting the severe slugging period for different pressures (0, 1 and 5 MPa) is proposed, and the average error is less than ± 7.9%. Due to the inhibition of high pressure, the amplitude of the riser differential pressure decreases at most working points and increases only at a few working points where flow pattern transition occurs.

Do soft soil layers reduce the seismic kinematic distress of onshore high-pressure gas pipelines?

AbstractOnshore high - pressure gas pipelines constitute critical infrastructure that usually cross seismic - prone regions and are vulnerable to Permanent Ground Deformations (PGDs) due to active seismic faults. In design, it may not be feasible to avoid fault rupture areas due to various technical, economical and topographic reasons. Moreover, the presence of soil layers affects the PGDs resulting from a tectonic fault, which in turn may alter the seismic demand on the pipeline. The current study investigates numerically the impact of soft soil layers on the seismic kinematic distress of onshore gas pipelines. For this purpose, a decoupled numerical modeling approach is adopted, consisting of two separate finite - element models for the simulation of soil response and pipeline distress, respectively. Soil non - linearities are taken into account utilizing the Mohr - Coulomb constitutive model with isotropic strain softening. An extensive parametric analysis is performed considering different faulting mechanisms and fault dip angles, as well as soil geometry and mechanical properties. Consequently, the maximum absolute values of both tensile and compressive pipeline strains are correlated with the seismic intensity level (i.e., in terms of bedrock offset which is associated with earthquake magnitude via simple relationships). The paper concludes with a set of design charts and tables for the preliminary seismic design of onshore high - pressure gas pipelines. These charts and tables predict with reasonable accuracy pipeline deformations, in terms of strains, for different magnitude, fault type, dip angle, sand type, and varying overlying soil layer thickness.

Case study: Analysis and research on pipeline vibration of liquid oxygen kerosene of rocket engine and vibration reduction measures Measures

Abnormal vibration often occurs in the liquid oxygen kerosene transmission pipe- line of rocket engines, seriously threatening the safety of rocket engines. Improper handling will result in rocket launch failure and enormous economic losses. Therefore, the vibration of the transmission pipeline must be studied. In this paper, a three-dimensional high-pressure transmission pipeline model comprising a corrugated pipe, a multi-section bending pipe, and other auxiliary structures is established. Using the two-way fluid–solid coupling method, vibration analysis is performed on the pipeline under external pressure pulse excitation. The accuracy of the computation results is verified by a thermal test. Two vibration reduction strategies are presented and validated by simulation in accordance with the findings of the vibration study. The main conclusions are as follows: (1) At the same frequency, the amplitude distribution of vibration acceleration significantly correlates with the flow field pressure, indicating that fluid pressure fluctuation is the root cause of the abnormal vibration of the pipeline, and the vibration of the pipeline increases with the average pressure. (2) The time-average value and fluctuation amplitude of the larger stress and strain are mainly concentrated in the two supports, namely, the inside of the elbow and the bellows, which is different from the distribution of vibration acceleration. Such places are prone to structural failure and should be given attention. (3) The guide plate and the support enhancement method can reduce the vibration, but the support enhancement method has a better effect, reducing the vibration velocity and acceleration by 86.4% and 93%, respectively.

Pipeline transportation model with pressure pulsation for high-concentration viscous paste

High-concentration viscous paste has a large conveying resistance during transport in high-pressure long-distance pipelines. When the pump reverses, the paste in the pipeline flows back, which not only causes violent vibration of the pipeline system, but also reduces the conveying efficiency. To study the transient flow characteristics and backflow of the paste in the pipeline during the reverse process, we established a quasi-two-dimensional model for the paste transportation in a high-pressure long-distance straight pipe based on the constitutive equation of viscoplastic fluid and assumed that the paste in the pipeline has an axisymmetric flow and weak compressibility. The finite-difference method was used to solve the model. Using this model, the pressure and velocity distributions along the pipeline under different working conditions were investigated, and the results indicated that the fluctuation amplitude of the pressure is significantly reduced by friction. The pressure fluctuation along the pipeline decreases approximately as an exponential function. The calculation results agreed well with previous analysis results and experimental data, validating the model. This study provides valuable guidance for analyzing the backflow and impulse of high-concentration viscous paste pipeline transportation systems.