Joints Of Pipelines Research Articles

Bilinear Constitutive Model Based Theoretical Study on Interfacial Properties of Pipeline Joints Coupling Tension and Temperature

Bilinear Constitutive Model Based Theoretical Study on Interfacial Properties of Pipeline Joints Coupling Tension and Temperature

Structural-phase characteristics of damage to welded joints of tpp steam pipelines from heat-resistant steels (Review)

Structural-phase characteristics of damage to welded joints of tpp steam pipelines from heat-resistant steels (Review)

Investigation on the Microstructure and Mechanical Property of Long Distance Water Pipeline Joint

Investigation on the Microstructure and Mechanical Property of Long Distance Water Pipeline Joint

Research on the Influence of Cone Angle on the Sealing Performance of Pipeline Joint

In order to evaluate the sealing performance of the pipe connectors, we developed a simplified 3D model by adjusting the cone angle of the nozzle and analyzing the contact pressure of the sealing structure, the width of the contact surface, and the equivalent stress as the response quantities. Based on a finite element analysis approach, we found that increasing the cone angle of the nozzle improves the sealing performance, but may negatively affect structural reliability and maintenance. As such, the optimal range for the nozzle cone angle is relatively reasonable between 55° and 60°. Furthermore, we use a sealed interface leakage model to calculate the joint leakage rate under theoretical conditions.

Research on Construction Welding of Apron Pipe Network

With the rapid development of the economy in recent years, economic and trade activities such as foreign exchanges and business exchanges in Shaanxi have become increasingly frequent. As a window and transportation portal of Shaanxi, Xianyang Airport also shows the momentum of rapid growth in the airport's aviation business. At present, the annual passenger throughput and annual flying racks of Xianyang Airport have exceeded the capacity of the design target year. The existing organic apron pipe supply will face the situation of insufficient supply and insufficient supply. According to the actual needs, the expansion of the oil engineering expansion project of Xianyang International Airport has begun to be officially constructed. In the implementation project, the fuel supply project will encounter non -stop construction and oil -with oil. It is the most difficult and most dangerous construction in the construction process of the apron pipeline. During the construction of the mouth, This article discusses the construction technology and standardized construction process for oil welding joints of pipelines during non-stop navigation on the apron.

Development of a technique for applying pa and tofd methods for mechanized ultrasonic testing of welded joints of main pipelines using the USD-60FR-16/128 flaw detector

A technique was developed and tested for selecting beam steering and focusing methods for mechanized ultrasonic testing of circumferential welds of pipelines up to 16 mm thick using phased antenna arrays. Criteria for the identification and interpretation of defects on the time-of-flight diffraction scans in the form of an atlas of defects were developed. The study was carried out using a new domestic flaw detector USD-60FR-16/128.

Обзор современных требований к сварке трубных высокопрочных низколегированных сталей

For many years, proven arc welding processes have been used to weld large pipes of oil and gas pipelines, the scope of which extends from manual arc welding with stick electrodes to the use of metal orbital welding machines. Introduction reflects that the creation of new steel compositions for oil and gas pipelines is an urgent task to ensure its high reliability. Research Methods. Low-carbon steels with ferrite-perlite structure are usually used in pipe production, but these steels are unable to meet the increased market demands. New grades of steel with bainitic structure are appearing. Results. The failure of welded joints of pipelines made of high-quality steel is becoming a serious problem for the pipeline industry. Discussion. This paper analyzes the characteristics of weld microstructure and its relationship with impact toughness. The prediction of impact toughness based on the microstructural characteristics of weld-seam metals is complicated due to a large number of parameters involved. The common practice linking this property to the microstructure of the last roll of a multi-pass weld turned out to be unsatisfactory because the amount of needle ferrite, the most desirable component, may not always be the main factor affecting the impact toughness. The present review reports on the most representative study regarding the microstructural factor in the welded seam of pipe steels. It includes a summary of the most important process variables, material properties, normative rule, as well as microstructure characteristics and mechanical properties of the joints. Conclusion. It is intended that this review will help readers with different backgrounds, from non-specialist welders or material scientists to specialists in various industrial applications and researchers.

