Pipe Section Research Articles

Three-dimensional analysis of the stress-strain state for straightening pipes on skew-roll straightening machines with special roll profiling

In order to increase the competitiveness of domestic metal products, in particular pipes, it is necessary to ensure their compliance with international standards in terms of the main quality indicators. The pipe straightening process provides quality indicators such as straightness and cross-sectional shape. Skew-roll pipe straightening machines are the most common and most effective for straightening pipes of small and medium diameters. The most modern are six-roll pipe straightening machines with special roll profiling, which provide straightening of two types: in the caliber of the profiled rolls and at the step between the roll clamps. But the lack of knowledge about the regularities of straightening pipes holds back the wide implementation of such machines. In the work, a finite element model was developed and with its use, a study of the influence of the straightening process parameters in profiled rolls with symmetric and asymmetric profiling of the extreme pairs of rolls on the indicators of pipe straightness and straightening force was carried out. According to the results of their implementation, it was established that straightening the pipe in gauge and pitch allows to reduce the residual curvature of the pipe by almost three times with a 2.5 times smaller overlapping of the middle rolls relative to the outer ones. At the same time, the force on the most heavily loaded middle rolls increases almost twice, which should be taken into account in view of the possibility of ovality in the section of thin-walled pipes. The use of additional asymmetric profiling of the extreme rolls with step adjustment practically does not affect the quality of straightening in the gauge, increases the quality of straightening at the step by up to 15 %, while reducing the maximum straightening force by 5—7 %. The developed finite-element model allows determining the rational values of rolls overlaps to ensure the minimum residual curvature of the pipes.

Direct Measurement of Beam-Induced Heating on Accelerator Pipes With Fiber Optic Sensors: Numerical Analysis Validation

In the field of accelerator physics it is crucial to account for heating caused by the passage of high intensity beams into accelerator components. This phenomenon is known as Radio Frequency (RF) Beam Induced Heating (BIH) and requires, other than an accurate design stage, to constantly monitor temperature-related parameters during the accelerator operations. This enables to warn for critical malfunctions and to prevent possible damages. Monitoring needs to meet various requirements, such as multiplexing capabilities, distributed sensing possibilities, and robustness in harsh environments. Fiber Bragg Grating sensors (FBGs) have been proven to be an ideal solution that meets all these requirements. This study aims to validate the use of FBGs for direct measurement of RF BIH. A section of the beam pipe in the CERN Large Hadron Collider was modeled in terms of impedance, and the resulting RF BIH was computed based on the traveling beam. The results of the numerical simulation were compared with experimental data obtained by FBGs installed along the beam pipe. The analysis shows that FBGs can be a valuable beam diagnostic tool for monitoring accelerated high energy particle beams by measuring RF BIH and may provide useful insights for improving the design and operation of future accelerators. The study highlights the significant advancements of FBG technology in direct temperature measurement and assessment of RF BIH and serves as a promising solution for mitigating RF BIH in the demanding environment of particle accelerators.

FLUID FLOW AND HEAT TRANSFER CHARACTERISTICS OF A CENTERED-WICK HEAT PIPE WITH ADDITIONAL WORKING FLUID: EXPERIMENTAL STUDY WITH VISUALIZATION

This article describes the experimental study of the centered-wick heat pipe with additional working fluid. A semi-transparent heat pipe is employed, and the heat transfer experiments are conducted in three orientation modes: horizontal, vertical, and sideways. The wick structure is a sintered copper powder, and the working fluid is water. The heat pipe has a small gap between the wick structure and the container wall. In each orientation mode, a condenser section of the heat pipe is water-cooled with a cooling jacket, and an evaporator section is heated with a heater. Fluid-flow and phase-change phenomena in the heat pipe are captured by using a video camera, and the temporal changes in the temperatures of the heat pipe are obtained by using thermocouples. Due to the additional working fluid, liquid slugs are found in vapor flow channels. The liquid slugs can be categorized into two types: a dynamic liquid slug and a static liquid slug. The experimental results demonstrate that the dynamic and static liquid slugs are distributed more effectively in the horizontal orientation mode. Thus, the thermal resistance of the heat pipe tends to be smaller and the maximum heat input to the heat pipe is larger in the horizontal orientation mode than in the other two orientation modes. The experimental results also confirm that the small gap is effective in the horizontal orientation mode. The additional working fluid is stored in the gap, which increases the thermal performance of the heat pipe.

