Pipe Structure Research Articles

As-built BIM reconstruction of piping systems using smartphone videogrammetry and terrestrial laser scanning

The increasing adoption of Building Information Modeling (BIM) in the construction industry has created a demand for methods to update existing facilities with accurate as-built BIM models. While terrestrial laser scanners (TLS) are commonly used for indoor surveys due to their speed and precision, they face limitations in areas with physical constraints like confined spaces and occlusions, with pipes being particularly affected. This paper presents a smartphone videogrammetry approach designed to enhance the accuracy and completeness of terrestrial laser scanner (TLS) point clouds for as-built BIM reconstruction. The method involves capturing missing areas within the TLS point cloud with smartphones and then seamlessly integrating these data into a more comprehensive multi-modal point cloud. This approach is validated using real scan data and offers convenience through the use of readily available and cost-effective smartphones, while its iterative nature facilitates progressive BIM reconstruction of pipe structures. Additionally, a compatible progressive BIM reconstruction framework is outlined, aiming to modernize scan-to-BIM practices in the construction industry, with a case study demonstrating its feasibility.

Thermal-mixing flow characteristics of mixing valve

Mixing valves play an important role in fluid transmission pipeline systems and fluid heat mixing in the chemical-energy industry. To limit thermal fatigue cracking failure of cross-combination pipelines and thermal-mixing equipment, this study investigated the effect of plunger strokes on the internal flow and temperature fluctuation of a mixing valve. A large eddy simulation method was used to study the temperature distribution and fluctuation mechanism of a fluid during hot mixing using a mixing valve with different plunger strokes. For mixing valves, the centroid of the effective jet section of the branch pipe moves to the negative Y-axis during plunger stroke operations, resulting in a jet angle change in the branch pipe. As the effective jet area of the branch pipe decreases, the vortex structure of the branch pipe also changes. When the plunger stroke is small, there is a higher and stronger temperature fluctuation in the 90° circumferential area of the wingspan section, whereas when the plunger stroke is large, there is a higher and stronger temperature fluctuation in the 270° circumferential area of the wingspan section. The results showed that valve operation should be avoided at these plunger strokes and monitoring at these positions is required during operation. The study results provide an industry reference for the internal hot-mixing flow characteristics of mixing equipment with adjustable flow channels.

Flow–solid coupling analysis of underground reinforced concrete forked pipe enclosing rock and structure

The stability of the surrounding rock for the construction excavation and the reinforcement of the lining structure during operation in the water-rich area is a difficult problem for the design of high-head underground turnout pipes. Firstly, according to the mechanism of excavation load release and surrounding rock damage evolution, the seepage effect of excavation in the construction of the forked caves is coupled to the surrounding rock stress damage, and an iterative method of numerical simulation of the coupled mutual feedback effect of excavation surrounding rock stress and seepage is proposed. Then, based on the cracking characteristics of the high internal water pressure reinforced concrete turnpike lining, a numerical analysis method of the coupling interaction between lining cracking and internal water seepage is proposed by coupling internal water seepage to stress damage in the lining by cracking the forked pipe structure. Applying the aforementioned method to a forked pipe project, the results show that: during the construction period, there is a significant increase in the damage zone, stress, and displacement of the rock around the cavern after considering the coupled iterations; during the operation period, with the increase in internal water pressure, the lining structure accelerates cracking due to the external infiltration of internal water; after the internal water is applied, the surrounding rock bears the main internal water pressure and the reinforcement bears only part of the circumferential force. The method provides theoretical support for the analysis and calculation of the reinforcement of similar underground high-pressure tunnels for rock support and lining structures and has certain theoretical and engineering significance.

