Strength Of Pipes Research Articles

Effect of vibration on the interface properties of welded steel joints and filled concrete in steel pipes

Concrete-filled steel tubes (CFSTs) have been increasingly utilized in engineering due to their excellent mechanical properties. Ensuring a solid bond between a steel tube and concrete is essential for optimizing their synergistic effect. This study introduces an internally welded steel bar structure within the inner wall of a steel tube to enhance the bond properties at the connection interface. The influence of various configurations of steel bars welded to the inner surface of the tube on the bond strength is investigated considering the impact of vibration on the load-bearing capacity of the component. This study comprises two groups of specimens, one with vibration and one without vibration, for a total of ten specimens. Each group included CFST members with five distinct internal welded steel bar structures. The experimental results, including load–displacement curves and strain data of the steel tube, were used to assess the impact of the internal welded steel bar configurations on the steel–concrete interface. The sliding process is described by correlating test data with curves and observed phenomena. To comprehensively compare the effects of structural dimensions on the bonding and slipping properties of the welded bars, finite element simulations replicating the experimental conditions were carried out using ABAQUS software, and the simulation results agreed with the experimental observations. The study demonstrated that incorporating internal welded steel bars substantially enhances the bond strength of steel pipe–concrete interfaces. While vibration weakens the bond strength in CFST members, internal welded steel bars mitigate this effect. These findings improve the structural performance of CFST structures and their resilience to external vibrations.

Application of Pattern Search and Genetic Algorithms to Optimize HDPE Pipe Joint Profiles and Strength in the Butt Fusion Welding Process

The rapid spread of the use of high-density polyethylene (HDPE) pipes is due to the wide variety of methods for connecting them. This study keeps pace with the developments of butt fusion welding of HDPE pipes by exploring the relationship between the performance of the weld joints by studying ultimate tensile strength and exploring the joint welding profiles by studying the shape of the joint at the outer surface of the pipe (height and width of the joint cap) and the shape of the joint at the internal surface (height and width of the joint root). Welding pressure, heater temperature, stocking time, and cooling time were the parameters for the welding process. Regression was analyzed using ANOVA, and an ANN was used to analyze the experimental results and predict the outputs. Two optimization techniques (pattern search and genetic algorithm) were applied to obtain the ideal operating conditions and compare their performance. The results showed that pattern search and genetic algorithms can determine the optimal output results and corresponding welding parameters. In comparison between the two methods, pattern search has a limited relative advantage. The optimal values for the obtained outputs revolved around a tensile strength of 35 MPa (3.45 and 4.5 mm for the cap and root heights, and 8 and 6.98 mm for the cap and root widths, respectively). When comparing the effects of welding parameters on the results, welding pressure had the best effect on tensile strength, and plate surface temperature had the most significant effect on the welding profile geometries.

Study on the effect of multi-factor compound action on long-term tensile performance of GFRP composite pipe and life prediction analysis

In this work, the glass fiber reinforced plastic (GFRP) composite pipes used as sewerage pipes in oil and gas field environments were studied. The accelerated aging experiments were carried out under the simulated environments of three typical oil field media which including circulating air, simulated produced water and standard simulated oil. Scanning electron microscopy (SEM) was adopted to observe the microscopic morphology of the aged GFRP tubes under the three conditions. The microstructural characteristics of the aged tubes and the evolution process of internal defects were also analyzed and evaluated in combination with micro-CT technology. The attenuation pattern of the hoop tensile strength of the aged pipes was measured via the separation disk method, and the service life prediction was carried out based on the Arrhenius theory with the hoop strength as the life index. The results show that the accumulation of aging time and continuous heat input will aggravate the expansion of internal pores and cause the aggregation of small-volume defects into large-volume defects. Especially in the simulated oil environment, which has the highest sensitivity to defects. The maximum porosity reaching 1.5 % and the maximum volume of individual defects exceeding 106 μm3 after aging for 4000 h at 95 °C. The thermal aging process under the three environmental conditions had similar aging characteristics, and interfacial damage of the glass fibers was observed in all of them. The variability of hydrothermal aging is related to the hydrolytic behavior of the glass fibers, which is associated with the progressive dissolution damage of the SiO2 network in the glass fibers, as well as the breaking of silane bonds. Thus, the hydrothermal environment had the most significant effect on the hoop tensile strength decay. Ultimately, 75 % strength retention was taken as the end-of-life indicator. The predicted service life based on the Arrhenius model for the three environments of thermo-oxygen, hydrothermal and simulated oil were 23.5, 23.1 and 28.5 years at 20 °C, and 12.2, 4.9 and 10.3 years at 40 °C, respectively.