Fluid Flow and Heat Transfer Characteristics of a Centered-wick Heat Pipe with Additional Working Fluid: Experimental Study with Visualization

This article describes the experimental study of the centered-wick heat pipe with additional working fluid. A semi-transparent heat pipe was employed, and the heat transfer experiments were conducted in three orientation modes: horizontal, vertical, and sideways orientation modes. The wick structure was a sintered copper powder, and the working fluid was water. The heat pipe had a small gap between the wick structure and the container wall. In each orientation mode, a condenser section of the heat pipe was water-cooled with a cooling jacket, and an evaporator section was heated with a heater. Fluid-flow and phase-change phenomena in the heat pipe were captured by using a video camera, and the temporal changes in the temperatures of the heat pipe were obtained by using thermocouples. Due to the additional working fluid, liquid slugs were found in vapor flow channels. The liquid slugs can be categorized into two types: a dynamic liquid slug and a static liquid slug. The experimental results demonstrated that the dynamic and static liquid slugs were distributed more effectively in the horizontal orientation mode. Thus, the thermal resistance of the heat pipe tended to be smaller and the maximum heat input to the heat pipe was larger in the horizontal orientation mode than in the other two orientation modes. The experimental results also confirmed that the small gap was effective in the horizontal orientation mode. The additional working fluid was stored in the gap, which increased the thermal performance of the heat pipe.

Effect of Welding Thermal Cycle on the Forming in a Section of Straight-Seam Pipes with Large Diameters

Effect of Welding Thermal Cycle on the Forming in a Section of Straight-Seam Pipes with Large Diameters

Full-scale tests of transporting pipeline sections : A review and consequences to our investigations

Hydrocarbon transport pipelines' safe operation is an economic and environmental interest. These pipelines are typically designed for static loads, but during their long-time operation - due to pressure changes and environmental impacts - they are also subject to cyclical loads. The individual pipe sections are connected by girth welds, which represent potential sources of hazards in terms of damage. In order to assess the reliability of girth welds, full-scale tests are carried out under simple and complex loads. The purpose of this article is twofold. On the one hand, summarize the full-scale tests on transmission pipelines, with special attention to the tests on girth welds; on the other hand, based on this, draw conclusions for the design and implementation of our own full-scale tests.

Three-Level Safety Evaluation of Suspended Sections of Underwater Buried Pipelines

The uneven riverbed, as well as the impact and erosion suspended on by water flow, make the underwater crossing pipeline vulnerable to exposure and suspension. Under the influence of water flow, the span of a suspended pipe section steadily grows, jeopardizing the integrity of pipeline operation. In order to investigate the mechanical properties and failure behavior of the suspended section of the crossing pipeline under the influence of water impact, according to the failure mechanism of the pipeline, the statics and dynamics analysis of the pipeline is carried out, and the graded safety evaluation technique of the crossing pipeline with suspended section is presented. First, a “static strength safety evaluation under static load condition” (level 1) is carried according to the mechanical features and stress state of the pipeline's suspended section. Second, the "resonance safety evaluation under dynamic load" (Level 2) is carried in accordance with the correlation between the natural vibration frequency of the suspended pipeline and the vortex emission frequency of water flow. Finally, the periodical change process of the pipeline's alternating stress is studied, the fatigue damage and fatigue life of the pipeline are solved, and the "fatigue strength safety evaluation under dynamic load condition" (level 3) is performed. Thus, a three-level safety assessment procedure for pipelines crossing the suspended section is suggested. The pipe stabilizing measures that fall short of the safety evaluation are suggested, and based on the calculation example, a specific calculation process is provided. This information serves as a theoretical guide for the safety evaluation of the suspended section of the underwater crossing pipeline.

Decay of secondary motion downstream bends in turbulent pipe flows

Decay of secondary motion downstream 180° pipe bends is investigated using large-eddy simulations for the bend radii of 1≤rB/dh≤3.375 at a Reynolds number of Reh=10 000. The velocity and turbulence characteristics are validated against experimental data for a straight pipe section as well as against experimental and direct numerical simulations data for a 90° pipe bend. As the bend radius decreases, a larger magnitude of turbulence intensity is induced immediately downstream of the bend, and for the largest magnitude, the highest gradient of the decay turbulence intensity is observed. As a result, the recovery length needed to reestablish the velocity profile downstream of the pipe bend decreases. Turbulence is transported at a higher rate, indicating that the recovery of the velocity profile is driven by turbulence transport. Secondary motions are induced by the curvature of the pipe bend, and as the bend radius decreases, the magnitude of the secondary motion increases. The results show how the secondary motion decay in magnitude as the flow moves downstream the pipe bend. At the outlet of the bend, secondary motions are dominating at the walls and within the bulk flow. As the fluid moves further downstream, the secondary flows dominate close to the walls, and at a length of x/dh=5, a negligible difference in secondary motion is observed for the different bend radii.