Comprehensive analysis of the performance of welding joints of gas pipelines with different viscosities

Full-scale tests of gas pipelines with different viscosities were carried out in landfill conditions, which are as close as possible to the natural conditions of operation of gas pipelines. The kinetics of crack propagation along welded joints - their trajectory, the transition from the weld seam to the base metal of the pipe and vice versa, the speed of movement of cracks in viscous and brittle metal and defined zones of plastic deformation - were experimentally investigated. It is known that tests on Menaget, Charpy and other samples, which have thicknesses that do not correspond to the thickness of the pipe walls, do not reflect the real picture of visco-plastic and brittle fractures, which does not allow to develop a methodology or model for predicting the final resource (non-accident) of long-term gas pipelines period of operation. At the same time, theoretical and laboratory researches do not always adequately answer the questions directly related to ensuring the durability and trouble-free operation of pipelines. It is likely that in the laboratory conditions of enterprises or scientific institutions it is difficult to reproduce and take into account all the factors that characterize the growth and spread of destruction in a real operating gas pipeline. Therefore, the data of laboratory studies must be checked and necessarily clarified according to the results of pneumatic tests of long pipe sections, i.e., at present, the need to combine laboratory and field tests of pipes of the gas pipeline network is urgently needed. Such tests are not massive, but as a result of their performance, important information is obtained regarding the behavior and properties of the metal in the conditions of loading and operation, which are closest to operational conditions. In field tests, pipes with a diameter of 1000x18 mm were used, which underwent controlled rolling (steel class X70 - grade 06G2BA) at a working pressure of RR = 9.7 MPa (in the northern - low-temperature version). Tensile tests, studies of impact toughness, strength and plasticity of the weld metal were carried out according to standard methods described in works [2-5]. During the experiments, a large number of sensors of temperature, pressure, strain, stress, crack propagation speed, etc. were used. The obtained results regarding the kinetics of the destruction of natural pipes in landfill conditions lay the groundwork for the development of a mathematical model of the engineering forecast of the residual (non-accident) resource of pipelines operating in oil and gas fields.

Deep Learning Enriched Automation in Damage Detection for Sustainable Operation in Pipelines with Welding Defects under Varying Embedment Conditions

Welded joints in metallic pipelines and other structures are used to connect metallic structures. Welding defects, such as cracks and lack of fusion, are vulnerable to initiating early-age cracking and corrosion. The present damage identification techniques use ultrasonic-guided wave procedures, which depend on the change in the physical characteristics of waveforms as they propagate to determine damage states. However, the complexity of geometry and material discontinuity (e.g., the roughness of a weldment with or without defects) could lead to complicated wave reflection and scatters, thus increasing the difficulty in the signal processing. Artificial intelligence and machine learning exhibit their capability for data fusion, including processing signals originally from ultrasonic-guided waves. This study aims to utilize deep learning approaches, including a convolutional neural network (CNN), Long-short term memory network (LSTM), or hybrid CNN-LSTM model, to demonstrate the capability in automation for damage detection for pipes with welded joints embedded in soil. The damage features in terms of welding defect types and severity as well as multiple defects are used to understand the effectiveness of the hybrid CNN-LSTM model, which is further compared to the two commonly used deep learning approaches, CNN and LSTM. The results showed the hybrid CNN-LSTM model has much higher classification accuracy for damage states under all scenarios in comparison with the CNN and LSTM models. Furthermore, the impacts of the pipelines embedded in different types of materials, ranging from loose sand to stiff soil, on signal processing and data classification were further calibrated. The results demonstrated these deep learning approaches can still perform well to detect various pipeline damage under varying embedment conditions. However, the results demonstrate when concrete is used as an embedding material, high attention to absorbing the signal energy of concrete could pose a challenge for the signal processing, particularly under high noise levels.