Novel vibration self-suppression of periodic pipes conveying fluid based on acoustic black hole effect

The pipes conveying fluid are concerned as extremely significant fluid-solid coupling structures due to the extensive application in the many engineering fields, but poor operating performances induced by unexpected vibration may destroy the related devices in the piping structures. To effectively attenuate the fluid-solid coupling vibration, a novel control technique is proposed to realize the vibration self-suppression of pipes conveying fluid with integration of the periodic acoustic black hole (ABH) wedges inspired by the extraordinary band gaps (BGs) behaviors of the metamaterials. On the basis of the Euler-Bernoulli (E-B) beam model, the mechanical model and dynamic equations are established by using Hamilton's principle. By applying the spectral element method (SEM) in conjunction with the transfer matrix method (TMM), as well as considering the Bloch theorem, the mechanism of elastic-wave distributions of such periodic ABH pipes conveying fluid are disclosed through investigating the BGs characteristic, frequency response and wave shapes. The results show the proposed technique can effectively form BGs in low frequency bands, and most of the energies are absorbed and scattered by the wedge edge of the pipes in the wave propagation. More importantly, by adjusting the system parameters, the proposed structure can enlarge the BGs regions and transfer it to the low frequency bands. It provides a simple design scheme for the manufacture of pipe conveying fluid with ultra-wide BGs.

Characteristics of residual stress distribution in wire-arc additive manufactured layers of low transformation temperature material

High heat input in wire and arc additive manufacturing (WAAM) tends to result in high tensile residual stress, which adversely affects performance and service reliability. However, low-transformation-temperature (LTT) materials are susceptible to compressive residual stresses due to their low phase-transformation point. Here, the LTT material 10Cr10Ni was used as the deposited material to fabricate a pipe structure, and the contour method was applied to measure the residual stress distribution in the cross-section. A thermomechanical coupling analysis model was developed to investigate the residual stress generation mechanism in 10Cr-10Ni(LTT) during the WAAM process. The simulated deformation and residual stress distributions agree well with the measurements. Through simulation analysis of the deposition of different layers, we found the key to the generation of compressive residual stresses in the LTT layers lies in whether there is a transformation from austenite to martensite during the final thermal cycle. When the deposition height exceeded 5.405 mm (approximately four layers), compressive residual stresses were only generated in the last four LTT layers and transformed into tensile residual stresses in the other layers. This results in a concept called the effective region, which can be used as a guide for reducing stress in WAAM using LTT materials.

Вплив газових сумішей водню з метаном на фізичну та хімічну структуру поліетиленових труб з ПЕ-80

Вплив газових сумішей водню з метаном на фізичну та хімічну структуру поліетиленових труб з ПЕ-80

Effects of the wall heat flux on the flow characteristics of large-scale coherent structures in a pipe with enhanced heat transfer

In this study, we use stereoscopic particle image velocimetry (SPIV) to measure the internal instantaneous flow field of a typical pipe with enhanced heat transfer (a single-start spirally corrugated pipe with a pitch-to-diameter ratio S/D = 2.22) with and without a wall heat flux for Reynolds number ReD = 10000 and 25000. Proper orthogonal decomposition (POD) is used to extract the large-scale structures of the internal flow field. The POD results for the flow in the spirally corrugated pipe are employed to quantitatively analyze the turbulent kinetic energy (TKE) and Reynolds shear stress (RSS) using the corresponding results for a straight circular pipe as a benchmark. The results reveal the flow patterns of the large-scale motions in the flow field of spirally corrugated pipes are not sensitive to the wall heat flux and Reynolds number. Nevertheless, convective heat transfer can boost the energy content of large-scale coherent structures in a spiral pipe because of an increase in in-plane velocity fluctuations. Furthermore, the large-scale coherent structures of the swirling flow are reflected in multiple Q2 and Q4 events, which contribute positively to the net RSS. However, convective heat transfer reduces the contribution of these structures to the total RSS through the various parameters associated with these events.

