Behavior Of Pipe Research Articles

Stability analysis of a vertical cantilever pipe with lumped masses conveying two-phase flow

This study investigates the vibration behavior of a vertical cantilever pipe conveying gas-liquid two-phase flow, focusing on the influence of lumped masses attached to the vertical cantilevered pipe. The governing motion equation based on small deflection Euler–Bernoulli beam theory is solved by using the generalized integral transforms technique. The proposed solution approach was first validated against available numerical and experimental results in the literature. The effects of the mass ratios, number and position of lumped masses on the stability of the pipe are investigated. Numerical results show that the parameters of the lumped masses affect significantly the stability of the pipe conveying two-phase flow, by altering the fluid–structure interaction dynamics and impacting natural frequencies and vibration modes of the pipe. Specifically, as the position of a single lumped mass moves downward from the fixed end to the free end, the critical flow velocity initially increases and subsequently decreases, thereby reducing the stability of pipe. Moreover, increasing the number of lumped masses significantly impacts the critical flow velocity due to the mass ratios and locations. Notably, modal “jumping” phenomena are observed, which demonstrate continuous shifts between equilibrium and non-equilibrium states in the cantilever pipes. These findings are crucial for ensuring the safe operation of pipes with discrete masses across various engineering applications.

Exploring Biomimetic Heat Pipes for Space Radiator Enhancement

This study investigates biomimetic heat pipes for space radiator applications, utilizing nature-inspired structures to potentially enhance heat transfer efficiency. The research addresses the imperative for improved heat dissipation mechanisms in nuclear space systems, crucial for effective thermal management. Heat pipes are passive heat transfer devices widely adopted for thermal control. The study aims to evaluate the effectiveness of a biomimetic heat pipe design in comparison to a traditional design while also validating the fabrication process through industry-made heat pipe comparisons. Innovative hot oil bath testing methods are employed to fabricate and test both heat pipe types, utilizing comprehensive thermal analysis, physical experiments, and validation techniques to assess heat transfer capabilities. Tests span varying temperature levels to analyze heat pipe behavior and performance. Findings suggest the potential for enhanced heat dissipation along the length of the biomimetic heat pipe, hinting at the biomimetic structure’s role in improving heat transfer. This study underscores the promise of biomimetic design principles and their potential for advancing heat pipe technology. Recommendations for further exploration include alternative materials, optimized testing procedures, and refined fabrication processes.

Thermal performance analysis and optimization of a heat pipe-based electronic thermal management system using experimental data-driven neuro-genetic technique

Heat pipes are highly efficient heat transfer devices and are used widely to dissipate heat generated by electronic components, thereby maintaining their operating temperatures and preventing overheating. The present study deals with the thermal performance prediction of a cylindrical heat pipe (length 380 mm) based electronic thermal management system using steady-state experimental investigation. The experiments are conducted under varying operational conditions, including heat inputs (10–50 W), condenser cooling water inlet temperatures (288.15, 293.15, and 298.15 K), and flow rates (10, 25, and 40 LPH). The study shows that the evaporator temperature of the heat pipe consistently rises with the increase in heat inputs for all tested conditions. The lowest evaporator temperature (311.42 K) is noticed for the cooling water inlet temperature of 288.15 K across all heat inputs. Notably, at 10 LPH, the heat pipe supplied with cooling water at 288.15 K exhibits reductions of up to 1.47 % and 2.29 % compared to 293.15 K and 298.15 K, respectively. Similar trends are also observed at 25 LPH and 40 LPH. The heat pipe’s thermal resistance is lowest (0.95 K/W) at a cooling water inlet temperature of 298.15 K. At 10 LPH, there are reductions of 10.19 % and 5.62 % compared to 288.15 K and 293.15 K, and at 40 LPH, reductions are 15.66 % and 7.89 %. The heat pipe’s evaporator heat transfer coefficient also plays a significant role and is maximum for the cooling water inlet temperature of 288.15 K at a flow rate of 10 LPH. To understand the complex behavior of the heat pipe and for better prediction of its thermal performance, a neuro-genetic (experimental data-driven artificial neural network and genetic algorithm) optimization technique is considered in the study. This predicts the optimal combination of operating parameters (heat input, cooling water inlet temperature, and flow rate) to minimize the heat pipe’s evaporator wall temperature which is found to be 312.54 K at a heat input of 10 W, flow rate of 10 LPH, and cooling water inlet temperature of 289.14 K. These input combinations are further validated through the experiments and the error in the heat pipe’s evaporator temperature is found to be 0.66 % only. Overall, this neuro-genetic technique underscores the importance of optimizing operational parameters for enhanced heat pipe performance and offers valuable insights for electronic cooling systems.

