Small Diameter Pipes Research Articles

Applicability evaluation technology for steel small diameter pipes containing external surface corrosion defects

With the continuous operation of oil and gas stations and petrochemical equipment, it has been found that steel small bore pipelines have different degrees of corrosion defects, which have led to pipeline cracking and medium leakage, and have increasingly attracted great attention of their oil and gas and chemical enterprises. In order to ensure the safe operation of the small diameter pipes with external surface corrosion defects, the influence law of the size of corrosion defects on the bearing capacity of the small diameter pipes were studied by finite element analysis and test simulation method, and the damage mechanism and failure form were analyzed, and the failure pressure prediction formula of the small diameter pipes with defects was fitted. It provides technical guidance for the applicability evaluation of corrosion-containing steel small diameter pipes in oil and gas chemical stations or installations.

Development of the technology of pressure welding with a magnetically impelled arc of small-diameter pipes using supercapacitors

Development of the technology of pressure welding with a magnetically impelled arc of small-diameter pipes using supercapacitors

Analytical relations for fields and currents in magnetic-pulsed «expansion» of tubular conductors of small diameter

Introduction. This work was initiated by the problems of cardiovascular diseases, which are one of the main causes of mortality of the population of our planet. More than ten years ago, in 2012, approximately 3.7 million people died of acute coronary syndrome worldwide. The fight against such pathologies is carried out with the help of so-called stents, the manufacture of which can be carried out by the method of magnetic pulse «expansion» from hollow metal cylinders. The limited production possibilities of magnetic pulse «expansion» were caused by the minimum cross-sectional size of the inductor-instrument, which can be practically manufactured. Other tools are required to perform this operation. Novelty. A system of magnetic-pulse expansion of thin-walled pipes of small diameter with an inductor that excites an azimuthal electromagnetic field in the case of direct current passing through the processing object and in the absence of its connection in an electric circuit with an inductor is proposed. Purpose. The main analytical dependencies for the characteristics of the electromagnetic processes taking place in the inductor systems for the expansion of cylindrical conductive pipes of small diameter when direct passage of current through the processed object and when it is not connected to an electric circuit with an inductor (insulated billet) is derived. Methods. The solution of the boundary value problem with given boundary conditions was carried out by applying Laplace transforms and integrating Maxwell’s equations. Results. Analytical expressions were obtained for the main characteristics of the processes: the intensities of the excited electromagnetic fields and currents in the system depending on the parameters of the studied systems. The analysis of possible technical schemes for solving the given problem indicated the choice of the optimal variant of an effective system of magnetic-pulse «stretching» of thin-walled cylindrical conductors of small diameter. Practical value. Based on the qualitative analysis of the obtained results, recommendations for the practical implementation of the proposed system were formulated. The obtained dependences allow us to give numerical estimates of the effectiveness of excitation of magnetic pressure forces on the object of processing and to choose directions for further improvement of the magnetic pulse technology for solving such problems. References 23, figures 2.

Image restoration of reflectors by the method of digital aperture focusing in thick-walled pipes of small diameter

In ultrasonic inspection of pipes of various diameters using antenna arrays and arrays, two technologies of reflector image reconstruction are widely used: antenna array focusing technology (PAUT) and digital aperture focusing (DAF) technology. If the tube diameter is larger than a hundred wavelengths, the DAF method can be used to reconstruct the reflector image by taking into account several reflections from the boundaries, assuming that the object of inspection is flat. In this case, the errors in the formation of DAF-image of reflectors will be insignificant. However, if the pipe diameter is several tens of wavelengths and the wall thickness is about half of the pipe diameter, then in this case the geometry of the inspection object must be taken into account to obtain a high-quality DAF-image of the reflectors. The paper considers the peculiarities of image formation at registration of echo signals by an antenna array or matrix, when scanning both on the external and internal surfaces of the object of control. In numerical and modeling experiments it is shown that both antenna array and antenna array can be used to obtain high-quality DAF-image of reflectors when scanning along the outer surface of a thick-walled pipe of small diameter. This is due to the presence of the effect of physical focusing of the ultrasonic field. But when scanning along the inner surface of a thick-walled tube of small diameter, because of the defocusing effect, it is necessary to register echoes with an antenna array to restore the image of reflectors.

