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Upon leakage in underground gas pipelines, the interaction between soil particles and gas will produce acoustic events exhibiting varied frequencies, amplitudes, and energy characteristics. In order to obtain the acoustic response of gas pipeline leaks that are buried, experiments were conducted using a two-dimensional visual leak testing facility. Employing time-domain parameter analysis, fast Fourier transform (FFT), and wavelet packet analysis (WPT), this study meticulously investigated the impact of gas pressure and soil moisture on the time-frequency characteristics of the acoustic waves throughout the leakage process. The results show that: (1) the amplitude, dominant frequency, and energy of acoustic waves closely relate to the deformation and disturbance of soil morphology, (2) the amplitude of acoustic waves increases and decreases exponentially with the increase of gas pressure and soil moisture content, respectively, (3) the main frequency response of acoustic waves during the erosion process predominantly lies within the 0 to 1 kHz range, exhibiting an "N-shaped" cyclical variation, and it tends to decrease with the increase in gas pressure and increase with the rise in soil moisture content, (4) as the leakage process continues, the energy ratio of 0–156.25 Hz increases continuously, the maximum is 45.24%, and the frequency bands of 0–156.25 Hz and 156.25–312.5 Hz demonstrate a strong responsive pattern to variations in soil moisture content and gas pressure, respectively. Therefore, these two can be utilized as the characteristic frequency bands to represent the effects of moisture content and gas pressure, and (5) the leakage acoustic sources primarily originate from pipe wall vibrations, gas impact on soil particles, and friction within the soil particle medium, with the latter two types of vibrations generating more propagative acoustic waves. The research results are of great significance to the prediction of soil structure damage and the acoustic monitoring of gas leakage. [ABSTRACT FROM AUTHOR]

A subway station's operation is susceptible to accidents when there is a high-pressure gas pipeline overlaying it, and analyzing the correlations between the safety influencing factors (SIFs) in this operating situation can provide paths to reduce safety accidents. Thus, this paper investigated the coupling correlations between the SIFs. We firstly identified the SIFs during subway station operation under a high-pressure pipeline (SSOUHP) based on a literature review and discussion with experts. Then, the analytic hierarchy process (AHP) and coupling degree analysis (CDA) were combined to assess the coupling correlations between the SIFs, and Y subway station was selected to test the proposed hybrid coupling analysis approach. Research results show that (a) 23 second-level SIFs were identified and these SIFs can be summed up into five first-level SIFs, namely, human-related SIFs, pipeline-related SIFs, station-related SIFs, environment-related SIFs, and management-related SIFs; (b) the proposed hybrid approach can be used to evaluate the coupling correlations between SIFs; (c) of the coupling situations during Y subway station's operation, the internal coupling correlations among environment-related SIFs, the coupling correlations between pipe-related SIFs and environment-related SIFs, and the coupling correlations among human-related SIFs, pipe-related SIFs, and environment-related SIFs are all greater than 1, and the coordination degree is 0.778, 0.781, and 0.783, respectively, which is a high security risk; (d) the overall coupling degree among all SIFs during Y subway station's operation is 0.995 and the coordination degree is 0.809, which is a low safety risk. The research can enrich knowledge in the safety evaluation area, and provide a reference for onsite safety management. The results are basically consistent with the conclusion of the enterprise report, which verifies the scientificity and validity of the evaluation method. [ABSTRACT FROM AUTHOR]

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The article discusses the problems of the occurrence of unaccounted-for-gas (UAG) during the operation of the gas pipelines. The paper proposes a simple and effective algorithm for the classification of UAG, as well as for the search for the origin of the cause of UAG, which is based on fuzzy logic methods. The article deals with the implementation of a fuzzy system of control and management over the balance of gas volume and the implementation of the algorithm for finding the causes of UAG. The article shows the ways of implementing this algorithm using the example of programming languages of the IEC 61131 standard, and also discusses issues related to dispatching control of gas pipelines, and the role of such systems in controlling the balance of gas volumes. [ABSTRACT FROM AUTHOR]

X70 steel gas transmission pipeline has a large market share and a long operation time, and the problem of pipeline integrity, represented by corrosion, is now becoming increasingly prominent. Under actual working conditions, the corrosion of gas transmission pipelines is complex. In order to study the corrosion characteristics of X70 steel gas transmission pipeline under different soil environments, help pipeline integrity management and ensure operational safety, the raw gas pipeline of an LNG project was used as the object of study, and firsthand data were obtained with the help of OLYMPUS 38DL PLUS thickness gauge with the help of special hanging sheet deployment mode on site. The data were brought into a suitable gray prediction model to detect trends in condition data and to predict future corrosion levels. Finally, a sampling inspection plan with the best combination of time and cost was obtained. The results are as follows: 1. The trend in the corrosion data exhibits a typical single-peak sequence, coupled with the "S"-shaped growth characteristics of biological growth, which ultimately reveals that SRB is the main cause of pipeline corrosion; 2. Among the uncoated original state hangings, the greatest corrosion depths can be observed in 2018 and 2019, with the greatest change in corrosion depth in 2020. 3. The best Verhulst model is with cumulative corrosion depths of 249.00 μm and 250.61 μm for the next 2 years. The next step is to perform a full inspection of 50 uncoated original hanging pieces, while performing sampling inspection of 15 three-layer PE parcel pieces will improve the integrity of the pipeline. [ABSTRACT FROM AUTHOR]

Location class is an essential factor in the gas pipeline project because it considers factors such as population density and the number of buildings along the gas pipeline route. As these parameters change, the pipeline operator needs to review the location class, also requiring a possible assessment of changes in allowable pipeline operating pressure. Brazilian regulations related to the safety of pipeline processes are defined in the Onshore Pipeline Technical Regulation and this document indicates the application of the requirements of the ASME B31.8 standard for changing the location class. Although there are preventive and mitigating measures in the ASME B31.8 standard, they are seen as overly conservative. Other international standards have different concepts, with evaluation criteria based on risk analysis. The issue has also been a challenge for other countries, which are reviewing their regulations and developing guidelines for gas pipeline operators. The main objective of this study is to carry out a survey of international practices related to changing the location class of gas pipelines and to propose a criterion based on the best international practices based on risk management, allowing a more comprehensive view of this subject. [ABSTRACT FROM AUTHOR]

Experimental setups using steel and transparent glass pipes, along with equally spaced steel stamped and transparent plastic tees, were designed for testing. The experimental results provided insights into the influence of flow directions, pig length, material properties, and air consumption on the dynamics and strength of the pigs within the tees. Furthermore, the study identified the causes of temporary halting, jamming, and the mechanisms of damage to cylindrical pigs made of hyperelastic materials within pipeline tees.