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.

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.

Effects of fiber characteristics on tensile and impact properties of long fiber reinforced High‐Density Polyethylene

AbstractDue to the requirements of high stiffness and impact strength of HDPE pipes, in this article, long fiber reinforced HDPE were developed and the effects of fiber length, volume fraction, types, and matrix/fiber interface on the mechanical properties were investigated. Tensile properties, notched impact strength, as well as microstructures were tested. The results showed that fibers increased the tensile strength, modulus, and impact strength, but decreased their plastic deformation. Larger fiber fraction indicates more fibers are involved in load bearing, but easy agglomeration. With ascending fiber length, tensile, and impact strength first increased and then decreased, whereas tensile modulus first increased and then maintained an almost constant value. Carbon fibers showed no advantages over glass fibers and basalt fibers in reinforcing HDPE due to the relatively poor interface bonding strength. Interface modification with KH550 improved the mechanical performance of composites, but the enhancement was limited. More effective methods should be developed for better performance.Highlights Fiber increases strength and modulus, but decreases plastic deformation. Critical fiber length for basalt LFT is 2.6 mm obtained from SEM. Larger fiber volume and length lead to agglomerations. Difference in BF, CF, and GF reinforced HDPE is determined by interface. Interface modification enhances mechanical properties of LFT but limited.

Research Status of Friction Interface Evolution Mechanism of Non-magnetic Steel

The non-magnetic drill pipe (composed of male and female thread joints and rod bodies) is the key component of the directional drilling technology equipment for gas extraction in coal mine tunnels. The thread joint and the drill pipe body are connected by continuous drive friction welding. In the study, it was found that the banded structure appeared in the joint of continuous drive friction welding of non-magnetic steel, which reduced the strength of drill pipe. At the same time, it is found that the heat flow mode is one of the key factors affecting the banded structure, and the heat flow mode is based on the evolution of the interface plastic ring. In this paper, through the review of the research status of the interface evolution law of non-magnetic steel continuous drive friction welding, the experimental method for the study of the interface evolution law of non-magnetic steel continuous drive friction welding is found.

Strength limit of titanium alloy drill pipe under combined tension and torsion load

With a focus on the issue of drill pipe failure brought on by the interaction of tension and torsion in deep and ultra-deep wells, the yield limit curve of the pipe body and joints under the combination of tension and torsion was drawn. According to the practice of DNV-RP-F201, it was investigated how temperature affected drill pipe strength. The findings demonstrate that as temperature increases, both yield and tensile strength decrease linearly, and the decreasing range gradually decreases when temperature exceeds 140°C, and yield strength decreases by 31.91% in 140°C. Under the conditions of the same yield strength and outer diameter, the larger the thickness of the drill pipe body is, the higher its tensile strength and torsional strength are. The resulting yield limit curve covers a wider range. As the temperature increases, the yield limit elliptic curves of titanium alloy drill pipes with various wall thicknesses gradually shrink. This work presents the foundation for the strength research of titanium alloy drill pipe under tension and torsion load.

Modeling the proof strength of pipe steels tempered with the application of artificial intelligence methods

