Inner Wall Of Pipe Research Articles

Identification of defects on the inner wall of water supply pipes based on the optimized residual network

ABSTRACT The urban water supply network is part of the infrastructure that sustains the economic and social functions of cities and regions. Timely inspection and maintenance of the network can effectively reduce resource wastage and prevent accidents. Traditional manual detection methods are inefficient and can be based on subjective judgments. A classification model based on an improved ResNet34 network has been proposed to classify and detect various types of corrosion on the inner walls of pipes under challenging conditions. The introduction of the attention mechanism and multi-scale feature fusion modules further improved the model's effectiveness in classifying defects within the inner walls of pipes. The model can detect various types of pipeline corrosion with a detection accuracy of 98.61%. This accuracy is significantly superior to that achieved with traditional models such as ResNet34, AlexNet, MobileNet, and VGGNet.

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.

The Design of A Robot for Laser Cladding of Inner Walls of Pipes

This paper presents a design scheme of an adaptive laser cladding robot for the inner wall of variable diameter pipes. The robot is in the shape of a capsule, with an adaptive walking system, a mechanical support and balance system, a laser cladding system and a water cooling system, which can achieve efficient laser cladding and strengthening of the inner walls of different pipes. Among them, innovative designs such as pressure overload protection device and beam focusing lens adjustment motor have significantly improved the stability and accuracy of robot operation. Compared with traditional equipment, the robot is simple in structure, easy to disassemble, reliable in performance, high in automation, easy to maintain, and low in energy consumption. It provides an effective solution for laser cladding of pipe inner wall under complex and changeable working conditions, and helps to promote the wide promotion and application of laser cladding technology.

Effect and influence mechanism of biofilm formation on the biological stability of reclaimed water

Microorganisms and sediments in reclaimed water adhere to the inner walls of pipes or water tanks, forming biofilms that support the continuous growth of microorganisms. These biofilms provide a protective barrier, shielding bacteria from disinfectants. This study investigated the impact of biofilms on bacterial growth and reproduction in reclaimed water and the factors limiting bacterial growth in reclaimed graywater (GMR) and reclaimed mixed wastewater (MWR). The results revealed that biofilm biomass gradually increased and reached a maximum value on Days 20–25, and the biomass of organisms continued to decrease after 40 days. Biofilms serve as a source of bacteria, continuously releasing them into reclaimed water systems. The presence of biofilms reduced the biological stability of the reclaimed water, leading to water quality deterioration. The concentration of assimilable organic carbon in the reclaimed water showed a positive correlation with the heterotrophic bacterial count and Escherichia coli levels in both the reclaimed water and biofilms. The threshold value of chlorine for inhibiting biofilms in reclaimed water was no <2 mg/L. High concentrations of free chlorine delayed the growth of biofilms but did not reduce the final biomass generated by the biofilms. Carbon was the limiting factor for the biological stability of reclaimed water, while nitrogen, phosphorus, and inorganic salts were not limiting factors. Thus, minimizing the concentration of organic matter in reclaimed water can reduce the nutrient sources available for biofilm formation. This study provides support for advancements in the wastewater reuse industry.

Micro characteristics and macro performance of HR3C/T92 steel joints after 100000 hours service at high temperature

In this study, HR3C/T92 dissimilar steel joint samples were taken from ultra-supercritical 1000 MW units of domestic power plants, and the microstructures, tensile property, hardness, and antioxidant performance as well as safety assessment of the welded joints were studied using OMR, SEM, UTM, and other equipment. The results reflected that the micromorphology characteristics and hardness of HR3C/T92 dissimilar steel joints are unaffected after 100000 hours of service. Nevertheless, tensile and impact tests revealed that the joints are prone to brittle fracture. Tensile fracture occurred on the weld fusion line of T92 steel, and the impact absorption energy was lower than the standard requirements. HR3C steel exhibited superior oxidation resistance and corrosion resistance. Moreover, there was no observable oxide layer on the inner wall of the pipe, and the outermost layer of the outer wall had an intact structure. The inner wall of the T92 steel pipe had a 300-μm-thick oxide layer comprising Fe2O3 and (Fe, Cr) oxides. The extrapolated performance of the dissimilar steel joint samples after operation for 200000 hours at high temperatures also met the service requirements.

Optimization of Plating Process on Inner Wall of Metal Pipe and Research on Coating Performance.

