Large Pipeline Research Articles

Modeling transient cavitating flow in large drop crude oil pipelines

Transient cavitating flow is a dangerous condition in the operation of large drop crude oil pipelines. Accurately predicting the high pressure generated by cavity collapse is the premise of analyzing and formulating pipeline safety management and control strategies. A new numerical simulation method for one dimension cavitating flow in crude oil pipelines considering the effect of unsteady friction was proposed. The unsteady friction (UF) term is coupled to the classical discrete gas cavity model (DGCM) for modeling the cavitating flow, and the proposed model is called UF-DGCM. The method of characteristics (MOC) is used to solve the UF-DGCM. The validity of the model has been verified with experimental data. The pipeline length of the two test cases is 37.23 m and 15.22 m, respectively, and the pipeline diameter is 22.1 mm and 20.0 mm, respectively. For the two test cases, the accuracy of the prediction results is improved by 6.7% and 4.4%, respectively. A case study of cavitating flow caused by pump shutdown in a pipeline with a length of 35 km and a diameter of 738 mm was performed using UF-DGCM, and the effects of water hammer wave speed, crude oil vapor pressure, and pump shutdown time on cavitating flow were analyzed. The results show that the maximum pressure peak is dependent on the water hammer wave speed. About the increase in the wave speed value of 200 m/s will lead to an increase in the maximum pressure head value of 10.1 m. The increase of pump shutdown time will inhibit the growth of cavities, and increasing the pump shutdown time by 4 s will shorten the existence time of cavities by about 3 s. The extension of the pump shutdown time will prevent cavitating flow. The proposed improved model is more suitable for transient cavitating flow analysis, and the results of flow parameters research will be helpful to prevent cavitating flow in crude oil pipelines.

Simulation analysis of the effect of single-chamber double-line pipe jacking through different soil materials on surface uplift and subsidence.

This article is based on the relocation project of the 330 kV overhead line in Xi’an, China. In this paper, the soil settlement under different jacking depths was calculated by using the modified Peck’s formula. Meanwhile, by modeling in ABAQUS, the jacking process of a single-chamber double-line large diameter pipeline under different soil conditions was simulated, and the ground deformation data under the different simulated working conditions were obtained. The results of the two methods were compared with the construction monitoring results, and it was found that the finite element simulation results were closer to the actual results. The control variable method was used in the analysis of the surface soil deformation law to analyze the effect of different soil parameters and pipe jacking depths on surface soil deformation. Finally, the best soil conditions applicable to single-chamber double-line large diameter pipe jacking construction were obtained through comparative analysis. The results show that (1) when using double-line construction, the maximum surface settlement under different soil conditions is located 11–15 m from the centerline of the soil above the pipeline, the minimum settlement location is inside the isolation pile, and with the increase in jacking distance, the settlement at the same section of the surface will gradually decrease and finally produce a small uplift. (2) In the first jacking, the settlement of powder clay is the largest, and the maximum settlement points in the surface section are more distributed. The maximum settlement value is approximately 11.66 mm. The settlement of powder soil is the smallest but produces a certain uplift deformation, and its maximum settlement is more concentrated in the surface section. After the comparison of deformation and soil parameters, loess-like soil is more suitable for single-compartment double-line large diameter pipe jacking construction. (3) When the top pipe burial depth changes, the greater the burial depth is, the smaller the settlement but the greater the lateral influence range. In the soil parameters, the modulus of elasticity only changes 3 MPa, and the settlement change value is approximately 5 mm. By changing the parameters, it can be obtained that the larger the modulus of elasticity of the soil is, the smaller its deformation. The larger the internal friction angle of the soil is, the smaller its deformation, but the maximum value of settlement change is only 1.7 mm, which means that the change in the internal friction angle has little effect on the soil deformation.