Analytical method for deformation and stress calculation of bell-and-spigot joints in PVC-U pipes

The stable operation of water supply pipelines relies significantly on the structural safety of pipe joints. A novel analytical pipe joint structural calculation method based on the Novozhilov thin shell theory was proposed to calculate the deformation and stress of bell-and-spigot joints in unplasticized polyvinyl chloride (PVC-U) pipes under internal pressure. An equivalent stress index was established to investigate and evaluate the safety performance of pipe joints. The effects of various factors, including spigot insertion depth, the clearance between the bell and spigot, internal pressure, and different pipe nominal outside diameter (DN) and nominal pressure (PN) series, on the maximum equivalent stress of pipe joints, were thoroughly analyzed. The results indicate that the maximum equivalent stress under nominal pressure is located on the inner surface of the bell and consistently exceeds the design stress. The influence of spigot insertion depth on the maximum equivalent stress is minimal. However, as the clearance value between the bell and spigot decreases and the internal pressure increases, the maximum equivalent stress increases significantly. Pipes with smaller DN and PN series result in a higher maximum equivalent stress at the joint. The analytical method indicates that increasing pipe thickness and reinforcing the bell with continuous carbon fiber filament winding are two potentially effective methods to enhance the mechanical performance of the joint and reduce the maximum equivalent stress. This study's findings offer valuable theoretical support for designing and selecting joints in PVC-U pipelines.

Dynamic Behavior and Safety Criteria of Buried Concrete Pipeline System under Blasting

In urban blasting engineering, researching the dynamic response of buried pipeline is a method for evaluating the stability of the pipeline. The dynamic response of buried pipeline under blasting includes peak particle velocity (PPV) and peak effective stress (PES) on the pipeline. This paper aims to analyze the dynamic response of the concrete pipeline with bell-and-spigot joints under a metro-connected aisle blasting, and provide a PPV safety criterion for evaluating the stability of the field concrete pipeline. This includes an analysis of the dynamic response of the concrete pipeline in the field monitoring and numerical simulation. The monitoring results reveal that the PPV is affected by the field factor, such as the explosion source distance, and it is noteworthy that the Sadovsky’s formula considering the influence of explosion source distance (data correlation coefficient—0.708) has higher accuracy in predicting the PPV compared to the original Sadovsky’s formula (data correlation coefficient—0.632). The dynamic response distribution characteristics of the concrete pipeline are analyzed based on the numerical simulation, and the results show that the PES of the joint is three times stronger than that of the barrel. A PPV safety criterion (1.43 cm/s) is provided for the site to evaluate the stability of the concrete pipeline according to the dynamic response of the pipeline joint.

Contact mechanical behavior and leakage prediction of metal lenticular gaskets in bolt flange joints of ultrahigh pressure pipelines

Metal lenticular gaskets have been widely applied in the bolt flange joints of high and ultrahigh pressure pipelines due to their semi-self-tightening sealing properties. However, research on the leakage prediction of the metal lenticular gaskets is still lacking, which limits their further optimal design and sealing performance improvement. In this paper, an elastoplastic contact mechanics analysis of a metal lenticular gasket used in the bolted flange joint of ultra-high pressure polyethylene pipelines was firstly carried out. The analytical formulas of contact stress and contact width were derived and compared with corresponding numerical results. Then, based on the surface topography measurement, a leakage model was established, in which the pipe surface was simplified to a smooth rigid flat surface, and the gasket surface was simplified to an equivalent rough surface composed of identical wedges. Finally, an analytical leakage prediction formula for the metal lenticular gasket was proposed. In addition, the effects of influence factors on leakage rate were discussed. It is shown that the analytical formulas can accurately calculate the contact stress and contact width in elastoplastic contact. The leakage rate increases with the decrease of the bolt load and the increase of internal pressure. For the ultrahigh pressure pipeline with internal pressure of 200 MPa, the minimum bolt load should be ensured to be higher than 120 kN in order to meet the T5 tightness level. In addition, the initial contact diameter is basically proportional to the leakage rate, while the change of gasket inclination angle has little effect on the leakage rate. Therefore, the contact diameter can be designed to be as small as possible within a reasonable range. This work can provide a theoretical basis for the sealing optimal design of metal lenticular gaskets.

Erosion-Corrosion Behavior of Friction Stud Welded Joints of X65 Pipelines in Simulated Seawater under Different Flow Rates.