The effect of pipeline sudden contraction structure on the deflagration characteristics of hydrogen-methane-air

Based on the visualized gas cloud explosion pipeline test platform, the influence of the sudden contraction structure on the deflagration characteristics of the hydrogen-methane-air gas cloud is investigated. The results show that the changes of flame propagation velocity, explosion overpressure, and flame temperature after deflagration of the premixed gas cloud all present three stages: rapid increase, rapid decline, and secondary acceleration caused by the sudden contraction of pipeline structure. The equivalence ratio significantly affects the hydrogen-methane-air detonation process in the sudden contraction of the pipe structure. As the hydrogen content increases, the flame propagation becomes faster and the explosion impact becomes greater. The formation of “Tulip” flame is closely related to the flame propagation speed. During the process of flame propagation, inertia dominates, causing the flame propagation speed to reach its first peak at the abrupt contraction structure.

Nonlinear vibration analysis of Z-shaped pipes with CLD considering amplitude-dependent characteristics of clamps

Under external excitation, the clamp-pipe structures may exhibit nonlinear vibration behavior due to stiffness softening and damping energy dissipation of the clamp. To implement vibration suppression on pipes, a semi-analytical modeling method is proposed for the Z-shaped pipe structure with partial constrained damping layer (CLD) treatment under the constraint of the clamp. The nonlinear vibration characteristics of the Z-shaped pipe with CLD in both in-plane and out-of-plane directions are further investigated by considering the nonlinear mechanical properties of the clamp. Specifically, the energy expressions of the laminated straight and curved pipe segments are deduced based on the Timoshenko beam theory. The coupling of pipe segments is introduced by the improving artificial spring technology. A novel equivalent mechanical model is developed to simulate the nonlinear mechanical properties of the clamp, which are expressed by nonlinear stiffness and damping with the amplitude-dependent characteristic. Next, an effective algorithm is presented for solving nonlinear dynamic equations in the frequency domain with the amplitude-dependent characteristic. The proposed linear and nonlinear models are verified by the FE analysis and experimental test results. The comparison demonstrates that the proposed method can accurately replicate the nonlinear vibration of the Z-shaped pipe with CLD treatment. Finally, the suppression mechanism of the CLD on the vibration of Z-shaped pipes and the nature of the amplitude-dependent characteristic are further investigated, which can guide the design and vibration reduction of pipes.

Design and fabrication of heat pipes using additive manufacturing for thermal management

With the increase in the integration level of chips, capillary heat pipes are becoming increasingly valuable for the thermal management of high-heat-flux electronic devices. Here, we employ a thermal circuit model and 3D printing for heat pipe design and fabrication. The model was developed to predict the heat transfer performance of the heat pipe, and a heat pipe structure suitable for dissipating 20 W of heat load was designed. The aluminum heat pipes were fabricated by metal 3D printing, with acetone as the working fluid. Heat transfer experiments were conducted on the heat pipes with acetone filling ratios of 60%, 100%, and 150% (heat load: 5–40 W). The lowest thermal resistance was achieved with the 150% filling ratio at 20 W. The thermal resistance achieved with the 100% filling ratio was similar to the model’s prediction. The effective thermal conductivity was determined to increase by 5.81-fold by comparing the thermal performances of the heat pipe and a solid aluminum plate of the same volume. The results confirmed that heat pipes with desired heat transfer performances can be obtained as designed by employing a thermal circuit model and 3D printing technology.

Study on the multi-factors interaction of annular pulsating heat pipe based on response surface method and temperature curve analysis

Pulsating heat pipe enable rapid heat transfer over long distances and is suited for solar collector applications. However, there is no pulsating heat pipe specially designed for evacuated solar collector, which leads to a large contact thermal resistance between the heat pipe and the evacuated pipe. In this paper, a new structure of annular pulsating heat pipe (APHP) was designed. In order to efficiently optimize the operation parameters and understand the interaction of factors, the three-factors three-levels Box-Behnken Design (BBD) model of response surface method (RSM) was used to establish the optimization program, and the accuracy was tested by analysis of variance. The significance and interaction of factors (heat transfer distance, cooling water temperature and cooling water flow rate) on the heat transfer performance were analyzed according to the temperature oscillation curve. The results show that heat transfer distance has a much more significant effect on the heat transfer capacity than the cooling water temperature and cooling water flow rate. Furthermore, over long heat transfer distance, adjusting the cooling water temperature has a greater impact on the heat transfer performance. While over short heat transfer distance, adjusting the cooling water flow rate has a greater impact. The optimal working condition predicted by RSM model is 375 mm heat transfer distance, 15 °C cooling water temperature and 1.0 L/min cooling water flow rate. The actual average heat flow obtained from experiment was 99.47 W, with an error of only 2.04% from the predicted value. This paper illustrates the feasibility and efficiency of the response surface method for studying the heat transfer performance of PHP. The significance and interaction analysis of factors can provide guidance for the practical application.