Internal Corrosion Rate Of Api 5l X-42 Steel In Crude Oil Production Installation Pipe

Steel pipes remain the preferred choice for distribution and crude oil installation pipes in the oil and gas industry due to their strength, surface hardness, and cost-effectiveness. However, their susceptibility to corrosion in harsh environments poses significant challenges. This research focuses on analyzing the corrosion rate of API 5L X-42 steel in a crude oil environment at a temperature of 40°C. The corrosion rate was determined using the weight loss method, revealing that the rate varies over time. The findings of this study provide crucial insights for the industry, particularly in preventing leaks in crude oil installation pipes caused by corrosion. By understanding the corrosion behavior of steel pipes under specific conditions, the oil and gas industry can implement more effective maintenance strategies and material selection, ultimately enhancing the safety and longevity of pipeline infrastructure. The study highlights the importance of regular monitoring and the adoption of preventive measures to mitigate corrosion-related issues, thereby ensuring the continuous and safe operation of oil and gas installations

Effect of Self-Filtering Layer on Tailings–Steel Wire Mesh Interfacial Shearing Properties and Bearing Behavior of Drain Pipes

Effect of Self-Filtering Layer on Tailings–Steel Wire Mesh Interfacial Shearing Properties and Bearing Behavior of Drain Pipes

Enhancing PEHD pipes reliability prediction: Integrating ANN and FEM for tensile strength analysis

In the pipe industry, pressure pipes have long made use of High-Density Polyethylene (HDPE), which is used extensively. Currently, HDPE pipes are installed in higher numbers in comparison with other plastic pipes. The purpose of this study is to evaluate and compare the predictive capabilities of two methods, including the finite element method (FEM) and artificial neural network (ANN) techniques, for predicting the tensile strength of HDPE pipes used in water distribution systems. Attempts have been made to improve prediction models to better predict the mechanical behavior of these pipes by improving our understanding of the structure and surface characteristics as well as the interactions between the interface and the operating environment. The results show that experimental trial results are in perfect agreement with machine learning techniques. The findings of this study highlight the benefits of using ANN to predict the behavior of HDPE pipes, which may have significant ramifications for the plastics and water distribution industries.

Low-cycle fatigue behavior and microstructure evolution of ODS steel pipes at high temperatures

Oxide-dispersion-strengthened (ODS) steels are candidate materials for application in advanced nuclear reactors. In this study, the low-cycle fatigue performances of 13Cr-ODS ferritic steel pipes were investigated at 600, 700, and 800 °C. Cyclic softening was observed at high strain amplitudes with an increase in the number of fatigue cycles. However, cyclic hardening appeared first, and then cyclic softening occurred at a low strain amplitude with the increase in the number of fatigue cycles. By comparing the cyclic stress–strain curves and the monotonic stress–strain curves, it was found that cyclic softening occurred regardless of the strain amplitude. The Coffin–Manson and Basquin equations were used to predict the fatigue of the pipes. Microstructure analysis indicated that cyclic softening was induced by the dynamic recovery and recrystallization, which reduced the number of low-angle grain boundaries in the deformed grains by promoting dislocation annihilation and reorganization. A complex multi-layer core–shell structure with a large size (∼500 nm) was observed.