Acoustic emission monitoring of abrasion and corrosion in double-walled pipelines

At KRONOS TITAN, double-walled pipelines are used in production of Titandioxid. An abrasive medium is transported in the inner pipe at high temperatures. In the outer pipe, cooling water ensures that the process is cooled down. During the process, it is important that no abrasion leads to complete wall erosion and thus to leakage between the inner and outer pipe. During a test campaign lasting several months, a section of such a pipe was instrumented with acoustic emission measurement system on the outer pipe and the abrasion process in the inner pipe was monitored with AE until the removal of the pipe section. Different AE-signal parameters (Events, Hits, Energy and Frequency) were investigated regarding their suitability and are discussed in this contribution. The results of the acoustic emission measurements with regard to the location and progress of damages were then compared and verified with classic NDT test results.

An experiment generates a specified mean strained rate turbulent flow: Dynamics of particles

This study aimed to simulate straining turbulent flow empirically, having direct similarities with vast naturally occurring flows and engineering applications. The flow was generated in 100<Reλ<500 and seeded with passive and inertial particles. Lagrangian particle tracking and particle image velocimetry were employed to extract the dynamics of particle statistics and flow features, respectively. The studies for axisymmetric straining turbulent flow reported that the strain rate, flow geometry, and gravity affect particle statistics. To practically investigate mentioned effects in the literature, we present the behavior of both passive and inertial particles from the novel experiment conducted on initially homogeneous turbulence undergoing a sudden axisymmetric expansion. We represent the result with two different mean strains and Reynolds–Taylor microscales. However, this study, in contrast to the previous studies, considers the fields of inertial particles in the presence of gravity. The result discloses that the novel designed and conducted experiments simulated the flow satisfactorily. Then, the particle behavior in such flow showed the effectiveness of the flow distortion on particle dynamics such as velocity root mean square and Reynolds stress. Straining turbulence flow is subject to many industrial applications and physics studies, such as stagnation points, external flow around an airfoil, internal flow in changeable cross section pipe, expansion in the engine mixing chamber, and leading edge erosion. This study's conclusion could apply constructively to these areas.

Energy and exergy analysis and optimization of a novel heating, cooling, and electricity generation system composed of PV/T-heat pipe system and thermal wheel

The present study aims to compare the energy and exergy performances of photovoltaic/thermal-thermal wheel (PT) and photovoltaic/thermal-heat pipe-thermal wheel (PHT) systems. These systems are able to preheat/precool the outside air in the cold/hot season and supply part of the electricity needed by a building. In the PT system, the ambient air exchanges heat directly with the photovoltaic panels, while in the PHT system, the evaporator section of heat pipes located under the panels transfers the heat received from the panels to the air stream through the condenser section of heat pipes. The annual useful energy and exergy produced by the system were taken as objective functions, the two-objective optimization of the systems was performed, and the performances of the optimal systems were assessed. Overall annual analysis of outcomes showed that the highest useful energy output is achieved by the optimal PT system which outperforms by 2.1% than that of the optimal PHT system, while the maximum useful exergy yield is attained by the optimal PHT system, which is 5.1% higher than that of the optimal PT system. The thermodynamic performance improvement of the PHT system is due to the electricity production increment by recovering the waste heat of photovoltaic panels.

Effects of Vibration on Adjacent Pipelines under Blasting Excavation

Exploring a pipeline’s response to blast vibration during tunnel excavation is critical for ensuring the safety of the pipeline. In this paper, the vibration monitoring and numerical simulation methods are used to evaluate the dynamic response of ground soil and pipelines to blasts. The attenuation law of peak particle velocity (PPV) and the distribution characteristics of peak effective stress (PES) in pipe sections under different working conditions are studied. The following findings are recorded: (1) A three-dimensional model considering in situ stress is established, and it is found the triangular equivalent load simulation blast effect method used in this paper can effectively reflect the impact of blasting on pipelines. The simulation error is controlled at 7.69%. (2) The ground PPV of each monitoring point decays continuously with the increase in horizontal and axial distance, and the cavity enlargement effect is exhibited above the excavation area. The oncoming blast side PPV of the pipe section is more significant than that behind the blast side. (3) When the blast vibration is transmitted to the pipe, there are differences in the PPV and PES distribution characteristics across the pipe cross-section. The PPV is greater in the lower part of the pipe section, while the PES value is greater in the upper part of the pipe section. The maximum PES of 1.53 MPa is significantly lower than the safety threshold (≤4.6 MPa) at the hazardous-section-monitoring point. (4) A pipeline PPV prediction model is proposed to guide subsequent blasting program development. An empirical formula for the safety criterion applicable to this study is proposed for the scientific implementation of safety assessments for subsequent construction. This safety evaluation framework can be used as a reference for similar projects.