Experimental study of oil-water two-phase flow patterns in a vertical large diameter pipe

The flow structure and the phase inversion have great influence on the flow measurement in vertical upward oil-water two-phase flow. This paper attempts to investigate the flow patterns in oil-water flows through a vertical upward large pipe with the designed mini-conductance array probes measurement system and the vertical multi-electrode array (VMEA) measurement system. According to the output waveform of the mini-conductance array probes, the oil-in-water flow, transition flow and water-in-oil flow can be identified effectively. The fluctuating signals of the VMEA is processed by the recurrence plot and the time-frequency representation, the results show that the VMEA conductance signal with average measurement characteristics can realize an effective identification of the above three flow patterns, which has a good agreement with the results of the mini-conductance array probes. Finally, via comparing with previous published flow pattern transition boundary models in different pipe diameters, it is founded that the boundary line of the transition to oil-in-water based on the kinematic wave-based model and the observation-based model in the same diameter pipe are consistent with our experimental data. And the pipe diameter affects the flow pattern transition, compared with the boundary in small diameter pipe, the phase inversion requires a larger oil velocity, and the transition zone becomes narrower in large diameter pipe.

Blockage dynamics in sewer pipes: investigating snagging, accumulation, and dissipation rates of wet wipes

ABSTRACT The increase in sewer blockages, exacerbated by the COVID-19 pandemic due to improper disposal of non-biodegradable items like wet wipes and sanitary products, along with fats, oils, grease, and the presence of defects in sewers, underscores the need for a more profound understanding of wipes’ contribution to these blockages. This study investigated the probability of wipe snagging on sewer imperfections and their subsequent accumulation and dissipation rates under various conditions through laboratory experiments. Findings indicated a significant variability in the likelihood of wipes snagging (ranging from 93% to 0) and accumulating (ranging from 71% to 0), which was influenced by the defect location and the sewer flow rate. Moreover, the study highlighted a direct relationship between the flow rate in the sewer and the rate at which wipes dissipate. Conversely, an inverse relationship was observed between the size of blockages and the dissipation rate of wipes, with larger blockages typically reducing the speed of this process. Importantly, while dissipation rates at low flow rates are nearly constant regardless of the number of wipes and duration, at medium to high flow rates, dissipation initially increases but levels off after 24 h, demonstrating the persistence of wipe-caused blockages in small-diameter sewer pipes.

Revealing flow structures in horizontal pipe and biomass combustor using computational fluid dynamics simulation

AbstractComputational fluid dynamics (CFD) is a powerful tool to provide information on detailed turbulent flow in unit processes. For that reason, this study intends to reveal the flow structures in the horizontal pipe and biomass combustor. The simulation was aided by ANSYS Fluent employing standard ‐ model. The results show that a greater Reynolds number generates more turbulence. The pressure drop inside the pipe is also found steeper for small pipe diameters following Fanning's correlation. The fully developed flow for the laminar regime is found in locations where the ratio of entrance length to pipe diameter complies with Hagen–Poiseuille's rule. The sucking phenomenon in jet flow is also similar to the working principle of ejector. For the biomass combustor, the average combustion temperature is 356–696°C, and the maximum flame temperature is 1587–1697°C. Subsequently, air initially flows through the burner area and then moves to the outlet when enters the combustor chamber. Not so for particle flow, the particle experiences sedimentation in the burner area and then falls as it enters the combustor chamber. This study also convinces that secondary air supply can produce more circulating effects in the combustor.