Analysis and optimization design of internal pressure resistance of flexible composite pipe

Flexible composite pipes have the advantages of light weight, corrosion resistance, scale resistance, and low cost compared to carbon steel pipes, and have attracted much attention in the application of onshore oil and gas gathering and transportation systems. Understanding the relationship between the pressure-bearing mechanical properties of composite pipes and their structural characteristics is crucial for guiding their process application. To investigate the mechanical behavior of flexible composite pipes under internal pressure loads, discrete and combined finite element models were established to analyze the stress-strain characteristics of flexible composite pipes. The bursting strength was predicted, and the influence of winding angle and number of reinforcement layers on the pressure-bearing capacity of flexible composite pipes was revealed. The applicability of the two models in the analysis of internal pressure resistance of flexible composite pipes was evaluated using whole pipe strain testing and instantaneous hydrostatic burst experiments. The results showed that the reinforcement layer is the main pressure-bearing layer of flexible composite pipes, and the innermost reinforcement layer bears the highest pressure. The pressure-bearing capacity of flexible composite pipes significantly increases when the winding angle is greater than 53°, and the increase in pressure-bearing capacity slows down when the number of reinforcement layers exceeds 3. Under the combination model, the strain and bursting strength of flexible composite pipes were closer to the experimental results. The study clearly defines the stress-strain characteristics of flexible composite pipes under internal pressure load and the impact of process parameters, providing a basis for the optimization design of single well oil transmission pipelines in Xinjiang oilfield.

Mechanical Behavior of Buried HDPE Pipe Subjected to Surface Load: Constitutive Modeling and Finite Element Method Simulations

Abstract In this paper, the Sherwood–Frost constitutive model was first used to simulate the stress response and deformation process of buried high-density polyethylene (HDPE) pipe subjected to surface load, where parameters in this model were obtained by fitting the results of uniaxial tensile tests with different rates and the pipe–soil model was conducted in abaqus. Apparent stress concentration and large deformation are observed in pipe cross section and are closely related to the magnitude and location of surface load. The increments of surface load and offset displacement have opposite effects on the mechanical behavior of pipes. Additionally, the location of the maximum stress appears to shift from the top or bottom to the left and right sides of the pipe cross section with the increment of surface load, and the region of peak hoop stress will show a decreasing trend of counterclockwise rotation. Then, based on stress failure criterion, the relationship between the ultimate bearing capacity of the pipe and the offset displacement was determined, which decided by the angle between the ground and the line connecting load center and cross section center of pipe. Finally, an offset of 0.6 m is a value of interest. When the offset between the load position and the pipe exceeds 0.6 m, the ultimate bearing capacity of the pipe will increase significantly with the increase of the offset. The results of the above research could provide the reference for the safety evaluation and maintenance strategy of gas polyethylene pipe under the surface load.

Effect of seawater salinity, pH, and temperature on external corrosion behavior and microhardness of offshore oil and gas pipeline: RSM modelling and optimization

This research aims to investigate the effects of seawater parameters like salinity, pH, and temperature on the external corrosion behaviour and microhardness of offshore oil and gas carbon steel pipes. The immersion tests were performed for 28 days following ASTM G-1 standards, simulating controlled artificial marine environments with varying pH levels, salinities, and temperatures. Besides, Field emission scanning electron microscopy (FESEM) analysis is performed to study the corrosion morphology. Additionally, a Vickers microhardness tester was used for microhardness analysis. The results revealed that an increase in salinity from 33.18 to 61.10 ppt can reduce the corrosion rate by 28%. In contrast, variations in seawater pH have a significant effect on corrosion rate, with a pH decrease from 8.50 to 7 causing a 42.54% increase in corrosion rate. However, the temperature of seawater was found to be the most prominent parameter, resulting in a 76.13% increase in corrosion rate and a 10.99% reduction in the microhardness of offshore pipelines. Moreover, the response surface methodology (RSM) modelling is used to determine the optimal seawater parameters for carbon steel pipes. Furthermore, the desirability factor for these parameters was 0.999, and the experimental validation displays a good agreement with predicted model values, with around 4.65% error for corrosion rate and 1.36% error for microhardness.

Correlation to predict thermal characteristics of pulsating heat pipes with long evaporator section