[Objective] High-frequency acoustic energy generated by gas passing through decompression devices induces high-order modes of the pipeline wall, leading to acoustic-induced vibrations of the pipeline structure. These vibrations can potentially trigger fatigue failures at discontinuous, such as welded supports, tees, and areas of pipeline corrosion defects, over a short period. [Methods] Initially, the infuence of sound source strength was quantified by calculating the noise spectrum and converting the sound power levels into sound pressure levels.A finite element model was created to simulate acoustic-induced vibrations in a gas pipeline featuring corrosion defects. Acoustic pressure was applied to the pipeline wall within the model to investigate the impact of corrosion defect dimensions on acoustic-induced vibrations,i.e. length, width, and depth. Subsequently, the obtained results were compared against the evaluation outcomes derived from the Energy Institute(EI) guidelines. [Results] Under varying dimensionless lengths of corrosion defects, the gas pipeline exhibited stress responses characterized by hump-like fuctuations. Specifically, the stress level initially increased and then decreased corresponding to increases in dimensionless defect length. However, the stress concentration weakened with increasing dimensionless defect lengths. As the defect width increased, the gas pipeline showed a uniform stress distribution. Additionally, the pipeline stress fuctuated in a saddle shape with increases in dimensionless defect depth. Specifically, the gas pipeline experienced initial decreases followed by rises in the stress level. [Conclusion] This study reveals the substantial impact of corrosion defects on gas pipeline's stress responses, highlighting the most noticeable impact from the length of corrosion defects. Furthermore, corrosion defects with dimensionless depths over 0.6 lead to significant increases in their infuence on the stress and vibration modes of gas pipelines. Consequently, future research should focus on investigating the impact of corrosion defect depths on acoustic-induced vibrations. The quantitative analysis outcomes of acoustic-induced vibration responses in gas pipelines with corrosion defects not only offer theoretical support for mitigating strong vibrations of gas pipelines but also serve as a reference basis for gas pipelines across design, construction, operation, and maintenance stages.

This paper primarily investigates the influence of spatial layout on the safety risks associated with urban natural gas pipelines. Drawing from the actual spatial configuration around the pipeline and local climatic characteristics, the study delves into the distribution patterns of natural gas leakage diffusion and explosion accident consequences, considering various factors such as leakage apertures, soil porosity, and spatial layouts. By integrating the outcomes of the consequence analysis, the quantitative risk of urban natural gas pipelines, accounting for the impact of spatial layout, was computed and juxtaposed with the results of traditional two-dimensional risk analysis. The findings underscore that spatial layout exerts a substantial impact on risk distribution, with significantly elevated risk values in more congested spatial layouts. Additionally, the introduction of a barrier along the pipeline leakage path resulted in a 91.4% reduction in risk compared to scenarios without obstruction. It is evident that the spatial layout surrounding the pipeline plays a pivotal role in influencing the distribution of pipeline failure risks, establishing the spatial environment as a critical factor in risk analysis. This study offers valuable insights for urban land planning, safety control line establishment, and related considerations.

Long-distance gas pipelines in service inevitably are exposed to harsh conditions such as extreme temperature. It is also recognized that corrosion is one of most influential factors on the structural reliability and safety of pipelines, even coated pipelines. Therefore, there is an important need to investigate the temperature effect on the failure behaviors of gas pipelines with corrosion. In this study, a thermomechanically nonlinear finite-element model of a corroded gas pipeline with a polyethylene protective layer was established, in which a large diameter is considered for the long-distance gas pipeline. Thermal stresses obtained from cases with and without the protective layer were compared. Based on the stress-based failure criterion, the failure pressure values of corroded pipeline at different temperatures were obtained, and the deformation and strain of the corroded pipeline were evaluated. The random forest algorithm was adopted to analyze the parametric sensitivity of failure pressure. Taking temperature into account, an estimation model for predicting the failure pressure of corroded pipelines is proposed using the nonlinear least-squares method, which could be useful for performing a preliminary assessment of the failure pressure of long-distance gas pipelines in practice. [ABSTRACT FROM AUTHOR]

Thermomechanical steels are widely used in oil and gas pipelines due to their high toughness and high resitance against crak growth. A large part of the steel pipelines used in the oil and gas industry in Iran is made of API X65 steel. The fluctuations of internal gas pressure in steel pipes can cause fatigue failure and lead to gas leakage and explosion. So, the control of damage initiation and structural integrity of gas pipelines is of great importance. In this study, the S-N curve and the fatigue strength of the base metal of the API X65 steel were estimated by performing fatigue tests. For this purpose, 24 and 25 test specimens along the seam weld in the coil transverse direction, and perpendicular to the seam weld along the coil rolling direction were prepared according to ISO 1143 standard, respectively. All test samples were cut from an spirally welded pipe with 1219mm outside diameter and 14.3mm wall thickness and were tested on a completely reverse rotating-bending fatigue machine. Statistical analysis of the results was performed by considering the normal logarithmic distribution. The mean curve, characteristic curve, and confidence interval of the results were obtained both in the finite fatigue life range and in the fatigue resistance. The mean endurance limit of the base metal perpendicular to and parallel to the seam seam were 305 and 291 MPa, respectively which were in the range of 0.4 to 0.6 of material tensile strength and above the seam weld endurance limit (258 MPa). [ABSTRACT FROM AUTHOR]

Measurements of residual stresses inherited by pipes during the pipe manufacturing process were carried out, and the relationship of SCC with these stresses in the pipe metal was studied. The obtained correlations demonstrate the possibility of optimizing the pipe manufacturing process to reduce their susceptibility to stress corrosion. [ABSTRACT FROM AUTHOR]