NBR/CR‐Based High‐Damping Rubber Composites Containing Multiscale Structures for Tailoring Sound Insulation

AbstractHigh‐damping acoustic composites with unique sound insulation feature is reported, demonstrating surprisingly stable soundproof properties over a wide bandwidth of frequency (63–6300 Hz) with good mechanical properties. The extraordinary acoustic properties are attributed to the multiscale synergy of lamellar and hollow structures by multifillers adding. The acoustic composites are designed and fabricated through a low‐temperature one‐time rubber mixing process using nitrile butadiene rubber(NBR), chloroprene rubber (CR) as matrix and mica powder (MP), hollow glass beads (HGB), and montmorillonite (MMT) as multifillers. The soundproof mechanism is discussed in detail. Results indicate that the synergism of damping and sound absorption behaviors in the composition has a considerable impact on the acoustic characteristics, which can be controlled by the blending ratio of NBR/CR matrixes and the multiscale structures of MP/HGB/MMT multifillers. The designed multifillers acoustic composites can adapt to broadband engineering noise control including walls in express train constructions, panels of vessel or aircraft cabins, and large transportation pipelines.

Study on connectivity of buried pipeline network considering nodes reliability under seismic action.

Currently, the connectivity calculation of complex pipeline networks is mostly simplified or ignores the influence of nodes such as elbows and tees on the connectivity reliability of the entire network. Historical earthquake damage shows that the seismic performance of municipal buried pipelines depends on the ability of nodes and interfaces to resist deformation. The influence of node reliability on network connectivity under reciprocal loading is a key issue to be addressed. Therefore, based on the general connectivity probabilistic analysis algorithm, this paper embeds the reliability of nodes into the reliability of edges, and derives a more detailed and comprehensive on-intersecting minimum path recursive decomposition algorithm considering elbows, tees, and other nodes; then, based on the reliability calculation theory of various pipeline components, the reliability of various nodes in different soil is calculated using finite element numerical simulation; finally, the reliability of a small simple pipeline network and a large complex pipeline network are used as examples to reveal the importance of considering nodes in the connectivity calculation of pipeline network. The reliability of the network system decreases significantly after considering the nodes such as elbows and tees. The damage of one node usually causes the failure of the whole pipes of the path. The damage probability is greater in the area with dense elbow and tee nodes. In this study, all types of nodes that are more prone to damage are considered in detail in the calculation. As a result, the proposed algorithm has been improved in computational accuracy, which lays the foundation for further accurate calculation of pipeline network connectivity.

Mathematical analysis of flow passing through a rectangular nozzle

Practically speaking, fluid flow in round and noncircular nozzle is a very regular occurrence. The cold and hot water used in our homes is delivered to us via pipes. Water is delivered throughout the city via large pipe networks. Large pipelines carry natural gas and oil hundreds of kilometres from one place to another. During the operation of an engine, cooling water is carried by hoses to the radiator’s pipes, in which it is cooled as it travels. Experimentally, we detected the results of the model because there is no restriction on the application of experimental research to a certain sector or kind of concept. It may be used for a broad range of events and circumstances. Under parabolic velocity conditions, fluid (Water Pr 6.9) flows from the inlet position. The top and bottom walls of the rectangular nozzle are also moving at the same velocity as they are at the inlet position. Due to the movement of the walls, fluid is compressed in the particular region and also exhibits the same parabolic behavior. The solution of the coupled equations is determined by using the Finite Volume Method (FVM). When partial differential equations are expressed as algebraic equations, the FVM may be used to evaluate them. It can be used to evaluate elliptic, parabolic, and hyperbolic partial differential equations. Using FVM, it is necessary to know the values (and derivatives) of multiple variables at the cell faces, when the values (and derivatives) of these variables are only known at the cell centres. When determining these variables for convective terms, it is common to take the direction of the flow into consideration. The numerical results of the velocity and the pressure could be seen in the rectangular nozzle.

A minimally designed soft crawling robot for robust locomotion in unstructured pipes

Soft robots have attracted increasing attention due to their excellent versatility and broad applications. In this article, we present a minimally designed soft crawling robot (SCR) capable of robust locomotion in unstructured pipes with various geometric/material properties and surface topology. In particular, the SCR can squeeze through narrow pipes smaller than its cross section and propel robustly in spiked pipes. The gait pattern and locomotion mechanism of this robot are experimentally investigated and analysed by the finite element analysis, revealing that the resultant forward frictional force is generated due to the asymmetric mechanical properties along the length direction of the robot. The proposed simple yet working SCR could inspire novel designs and applications of soft robots in unstructured narrow canals such as large intestines or industrial pipelines.