The paper demonstrates the results of modeling the proof strength in pipe steels improved by tempering heat treatment. The main types of models used in this study are described, and information about the pros and cons of different approaches to modeling the target variable is summarized. Empirical equations relating hardness to yield strength and tensile strength are given. The role of the parameter n in these equations is indicated. The reasons for choosing the applied set of independent variables in the models are explained. The distribution of the target variable in the data sample is shown, and information about the feature space used for each of the models is provided. A general description of the source data is given. The structure of the main data sample is studied by the DBSCAN clustering method and the t-SNE dimension reduction algorithm. The reason for splitting the sample into clusters is substantiated in the context of reducing the spread of the predicted value of proof strength. The effectiveness of splitting the sample is estimated by using the measure of the spread of n. Various regression models for predicting yield strength are compared. It is shown that the regression model based on gradient boosting over the decision trees (LightGBM) has the smallest prediction error among the models considered. The permutation significance of the features of the model with the smallest prediction error is determined, the calculated significance of the features being compared with that from the metallurgical theory. The validity of the obtained prediction models is evaluated in view of the significance of the features and the metric estimate used in this study. The hypothesis of using a proxy variable (n) obtained from theoretical calculations as a predictor in the yield strength prediction model is tested. It is demonstrated that the application of the grouping method together with the parameter n makes it possible to obtain satisfactory prediction results on a smaller feature space.

Experimental research on the thermal and mechanical response of flowing pipelines under the horizontal jet flame

The safe operation of parallel pipelines has become a focus of attention. The jet flame generated by the initial pipe accident may cause adjacent pipe section failure. Therefore, it is necessary to study the thermal impact of jet flame on adjacent pipelines. In this paper, we design and establish a thermal effect test platform to determine the change in pipe wall temperature and mechanical properties under the horizontal jet flame. Firstly, the flame combustion characteristics, such as flame form, temperature, and heat flux, are tested and analyzed. Then, the quantitative variation law of the pipe wall and oil temperature under different flow rates, wall thicknesses, and heating lengths is obtained. Combined with the mechanical test results of experimental pipelines, a pipe-bearing capacity calculation model is established via the GA-BP machine learning algorithm. Finally, the safety evaluation method and classification of the stress margin are established. The results indicate that the temperature and heat flux of the fire-facing surface is significantly higher than other clock orientations, where the values are 1287.38 ℃ and 12.37 kW/m2, respectively. As the flow rate decreases and the wall thickness and heating length increase, the pipe wall temperature rises linearly, and the tensile strength and impact toughness reduce logarithmically. The average relative error of the pipe strength prediction model is less than 2.44 %. The established safety evaluation method can be applied to determine the thermal risk level of steel pipelines under the jet flame.

Wear analysis and life prediction of sucker rod and tubing under ternary emulsion lubrication in Daqing oilfield: a case study in block H

Daqing Oilfield as the world’s largest application area of alkali–surfactant–polymer (ASP) flooding, in recent years, with the increase in aging wells, the eccentric wear and deformation of sucker rod and pipe during oil production has become more and more serious. In order to study the effect of emulsion lubrication in ternary composite flooding on eccentric wear of sucker rod and tubing, this paper establishes a calculation model for the depth of tubing wear under different emulsion lubrication conditions through indoor friction and wear experiments combined with White and Dawson wear efficiency theory. Based on this, the finite element method is used to predict the safe wear life of tubing under different component emulsion lubrication. The results show that compared to intact oil pipes, the residual internal pressure strength of oil pipes with defects decreases, and stress concentration occurs at the edges and middle of the defects. The wear life of oil pipes decreases with the increase in pump depth and wear coefficient under emulsion lubrication. The water content and alkali concentration have the most significant effects on the wear life of oil pipes under emulsion lubrication conditions. The safe wear life of sucker rod pipes under emulsion lubrication with a water content of 75% will be increased by 37.8% compared to those in emulsion lubrication with a water content of 95%, and under emulsion lubrication with an alkali concentration of 500 mg/l, the safe wear life will be increased by 50.6% compared to those in emulsion lubrication with a concentration of 2000 mg/l. The research results can provide theoretical and technical support for oilfield enterprises to reduce rod and pipe wear in ASP flooding oil wells, improve the pump inspection cycle of pumping wells, and ensure the safety of oil well work.