In order to scientifically evaluate the impact of gas pipeline disasters in karst area, two typical consequence modes of jet fire and vapor cloud explosion were determined based on pipeline failure characteristics, and the hazard criteria of thermal radiation and shock wave overpressure applicable to gas pipeline disasters in karst area were selected. The evaluation model system for the severity of gas pipeline disaster consequences in karst areas was proposed from the four dimensions of hazard area, casualties, economic loss and environmental damage, and the software for analysis of gas pipeline disaster consequences in karst area was developed based on Visual Studio platform. Based on the actual engineering case in karst area, combined with the regional economic and social development, karst natural geology and gas pipeline engineering characteristics, the impact scope of disaster consequences was simulated and analyzed based on PHAST software. Targeted disaster risk control measures were proposed for personnel and objects in the affected area based on hazard criteria. By introducing relevant standards and regulations issued by the government, industry and enterprises, the impact degree of disaster consequences were quantified. The results show that the proposed PHAST-Visual Studio integration method can make up for the subjectivity problems in the evaluation process of previous studies, bring social science ideas into the engineering risk assessment research, and improve the efficiency of disaster consequence analysis through computer software programming, which is helpful to significantly reduce the level of disaster consequences of gas pipelines in karst area. [ABSTRACT FROM AUTHOR]

The most rapid and efficient method to transport natural gas from its source to its destination is through a pipeline network. The optimal functioning of control stations for natural gas pipelines depends on the use of electrical devices, including data loggers, communication devices, control systems, surveillance equipment, and more. Ensuring a reliable and consistent power supply proves to be challenging due to the remote locations of these control stations. This research article presents a case study detailing the design and dynamic modeling of a hybrid power system (HPS) to address the specific energy needs of a particular natural gas pipeline control station. The HOMER Pro 3.17.1 software is used to design an optimal HPS for the specified location. The designed system combines a photovoltaic (PV) system with natural gas generators as a backup to ensure a reliable and consistent power supply for the control station. Furthermore, it provides significant cost savings, reducing the cost of energy (COE) by USD 0.148 and the annual operating costs by USD 87,321, all while integrating a renewable energy fraction of 79.2%. Dynamic modeling of the designed system is performed in MATLAB/Simulink R2022a to analyze the system's response, including its power quality, harmonics, voltage transients, load impact, etc. The experimental results are validated using hardware in the loop (HIL) and OPAL-RT Technologies' real-time OP5707XG simulator. [ABSTRACT FROM AUTHOR]

This article examines the prospects for increased Turkish-American relations in the Caspian region, namely, joint areas of activity for the development and consolidation of cooperation between both states. Utilizing a historical-comparative method, we comprehensively study Turkish-American relations in this region from a historical viewpoint and predict the further development of this cooperation in the future. The key characteristics and features of Turkish-American relations in the Caspian region from 1991 to 2022 are identified, as are the causes of crises in relations between the two countries against the background of a change in US policy. Finally, we emphasize the importance of further strengthening strategic cooperation between Turkey and the US in the Caspian region. [ABSTRACT FROM AUTHOR]

To mitigate the risk of gas pipelines in karst sinkhole-prone areas, this study employs the DEMATEL/ISM method to elucidate the hierarchical structure and causal relationships among various factors in the system, considering four categories of accident causes: human, material, environment and management. Additionally, the MICMAC method is utilized to analyze the dependence and driving force of risk factors. Utilizing the Visual Studio platform, the software for risk analysis of gas pipelines in karst sinkhole-prone areas is developed. This research introduces the D/I-MICMAC-VS integrated risk analysis method and provides an example analysis. The results demonstrate that: (1) The risk factors for gas pipelines in karst sinkhole-prone areas are distributed across six levels. The possibility of risk accidents can be reduced in the short term by rigorously managing surface-level direct factors, while middle-level indirect factors play an intermediary role in the system. Effective control of gas pipeline accidents can only be achieved by addressing deep-rooted factors fundamentally. (2) The spontaneous cluster serves as a key element for risk management and control of gas pipeline accidents, and prioritized intervention significantly aids in accident prevention. The independent cluster directly influences the system’s risk level through its own changes and development. The linkage cluster plays a pivotal role in transmitting and promoting the evolution and development of accidents. Effective risk management and control can be achieved by discerning the deep root factors that inducing changes in the dependency cluster.

We develop a weakly intrusive framework to simulate the propagation of uncertainty in solutions of generic hyperbolic partial differential equation systems on graph-connected domains with nodal coupling and boundary conditions. The method is based on the Stochastic Finite Volume (SFV) approach, and can be applied for uncertainty quantification (UQ) of the dynamical state of fluid flow over actuated transport networks. The numerical scheme has specific advantages for modeling intertemporal uncertainty in time-varying boundary parameters, which cannot be characterized by strict upper and lower (interval) bounds. We describe the scheme for a single pipe, and then formulate the controlled junction Riemann problem (JRP) that enables the extension to general network structures. We demonstrate the method's capabilities and performance characteristics using a standard benchmark test network. • Formulation of a stochastic hyperbolic PDE as a high-dimensional parametric PDE. • Novel SFV method for quantification of intertemporal uncertainty in systems of conservation laws posed on graphs. • Formulation of the stochastic junction Riemann problem to compute numerical fluxes at the nodes of the graph. • Application of the SFV method to a real-world problem of stochastic gas flows on networks. • Convergence analysis for the statistical moments of the solution. [ABSTRACT FROM AUTHOR]

In order to scientifically assess the disaster-causing possibility of gas pipeline in karst area, based on the disaster system theory, the disaster event system was comprehensively analyzed based on the disaster system theory from the multiple dimensions of the activity of disaster-producing environment, the risk of disaster factors. Combining the advantages of belief propagation and updating of Bayesian network, the disaster-causing probability of disaster events was calculated layer by layer. Combined with the theory of vulnerability and reliability analysis, mathematical models were constructed based on the finite element simulation results and the characteristics of polyethylene pipeline. From the perspective of the interaction between disaster damage intensity and disaster resistance ability, the vulnerability probability of the pipeline was comprehensively calculated. The disaster-causing probability research paradigm of “event risk + pipeline vulnerability” was innovatively proposed, and an example analysis was carried out. The results show that the disaster-causing probability analysis based on the integrated perspective of vulnerability theory and disaster system theory is conducive to the scientific measurement of hazard probability of disaster-causing events based on the systematic perspective, and is also conducive to the accurate assessment of the important impact of pipeline anti-external load capacity on the disaster-causing process. The disaster causing probability of gas pipeline in ZJ karst section is 0. 866 2 × 10-3, which belongs to the unacceptable level. It is necessary to carry out continuous monitoring and scientific evaluation on karst development degree, pipeline safety level, disaster evolution trend, etc. according to cost and benefit. [ABSTRACT FROM AUTHOR]