In order to study the complex erosion-corrosion mechanism of friction stud welded joints in seawater, experiments were carried out in the mixed solution of 3 wt% sea sand and 3.5% NaCl at flow rates of 0 m/s, 0.2 m/s, 0.4 m/s, and 0.6 m/s. The effects of corrosion and erosion-corrosion at different flow rates on materials were compared. The corrosion resistance of X65 friction stud welded joint was studied by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) curves. The corrosion morphology was observed by a scanning electron microscope (SEM), and the corrosion products were analyzed by energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The results showed that the corrosion current density decreased first and then increased with the increase in the simulated seawater flow rate, which indicated that the corrosion resistance of the friction stud welded joint increased first and then decreased. The corrosion products are FeOOH (α-FeOOH and γ-FeOOH), and Fe3O4. According to the experimental results, the erosion-corrosion mechanism of friction stud welded joints in seawater environment was predicted.

Evaluation of the seismic performance of butt-fusion joint in large diameter polyethylene pipelines by full-scale shaking table test

High-density polyethylene (HDPE) pipelines in nuclear power plants (NPPs) have to meet high requirements for seismic performance. HDPE pipes have been proved to have good seismic performance, but joints are the weak links in the pipelines, and pipeline failures usually initiate from the defects inside the joints. Limited data are available on the seismic performance of butt-fusion joints of HDPE pipelines in NPPs, especially in terms of defects changes inside the joints after earthquakes. In this paper, full-scale shaking table tests were performed on a test section of suspended HDPE pipelines in an NPP, which included straight pipes, elbows, and 10 butt-fusion joints. During the tests, the seismic load-induced strain of the joints was analyzed by strain gauges, and it was much smaller than the internal pressure and self-weight-induced strain. Before and after the shaking table tests, phased array ultrasonic testing (PA-UT) was conducted to detect defects inside the joints. The locations, numbers, and dimensions of the defects were analyzed. It was found that defects were more likely to occur in elbows joints. No new defect was observed after the shaking table tests, and the defects showed no significant growth, indicating the satisfactory seismic performance of the butt-fusion joints.

Study on stress asymmetry of pipeline welded joint in mountainous areas with large slopes

Residual stress strongly influences the safety of welded joints of pipelines in mountainous areas with large slopes. But there isn't an effective calculation model. This paper bases on the Thermal-Metallurgic-Mechanical (TMM) method and establishes the calculation model to study the thermal, microstructure, and stress on X70 pipeline welded joints in mountainous areas with a slope of 25°. A series of simulation cases are conducted to explore the mechanism of stress distribution based on this model. Both the hole-drilling method and the coercive method are used to ensure the error is within 10 %. Compared with the pipeline without slope, the stress distribution of pipelines with large slopes is asymmetric, which is, the heat source deflection and axial force lead to the stress of the higher side is 75 MPa higher than that of the lower side. Furthermore, through the theory of thermal and stress evolution, this paper reveals that the heat source deflection is the initial force, and the axial force is the driving force of the stress asymmetry distribution.

Structural design and strength analysis of the calorimeter pipeline joint for the negative neutral beam injection system of China fusion engineering test reactor

The negative ion-based neutral beam injection (NNBI) verification prototype system is one of the core components of China Fusion Engineering Test Reactor (CFETR). To effectively cut off the beam and debug the neutral beam device, the power measurement system plays an indispensable role. In this study, we examine the detailed design of the pipeline joint structure of the calorimeter verification prototype, focusing on the impact of the structural design of the target panel pipeline joint on the structural strength and manufacturing process required by the cooling circular pipeline joint of the calorimeter. Based on this, the manufacturing process and strength of the integrated pipeline structure of the target panel are inspected under a design pressure of 4 MPa, including theoretical analysis of the integrated pipeline pressure-bearing structural design, welding technology design, and finite element simulation under high pressure. Accordingly, the feasibility of the final manufacturing scheme and key technologies are analyzed. The pressure test of the sample under an internal N2 pressure of 4 MPa verifies that its structure can meet the design requirements, thereby providing reference for the effective structural design and manufacturing of the NNBI calorimeter prototype.