Pipeline Rescue Robot using Raspberry Pi

Nowadays, a lot of work is being carried out by the government to build new flyovers, improve the underground pipeline system, development of smart city etc. for which a lot of holes are being dug. Some of them are very deep which could be a threat not only to the workers children but also to the children leaving in that neighborhood. Most of these works have not yet been completed and it is very risky for the children to play or move around it. Sometimes there are larger pipelines or boreholes dug and left uncovered and there are no precautionary measure taken around it. These boreholes or pipelines are not only dug the government but also by some of the individual houses or apartments to solve water problems. Children playing around it often fall down in it borehole which is left uncovered in most of the places and get trapped in there. It is very arduous and also dangerous to rescue the child trapped inside a borehole or pipeline and rescue operation must be carried out safely, such that it should not harm or injure the child during the rescue process. A small delay, might put the child’s life in danger. Currently, the rescue operation is carried out manually. Whenever there is a requirement to rescue a child, a man would tie himself, equipped with oxygen and with the help of his fellow colleagues go down into the borehole or pipeline. This procedure takes time and it also puts the life of the person who goes down for rescue operation to risk.It is also a time consuming process. If the depth of the pipeline is very deep, this kind of rescue process is very dangerous and time consuming. Since time is the key in this type of situation, it is necessary to come up with the alternate method of rescue, which is safe for the child and the rescue team. It should also not consume too much time unless there are no hinders. The main objective of this project is to design and construct a pipeline rescue robot (i.e. a robot designed to rescue a trapped child without any person manually entering inside the pipeline or borehole). This project is a human controlled and monitored robot that gives a clear view of the child that needs to be rescued safely and steps taken appropriately to achieve that. The project focuses in designing a “Robot to rescue a child stuck in a pipeline or borehole” which moves inside the pipeline according to the commands given by the user through PC. The robotic arm used in here can also be used for other application just by replacing the gripper. The robot is handled through PC by making use of Zigbee technology and a camera which provides a view in the PC. This robot uses LDR which gets activated in dark surroundings thus making LED glow. DC motor helps in upward and downward movement of the robotic arm accordingly to the depth of the pipeline. It is a low cost robot, which can be modified and used for various other applications.

Numerical simulation study on the effect of large explosive contact pipeline explosion on pipeline damage

In this study, the influence of the size of an explosive and pipeline parameters on pipeline damage caused by large explosives was analyzed via numerical simulation. The size of the contact surface, the thickness of the pipeline wall, the diameter of the pipeline diameter, and the internal pressure of the pipeline were investigated. The shape and length of the pipeline crevasse after the explosion were analyzed. The results show that when the size of the contact surface between the explosive and the pipeline increased in the axial and circumferential directions, the change trends of the shape and length of the pipeline crevasse were different. When the wall thickness of the pipeline increased, the size of the pipeline crevasse decreased. When the size of the contact surface of the explosives and pipelines was small, no correlation existed between the size of the pipeline crevasse and the diameter of the pipeline. However, when the contact surface size of the explosive and pipeline was large, the size of the pipeline crevasse increased with the diameter of the pipeline. The increase in internal pressure inside the pipeline had no significant effect on the size of the pipeline crevasse. These results can provide a theoretical basis and reference for pipeline safety and accident investigation.

Electromagnetic Feet With Soft Toes for Adaptive, Versatile, and Stable Locomotion of an Inchworm-Inspired Pipe Crawling Robot.

Feet play an important role in the adaptive, versatile, and stable locomotion of legged creatures. Accordingly, several robotic research studies have used biological feet as the inspiration for the design of robot feet in traversing complex terrains. However, so far, no robot feet can allow legged robots to adaptively, versatilely, and robustly crawl on various curved metal pipes, including flat surfaces for pipe inspection. To address this issue, we propose here a novel hybrid rigid-soft robot-foot design inspired by the leg morphology of an inchworm. The foot consists of a rigid section with an electromagnet and a soft toe covering for enhanced adhesion to a metal pipe. Finite element analysis , performed under different loading conditions, reveals that due to its compliance, the soft toe can undergo recoverable deformation with adaptability to various curved metal pipes and plain metal surfaces. We have successfully implemented electromagnetic feet with soft toes (EROFT) on an inchworm-inspired pipe crawling robot for adaptive, versatile, and stable locomotion. Foot-to-surface adaptability is provided by the inherent elasticity of the soft toe, making the robot a versatile and stable metal pipe crawler. Experiments show that the robot crawling success rate reaches 100% on large diameter metal pipes. The proposed hybrid rigid-soft feet (i.e., electromagnetic feet with soft toes) can solve the problem of continuous surface adaptation for the robot in a stable and efficient manner, irrespective of the surface curvature, without the need to manually change the robot feet for specific surfaces. To this end, the foot development enables the robot to meet a set of deployment requirements on large oil and gas pipelines for potential use in inspecting various faults and leakages.