The present study investigates the hourly activity patterns of mammals inhabiting the area surrounding the Camisea gas pipeline that crosses the Machiguenga Communal Reserve. From February 2020 to January 2021, a photographic record was conducted using camera traps placed along the gas pipeline. Activity patterns were estimated using Kernel density functions. During the study period, 25 mammal species were recorded. It was found that Dasyprocta kalinowskii and Eira barbara exhibit a diurnal activity pattern, whereas Cuniculus paca, Tapirus terrestris, Dasypus spp., and Mazama spp. display predominantly nocturnal behavior. It is suggested that observed activity patterns could be influenced by various factors such as competitive exclusion between D. kalinowskii and C. paca, seasonal food availability for T. terrestris, temperature and precipitation variations for Dasypus spp., phylogenetic constraints in Mazama spp., and temporal segregation with other carnivores for E. barbara. The significance of collaboration between energy industry companies, native communities, and governmental organizations is emphasized. [ABSTRACT FROM AUTHOR]

In order to analyze the effect of pipeline-soil action on the gas pipeline crossing under the soil landslide, the pipeline route selection in the landslide affected area was discussed. Based on smooth particle hydrodynamics and finite element coupling method (SPH-FEM), the force analysis model of pipeline under landslide was established. From the design point of view, the position of pipeline laying was comprehensively considered, the influence of pipeline wall thickness, buried depth and other factors was discussed, and the force deformation characteristics of pipeline under large soil deformation were analyzed. Based on the results, some suggestions are provided for pipeline routing optimization in landslide area. Results show that for the thrust-type landslide, when the pipeline is laid in the sliding mass, the stress and displacement of the pipeline at the leading edge of the sliding mass are small, and the damage of the pipeline at the posterior border is more likely. When the thickness of the pipeline wall is increased, the bearing capacity of the pipeline can be effectively improved, but with the increase of the buried depth, the effective yield strain of the pipeline increases first and then decreases. When the pipeline is laid outside the landslide, the stress of the pipeline located at the leading edge of the landslide is less than that at the posterior border, and it presents different stress states, which meet the safety of operation. At the same time, the increase of wall thickness can reduce the stress of the pipeline. The conclusions can provide suggestions for pipeline routing optimization in landslide area in the design stage, which has certain engineering significance and application value. [ABSTRACT FROM AUTHOR]

To mitigate the risk of gas pipelines in karst sinkhole-prone areas, this study employs the DEMATEL/ISM method to elucidate the hierarchical structure and causal relationships among various factors in the system, considering four categories of accident causes: human, material, environment and management. Additionally, the MICMAC method is utilized to analyze the dependence and driving force of risk factors. Utilizing the Visual Studio platform, the software for risk analysis of gas pipelines in karst sinkhole-prone areas is developed. This research introduces the D/I-MICMAC-VS integrated risk analysis method and provides an example analysis. The results demonstrate that: (1) The risk factors for gas pipelines in karst sinkhole-prone areas are distributed across six levels. The possibility of risk accidents can be reduced in the short term by rigorously managing surface-level direct factors, while middle-level indirect factors play an intermediary role in the system. Effective control of gas pipeline accidents can only be achieved by addressing deep-rooted factors fundamentally. (2) The spontaneous cluster serves as a key element for risk management and control of gas pipeline accidents, and prioritized intervention significantly aids in accident prevention. The independent cluster directly influences the system's risk level through its own changes and development. The linkage cluster plays a pivotal role in transmitting and promoting the evolution and development of accidents. Effective risk management and control can be achieved by discerning the deep root factors that inducing changes in the dependency cluster. [ABSTRACT FROM AUTHOR]

Background. During operation, the main pipeline needs to be repaired. During periodic diagnostics of the pipeline state defects are detected, some of which are unacceptable. The classic repairing method, that involves the shutdown of the pipeline with subsequent replacement of its defective spots, requires significant financial costs and is associated with a forced pipeline outage and environmental violation. Objective. The purpose of this article is to improve the technology of reinforcing sections of main high-pressure pipeline with welded couplings, which are filled with molten metal by allowing obtaining high efficiency of pipe strengthening of medium and small diameters. Methods. Strength improvement of the active pipeline spots is realized by installing brazed-welded couplings on an active main pipeline. Strengthening the pipeline with the coupling consists in the redistribution of the load part from the pipe to the wall of the coupling, which leads to a decrease of the stress level in the pipe wall. The reinforcement efficiency of the pipeline could be evaluated by the degree of reduction of circumferential stresses in the fixed pipe wall. Results. The article suggests a technique for strength improvement of pipeline spots using couplings filled with a molten metal that has a high elasticity modulus. The operations of formation of under-coupling layer with the parameters that provide achievement of the maximum value of the stresses reduction degree in the reinforced pipe are proposed, while ensuring an even load distribution between the wall of the pipeline spot being repaired and the coupling shell. An improved technology for fixing defective spots of the active pipeline has been proposed, designs for front seals have been proposed that facilitate the formation of under-coupling layer with optimal parameters. The proposed technique makes it possible to increase the efficiency of the pipe strengthening of small and medium diameters. Conclusions. The article proposes an improved technology of the defective spots reinforcing of the active main pipeline using braze-welded coupling. The focus is on the design of mechanical seals that ensure the tightness of the under-coupling space during the formation of the coupling layer. Further research would be performed in the direction of developing a mathematical model of the pipeline reinforced with braze-welded coupling, taking into account temperature changes during heating and cooling of the coupling structures during the formation of the under-coupling layer. Some research will be also performed to improve the coupling structures and methods of quality control of their mounting on the pipe.