An innovative brush plating process for preparing coatings on the inner wall of metal pipes is proposed, which aims to solve the limitations of current electroplating technology and improve the performance of the inner walls of metal pipes. While optimizing the process, the effect of working voltage on the microhardness, thickness, surface morphology, corrosion resistance, and elastoplasticity of the Ni coating on the inner wall of the tube was studied under the new process. The results indicate this technique can produce high-quality coatings on the inner wall of pipes in a simple and efficient manner. As the working voltage increases, the surface quality and comprehensive performance of the coating show an increasing trend followed by a decreasing trend. At 12 V, the coating exhibits the highest surface density and uniformity, the lowest surface roughness, the best corrosion resistance, and the maximum microhardness of 575.8 HV, with a corrosion current density of 1.040 × 10-5 A·cm-2, a corrosion rate of 0.122 mm·a-1, the maximum elastic recovery ratio he/hmax of 0.36, and the best deformation resistance. This study demonstrated the effectiveness of this method in improving the durability and functionality of metal pipes and its potential for various industrial applications.

Small-Diameter Tube Wall Damage-Detection Method Based on TE01 Mode Microwave.

Accidents occur frequently in urban gas pipelines, and pipeline damage detection is an important means of ensuring pipeline safety. Aiming at the problem that the small diameter pipeline is difficult to detect, this paper proposes a detection method for the inner wall damage of a small-diameter pipeline based on the TE01 mode microwave and uses the TE01 mode to detect the inner wall damage of the pipeline by the terminal short-circuit reflection method. By analyzing the transition of microwave propagation mode at the defect, based on the Maxwell equation and the field distribution equation of the TE01 mode microwave in the pipe and the pipe wall current equation, the microwave reflection coefficient at the defect is established when the microwave distortion modes at the defect are TE and TM modes. A small-diameter pipeline simulation model is established, and the influence of the electric field, magnetic field, wall current distribution, and reflected wave reflection coefficient in the pipeline when inner wall defects of different widths are analyzed using the finite integral theory during microwave detection of the TE01 mode. An experimental platform for the microwave detection of small-diameter pipes was built to detect defects on the inner walls of pipes with different widths. The results show that the inner wall defect causes the electric field, magnetic field, current propagation period, and energy distribution of the TE01 mode microwave propagated in the pipe to be distorted, and the microwave reflection coefficient and return loss exhibit a significant frequency shift with the change in the defect width. The experimental and simulation results had a good consistency.

Influence of the thickness of the layer of internal deposits in pipelines of water supply and discharge systems on their remaining service life

Introduction. The practical operation of water supply networks, made of steel and gray cast iron, has proven that deposits accumulate on the inner surface of pipes under certain conditions. Deposition depends on the quality of transported water and the water flow regime, same as in gravity sewerage networks. A sediment layer accumulates in the flume of pipes if the actual flow rate is smaller than the minimum standard one. A layer of deposits in metal water pipes changes the value of the actual inner diameter of pipes and rises the pressure loss due to resistance along the pipeline length, which contributes to an increase in the energy consumption by the pumping equipment and affects the pressure value at the end point of a network. A layer of sediment in the flume of a gravity drainage network also rises losses along its length, slows down the flow rate and may block the water flow in the network. The purpose of the study is to find dependence between the remaining service life of water supply and sewerage networks, having internal deposits, and the thickness of the layer of deposits on pipe walls. Materials and methods. The authors use the dependences, that they have already derived for the hydraulic analysis of metal water supply networks and gravity sewerage networks, having internal deposits. Results. The authors have identified dependence between the remaining service life of water supply pipelines and sewerage systems and the thickness of deposits on the inner walls of pipes. Examples, confirming such a relationship, are provided. They are substantiated by graphs showing dependence between the remaining service life and the thickness of the layer of deposits in pipelines. A hydraulic criterion is proposed for projecting the term of operation of water supply and sewerage networks with internal deposits. Conclusions. The authors have proven the need to use special tables to analyze the characteristics of pipes within the framework of a hydraulic analysis of water supply and sewerage networks, having internal deposits.