Numerical analysis of the internal biased flow mechanism of the siphon outlet pipe under the action of axial flow pump

One of the often employed flow structures in vertical pumping stations is the siphon outlet pipe. It has a complicated geometric structure and internal flow field, which directly affects how effectively, safely, and steadily pumping stations operate. The entire flow conduit of the vertical axial flow pump device was adopted as the study object in order to elucidate the mechanism of the internal biased flow of the siphon outlet pipe caused by the axial flow pump under different flow conditions, and the three-dimensional unsteady flow field of the vertical axial flow pump device was numerically solved using the numerical simulation technique. Physical model tests were used to confirm the results of the numerical simulation. The findings demonstrate that there is a horizontal bias in the flow of the inlet surface and outlet surface of the elbow pipe of the siphon outlet pipe, and that when the flow rate rises, the degree of the horizontal bias in the flow gradually diminishes, and the ratio of biased flow gradually decreases. The flow in hump segment presents up-and-down flow, and when the flow rate increases, the ratios of biased flow first rises before falling. The major causes of the production of biased flow in the outlet pipe are residual velocity circulation at the guide vane's outlet, wall constraint at the elbow pipe, and flow inertia; Under various flow conditions, the morphologies of the vortex structures in the outlet pipe vary; the characteristics of the energy conversion of each part of the pump device are disclosed, with the inlet pipe having the lowest proportion of energy conversion. Under the optimal flow condition, the elbow-inlet pipe's proportion of energy conversion is only around 1.04%, and the proportions of the guide vane, 60° elbow pipe, and siphon outlet pipe's energy conversion are significant and fluctuate with time. The proportion of energy conversion in the elbow-inlet pipe and siphon outlet pipe steadily increases as flow rate rises, but the proportion in the guide vane and 60° elbow pipe drops initially before increasing.

A shear horizontal phased array steering excitation technique for remnant wall thickness quantification

Precise wall loss quantification in pipe and plate structures is a critical and challenging task, especially in cases where direct access to the component is limited. Accurate knowledge of the remaining wall thickness allows for timely maintenance or replacement to avoid catastrophic failures. In this work, wall loss quantification is performed utilizing the cut-off frequency of mode SH1. The approach requires the excitation of SH1 across a range of frequencies. For this reason, a novel excitation technique using guided wave phased array steering is developed. Specifically, an array generating shear horizontal waves is employed. The influence of the array’s length, pitch, element width, and mode excitability on excitation is investigated. By appropriately phasing the elements of the array, mode SH1 is targeted and dynamically excited over a wide frequency-wavelength range. The directionality of SH1 is also studied, as in certain conditions, this can be critical for the success of the quantification. Simulation results show the technique can accurately quantify a 65 % wall thinning defect, offering a 15 % increase compared to established techniques. This is critical, as commonly, wall loss defects above 50 % are considered severe. Additionally, using electronic steering, rapid quantification can be achieved. Experiments using an EMAT and synthetic steering on an intact area and an artificially machined corrosion-like defect validate the technique.