In terms of employing closed-loop pulsating heat pipes as heat transfer devices in solar water heaters, the evaporator should be extremely long according to the length of the solar collector. However, there is a noticeable shortage of Semi-Empirical Correlations for predicting the thermal performance of extra-long closed-loop pulsating heat pipes utilized for heat absorption within solar collectors. The primary objective of this study was to formulate a Semi-Empirical Correlation specifically designed for predicting the thermal efficiency in extra-long closed-loop pulsating heat pipe configurations. This study extensively examined the thermal efficiency of a comprehensive design of closed-loop pulsating heat pipe samples when implemented in an evacuated-tube solar water heater system strategically designed for individual households. The specified maximum length for the evaporator section of the closed-loop pulsating heat pipes is set at 1.50 m, in contrast to the conventional design, which typically features an evaporator section of approximately 0.15 m. Furthermore, the investigation encompasses a number of sets, varying as one, two, and four. Therefore, a Semi-Empirical Correlation derived from the experimental data concerning seven pertinent non-dimensional parameters is presented, demonstrating a standard deviation percentage of 4.4 %. Among these parameters, the number of sets emerged as the most influential, inducing a maximum percentage change in the heat rate of water of 20.47 %. Moreover, compared with other studies utilizing pulsating heat pipes in solar water heaters, the correlation exhibited a 1.52 % error. These findings suggest that the developed Semi-Empirical Correlation is a valuable tool for predicting the thermal performance of an extra-long closed-loop pulsating heat pipe. It is particularly well suited for estimating the thermal behavior of closed-loop pulsating heat pipes with extended configurations, showcasing its enhanced accuracy and relevance in capturing the distinction of heat transfer in extra-long closed-loop pulsating heat pipe systems.

The performance of transmission pipelines on February 6th, 2023 Kahramanmaras earthquake: a series of case studies

AbstractThe Mw 7.8 earthquake that struck Kahramanmaras on February 6, 2023, caused significant damage to hydrocarbon and water transmission lines due to permanent ground deformations. Explosions occurred in the Kahramanmaras–Gaziantep Natural Gas transmission pipeline causing disruption of gas in the cities of Gaziantep and Hatay Fault Displacement Hazard. Water transmission pipelines were also damaged due to extreme fault offsets. This paper presents the findings from the earthquake affected zones. Particular attention was given to the performance of the 2600 mm diameter Duzbag–Gaziantep water transmission pipeline due to three reported challenges: (#1) The behavior of the pipe in the Duzbag tunnel, (#2) The pipe bend behavior at the fault crossing, and (#3) The pull-out of the pipe at valve room. Based on field observations, extreme damage forms at pipes were presented. A three-dimensional nonlinear numerical analysis was performed to simulate the observed damage of the reoriented water pipe at the fault crossing for Case #2. The nonlinear finite element model was able to capture the complex nature of the post-yield behavior of steel pipe as well as the damage locations along the pipe and their sequence of occurrences. As a mitigation measure for new pipes, the need for using flexible connections at critical crossings was highlighted. For existing pipes, the importance of developing secondary (by-pass) lines was emphasized.

Startup characteristics of a water loop heat pipe with dual heat sources for battery thermal management system in electric vehicle

Abstract The usage of electric vehicles has significantly reduced emissions of greenhouse gases and other pollutants. However, the high heat release generated by the electric vehicle batteries poses a challenge. To solve this problem, scientists have created a passive cooling thermal management system specifically for electric vehicle based on heat pipes, particularly loop heat pipes. A battery pack often consists of several battery modules, which results in multiple heat sources being dispersed according to their power capacity. Startup behavior of loop heat pipe has been investigated extensively in the literature. However, most of the studies use only one heat source. This paper aims to fill the research gap, particularly when the system is implemented in dual heat sources managed by only one evaporator. To achieve the research objectives, a custom loop heat pipe was constructed. This cooling system’s design is briefly described. The evaporator is made of copper, deionized water was selected as the working fluid because of its high merit number, which indicates strong performance as a heat pipe working fluid and the stainless-steel wire mesh serves as the porous wick. Battery simulator was built using aluminum material and a cartridge heater to mimic the heat produced by the battery. Two case studies were done. First, only one battery simulator was used. Second, two battery simulators were placed on both sides of the evaporator. A type-K thermocouple attached to the NI DAQ 9214 module was used to measure the temperature while the electric heat load varied between 10 W and 50 W. The study investigated the interaction between the heat load distribution and the startup behavior of the loop heat pipe. Startup behavior is crucial for the performance of the loop heat pipe. Based on the experimental results, the loop heat pipe demonstrates outstanding startup performance. It can effectively initiate operation even at a minimal heat load as low as 30 W for the first and second case study. The findings of the study indicate that the dual heat source arrangement effectively mitigates overshoot temperatures and enhances heat transfer performance by increasing the contact area.