OPTIMIZATION TEMPERATURE AND FRICTION STENT PRODUCTION PROCESS BY EXTRUSION METHOD

"The stent is manufactured by traditional machining methods. This study has been carried out to improve the mechanical properties of stents produced by removing swarf. Production methods have been examined and extruded to produce a seamless cylindrical section pipe. The Mg-Zn-XX alloy used in stent production was used in this study. Extrusion mold design is made to produce stent with Mg-Zn-XX alloy. These parameters are optimized because temperature and friction values from the Extrusion parameters affect the shaping parameters of the generated stent. During optimization, the Simufact finite elements program was used. The optimization has shown that the Mg-Zn-XX alloy has the best styling results of friction of 300 o C de Coulumb 0.4. "

Variation of the collective drainage pipelines parameters when passing the transit flow

Simple and convenient dependences for calculating basic hydraulic and design characteristics of pressure collecting horizontal drainage pipelines operating in the presence of transit flow, in which the fluid collection along the path occurs in the filtration mode, are presented in the paper. They are based on the analysis of a system of differential equations that describe the fluid motion in such pipes. The solutions are based on the assumption that the member, which takes into account the effect of the flow variation along the pass, is neglected. The concept of a fictitious infinitely long collecting drainage pipeline or a pipeline with an infinitely large amount of the pipe walls permeation is used in the analysis. It is assumed that the actual flow at the end of this pipelines is replaced by a conditional flow, which is collected at the fictitious end section of the pipeline. The flow in the end section of the fictitious pipes is assumed to be zero. The introduced assumptions allow to use formulas for calculation of the mentioned pipelines with a certain approximation which are applied at calculation of pipelines operation without transit. These dependences allow to calculate the effect of transit flow on the hydraulic characteristics of the collecting drainage pipelines.

Latent and sensible heat thermal storage in a heat pipe-based evacuated tube solar dryer: A comparative performance analysis

A new solar dryer system that can work with multiple heat storage mediums was developed and conducted a comparative performance analysis. Latent and sensible heat thermal storage mediums can be accommodated in the drying system. The solar dryer consist of evacuated tubes with thermal storage unified heat pipe solar collector. A new heat pipe layout was developed and placed inside the collector by linking the evaporator sections of the heat pipe with a single heat pipe condenser segment linked to a chamber that can accommodate various types of thermal energy storage mediums. Two heat storage mediums like benzoic acid and therminol-55 were used during the study. A maximum of 118 °C drying air temperature was obtained from the system with Therminol-55 heat storage medium. The collector and dryer system has a maximum energy efficiency of 29 % and 24 % respectively. The Benzoic acid stored a maximum of 3069 kJ energy whereas therminol-55 stored a maximum of 1881 kJ. Drying experiments conducted using therminol-55 as the thermal storage medium needed 16 h to dry 1 kg of apple to 45 g, whereas Benzoic acid required 17 h of drying time. The drying system performed well with therminol-55.

Numerical Study on Urban Infrastructure Diagnosis in Laterally Heterogenous Soils Using Resistivity and Ground Penetrating Radar Techniques

Urban environment can be considered a complex system consisting of the engineered pavement physical structure over the buried utilities (water, gas, sewer) network embedded in the background soil environment. Assessment of buried pipeline civil infrastructures using proximal geophysical methods in such instances has to consider possible interferences, difficulties, and incorrect inferences. In this study, we have conducted a numerical modelling investigation to understand and evaluate how electrical resistivity profiling (ERP) and ground penetrating radar (GPR) can be utilised to provide subsurface information that otherwise may not be possible if either one of the techniques is used. A model geometry consisting of a typical pavement structure (asphalt, base/subbase, and background soil) with a single 2 m pipe buried at a depth of 1 m was used. Strong lateral variations in soil type were incorporated over the short pipe section in order to understand the complexities that can arise, especially with ERP measurements. The 3D electrical resistivity measurements were simulated in Comsol using the 4-probe method, while the 2D GPR measurements were simulated in gprMax to obtain the subsurface information. The results from both ERP and GPR were used to develop a practical framework that can be utilised by relevant authorities for proximal condition assessment of their buried assets. It was suggested that ERP can be used as a first level screening tool over the whole pipeline length, followed by discretely selected GPR scans in order to further gain information on the pipe health. This is attractive practically since, following delineations of a large pipe section into shorter subsections, advanced condition assessment approaches that are generally intrusive in nature can then be economically deployed within the subsections suspected of experiencing significant corrosion damage.