Review of Gully Erosion in Anambra State: Geology, Causes, Effects, Control Measures and Challenges Associated with Its Mitigation

In South-Eastern Nigeria, particularly in Anambra State, gully erosion presents a serious environmental challenge. With over 100 gully sites in the state, only about 30 have received measures of control but are still not fully under control. Observations have shown clearly that the underlying geology exerts major control over the development of gully erosion in the study area. Progressive gullies in certain areas of Anambra State are caused by various factors, including topography, soil and water pH, lithology type, deforestation, hydrogeology, and geotechnical rock properties. This erosion activity has resulted in the loss of productive lands, water pollution, sedimentation of waterways, and the loss of lives and properties almost every year. However, several government agencies have attempted to manage it using concrete structures, stabilization work such as planting bamboo and cashew trees to increase water intake, and pipe structures to channel the water directly to nearby surface waters through the construction of check dams, embankments, and retention ponds to control the flow of water and sediments. Despite these control efforts, several challenges persist in effectively managing gully erosion in Anambra State. Majority of the concrete structures used to control these gullies have collapsed, leading to the incessant spreading of the site. Inadequate funding, failure of engineering structures, flooding, the geologic setting of the area, limited technical expertise, population growth, urbanisation, a lack of public awareness, and a lack of proper coordination among stakeholders hinder the implementation of comprehensive erosion control measures. It is recommended that concrete drainage channels should not only be used in controlling these gullies but also be integrated with other measures to yield a positive result.

Improvement of biocorrosion resistance on steel using full annealing heat treatment

The performance of a material structure can be affected due to corrosion damage. Corrosion is a decrease in metal quality caused by electrochemical reactions between metals and their surrounding environment. One of the causes of corrosion is microalgae or called biocorrosion. Corrosion can cause failure of the pipe structure which causes the pipe to not operate properly. The purpose of the research was to determine the corrosion rate of ASTM A53 steel material with full annealing heat treatment and without heat treatment. Second research aim was to determine the biocorrosion with added of microalgae and without the addition of microalgae. Heat treatment and non-heat treatment materials were testing using the immersion corrosion test method, which was soaked in artificial seawater with a salinity of 35‰. Based on the results, the highest biocorrosion rate on non-heat treated materials with the addition of Chrorella vulgaris reached 0.2780 mpy. While the biocorrosion rate after full annealing treatment was 0.1434 mpy and the size of uniform corrosion and pitting decreased. The percentages reduction of biocorrosion rete was 46.58%. This indicates that the addition of Chlorella vulgaris can accelerate the corrosion rate and full annealing can inhibit the biocorrosion rate.

Characteristic Parameters of Magnetostrictive Guided Wave Testing for Fatigue Damage of Steel Strands.

Steel strands are widely used in structures such as bridge cables, and their integrity is critical to keeping these structures safe. A steel strand is under the working condition of an alternating load for a long time, and fatigue damage is unavoidable. It is necessary to find characteristic parameters for evaluating fatigue damage. In this study, nonlinear coefficients and attenuation coefficients were employed to evaluate fatigue damage based on magnetostrictive guided wave testing. Unlike pipe and steel wire structures, there is a phenomenon of a notch frequency when guided waves propagate in steel strands. The influence of the notch frequency on the nonlinear coefficient and attenuation coefficient is discussed. The relationship between the nonlinear coefficient, attenuation coefficient, and cyclic loading times was obtained through experiments. The amplitudes of the nonlinear coefficient and attenuation coefficient both increased with the increase in cyclic loading times. The experiments also showed the effectiveness of using these two characteristic parameters to evaluate fatigue damage.

Determination of the load bearing capacity of pre-stressed expandable props for ground support in underground mines

This paper aims to determine the load bearing capacity of pre-stressed expandable props with different geometries and load eccentricities for flexible support in underground mining or excavation. It is deduced that the expandable device could have much higher strength (>89 MPa) by laboratory tests, and the load bearing capacity of the expandable prop may depend on the stability of the supporting steel pipe structure. A good agreement was found between the laboratory test and numerical results in terms of the load bearing capacity and the final macro-bending failure pattern for expandable props with heights of 1.5 and 2.7 m, and the theoretical calculation for the strength of traditional steel structures is not directly suitable for the expandable props. Moreover, additional numerical simulations were performed for the expandable props with different normalized slenderness ratios λn and loading eccentric distances e. The variation of stability coefficient of the expandable prop is in line with the Perry-Robertson equation and its correlation coefficients are fitted as a of 0.979 and b of 0.314. For estimating the load bearing capacity of the expandable props, the strength equation for traditional steel structures is improved by introducing a bending magnification factor and by modifying the normalized slenderness ratio to a converted slenderness ratio. Based on the underground field monitoring for the strength of expandable props with different heights, the empirical eccentric distances were back calculated, and a safety factor is introduced to obtain the designed strength of the expandable prop. In addition, a four-step design procedure is proposed for the expandable prop.