Effect of contact blast loading on the plastic deformation forming ability of large steel pipes

Plastic deformation forming with metal pipe blanks by contact blast loading inside pipes is an interesting moldless forming technique, also a complex and error-prone process. Some advantages are very characteristic of this forming technique such as no cost of mold, tooling and low energy consumption, no complicated control equipment compared to other forming techniques such as casting, rolling, tube hydrostatic forming, bending – welding. Up to now, the calculation and design of this forming technique mainly use some existing reference empirical formulas, so the experimental results are only suitable in the range of small pipe diameters, and still there are significant deviations for larger pipe diameters. In order to increase the predictability and accuracy of forming process by contact blast loading inside large pipes, this paper presents a study on the influence of the mass of highly explosive material – TNT to the forming ability of large steel pipes from API-5LX-42 mild steel materials by modern 3D numerical simulation – using Abaqus/Cae software. Four output criteria with maximum values are used to evaluate the efficiency of this forming process, including maximum diameter of the blast zone (Dmax£2D0), Von Mises stress (Smax£UTS), Hoop plastic strain component (PE22max£1), and Pipe wall thinning rate (eT-max£60 %). The results of this research on the plastic deformation forming process using numerical simulation can be used for the next experimental step to evaluate the difference between simulation and experiment, as well as use this data in the calculation and design of pipe products with circular or square cross-sections to save both time and money of trial and error before application in actual manufacturing

Compressive load analysis of mechanical setting process of test string Packer in Ultra-high-pressure Gas Wells

ABSTRACT To address the packer setting problems under complex operating conditions in ultra-high pressure gas wells, a mechanical analysis model for the mechanical setting process of packer in ultra-high pressure gas wells is established. The model takes into account factors such as wellbore trajectory, bending moment, internal and external fluid pressure, and the coupled effect of axial load, frictional resistance and buckling. The established model can be used to calculate the axial force of tubing string in ultra-high pressure gas wells, and analyze the effects of the tubing string length below packer, line weight combination, friction coefficient and the released wellhead suspended load on the packer setting force. The case calculation and parameter sensitivity analysis indicate that the original design of a high-pressure gas well cannot meet the requirements of packer setting. The setting performance of the packer can be effectively improved by adjusting the released wellhead suspended load, optimizing the tubing string length below the packer, reducing the friction coefficient and optimizing the length configuration of tubing string with small diameter. An increase in wellhead release weight by 60 kN was accompanied by a corresponding increase in packer pressure of 12.48 kN. When the lower string length was extended by 600 m, the packer weight without suspension was reduced by 65.34 kN, whereas the packer weight with release was diminished by 21.69 kN. Furthermore, an augmentation in the friction coefficient by 0.15 resulted in a decrease in the pressure weight of the packer under release suspension by 55.79 kN. Additionally, a reduction in the small pipe diameter length by 1000 m caused an increase in the packer weight with a release load of 17.98 kN. The research content not only provides theoretical guidance for the long-term safety of test string in high-pressure gas wells, but also offers practical insights for the design and operation of packers.

Numerical analysis of the effect of hydrogen doping ratio on gas transmission in low-pressure pipeline network

In the context of a global shift towards clean energy, the integration of hydrogen into existing natural gas pipeline networks is essential for facilitating the energy transition. Specifically, low-pressure natural gas pipeline networks are crucial for transporting gas efficiently and with minimal losses from the source to end-users in nearby cities. The physical properties of hydrogen differ significantly from those of natural gas, which implies that introducing hydrogen into the pipeline network will modify operational parameters and impact the safety and efficiency of gas transmission. Therefore, this study concentrates on the efficiency of transporting and scheduling hydrogen-blended natural gas through existing low-pressure direct pipelines. Utilizing the BWRS (Benedict-Webb-Rubin-Starling) equation of state, mathematical models were developed to calculate gas properties and to simulate both the steady and transient states of hydrogen-blended natural gas networks. These models were then validated with TGNET software. This study examines a low-pressure natural gas transmission and distribution network that transports gas directly from a production site in Sichuan to urban areas. It conducts simulations of hydrogen blending and analyzes the impact of various hydrogen blend ratios on the transport and scheduling responses of the network. Research suggests that maintaining the hydrogen blend below 30% ensures the safe operation of low-pressure gas pipelines and prevents the transmission pressure from exceeding 3 MPa. Additionally, under a fixed energy flow output, blending hydrogen intensifies the challenges associated with pressure drops and temperature increases due to high flows in small diameter pipes, and further complicates the management of interruptions resulting from faults. Therefore, it is recommended that the hydrogen blend ratio be maintained at no more than 30%, and that accident handling procedures be established in advance to control pressure variations following a shutdown.