Experimental study on anti-clamping damage structure of drill pipe against slip-crushing

Deep ground conditions bring higher challenges to drill pipe and slip tools, and the slip is more likely to seriously bite or crush the drill pipe, which will easily lead to failure of the drill pipe, seriously affecting the safety of drilling operations. Based on the theoretical analysis of the mechanical behavior and damage characteristics of the drill pipe held by slips, the deep ground suitability test of API-S135 conventional drill pipe and S135 and V150 anti-slip crushing drill pipe combined with micro-teeth marks hydraulic slips with thickened slip holding area is carried out. The test results show that: Compared with S135 common drill pipe, S135 and V150 anti-slip crushing drill pipe have an average change in outside diameter of 43% and 0.19%, with a reduction of 8.31% and 4.9% in the proportion of the maximum depth of the tooth mark, both of which have good mechanical resistance to slip crushing and biting, and the tensile load capacity of the clamped pipe body has been significantly improved. Combined with micro-tooth mark slips, the slips in deep drilling operations can tighten the drill pipe and make the bite damage of the drill pipe less. It can effectively ensure the safety and efficiency of deep drilling operations.

Impact damage characterization approach for CFRP pipes via self-sensing

The growing usage of carbon-fiber-reinforced polymers (CFRPs) has necessitated the development of structural health monitoring (SHM) for ensuring their integrity and safe operation. This paper presents a novel technique for monitoring the structural health of 3D CFRP pipe structures subjected to multiple impacts based on real-time electrical resistance monitoring. Damage characteristics such as its location and type were identified using the monitoring data and machine learning techniques. Additionally, finite element analysis was deployed to rationalize the electromechanical behaviors of pipes with varying stacking types and thus different fracture mechanisms. Analysis of the electrical resistance data coincided with the results of the finite element analysis in terms of damage modes and types. Therefore, a simple real-time electrical resistance measurement can detect the damage type without numerical analysis. A damaged section was identified by comparing the intensity of the data. Through machine learning techniques, the timepoints of damage severity demarcation were accurately predicted within error of 10 s and accuracies over 96 %. The machine-learning tools applied are unsupervised, thus reducing the effects of data dependency, labeling, and imbalance, as well as ensuring flexibility and general applications. The proposed technique was able to detect the damage location, severity, and type in real-time; hence, it has various potential applications in structural health monitoring including CFRP materials and is one of the few methods used to assess 3D structure characterization using self-sensing, which can result in mature technology and the optimal operation of CFRP systems.

Stress relaxation experimental research and prediction of GFRP pipes under ring deflection condition

Abstract Glass fiber-reinforced plastic (GFRP) pipes are widely used as buried pipes in petrochemical and other industries. At present, in-depth studies have been conducted on GFRP pipes in terms of internal hydrostatic pressure, axial compression, and cyclic internal pressure, especially limited research has been carried out on transverse load, especially stress relaxation behavior. In this study, GFRP pipes with three different component contents were subjected to different initial deflections at different temperatures and subjected to stress relaxation tests for 1000 h. The findings demonstrate that the stress relaxation behavior of GFRP pipes is not affected by the initial deflection. Rather, it is primarily influenced by temperature and sand entrapment content, which are identified as the key factors determining the stress relaxation behavior of GFRP pipes. In addition, the time-temperature superposition principle (TTSP) was used to pass the test results to obtain a smooth master curve and verify the applicability of TTSP on GFRP pipes. Subsequently, the relaxation performance of GFRP pipes was predicted after 50 years. This research result contributes to a more comprehensive understanding of the stress relaxation behavior of GFRP through accelerated testing and offers crucial insights into the application of GFRP pipes.

Corrosion and degradation behavior of bent aluminum and copper pipes for practical use in air conditioning

AbstractAlthough copper (Cu) pipes are widely used in refrigerant piping owing to their high thermal conductivity and weathering resistance, there are concerns regarding the increasing price and limited supply of Cu. Consequently, our focus has shifted to aluminum (Al), which is relatively abundant and inexpensive, to investigate its application in refrigerant piping. We previously examined corrosion factors on both the internal and external surfaces of straight piping and conducted accelerated degradation tests, showing that Al has a durability comparable to that of Cu. However, bending sections are always used in addition to straight pipes, and bending induces tensile stress on the outer side of the bending curvature and compressive stress on the inner side. Notably, stress corrosion cracking may occur under tensile stress in corrosive environments. Herein, we investigate the mechanical, electrochemical, and weather resistance properties of bent Al and Cu pipes to evaluate the practicality of Al refrigerant piping.