Research on Turbulent Drag Reduction of Surfactant-Polymer Mixed Solution Using Flow Visualization Technique

Objective: To explore the drag reduction effect of surfactant-polymer composite system in a turbulent flow. Methods: The turbulent drag reduction experiment of the one-component solution and the composite solution was carried out in a rectangular pipeline platform, respectively. Moreover, Particle Image Velocimetry (PIV) was utilized to measure the turbulent flow field of the drag-reducing flow. Results: Experimental results show that the composite drag reduction system has a drag reduction gain effect in comparison with the one-component surfactant or polymer solution. Especially in the destroyed drag reduction zone, the composite drag reduction system has a strong shear resistance. When Polyacrylamide (PAM) is added, the Reynolds drag reduction range of Cetyltrimethylammonium Chloride (CTAC) solution is broadened and the drag reduction gain efficiency reaches 46%, which will provide favorable conditions for oil transportation and other industries. Conclusion: Compared with a one-component CTAC solution, the mean velocity distribution of the composite solution moves up in the logarithmic-law layer, the velocity fluctuation peaks of the streamwise direction shift away from the inner wall of pipe, and the inhibition degree of the normal velocity fluctuation increases with the augment of PAM concentration. In contrast with water, the Reynolds shear stress of one-component CTAC solution and composite solution is reduced significantly, and the vortex structures in the region near the wall are suppressed dramatically with the decrease of vorticity intensity.

Assessment of stress distribution in premium connections with ultrasonic phased array and metal magnetic memory

The strength and sealing performance of premium connections in high temperature-high pressure (HTHP) gas well is one of the key factors for the integrity of wellbore, in which, the distribution of contact stress is the guarantee of metal-to-metal seals, while the stress distribution will affect the strength on the threaded connection. This paper explained the ultrasonic phased array (UPA) detection for contact stress of sealing surface and metal magnetic memory (MMM) detection for thread stress. The magnetic-acoustic detection test of the full-scale joints was carried out during make-up, with signals characterized the stress changes in the premium connections under the torque, the detection was also carried out during axial tension, with the contact stress of sealing surfaces quantitatively characterized by the reflection coefficient of sealing surfaces and the peak echo ratio between sealing surfaces and the inner wall of pipe. The variation of tangential component of magnetic field intensity has the same trend with that of threaded connection stress, which is linearly related to the change of contact stress in metal-to-metal seals. These findings show that the combination of UPA and MMM provides a reliable detection method for performance assessment on premium connections, both in quality control and in its field inspection.

Measurement of Gas Holdup in Oil-Gas-Water Flows Using Combined Conductance Sensors

In this study, a new method for gas holdup measurement in water continuous oil-gas-water multiphase flow based on conductance sensors is proposed. This method includes the use of the combined conductance sensors and the establishment of gas holdup model. A cross-sectional type conductance sensor is applied to acquire the conductivity of oil-gas-water mixture. For the purpose to derive gas holdup from the mixture conductivity, a novel liquid conductivity sensor which has shallow detection depth is proposed and it is flush-mounted on the inner wall of pipe to detect the liquid conductivity. The performances of the cross-sectional type conductance sensor combined with the liquid conductivity sensor are evaluated by experiments. And the results indicate that the liquid conductivity sensor can online detect the liquid conductivity in the multiphase mixture effectively. Based on the measured conductivity of multiphase mixture and the conductivity of liquid, the normalized conductivity which is related to the gas holdup is defined. The gas holdup model based on flow structures is investigated and established, and finally the measurement of gas holdup independently of salinity in oil-gas-water multiphase flow based on the conductance method is achieved for the first time.

Developments in how the boundary layer lower the pipe drag reduction in transport of dense paste

AbstractWall slip phenomenon occurs near the inner wall of pipe when dense paste is transported, and it reduces the frictional resistance loss and saves energy. To determine how the boundary layer influences the flowing law, more pipe transporting tests have been performed. Taking coal slime as test material, water and PEO (plasma electrolytic oxidation) were injected into the boundary layer part. Many factors, such as mass concentration, pipe diameter, flow velocity, boundary layer thickness, were systematically studied on their changes influencing pressure loss. The pressure loss decreases exponentially with the increase of boundary layer thickness. Drag reduction effect of PEO as the injecting liquid is better than water, and the pressure loss declines about 20%. The smaller the pipe diameter, lower flow rate, and the more obvious the drag reduction effect will be.

Analysis on the cause of crack in connection pipeline of subcritical boiler reheater

Several coal-fired thermal power boilers with the same sub-critical parameters in Mengxi area of Inner Mongolia have successively suffered from cracking and leakage failure events of reheater connecting pipes, most of which occur at chamfered back tool grooves on the inner wall grooves of pipe welding joints. In order to find out the cause of cracking, typical failure samples were intercepted for macro-morphology, microscopy, SEM, chemical composition, mechanical properties, wall thickness measurement analysis and design and operation data investigation of several boiler equipment. The results show that comprehensive factors such as deviation of burning coal type from design of boiler, automatic dispatching of AGC load in power grid, low nitrogen combustion modification and so on cause changes in boiler combustion conditions and operation, which results in excessive high input level of reheater cooling water, resulting in long-term alternating thermal stress and non-periodic vibration of straight pipe and elbow arranged after fine-tuning of refrigerant flow direction in reheater. Finally, thermal fatigue cracks are induced to initiate and propagate through the stress concentration area of the chamfered knife groove of the inner wall of pipe welded joints.