A defect contour imaging method of small diameter pipeline based on self-made three-dimensional magnetic sensor

PurposeThe purpose of this paper is to use the corresponding magnetic sensor and detection method to detect and image the defects of small diameter pipelines. Urban gas pipeline is an energy transportation tool for urban industrial production and social life, which is closely related to urban safety. Preventing the occurrence of urban gas pipeline transportation accidents and carrying out pipeline defect detection are of great significance for the urban economic and social stability. To perform pipeline defect detection, the magnetic flux leakage internal detection method is generally used in the detection of large-diameter long-distance oil and gas pipelines. However, in terms of the internal detection of small-diameter pipelines, due to the heavy weight, large structure of the detection device and small pipe diameter, the detection is more difficult.Design/methodology/approachIn order to solve the above matters, self-made three-dimensional magnetic sensor and three-dimensional magnetic flux leakage imaging direct method are proposed for studying the defect identification. Firstly, for adapting to the diameter range of small-diameter pipelines, and containing the complete information of the defect, a self-made three-dimensional magnetic sensor is made in this paper to improve the accuracy of magnetic flux leakage detection. And on the basis of it, a small diameter pipeline defect detection system is built. Secondly, as detection signal may be affected by background magnetic field interference and the jitter interference, the complete ensemble empirical mode decomposition with adaptive noise method is utilized to screen the detected signal. As a result, the useful signal is reconstructed and the interference signal is removed. Finally, the defect contour inversion imaging of detection is realized based on the direct method of three-dimensional magnetic flux leakage imaging, which includes three-dimensional magnetic flux leakage detection data and data segmentation recognition.FindingsThe three-dimensional magnetic flux leakage imaging experimental results shown that, compared to the actual defects, the typical defects, irregular defects and crack groove defects can be analyzed by the magnetic flux leakage defect contour imaging method in qualitative and quantitative way respectively, which provides a new idea for the research of defect recognition.Originality/valueA three-dimensional magnetic sensor is made to adapt the diameter range of small diameter pipeline, and based on it, a small-diameter pipeline defect detection system is built to collect and display the magnetic flux leakage signal.

Magnetic Flux Leakage Defect Identification Method for Small-Diameter Pipeline Elbow Based on the Improved YOLOv5

Abstract The elbow is an important constituent of oil and gas pipeline systems and plays a key role in changing the direction of pipelines. Corrosion defects pose a significant risk to the safe operation of elbows. Magnetic flux leakage (MFL) detection has been developed as a suitable technique for identifying defects in pipelines. To address the distortion of elbow defect signals in the images arising from variations in the liftoff value of the leakage detector, this paper proposed an image identification method based on an improved YOLOv5 network. The differences in defect images are simulated by analyzing the liftoff value of the magnetization unit. A defect image enhancement method of multiscale retinex with color restoration fusion homomorphic filtering (MSRCR-HF) is employed to enhance the features of defective MFL signal images. To further improve the accuracy of the model, the YOLOv5 network is optimized by integrating the convolutional block attention module (CBAM) and the space-to-depth-nonstrided convolution (SPD-Conv) module. The results show that the proposed image enhancement method effectively accentuates the features of defect images. Moreover, the suggested image identification method exhibits superior accuracy in identification. The mean average precision (mAP) values for the original image set and the enhanced image set are 85.0% and 91.4%, respectively. Consequently, the proposed method is shown to be highly viable for the automatic identification of MFL defects in small-diameter pipe elbows.

EDDY CURRENT QUALITY CONTROL OF THIN-WALLED REFRACTORY ALLOY PIPES

The experience of non-destructive quality control of thin-walled pipes of small diameter from a refractory non-magnetic alloy based on eddy current and X-ray television methods is considered. An analysis of the signal of an eddy current differential transducer during scanning of defects of various types was performed. The possibility of detecting and classifying such pipe defects as cracks, pores, local wall thinning, and ferromagnetic inclusions is shown.