Modeling of Gas Migration in Large Elevation Difference Oil Transmission Pipelines during the Commissioning Process

Oil pipeline construction and operation in mountainous areas have increased in southwestern China, with oil consumption increasing. Such liquid pipelines laid in mountainous areas continuously undulate along the terrain, resulting in many large elevation difference pipe segments. Serious gas block problems often occur during the commissioning process of these pipelines due to the gas/air accumulation at the high point of the pipe, which causes pipeline overpressure and vibration, and even safety accidents such as bursting pipes. To solve this problem, the gas–liquid replacement model and its numerical solution are established with consideration of the initial gas accumulation formation and the gas segment compression processes in a U-shaped pipe during the initial start-up operation. Additionally, considering the interactions of the gas-phase transfer in the continuous U-shaped pipe, and the influence of the length, inclination angle, and backpressure on the air vent process, the gas migration model for a continuous U-shaped pipe is established to predict the gas movement process. Finally, the field oil pipe production data were applied to verify the model. The results demonstrate that the maximum deviation between the calculated pressure during the start-up process and real data is 0.3 MPa, and the critical point of crushing the gas in the pipe section is about 0.2 Mpa. Additionally, the results show that the mass transfer of the gas section in the multi-pipe hydraulic air vent process causes the gas accumulation section to increase in downstream of the pipe. This study’s achievements can provide theoretical guidance and technical support for the safe and stable operation of continuous undulating liquid pipelines with large drops.

Complex stiffness model of an air spring with auxiliary chamber considering inertial effects of gas in connecting pipeline

In this paper, an analytical complex stiffness model of an air spring system with auxiliary chamber is established considering inertial effects of gas in connecting pipeline. The established model can reflect the resonance phenomenon of the dynamic stiffness curve due to the gas inertia in connecting pipeline as well as the amplitude dependent characteristic of the dynamic stiffness. To obtain the key parameters of the model, a finite element model of the air spring system and a CFD model of the pipeline are developed respectively, then relative simulation analyses are operated. The complex stiffness of air spring system is calculated and investigated with the proposed model. The calculation results are compared with that of the experiments and the existing complex stiffness model. It shows that the calculation results of the proposed model agree well with the experimental results. The proposed model is especially suitable for air spring systems with large pipeline gas inertia and low pipeline damping. Moreover, it is deduced that when the inertial effect of gas in the pipeline decreases and the damping of the pipeline increases, the proposed model in this paper can be transformed into the existing model. Thus, this new complex stiffness model has a wide application range.

Self-Powered Sensing for Non-Full Pipe Fluidic Flow Based on Triboelectric Nanogenerators.

Fluidic flow monitoring of a non-full pipe is of great significance in the field of energy measurement and pipeline transportation. In this work, a monitoring method based on triboelectric nanogenerators for non-full pipe fluidic flow of large pipelines is proposed. Specifically, a triboelectric non-full pipe flow sensor (TNPFS) is fabricated, which can monitor the flow velocity and the liquid level simultaneously, and then the flow can be obtained by conversion. For flow velocity monitoring, the flexible blades slide between electrodes, generating periodic electrical signals. Interestingly, the frequencies of the voltage and flow velocities show a good linear relationship. For liquid level monitoring, according to the principle of liquid-solid contact electrification, a variable area interdigital electrode with a stable signal distributed on a polytetrafluoroethylene tube is designed. The experiments demonstrate that the peak number and trend of the voltage derivative curve are related to the liquid level. Finally, a real-time flow-monitoring system is established to effectively monitor the flow from 94 to 264 L/min. Compared with the actual measured flow, the error rate is under 1.95%. In addition to this, the TNPFS also has good responsiveness in sewage. This work provides a novel method for fluidic flow monitoring, especially the non-full pipe flow of large pipelines.