A subway station’s operation is susceptible to accidents when there is a high-pressure gas pipeline overlaying it, and analyzing the correlations between the safety influencing factors (SIFs) in this operating situation can provide paths to reduce safety accidents. Thus, this paper investigated the coupling correlations between the SIFs. We firstly identified the SIFs during subway station operation under a high-pressure pipeline (SSOUHP) based on a literature review and discussion with experts. Then, the analytic hierarchy process (AHP) and coupling degree analysis (CDA) were combined to assess the coupling correlations between the SIFs, and Y subway station was selected to test the proposed hybrid coupling analysis approach. Research results show that (a) 23 second-level SIFs were identified and these SIFs can be summed up into five first-level SIFs, namely, human-related SIFs, pipeline-related SIFs, station-related SIFs, environment-related SIFs, and management-related SIFs; (b) the proposed hybrid approach can be used to evaluate the coupling correlations between SIFs; (c) of the coupling situations during Y subway station’s operation, the internal coupling correlations among environment-related SIFs, the coupling correlations between pipe-related SIFs and environment-related SIFs, and the coupling correlations among human-related SIFs, pipe-related SIFs, and environment-related SIFs are all greater than 1, and the coordination degree is 0.778, 0.781, and 0.783, respectively, which is a high security risk; (d) the overall coupling degree among all SIFs during Y subway station’s operation is 0.995 and the coordination degree is 0.809, which is a low safety risk. The research can enrich knowledge in the safety evaluation area, and provide a reference for onsite safety management. The results are basically consistent with the conclusion of the enterprise report, which verifies the scientificity and validity of the evaluation method.

[Objective] Surface gas transmission pipelines suffer serious internal corrosion. To ensure the service safety of pipelines, it is necessary to accurately predict their internal corrosion rate. [Methods] The main control factors that affect corrosion were screened based on the Rough Set(RS) theory, and the reconstructed data set was used as the input while the corrosion rate was used as the output to train the Kernel Based Extreme Learning Machine(KELM) model. Additionally, the Improved Seagull Optimization Algorithm(ISOA) was used to optimize the model hyperparameters, and a prediction method of internal corrosion rate based on the RS-ISOA-KELM model was proposed. The prediction precision was compared with that of other combination models, and the long-term prediction effect and model universality were analyzed. [Results] The convergence analysis for the ISOA algorithm was conducted on five benchmark functions including Sphere, Schaffer, Rosenbrock, Rastrigin, and Griewank, and it was found that the ISOA algorithm had better performance in terms of solution precision and calculation stability. The model was verified using actual operating data from a gas field block. For the selected data set, the temperature, CO2 partial pressure, H2S partial pressure, flow rate, Cl-content, moisture content, and corrosion inhibitor residual concentration were crucial factors that affect internal corrosion. Among them, H2S partial pressure, flow rate, and corrosion inhibitor residual concentration had the largest weight. The RS-ISOA-KELM model was used to predict the corrosion rate, and its average relative error was 1.498%, root mean square error was 0.002 1 mm/a, and coefficient of determination was 0.999 3, which were all better than other common comparison models. [Conclusion] The combined model has strong generalization performance and high prediction precision. By expanding and updating the original database,it can predict the medium-and long-term corrosion rate of pipelines.With different corrosion parameters,data sizes,and training test ratios,the model still maintains a good prediction effect.

Aiming at the current challenges of enormous scale, complex structure, difficult control and frequent accidents of city gas high-pressure pipeline network, there are still three aspects of difficulties in the risk monitoring and control of China’s city gas high-pressure pipeline network, namely, rough data, shallow assessment, and lack of power. This paper proposes an intelligent management system for gas pipelines based on C/S model and J2EE enterprise-level framework, in which the failure warning models of gas leakage, Gaussian plume diffusion, and fire and explosion are established. And the Kalman filter algorithm improved by DS evidence theory is used for intelligent fusion of Multi-source data, analyzing and screening the unified adequate information on data types, extracting state characteristics, classifying warning levels, and developing an integrated and visualized pipeline remote diagnosis and warning platform. In the simulation of the intelligent management system of gas pipeline, when the wind speed is 1.5m/s in winter, the ground surface is a safe area within 12.15m of the gas pipeline. When the maximum wind speed is 10m/s, the upper limit distance of the gas leading to fire and explosion is only 2.43m, and the hazardous range of the gas pipeline jet fire is within 12.69m. Relying on the gas high-pressure pipeline network in L city for practical experiments and applications, it provides technical support and decision-making basis for the construction of intelligent pipeline network, comprehensively improves the risk control capability of city gas high-pressure pipeline network, and has reference significance for the risk control of national city gas high-pressure pipeline network.

Relevance. Determined by the importance of predictive modeling of thermal state of pipeline transport facilities located in the permafrost zone. Prediction of geocryological effects is possible through computer simulation of heat and mechanical interactions between a pipeline and a soil medium. Such simulators use data on climatic and geocryological conditions and processes, as well as the information about design and process-dependent parameters of the pipeline, data on its spatial positioning. The presence of various factors influencing heat and mass transfer, as well as the complexity of their numerical simulation, can lead to incorrect design decisions. Such decisions in their turn are always associated with a loss of mechanical safety in an underground pipeline operation. To eliminate this design problem, it is necessary to correctly take into account and adopt the most relevant methods for modeling processes and soil characteristics. Aim. To conduct an analytical comparison of the results of thermal engineering calculations of one section of the route with insular permafrost in order to identify the influence of the model initial parameters on the stress-strain state of the pipeline. Methods. Analyzing the results of engineering surveys for the object of study, conducting a number of numerical calculations, and factorial comparison of the calculation results. Results. At the first stage, the authors have selected the route section of the underground pipeline corresponding to the purpose of the research, the factors influencing the results of thermal modeling. These factors will be considered in this study. At the second stage, the authors carried out modeling of 30 calculation models of one route section with a different set of input data. A factorial comparison of the effect of heat engineering calculation on the results was carried out. At the last stage, the authors carried out the strength calculations of all options for the selected section of the pipeline route as a resulting indicator of the influence of factors.