Experimental Evaluation of an Empirical Equation in a Gaseous Flow

In this paper, the estimation error of Dr. Pole's empirical equation was evaluated using copper pipes of different diameters (0.00953, 0.0127, 0.01588 m), under different flow pressure conditions (0, 300, 500, 1000, 1500, 2000, 2500, 3000 L/h). To carry out the experiments, the following instruments were used: an air compressor, 2 flow valves, a needle valve, a gas rotameter, copper piping, pressure gauges and transmitters, a Norus data logger with 4 to 20 mA output signals, thermocouples, and thermoresistors. They allow us to establish that the air pressure drops when the flowing through the pipes is higher (380 Pa) for small diameter pipes (0.00953 m), compared to larger diameters (0.01270 m and 0.01588 m) with a maximum of 54 and 28 Pa, respectively; and in relation to the flow rates, the pressure drop increases with a quadratic trend with respect to the flow rate. Finally, the residual errors that the empirical equation has in the pressure drop calculations, in general terms, are not of great magnitude.

Multi-gait snake robot for inspecting inner wall of a pipeline

In the field of pipeline inner wall inspection, the snake robot demonstrates significant advantages over other inspection methods. While a simple traveling wave or meandering motion will suffice for inspecting the inner wall of small-diameter pipes, comprehensively and meticulously inspecting the inner wall of large-diameter pipes requires the snake robot to adopt a helical gait that closely adheres to the inner wall. Our review of existing literature indicates that most research and development on the helical gait of snake robots has focused on the outer surface of cylinders, with very few studies dedicated to developing a helical gait specifically for the inspection of the inner wall of pipes. Therefore, in this study, we propose a helical gait that is suitable for the inner wall of pipes and meets the requirements of gas pipeline engineering. The helical gait is designed using the backbone curve method. First, we create a mathematical model for a circular helix curve with constant curvature and torsion, ensuring it is applicable to a snake robot prototype in a laboratory environment. Subsequently, we calculate the joint angles required for two conical spiral curves with variable curvature and torsion, establish a new model, and define the physical significance of the specific parameters. To ensure the feasibility of the proposed gait, we conduct experiments involving meandering and traveling wave motions to verify the communication and control between the host computer and the snake robot. Building upon this foundation, we further validate the mathematical model of the complex helical motion gait through simulation experiments. Our findings provide a theoretical basis for realizing helical movement with a real snake robot.

Establishment of rigid-flexible coupling model of leaf spring detector detection arm and the optimization of its accuracy

A pipeline through-diameter detector is vital in pipeline detection. Still, the commonly used through-diameter detector is a generally complex structure, sizeable structural size, not suitable for small pipe diameters, significant deformation of the pipeline, as well as high-precision detection requirements (Zhang et al., 2019). In this paper, the rigid-flexible coupling system and accuracy optimization of the detection arm of the leaf spring detector is proposed to improve the detection accuracy under the rigid-flexible coupling state. Under the condition of rigid-flexible coupling, the process and stage of over-convex defects are studied, the effects of different motion speeds, different preload forces, and different defect L/D ratios on the detection accuracy are analyzed, and the fitting values of the defects of the leaf spring detector detecting arm are obtained under the motion condition, which needs to be corrected for the right values to reduce the error and improve the detection accuracy under the condition of rigid-flexible coupling.

Design and experimental study of electromagnetic ultrasonic single-mode guided wave transducer for small-diameter stainless steel tubes

ABSTRACT Small-diameter stainless steel pipes find widespread application in nuclear power systems. In order to detect surface axial wear defects that may occur during their service life, a circular fully enclosed probe has been developed for inspecting these small-diameter stainless steel pipes. The probe is composed of a periodic permanent magnet (PPM) and a racetrack-shaped coil. Through the optimised design of the PPM structure, two probes were devised to excite single flexural and single torsional modes, respectively. Furthermore, employing the non-equivalent concept, the torsional mode guided wave probe underwent optimisation, resulting in a 54% increase in the received signal amplitude. Finally, two types of guided wave probes were utilised to conduct detection experiments on artificially induced defects in an outer diameter 10 mm sample pipe. The results indicate that both T(0,1) and F(1,2) mode guided waves can detect axial defects. Moreover, the detection amplitude of the T(0,1) mode guided wave surpasses that of the F(1,2) mode guided wave by a maximum of 53%.