Testing, simulation, and design for analyzing the behavior of lined pipes under torsion

Offshore oil and gas development requires increased corrosion resistance due to exposure to harsh and corrosive environments. The use of lined pipes with both significant mechanical and corrosion-resistant properties has become increasingly widespread in the offshore oil and gas industry. The potential pipeline torsion trend during the installation stage may affect the structural integrity of the adopted lined pipe and has become threats to offshore construction. This study conducted torsion tests on lined pipes and captured the structural behaviors. Finite element (FE) models were developed to investigate the failure modes, the developments of the liner wrinkle and the interaction stress between the outer and liner pipes. The mechanism of how the interaction behaviors developed and the improvement of composite action between the constitutive parts had been quantitively discussed. Additionally, a series of parametric studies were conducted to study the effects of the outer pipe strength, the outer pipe thickness and the length of the lined pipe. Finally, the improved method for the design torque, considering the contribution from the liner pipe, has been proposed. This study can provide valuable references for the design and installation of lined pipes under torsion.

Development of a Design Method for Casing and Tubing Strings under Complex Alternating Loads

With the escalating intricacy of downhole operational scenarios, encompassing frequent well cycling, acidification, multi-stage fracturing, steam injection, and intensive extraction, the efficacy of traditional casing-string-design methods rooted in strength considerations is progressively unveiling its limitations. Henceforth, it becomes imperative to establish string-design method standards that embrace the entirety of a well’s lifecycle, encompassing the phases of drilling, completion, fracturing, and production operations. Beginning with an analysis of the advantages and limitations of traditional casing-string-design methods, this paper introduces the features of strain and sealing design methods developed for the full lifecycle of the string. The strain design method, a departure from conventional design philosophies, enables the design concept of the controllable deformation of the pipe string. The sealing design method currently stands as the sole standard method for the design of tubing strings. Simultaneously, this paper proposes the establishment of a time dimension-based lifecycle pipe string-design method standard. This approach considers the trend of pipe strength degradation, effectively addressing the safety concerns related to pipe string design in production and operation.

A data assimilation approach for estimating strength of steel pipes reinforced with composite sleeves under unsteady pressure-flow conditions

A data assimilation approach for estimating strength of steel pipes reinforced with composite sleeves under unsteady pressure-flow conditions

Influence of transverse vibration induced by fluid-structure interaction on pipeline strength

The transverse vibration of a pipe induced by fluid–structure interaction can cause abnormal fluctuation, buckling and flutter. In this paper, the effect of fluid–structure interaction on the transverse vibration of nuclear power pipelines is analyzed theoretically and numerically. Firstly, a theoretical model of the nuclear power pipe and the fluid that flows internally is established based on Hamilton’s principle. Then, an analytical solution of the transverse vibration differential equation considering the fluid–structure interaction is obtained. Next, a finite element analysis of the transverse vibration of nuclear power pipe due to fluid–structure interaction is carried out. In the end, the analytical solutions of natural frequency, vibration performance, mechanics characteristic of pipes are compared with the finite element solution. The results show that the analytical solutions of transverse vibration of pipes are consistent with the finite element solutions. In addition, the results show that the negative effect of transverse vibration due to fluid–structure interaction on the pipe strength is worthy of attention only at a high internal pressure or velocity. It is of great significance to improve the safety and economic benefits of fluid-filled pipes.

塩化ビニル管の繰返し曲げ挙動

Many buildings have been reported to stop their service due to damage to non-structural members such as equipment piping after large-scale earthquakes. Although data on deformation capacity and strength of carbon steel pipe for ordinary piping is being collected, few studies are conducted on polyvinyl chloride pipes (PVC pipes) for drainage. Cyclic bending tests are conducted of PVC pipes with nominal diameters of 40A, 50A and 75A to evaluate their deformation capacity and strength. The result is that the deformation of PVC pipes is larger than that of steel pipes, and shows brittle failure.

The Strength Behavior of O-Core Sandwich Pipe

Due to the characteristics of light weight, high specific strength, high specific stiffness and multi-function, sandwich structure is widely used in automotive industry, aerospace, offshore platform, construction, wind power generation and other fields. In recent years, the preparation and properties of new high-performance sandwich structures are the frontier research topics in the field of materials engineering. The research on the preparation method and mechanical properties of the sandwich pipes is favored by researchers at home and abroad. This paper, the O-core metal sandwich pipes is taken as the research object. The material is 304 stainless steel. By designing the orthogonal experiment, the sandwich pipes with 3 core pipes and 4 core pipes is prepared by laser welding. The tensile test of the sandwich pipes was carried out by Z250SNS electronic universal testing machine. At the same time, the finite element model of the sandwich pipes was established by using ANSYS finite element analysis software, and the strength of the sandwich pipes was further numerically simulated. Results show that the curves of the simulation and experiment data are in good agreement. Besides, when compare with an empty pipe, the carrying capacity of the sandwich pipe during stretching is significantly improved. The number of cores has a visible effect on the strength of the sandwich structure pipe, and the elastic limit is approximately proportional to the number of cores. In this paper, the mechanical properties of O-core metal sandwich pipe are studied, and the research method is clarified, which provides a new idea for the future research of sandwich pipe.