Comparison of theoretical modeling of natural frequencies of a pipe section with data obtained empirically

The article explores the issue of modeling a pipeline section, to determine the possibility of diagnosing the state of the pipeline walls, by analyzing the frequencies of natural vibrations. This method is considered as a possible alternative to in-line diagnostics of main pipelines. Frequency analysis allows to determine the defective state of the walls by reading vibrations with a vibration sensor located on the body of the pipeline.

Autonomous control for miniaturized mobile robots in unknown pipe networks.

Despite recent advances in robotic technology, sewer pipe inspection is still limited to conventional approaches that use cable-tethered robots. Such commercially available tethered robots lack autonomy, and their operation must be manually controlled via their tethered cables. Consequently, they can only travel to a certain distance in pipe, cannot access small-diameter pipes, and their deployment incurs high costs for highly skilled operators. In this paper, we introduce a miniaturised mobile robot for pipe inspection. We present an autonomous control strategy for this robot that is effective, stable, and requires only low-computational resources. The robots used here can access pipes as small as 75 mm in diameter. Due to their small size, low carrying capacity, and limited battery supply, our robots can only carry simple sensors, a small processor, and miniature wheel-legs for locomotion. Yet, our control method is able to compensate for these limitations. We demonstrate fully autonomous robot mobility in a sewer pipe network, without any visual aid or power-hungry image processing. The control algorithm allows the robot to correctly recognise each local network configuration, and to make appropriate decisions accordingly. The control strategy was tested using the physical micro robot in a laboratory pipe network. In both simulation and experiment, the robot autonomously and exhaustively explored an unknown pipe network without missing any pipe section while avoiding obstacles. This is a significant advance towards fully autonomous inspection robot systems for sewer pipe networks.

Investigation of the Thermal Performance of a Nanofluid-filled Grooved Cylindrical Heat Pipe for Electronics Cooling

Thermal management of electric and electronic components is a critical issue and needs to consider enhanced cooling systems such as heat pipes. This study deals with the theoretical modeling of a nanofluid-filled copper cylindrical heat pipe for electronics cooling applications. The heat pipe includes helicoidal and trapezoidal capillary grooves. The model can predict the capillary limit as well as the heat transfer in the different sections of the heat pipe. The thermal resistances of the evaporation and condensation sections are calculated based on correlations for heat transfer, which are determined from experiments. Two working nanofluids are considered: water/CuO and water/Al2O3. The thermal performances are predicted for different concentrations and heat sink temperatures, and the heat pipe is positioned horizontally. For both nanofluids, the results indicate that augmenting the concentration of the nanoparticles leads to a capillary limit increase reaching up to 14 % and 25 % for water/Al2O3 and water/CuO, respectively, and an overall thermal resistance decrease reaching up to 51 % and 68 % for water/Al2O3 and water/CuO. Moreover, decreases up to 24 %, and up to 18 % in the evaporator wall temperatures are obtained for water/CuO and water/Al2O3 nanofluids, respectively. The nanofluid water/CuO gives the best thermal performance whatever the nanoparticle concentration and heat sink temperature.

Stress Shifting Effect of Hydrogen Mixed Natural Gas Pipe Under Seismic Wave

Abstract Hydrogen energy is a kind of clean secondary energy sources. Mixed hydrogen natural gas transportation technology is a new scheme of hydrogen transportation. Using natural gas pipe to transport hydrogen is expected to further promote its application. In order to study the mechanical properties of buried steel pipe under seismic waves, a numerical model is established. The time history and stress distribution of pipe section under seismic wave are analyzed. Effects of seismic intensity, surrounding soil, buried depth and seismic wave type on pipe's mechanical properties are discussed. The results show that the pipe section stress fluctuates under seismic wave, and the stress shifting effect occurs. The maximum stress is located in the directions of 45 deg, 135 deg, 225 deg, and 315 deg. Stress increases with the increasing of seismic intensity, and the stress distribution of pipe section is also changed. Stress responses of the pipe in different soil are different, and the stress distribution of pipe section at the maximum stress time is similar. The deeper the buried depth is, the greater the pipe stress is. Pipe stress is related to the maximum acceleration of the seismic wave and spectrum characteristics. Those results can provide a basis for the design and safety evaluation of mixed hydrogen natural gas pipes.