A Gas Flow Measurement System Based on Lead Zirconate Titanate Piezoelectric Micromachined Ultrasonic Transducer.

Ultrasonic flowmeter is one of the most widely used devices in flow measurement. Traditional bulk piezoelectric ceramic transducers restrict their application to small pipe diameters. In this paper, we propose an ultrasonic gas flowmeter based on a PZT piezoelectric micromachined ultrasonic transducer (PMUT) array. Two PMUT arrays with a resonant frequency of 125 kHz are used as the sensitive elements of the ultrasonic gas flowmeter to realize alternate transmission and reception of ultrasonic signals. The sensor contains 5 × 5 circular elements with a size of 3.7 × 3.7 mm2. An FPGA with a resolution of ns is used to process the received signal, and a flow system with overlapping acoustic paths and flow paths is designed. Compared with traditional measurement methods, the sensitivity is greatly improved. The flow system achieves high-precision measurement of gas flow in a 20 mm pipe diameter. The flow measurement range is 0.5-7 m/s and the relative error of correction is within 4%.

Обследование скрытых участков стальных труб малого диаметра с применением ультразвуковой дефектоскопии

According to the current regulatory documents, as the established service life of gas pipelines for various purposes expires, they must be inspected in order to assess the current technical condition, make a decision on the residual life and the possibility of further operation at hazardous production facilities, as well as other buildings and structures. The possibility is considered related to using ultrasonic testing for detecting damage of corrosion origin in the sections of such pipelines hidden from the direct observation in interfloor ceilings and passages through the walls of buildings at the facilities in various branches of industries, as well as in gas distribution and gas consumption systems, and water pipelines. In addition, the possibility of identifying layered deposits of various origins in the cavity of small-diameter steel pipes is considered. At energy facilities, as well as in water supply pipelines, such deposits can lead to a significant reduction in the flow area of the pipeline, up to its complete blocking. Deposits inside the pipelines form an anisotropic layered medium, and the passage of ultrasonic waves through it has a number of features that prevent the use of traditional ultrasonic echo testing. For small-diameter pipes, the criterion is given under which it is possible to perform «remote» (waveguide) ultrasonic testing of the hidden sections of pipes at a distance of up to 600 mm. It is illustrated how, from such a distance, it is possible to detect corrosion deposits in pipes by ultrasonic testing methods using phased array antennas. At the same time, it is possible to assess the thickness («power») of layered deposits and their structure even when the passage section of the pipeline is filled with such deposits up to 100 %. Use of the methods presented in the article allows to increase the accuracy of calculating the residual life of the pipeline and reduce the uncertainty in setting safety factors in such calculations.

Comparing the results of testing a longitudinal tube weld by nondestructive methods

Defects of longitudinal tube welds identified by X-ray inspection are studied in order to determine possible causes of their occurrence and to assess the reliability of nondestructive testing results. Metallographic analysis shows that the base metal and weld metal meet the requirements of regulatory documents. The strength properties and the chemical composition conform to the standards. The contamination with non-metallic inclusions in the segregation streamers of the sheet extending to the edge and falling into the fusion zone was detected in X-ray photographs and incorrectly interpreted as a defect. This assumption is based on the correlation of X-ray patterns with the position of the grooves in the zones of the studied welded joints, but it ignores the results of studying by other nondestructive testing methods, and most importantly, it is not confirmed by metallographic studies. Neither were these defects found in the tubes during magnetic flaw detection by means of a UMD-101M device in the line of production of longitudinally electric-welded tubes. Erroneous defect identification during X-ray inspection happens in tube making. The results of the study show the expediency of the integrated application of different testing methods for a reliable assessment of the quality of tubes or pipes of both small and large diameters.