The hazard coefficient for leakage diffusion of gas transmission pipeline is extremely high, which can easily lead to explosive accidents. The amount of gas leakage is an important factor in the safety assessment of pipeline leakage. Therefore, this paper considers the influence of gas interactions inside and outside the pipeline on pipeline leakage and establishes a three-dimensional leakage diffusion model that is coupled with the pipeline and air domain. Through the use of theoretical, experimental, and numerical simulation methods, this paper investigates the effects of leak hole diameter, leak hole shape, and changes in transport pressure on pipeline leakage. Finally, based on simulated leakage data, we analyze the sources of error and propose a high-precision formula for calculating leakage from small holes in pipelines. The results show that an increase in the diameter of the leak hole leads to a decrease in the central velocity of the leak hole and a sharp increase in leakage volume. The leakage volume of different leak hole shapes is ranked in the following order: rectangle > diamond > circle. When the leak holes are rectangle and diamond, the leakage velocity distribution range of the leak hole is larger and more regular than that of the circular leak hole. Also, the volume of gas leakage increases with the increase in delivery pressure, while the central velocity of the leak hole remains relatively unchanged. Based on the proposed pipeline leakage correction formula, it is calculated that under the same working condition, the relative error range between the numerical simulated leakage rate and the theoretically corrected leakage rate is significantly reduced from −8.40%~18.03% to −1.58%~2.60%, and the calculation accuracy is significantly improved. [ABSTRACT FROM AUTHOR]

A methodology using the subset simulation and the modified Metropolis-Hastings algorithm with delayed rejection (SS-MMHDR) is developed to evaluate the time-dependent reliability of corroded pipelines under multiple failure modes. This methodology considers the competition between the small leak and burst failures and the correlated non-normal distribution of the defect variables, and characterizes the defect geometric probability distribution from extensive inspection data. Results demonstrate that SS-MMHDR has high accuracy and low variability in evaluating the pipeline failures, outperforming the SS-MMH and Monte Carlo simulation algorithms, especially under low probability levels, but with slightly increased computation time. The Generalized Extreme Value Type II (GEVII) distribution is the optimal distribution for internal corrosion defect lengths from the Kolmogorov-Smirnov test. Lognormal, Weibull and Normal distributions provide more conservative estimates on burst and composite failure probabilities and limiting maintenance times than GEVII. Effects of operating pressure and its variability, corrosion rate on failure probability, and pipeline limiting maintenance time are also revealed through numerical cases. [ABSTRACT FROM AUTHOR]

Straight-wall arch cross-sections are usually designed at the entrance and exit tunnels of subway stations, and dense underground pipelines often cross these cross-sections at close range. Among these pipelines, gas pipelines have the highest risk level. Therefore, it is necessary to reduce the deformation influence of underground crossing construction on existing gas pipelines. Based on the No. 2 entrance and exit tunnel project of Zhongshan Road Station of the Hohhot Metro Line 2, using the methods of numerical simulation and field monitoring, this paper has particularly investigated the influence of straight-wall arch tunnel construction by applying the pre-grouting reinforcement and double-side drift method to the deformation of existing gas pipelines. The research results show that the double-side drift method is an efficient and sustainable construction method for straight-wall arch tunnels, which can effectively reduce the crossing construction disturbance to overlying gas pipelines. The measured maximum settlement of the existing gas pipeline is 18.46 mm, and the maximum settlement of the new tunnel vault is 22.86 mm, with both values satisfying the requirements for deformation control. The simulation results are consistent with the measured results of gas pipeline settlement. This study shows that the safety control scheme employed in the field with a tunnel excavation step of 6 m, stratum reinforcement with upper semi-section grouting, and a grouting reinforcement range of 2.0 m is reasonable and effective. This scheme can provide a reference for the deformation control of similar underground gas pipelines in the crossing construction of straight-wall arch tunnels at close range. [ABSTRACT FROM AUTHOR]

This study addresses a significant research gap related to hydrate formation in subsea gas pipelines, with a specific focus on deposition rates during shutdown scenarios, which has received limited attention in previous studies. Past research has employed various methodologies, including experimental, analytical, and computational fluid dynamics (CFD) approaches, to predict hydrate formation conditions, but none have tackled the prediction of hydrate deposition during shutdowns. In this study, we employ a multiple linear regression modeling approach using the MATLAB regression learner app. Four distinct regression models were developed using data generated from 81 CFD simulations, utilising a 10 m length by 0.0204 m diameter 3D horizontal pipe model in Ansys Fluent, as previously developed Through cross-validation against experimental data, the standard linear regression model emerged as the most reliable choice for predicting hydrate deposition rates, providing predictions within ±10% uncertainty bounds of experimental results up to pressures of 8.8 MPa at hydrate-forming temperatures. The uniqueness of this new model lies in its ability to estimate the risk of hydrate deposition in subsea gas pipelines, especially with low gas flow rates and during shutdown periods, which are critical for maintenance planning. Furthermore, by estimating depositional volumes, the model predicts hydrate slurry volumes at receiving facilities, contributing to energy sustainability and benefiting gas transport pipeline operators, particularly in aging gas fields with declining production. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study is to assess the opportunity for the development of hydrocarbon transportation using high-strength steel (HSS) in pipeline construction in terms of cost savings and reliability. Design/methodology/approach: Several optimizations of pipeline design and operations were performed to estimate the total life-cycle cost variation associated with different grades of high-strength steel. The generalized reduced gradient (GRG) method was used in an Excel table to determine optimal total life cycle each pipeline. Variables used in this optimization with respect to each steel grade were as follows: pipeline external diameter, wall thickness, number of compression stations and installed power in each compression station. The reliability of a pipeline with optimal cost was assessed to highlight the impact of steel grade on pipeline reliability. Findings: The study showed that the cost reduction is strongly dependent on the adopted gas pipeline configuration. The number of compression stations and external diameter are the main factors influencing the pipeline total life cycle cost, while the steel price seems to have a minor effect, the reduction of the gas pipeline total life cycle does not exceed 5% even with a 50% difference in pipe steel prices between X70 and X100 steels. On the other side, for the same external diameter, X100 steel presents better pipeline reliability against carbonic corrosion compared to X70 steel. Practical implications: The main contribution of this study is to provide a decision-support tool to help pipeline constructors enhance the profitability of natural gas transmission pipelines. The optimization method used is simple to use for design engineers during a feasibility study. Originality/value: The present study presents one step to fill the gap concerning the question of balancing the trade-off between cost savings and structural reliability in high-strength steel pipelines during the early stages of feasibility studies. The optimal design and operations parameters ensuring cost savings on total life cycle costs are identified via an optimization method. The impact of selected optimal parameters on the long-term pipeline service life was estimated via a structural reliability analysis. [ABSTRACT FROM AUTHOR]