Competition law and pricing among biologic drugs: the case of VEGF therapy for retinal diseases.

Neovascular age-related macular degeneration (AMD) is a progressive eye disease and is a leading cause of vision loss in the Western world. Vascular endothelial growth factor inhibitors have become a mainstay of treatment for this disease. Currently, treatment options include three originator biologics with approvals for neovascular AMD (aflibercept, ranibizumab, and brolucizumab-dbll) and one biologic that is commonly used off-label for the condition (bevacizumab). In the USA, Medicare spending on these drugs consistently surpassed $4 billion per year between 2015 and 2019, driven by high prices and varying off-label use of bevacizumab, which is substantially cheaper than the other biologics used to treat neovascular AMD. In this article, we discuss how legal reform can improve market competition for biologic drugs, using AMD therapies as a case study. We chose this group of drugs for their significant contribution to Medicare spending, the price difference between approved therapies and intravitreal bevacizumab, and because there currently exists a large biosimilar pipeline with many drug candidates in the final stage of development. We propose mechanisms for anticipating and facilitating the market introduction of biosimilars, as well as changes to the pricing model in Medicare that can promote use of cost-effective therapies. Reforms such as empowering Medicare to negotiate drug prices may help ensure that introduction of new biologics and biosimilars for AMD will lower spending and increase patient access.

Natural Gas in Central and Southeastern Europe: Market Unification and New Challenges

Gas consumption and its source are a strategic issue for all European countries. Our study examines the consumption of natural gas in Central and Southeastern Europe, the level and structure of consumption in the region, and analyses the network developments and the construction of LNG ports over the past decade and a half. The rules adopted by the EU created a unified market by providing access to the use of the network. Since the construction of natural gas pipelines in the 1970s, gas imports from Russia have played a dominant role in the supply of Central and Southeastern Europe. In the last 10–2 years, further large capacity pipelines have been built from the east to Europe, which created an opportunity for new connection points for the countries in the region. With the interconnectors built between the individual countries of the region, the market of the region can be now considered unified, where access to the network is provided at moderate costs. At the same time, the consumption and transport of natural gas in the region have been and still are highly politicised issues. On the one hand, the new climate policy concepts and agreements announced have a considerable impact and, on the other hand, geopolitical tensions also affect the transport of natural gas. In 2021, an increase in consumption was still likely. This was due to the fact that the states in the region wished to shift from coal-fired power plants to electricity generation based on a combination of renewables and natural gas, while the new southern pipelines in the Balkans would have allowed for greater imports than before. In the changed circumstances, the previously planned level of natural gas use is expected to be reduced. High prices and the fact that access to Russian gas imports may even be limited due to the atmosphere reminiscent of the Cold War are also factors that point in this direction.

State identification of large diameter wet steam pipeline in nuclear power conventional island

The safety of nuclear power plant is an inevitable condition for maintaining the long-term and stable development of nuclear power. Pipeline vibration is one of the common causes of power plant operation faults. Therefore, the state identification of pipeline vibration is very important. Taking a nuclear power heating pipeline as an example, the original vibration signal is decomposed and reconstructed by Wavelet Packet Transform, and the energy eigenvectors in X, Y and Z directions are established. In order to analyze the state of pipeline more accurately, two recognition algorithms of support vector machine (SVM) and SOM neural network are proposed. By comparing the classification effect and classification accuracy of the SVM before and after optimization, the optimized SVM and SOM neural network, it is concluded that the optimized SVM has better effect on pipeline state recognition, and the effectiveness of this method on pipeline state recognition is verified.

Study on Settlement Influence of Newly Excavated Tunnel Undercrossing Large Diameter Pipeline

With the rapid development of tunnel construction, there will be an increasing number of engineering cases about undercrossing existing pipelines. During the undercrossing process, the settlement control of existing pipelines is relatively strict. If the construction is not handled properly, the existing pipelines will cause a larger settlement, which will affect their normal use. This paper takes an existing pipeline project in Nanjing as the research object and uses numerical simulation to explore the influence of different excavation sequences and grouting reinforcement scopes on the existing pipelines above the newly built tunnels when using shallow tunnel excavation. The results show that the sections are constructed first on both sides of the construction, and the middle section is constructed subsequently, which not only increases the excavation speed but also the pipeline deformation is smaller, especially in controlling the differential settlement on both sides of the pipeline. By studying the relationship between the grouting reinforcement range and the vertical distance from the newly built tunnel to the existing pipeline, it is found that the soil engineering effect within 0.3 d above the arch line is more reasonable, and the feasibility of the proposed scheme is verified through actual monitoring data. This research can provide a reference for similar projects in the future.