Data-driven collapse strength modelling for the screen pipes with internal corrosion defect based on finite element analysis and tree-based machine learning

Aiming to address the difficulties in predicting the collapse strength of sand control screen pipes with internal corrosion defects under the external pressure in offshore unconsolidated sandstone oil and gas reservoirs development, a parametric analysis model of a screen pipe with corrosion defects was established based on secondary development of ABAQUS by Python script, and was verified by the published experimental data. Then, the effect of corrosion defect and hole parameters on the collapse strength of the screen pipes was analyzed. Furthermore, a novel data-driven model with the gradient boosting regression tree (GBRT) method was used to explore and characterize the laws contained in the numerical simulation data based on a large volume of numerical simulation data. The results demonstrated that the proposed data-driven prediction model for the collapse strength of screen pipes exhibited a stable prediction average difference of 3.97% in the test set. And a large number of generalization practices based on data-driven prediction model indicated that corresponding corrosion parameter warning interval existed when the screen pipe design structure was determined, and when the corrosion defect size was greater than the warning interval, the collapse capacity of the screen pipe was considerably weakened. Moreover, the collapse strength was the lowest when the corrosion defect was located at the center of the screen pipe. And the collapse strength of the screen pipe gradually decreased with an increase of corrosion defects parameter and hole arrangement parameter. This study can provide a reference for evaluating the strength and establishing a safety-related warning mechanism of sand control screen pipes with corrosion defects.

Residual strength prediction of X80 steel pipelines containing group corrosion defects

As subsea oil and gas pipelines are corroded by moisture, soil, and other external factors, their surfaces develop groups of corrosion defects, which are prone to stress concentration and affect the residual strength of the pipeline. To this end, a finite element (FE) model of an X80 pipeline containing group corrosion defects is established here using ABAQUS. Considering the influence of various defect sizes on the residual strength of the pipe, 46 sets of failure data for group corrosion pipes with different geometries and 364 sets of maximum von Mises stresses versus internal pressure for different operating conditions were obtained. The accuracy of the FE model was verified using burst tests. The residual strength prediction model of the pipes was obtained by 1stopt software. The results show that the key factor affecting the residual strength of pipes containing group corrosion defects is the depth of the deepest defect and the strength of the interaction between the group corrosion defects. Based on the DNVRP-F101 standard, a more accurate method for calculating the failure pressure of group corrosion pipes was obtained by introducing correction factors. The results of this study can provide theoretical support for the safe management of group corrosion X80 pipelines.

Study on Dynamic Behavior of a Titanium Alloy Drill Pipe in Complex Wells

Traditional steel drill pipes can no longer meet the requirements of complex wells with ultradeep, ultrahigh pressure, and long horizontal section; hence, titanium alloy drill pipes are an ideal substitute. This paper explores how titanium drill pipes behave in complex wells. The extrusion and tensile test of titanium alloy pipe was first established. Then, based on the experimental data, the downhole mechanical behavior of a titanium alloy drill pipe was studied from the buckling, contact force, and operating friction with an actual complex well. Meanwhile, the mechanism of friction reduction is analyzed and discussed. The research achievements indicate that the strength of a titanium alloy drill pipe is equal to that of a steel pipe and has good plastic deformation capacity. The titanium alloy drill pipe is more prone to buckling during operation, but it has a smaller contact force, which can effectively reduce the operation friction. It was found that the influent of buckling on slide force was much less than of the gravity and stiffness by mechanism analysis. The research achievements can provide specific theoretical and practical references for the revelation of the mechanical behavior and functional performance of titanium alloy drill pipe in the field operation.