Использование средств информационных технологий и уровня автоматизации процессов управления значительно повышают роль технического прогресса и решают поставленные задачи Республикой Узбекистан по обеспечению целевым продуктом населению. Вместе с тем возможности современных компьютерных систем и развитие математических методов моделирования используются далеко не полностью из-за неформализации многих задач, а также несовершенства или отсутствия ряда алгоритмов, обеспечивающих возможность произвести анализ функционирования объекта, обработать поступающую информацию и принять соответствующие решения по оптимальному управлению многосвязных систем. В связи с этим разработка и исследование компьютерных моделей, вычислительных алгоритмов и на их основе создание объектно-ориентированных программных средств в этом направлении представляется актуальной проблемой дальнейшего развития автоматизации научных исследований для различных предметных областей, в частности трубопроводных систем. Всякая реальная энергетическая сеть, в том числе и газовая, по своей топологической структуре эквивалентна некоторому графу. Провести расчет и анализ несогласованности исходной информации сетей с более одним кольцом затруднительно. В этих случаях необходимо обратиться к законам Кирхгофа и соответствующим замыкающим соотношениям. Тем не менее, топология сети отличается разнообразием, чему свидетельствуют, в частности, схемы городских сетей теплоснабжения. В таких условиях основная тяжесть гидравлического или экономического расчета должна концентрироваться на стадии формирования топологии сети, для чего используются теории графов. В данной статье рассматриваются алгоритмы построения и оптимизации функционирования газопроводных многоконтурных сетей методом теории графов и программное обеспечение для оптимального управления, анализа и синтеза трубопроводных систем. Таким образом, разработанные вычислительные алгоритмы и компьютерная программа расчета можно применять для оптимизации функционирования газопроводных сетей, когда сеть имеет сложную лучистую и многокольцевую структуру.

Predictive approaches play an important role in detecting events, controlling risks and reducing maintenance and repair costs. The purpose is to provide a model for predicting critical and prioritized risks based on data mining algorithms. Data mining method was planned based on the CRISP methodology. Data modeling has been done in two parts: "descriptive" and "predictive" data mining and the use of "clustering" and "classification" algorithms."Sillhouette index" is considered for clustering and the K-Means, Kohnen, Two Step algorithm is used; the best value is based on the K-Means algorithm. Silhouette is equal to 0.6446 with the number of clusters 5. Next, Neural Network Algorithms, C.5 tree, Nearest Neighbor and Support Vector have been used for classification. These techniques recognizing data classification patterns and their integration increases the amount of data learning. The results showed learning in 97.56% of the agreed data and the accuracy and validity of the combined model for data classification was estimated at 92.86%. Based on the results, 13 critical risks have been identified; "release of polluting gases and chemicals" and "lack of training and justification of contractors regarding the pipeline" have the highest and lowest priority, respectively.

The sabotage related to the Nord Stream pipelines does not only signify the Russo ‑Ukrainian War’s escalated realities and potential future risks, also tied to the energy security of supply, but in addition to traditional economic and energetic dilemmas, it also has a specific meaning in light of classic geopolitical concepts. Our study aims to highlight that the contradictions between the direct or indirect nation-state stakeholders, even nowadays, fit into the logic of the power plays illustrated in traditional geopolitical theories. And thus, the events related to the Nord Stream 2 project, as guiding principles, underline not only the energy relations of relevant international state actors appearing in the pipeline’s environment but also in the context of geopolitical positions and the structure of potential geopolitical transformations.

The most rapid and efficient method to transport natural gas from its source to its destination is through a pipeline network. The optimal functioning of control stations for natural gas pipelines depends on the use of electrical devices, including data loggers, communication devices, control systems, surveillance equipment, and more. Ensuring a reliable and consistent power supply proves to be challenging due to the remote locations of these control stations. This research article presents a case study detailing the design and dynamic modeling of a hybrid power system (HPS) to address the specific energy needs of a particular natural gas pipeline control station. The HOMER Pro 3.17.1 software is used to design an optimal HPS for the specified location. The designed system combines a photovoltaic (PV) system with natural gas generators as a backup to ensure a reliable and consistent power supply for the control station. Furthermore, it provides significant cost savings, reducing the cost of energy (COE) by USD 0.148 and the annual operating costs by USD 87,321, all while integrating a renewable energy fraction of 79.2%. Dynamic modeling of the designed system is performed in MATLAB/Simulink R2022a to analyze the system’s response, including its power quality, harmonics, voltage transients, load impact, etc. The experimental results are validated using hardware in the loop (HIL) and OPAL-RT Technologies’ real-time OP5707XG simulator.

To study the influence of fluid solid coupling erosion on the joints of gas pipelines, the Fluent DPM model was first used to conduct finite element analysis on several commonly used gas pipeline joints through gas-solid coupling numerical simulation. Secondly, the reasons for erosion of four-way joints and fish tail joints were studied, and the effects of fluid velocity, particle mass, and particle diameter on erosion were compared and analyzed. Finally, two optimization schemes were proposed for these two types of joints. The results show that fish tail joint is generally lower than that of the three-way channel structure. The erosion rate of the fish tail pipe is caused by the large angle between the inlet and outlet channels, which causes particles to directly impact the projection direction of the inlet channel. The erosion rate increases with the increase in velocity and increases with the increase in particle diameter. The use of a double lobe guide structure in the four-ways joint and fish tail joint not only effectively optimizes the internal flow channel, but also reduces wall erosion and avoids large flow velocity zones. [ABSTRACT FROM AUTHOR]

The brief information presented on the unexpected resurfacing of two lines at the underwater crossing through the Baidaratskaya Bay in Yamal indicates that in the course of the development of projects, full studies were not carried out on the issues of ensuring the strength and stability and maintaining the gas pipelines in the design position. To identify one of the main reasons for the ascent, the problem of the stress-strain state of the underwater section of the offshore gas pipeline was posed and solved, taking into account partial and complete flooding of the soil in separate underground parts. The considered underwater section of the underwater gas pipeline in the design scheme is conditionally divided into three parts. In its middle part there is a blurred bare part, which is formed due to liquefaction and erosion of the soil. Underground parts adjoin it on the left and right. A one-dimensional rod system in an elastic medium, consisting of curvilinear and straight three-layer rods of a tubular section and their junctions, is taken as a mathematical model of the calculated section of the gas pipeline. The stress-strain state of the rod element is described by a system of differential equations, which consists of geometric and physical nonlinear relationships, nonlinear differential equilibrium equations. The solution of the problem is carried out by the method of finite elements in displacements. A numerical experiment has found the critical values of the operation parameters and the shape of the bend of the gas pipeline preceding its ascent for different lengths of the washed-out bare part, changes in the state of the soil in the underground parts and various values of the gas pipeline operation parameters. [ABSTRACT FROM AUTHOR]