Static and dynamic responses of buried steel pipe under truck load: An experimental study

The behavior of a buried pipe under static and dynamic loading conditions has been investigated through full-scale field tests. A plain steel pipe with a diameter of 762 mm was gauged at the outer surface of two pipe sections. A dump truck was employed for the static and dynamic loading tests. Under static loading, the measured pipe strains increase with increasing axle load and decreasing cover depth. The measured strains under dynamic loading show three peaks, which correspond to the times at which the front, middle, and rear axles, respectively, reach the pipe centerline. The offset loading pattern produces greater strains than the non-offset one while keeping the axle load constant under both static and dynamic loads. It is discovered that the pipe strains caused by each truck axle vary with truck speed. Since the load transfer is influenced by a number of factors, including the truck load, road roughness, truck speed, and others, a moving truck load does not always result in higher pipe strains as compared to a static load. The complexity of dynamic pipe responses can be explained in part by a single-degree-of-freedom (SDOF) model.

Evaluation of thermo-fluidic performance of micro pulsating heat pipe with and without evaporator side surface structures

Interfacial behaviour and thermal performance of a 4-loop micro pulsating heat pipe are examined through experiments performed at different filling ratio (30–60 %), working fluid (acetone, ethanol, and methanol), and heat input (0–40 W). During the heat pipe operation, nucleation, growth and merging of bubbles, elongation, and movement of vapor plug, and dry out conditions are noticed upon ramp heating (0–40 W) inside smooth surface evaporator pulsating heat pipe. Experiments show that preparation and boiling inception lead to steady operation of heat pipe. Pulsating heat pipe showed minimum thermal resistance when operated with 40 % filling ratio and acetone as working fluid, which has low viscosity, surface tension and boiling point. Additionally, effect of surface structures (rectangular pillar protrusion and hemispherical dimple cavity) on the evaporator section is tested against base smooth surface micro pulsating heat pipe to understand augmentation of heat transfer. Hemispherical dimple cavities show better nucleation, bubble growth, and vapor plug elongation and thereby reduction in thermal resistance. On the other hand, rectangular pillar protrusions showed clogged bubble, least bubble detachment and vapor plug length in the adiabatic zone which results in higher thermal resistance than even smooth surface.

Inhomogeneity in mechanical properties of ductile iron pipes: A comprehensive analysis

Ductile iron pipes are widely used in pipe manufacturing for water and sewage transmission and distribution. In pipeline standards such as EN545, the pipe material is assumed isotropic and its mechanical properties are determined by tensile testing of round bars extracted along the longitudinal direction. This study experimentally examined the mechanical properties of centrifugal casting ductile iron pipes, focusing on the effects of sampling orientation, location, preparation, and test methodology. A ring hoop tension test (RHTT) was designed to evaluate circumferential properties. Force analysis of RHTT was performed and theoretical equation was derived to quantify the friction coefficient that existed between the coupon specimen and the loading fixture. A numerical study was conducted to further validate the effectiveness of the proposed theory. The test results indicated that the pipe mechanical property was inhomogeneous across the wall thickness, being inferior in the internal section and superior in the middle and external sections. This inferior layer would develop crack first and lead to subsequent outward propagation. This phenomenon led to a substantial degradation in the overall mechanical performance of the entire specimens, in comparison to the material in the middle portion. The material exhibited better performance in the circumferential direction compared to the longitudinal direction in terms of its mechanical properties, such as tensile strength and ductility. Flattened specimens showed enhanced strength and reduced ductility compared to the base pipe material. Fractographic and metallographic analyses revealed the existence of casting defects of porosity and agglomerated graphite in the internal section, which were the primary cause of material inhomogeneity. The round bars suggested per EN545 tended to overestimate the actual mechanical behaviour of ductile iron pipes, and may not be a true representation of the finished product of pipes. Flattened specimens as per ASTM E8/E8M were not recommended for ductile iron pipe material assessment, as the flattening process altered the stress–strain characteristics significantly.