Компьютерное проектирование больших трубопроводных сетей высокого ранга оптимальности

The paper presents a computer-aided optimal design of hydraulic systems. The method is based on dividing the network synthesis problem into two stages resulting in a dimensional reduction. This allows the optimal networks design of the higher rank. The proposed technique is intended for automated design of large pipeline networks for rural and interregional water supply.

Comparative analysis of transient valve-induced flow characteristics between opening and closing processes

Transient control of process valves, including opening and closing processes, is consistently encountered in many fluid transportation and control industries. During opening and closing processes, valve-induced transient flow presents different unstable flow characteristics. This transient valve-induced unstable flow that develops along the pipeline can cause violent pressure and velocity fluctuations that considerably influence accurate flow measurement downstream. In this paper, gate valve-induced flow characteristics during opening and closing processes were comparatively studied. An experimental system was developed to monitor the downstream pressure along the pipeline, and corresponding transient numerical simulations were performed on opening and closing processes using a user-defined function and dynamic grid technology. The pressure distributions along the pipeline's downstream area during valve opening and closing processes were investigated to verify the accuracy of the numerical simulation. The mechanism of transient flow difference under the same valve opening during opening and closing processes was determined to be a hysteresis effect. The jet flow intensity under a small valve opening in the opening process was greater than that in the closing process, and the difference in flow field under the 50% valve opening was the largest. Moreover, the velocity and turbulent kinetic energy distributions in different downstream cross-sections during valve opening and closing processes were comparatively analyzed. The change rate of the maximum turbulent kinetic energy was introduced to further analyze the different effects of opening and closing processes on the transient flow stability downstream of the valve. Results showed that the flow stability between 40% and 50% valve opening was the worst irrespective of the adjustment process, that is, a large pipeline distance was required to stabilize this transient flow. This study helps in understanding transient valve-induced flow characteristics in fluid transportation pipelines and provides guidance for accurate flow metering industrial applications.

Synthaser: a CD-Search enabled Python toolkit for analysing domain architecture of fungal secondary metabolite megasynth(et)ases

BackgroundFungi are prolific producers of secondary metabolites (SMs), which are bioactive small molecules with important applications in medicine, agriculture and other industries. The backbones of a large proportion of fungal SMs are generated through the action of large, multi-domain megasynth(et)ases such as polyketide synthases (PKSs) and nonribosomal peptide synthetases (NRPSs). The structure of these backbones is determined by the domain architecture of the corresponding megasynth(et)ase, and thus accurate annotation and classification of these architectures is an important step in linking SMs to their biosynthetic origins in the genome.ResultsHere we report synthaser, a Python package leveraging the NCBI’s conserved domain search tool for remote prediction and classification of fungal megasynth(et)ase domain architectures. Synthaser is capable of batch sequence analysis, and produces rich textual output and interactive visualisations which allow for quick assessment of the megasynth(et)ase diversity of a fungal genome. Synthaser uses a hierarchical rule-based classification system, which can be extensively customised by the user through a web application (http://gamcil.github.io/synthaser). We show that synthaser provides more accurate domain architecture predictions than comparable tools which rely on curated profile hidden Markov model (pHMM)-based approaches; the utilisation of the NCBI conserved domain database also allows for significantly greater flexibility compared to pHMM approaches. In addition, we demonstrate how synthaser can be applied to large scale genome mining pipelines through the construction of an Aspergillus PKS similarity network.ConclusionsSynthaser is an easy to use tool that represents a significant upgrade to previous domain architecture analysis tools. It is freely available under a MIT license from PyPI (https://pypi.org/project/synthaser) and GitHub (https://github.com/gamcil/synthaser).

Key Points of Construction Management for Directional Drilling Crossing of Large Diameter and Long Distance Transmission Pipeline

Key Points of Construction Management for Directional Drilling Crossing of Large Diameter and Long Distance Transmission Pipeline