Based on the Jilin Songyuan gas pipeline accident, FLACS software was used to numerically simulate its leakage and explosion process in order to study the change law of the equivalent gas cloud volume of gas leakage diffusion under various influencing factors. The simulation results were compared and analyzed with the accident investigation report in order to ensure the accuracy of the simulation results. On this premise, the three primary influencing factors—the obstacle distribution technique, the ambient wind speed magnitude, and the ambient temperature—are varied in order to study the equivalent gas cloud volume variation features of the leaking gas cloud. The findings indicate a positive association between the maximum equivalent gas cloud volume of the leaking gas cloud and the density of the obstacle distribution. There is a positive correlation between ambient wind speed and the equivalent gas cloud volume when the ambient wind speed is less than 5.0 m/s, and a negative correlation between ambient wind speed and the equivalent gas cloud volume when the ambient wind speed is greater than or equal to 5.0 m/s. A drop in Q8 is proportionately increased by around 5% for every 10 °C increase in ambient temperature when the temperature is below room temperature. There is a positive association between ambient temperature and the equivalent gas cloud volume Q8. When the temperature is higher than room temperature, the drop in Q8 is correspondingly increased by about 3% for every 10 °C increase in ambient temperature. [ABSTRACT FROM AUTHOR]

In the process of reconstruction and expansion of gas pipeline, it is easy to destroy in-service gas pipeline and cause safety accidents. In order to realize the detection of in-service pipelines, based on the characteristics of low sound pressure level and easy attenuation of acoustic signals of gas pipelines, the detection and identification method of gas pipelines based on acoustic signal feature analysis was studied by using Hilebert–Huang transform algorithm and optimized Back Propagation (BP) neural network. This method takes the gas pipeline flow noise signals obtained by numerical simulation and experimental verification as the research object, and the underwater acoustic signals are collected for comparative analysis. Empirical Mode Decomposition (EMD) was used to decompose the two signals, and the time-domain waveform of Intrinsic Mode Functions (IMF) component was obtained, and the characteristic parameters of peak value and peak frequency were determined. The energy characteristic parameters of Hilbert marginal spectrum were calculated, and the characteristic database of gas pipeline flow noise signal was obtained. The optimized BP neural network was used for pattern recognition. The results show that the identification rate of gas pipeline acoustic signal can reach 97.5% by using this method, which verifies the effectiveness of the gas pipeline detection and identification method in this paper. [ABSTRACT FROM AUTHOR]

Due to the emergence of new technologies that make it possible to obtain hydrogen from associated petroleum gas, it has become necessary to store and transport it. As a solution to this problem, the possibility of hydrogen transportation as a methane-hydrogen mixture was considered, i.e. natural gas with a certain hydrogen content. The article considers the issues of methane-hydrogen mixture (MHM) transportation through existing main gas pipelines at various percentages of hydrogen to natural gas. As an example, the Urengoyskoye field was chosen, where it is possible to produce hydrogen from the associated gas of gas condensate fields, and a section of the Novopskovskiy corridor, through which it is possible to transport MHM. In the work, the influence of the hydrogen content in the methane-hydrogen mixture on the gas-dynamic characteristics of the pipeline, mainly on the pressure and throughput capacity of gas in the pipeline, as well as the influence of its content on the operating mode of the compressor station and the power of the gas turbine, when using MHM for the station's own needs, was studied. The obtained results show an insignificant effect of the hydrogen percentage in the mixture on the pressure and throughput of the gas pipeline, which is a weighty argument in favor of the possibility of transporting hydrogen through existing gas pipelines. [ABSTRACT FROM AUTHOR]

The relevance of the study lies in preventing the surfacing of underwater sections of the offshore gas pipeline and keeping them in the design position. Purpose: identification of the length of the blurred exposed part, soil condition on the adjacent underground parts, internal pressure and temperature stresses for the ascent of the underwater section of the gas pipeline, as well as the establishment of effective operation of compensators. Objects: underwater sections of the gas pipeline, expansion joints. Methods: joint integration of a system of differential equations describing the stress-strain state of a blurred exposed part and adjacent underground parts. Results. The paper introduces brief information about the ascent of two of four threads of the Nord Stream-2 at the site of the underwater passage through the Baydaratskaya Bay in Yamal. The following three statements of the problem of the stress-strain state of the calculated underwater section of the gas pipeline are considered: taking into account the effect of internal pressure and temperature stresses on the bending of the pipeline, causing additional bending of the gas pipeline; neglecting the effect of internal pressure and temperature stresses on the bending of the pipeline; with compensators installed at the beginning and end of the calculated section. The presented solution for the first formulation of the problem depends on the usual trigonometric functions, for the second formulation of the problem – on polynomials, and in the third formulation – on hyperbolic and trigonometric functions. For these three problem statements, the main characteristics of the stress-strain state of the gas pipeline are calculated, diagrams of its deflection and bending stresses are constructed, the tables show the extreme values of these characteristics for different values of the parameters of the operation of the gas pipeline for different lengths of the blurred exposed part, and taking into account changes in soil state on adjacent underground parts. The effective operation of compensators designed to prevent the surfacing of underwater sections of the offshore gas pipeline and to keep them in the design position was established.

The national strategic goal of the Russian Federation is to ensure the safety of critical technologies and sectors, which are important for the development of the country's oil and gas industry. The article deals with development of national technology for intelligent monitoring of the condition of industrial facilities for transport and storage of oil and gas. The concept of modern monitoring and safety control system is developed focusing on a comprehensive engineering control using integrated automated control systems to ensure the intelligent methodological support for import-substituting technologies. A set of approved algorithms for monitoring and control of the processes and condition of engineering systems is proposed using modular control robotic complexes. Original intelligent models were developed for safety monitoring and classification of technogenic events and conditions. As an example, algorithms for monitoring the intelligent safety criterion for the facilities and processes of pipeline transport of hydrocarbons are presented. The research considers the requirements of federal laws and the needs of the industry.

An analysis is carried out on the problem of creating methodological foundations for the optimal construction of information technologies that provide integrated logistics support for the life cycle of gas transmission system samples with uncertainty of the initial data. The analysis of the state of research of the problems of analysis, synthesis and forecasting of the development of complex.

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