Numerical Simulation of Assembly Process and Sealing Reliability of T-Rubber Gasket Pipe Joints

Underground pipelines are vital parts to urban water supply, gas supply, and other lifeline systems, affecting the sustainable development of cities to a great extent. The pipeline joint, which is a weak link, may be seriously damaged during natural disasters such as earthquakes. The failure of pipe joints can cause leakage accidents, resulting in system failure and interruption, and even some secondary disasters. Herein, based on uniaxial and plane tensile test results of a T-rubber gasket material, the assembly process and sealing performance of a T-rubber gasket joint of a ductile iron pipe are numerically simulated using the Ogden third-order strain energy density function to fit the material constant. The simulation accounts for severe nonlinearities, including large deformations, hyperelasticity, and complex contacts. The effects of the assembly friction coefficient, assembly depth, and radial clearance deviation of the socket and spigot on the seal contact pressure are analyzed. The results suggest that the entire history of the deformation and stress variations during assembly can be clearly visualized and accurately calculated. For the different friction coefficients, the assembly depth corresponding to the sliding friction condition of the spigot pipe was 74 mm, while the minimum pushing force required to assemble the T-rubber gasket joint of a DN300 ductile iron pipe was 6.8 kN at the ideal situation with a friction coefficient of 0. The effective contact pressure of the rubber gasket seepage surface under various operating conditions is much higher than the normal pressure of municipal pipelines, thus indicating that the rubber gasket joint exhibits the ideal sealing performance. Furthermore, a certain deviation, which is about 20 mm, is allowed for the assembly depth of the rubber gasket joint such that the axial displacement of the pipe joint can be adapted under an earthquake or ground displacement.

Effect of sensitization on service properties of welded joints of austenitic pipelines under operation conditions of RP RBMK 1000

In order to assess the effect of metal sensitization of welded joints of pipelines Du300 from austenitic steel on their service characteristics under the operating conditions of the RP RBMK 1000, samples were tested from steel grade 08Kh18N10T with a constant strain rate from 10 –7 to 10 –3 s –1 in high water parameters and analysis of changes in their properties.

SSWT-UUNet++ Submarine Oil Pipeline Spill Detection Approach

The existing leak detection methods of submarine oil pipelines mainly rely on compositing synthetic aperture radar (SAR) satellite images to detect oil spills on the sea surface or installing underwater cameras to monitor the joints of submarine pipelines manually. The former is poor in timeliness and high in cost, while the latter is inflexible. Aiming at this, this paper studies the underwater image processing method of intelligent oil spill recognition using an underwater camera. Nevertheless, this method is currently faced with challenges such as poor quality of datasets, unclear goals, and scarce quantity. The U-Net++ algorithm can theoretically reduce the dependence on the number of datasets. However, the pixel feature extraction method used by U-Net++ is difficult to achieve the segmentation effect of oil spill images, so a new network architecture SSWT (Suitable Superpixel With Texture)-UNet++ based on texture superpixel is proposed. In SSWT-UNet++, the input is the oil spill image with texture superpixel division, and the output was changed to the middle layer. In addition, the resolution of each layer and the ratio of up/down sampling were adjusted. This algorithm completes the classification of oil spill texture superpixels and finally realizes oil spill detection according to the minimum bounding rectangle of the classification result of the oil spill region. Experimental verification shows that the final detection effect of the proposed algorithm is higher than that of other algorithms, with an average precision of 0.985.

Features of ultrasonic testing of welded seams of pipes made of multilayer polyethylene

The quality control of welded joints of multilayer polyethylene pipelines made by butt welding with a heated tool is considered. It is shown that in addition to the control of welding parameters and selective mechanical testing of seams, it is advisable to use non-destructive ultrasonic testing, which makes it possible to detect such defects as cracks, solid inclusions, and pores. Examples of using a chord scheme of ultrasonic testing to detect model defects with a diameter of 1 mm are given. Keywords:welding seam, pipe, polyethylene, multilayer material, defect, chord scheme. aleshin@bmstu.ru, shchipak@bmstu.ru, N. A. Semenov@ck-cwd.ru