Heat loss optimization and economic evaluation of a new fourth generation district heating triple pipe system

In response to the heat loss caused by the temperature difference between the heating pipes and external environment during the pipe transportation, heat contradiction between the total heat loss of the piping system and heat transfer between tubes, as well as economic balance between the cost of heat loss and cost of material loss. Based on TOTS (Two-supply/One-return, triple pipe structure) heat loss theory of the fourth-generation district heating system, this paper optimizes structure of pipes by setting dimensionless characteristic parameters θ and β. Finally, a mathematical model is proposed to calculate economic efficiency of pipeline network by considering the cost of initial construction material loss and operation heat loss of the pipe. Results show that, from energy perspective, comprehensive heat as system energy consumption evaluation index is positively correlated with θ, decreases first and then increases as β increases. Total heat loss of system dominates comprehensive heat. Lowest comprehensive heat of system is 18.12 w/m for θ of 0.1945 and β of 0.0739. From economic perspective, total system loss cost as system economic evaluation index is positively correlated with both θ and β. Total system heat loss cost dominates total system loss cost. Lowest total system loss cost is $29.39/m for θ of 0.1945 and β of 0.0509.

Numerical methods to predict aero thermally induced vibrations of a curved pipe structure reinforced by GPLs

The use of randomly distributed graphene platelets as a reinforcing material in tilted curved pipes subjected to supersonic airflow has become an increasingly popular area of research due to their potential to enhance the mechanical and thermal properties of the pipes. In this study, the focus is on investigating the frequency or dynamic response of these reinforced pipes under supersonic airflow conditions. In doing so, a higher-order shear deformation theory is utilized for modeling the displacement field in the tilted pipe structure. Moreover, the classical theory of elasticity with the incorporation of the effects of thermal loading is considered in obtaining governing equations. The study aims to determine the effects of the randomly distributed graphene nanoplatelets (GPLs) on the dynamic behavior of the tilted curved pipes in a thermal environment and identify any changes in their natural frequencies. The verification study shows that the results are verified with the previously published articles. As well as this, the results are compared with the outcomes of finite element software. The findings of this study may provide valuable insights into the design and optimization of graphene-reinforced pipes for use in high-speed airflows.

Microstructure, Mechanical Properties, and Fatigue Resistance of High-Carbon Steel for Tensile Wires Used in Flexible Pipes for Offshore Oil and Gas Transportation

Abstract Tensile armor carbon steel wires are structural elements assembled in the complex construction of flexible pipes used in the oil and gas industry. Recently, failures of flexible pipes were associated with tensile armor fractures. Despite the relevant key of these elements in the structure of flexible pipes, manufacturers and steelmakers do not provide sufficient information about the materials and their production flow. The objective of the present study was to characterize a tensile wire made of cold worked high carbon steel regarding the microstructure and mechanical properties. The microstructure was investigated by high resolution scanning electron microscopy. The steel has nearly eutectoid chemical composition (0.69 % carbon) and presents a microstructure of very fine and deformed pearlite. Some cementite carbides appeared fragmented and spheroidized in the ferrite matrix. These microstructural features are typical of patented steel, which was subsequently cold deformed by rolling and drawing. The tensile curve of the material was obtained and modeled by Hollomon’s, Voce’s and Ludwik’s constitutive equations. The S– N fatigue curve of the wire was constructed with four-point bending tests with ratio R = 0.1. The endurance limit for R = 0.1 was estimated, and the correspondent value for R = −1 was calculated based on Goodman’s relation.