Developing an adaptable pipe inspection robot using shape memory alloy actuators

To detect and repair the faults existing in pipes and narrow ducts in the industry, access to the inside of these pipes is often required. In this article, the conceptual design for a miniature robot for inspecting the inner walls of pipes is presented, such that the proposed robot can operate adaptably and freely in vertical, inclined, and bent paths. The robot utilizes a simple mechanism based on shape memory alloy actuators for adjusting the contact force between the robot and the inner wall of the pipe. Use of shape memory alloys as actuators for the adaptive part will result in a smaller and lighter robot, further increasing its mobility in narrower ducts. Modeling, simulation, and control of the proposed system is conducted and simulation results are validated by performing practical laboratory experiments on a built prototype.

Influence of obstacles on the wall heat transfer for 2D and 3D helically ribbed pipes

Obstacles placed on the inner walls of pipes lead to flow separation and subsequent reattachment with an overall beneficial effect on the local heat transfer. In this work, the effects of both a continuous and a discontinuous helicoidal turbulator on the local heat transfer are investigated and compared for Reynolds numbers in the range from 20,000 to 80,000. Both turbulators are cylindrical helixes with constant angle and fixed direction. The continuous geometry has a pitch-to-diameter-ratio (p/D) equal to 11, an inclination angle of 80° and a uniform obstacle height-to-diameter-ratio (e/D) equal to 3.6%. The discontinuous geometry is equivalent to the continuous one except that it has a varying obstacle height throughout the helix. Steady-state heat transfer measurements are carried out by means of Liquid Crystals Thermography (LCT). A recently developed calibration method for the narrow-band Thermochromic Liquid Crystals (TLCs) is successfully modified to lower the angular effects on the measurement uncertainty. The local wall heat transfer rates and the temperature distributions are strongly influenced by the flow reattachment and thus by the geometry of the investigated turbulators. Compared to a smooth pipe at the same Reynolds number, the continuous and the discontinuous turbulator increase the average Nusselt number by factors of approximately 1.8 and 1.5 respectively. These heat transfer measurements with respective uncertainties are meant to be a valuable dataset for the validation of Large Eddy Simulations (LES) of turbulent flows in pipes equipped with turbulators.

Yield-strength prediction of flattened steel pipes by competing Bauschinger effect and strain hardening during pipe-forming

Since flattened steel sheets often show the unexpectedly lower or higher yield strength than leveled sheets, unceasing efforts have been made to accurately predict the yield strength in pipe-forming industries. In the present investigation, the yield strength of line-pipe or casing-pipe steels was predicted by competing Bauschinger effect and strain hardening occurred during the pipe-forming. Yield drop (YD) and yield rise (YR) parameters were newly defined from cyclic simulation analyses of outer and inner walls of pipes to express more reasonably the Bauschinger effect and strain hardening. The YD increased abruptly until the pre-strain of about 1%, and then saturated, while the YR increased linearly with increasing pre-strain. By combining the YD and YR, the variation in yield strength (Δσ) showed a down-and-up behavior as the Bauschinger effect and strain hardening were dominant at low and high pre-strains, respectively, and plausibly explained the relationship of Δσ and piping strain used in pipe-forming industries. According to the microstructural analyses related to the down-and-up Δσ behavior, the polygonal ferrite reduced the yield-strength reduction in the low pre-strain range, whereas the granular bainite or pearlite expanded it. This yield strength prediction coupled with microstructural analyses provide a good idea for designing and reliably predicting the yield strength of in various steel pipes.

Investigation of convection heat transfer coefficient of circular cross-section short pipes in hot stamping dies

Since the cooling system design in hot stamping dies is an important issue in hot stamping technology, the heat transfer characteristics between water flow and the inner wall of pipes becomes particularly important for its remarkable effect on hot stamping process. In order to investigate the heat transfer characteristics between H13 tool steel and the water flow in hot stamping dies, a self-developed Convection Heat Transfer Coefficient (CHTC) measuring equipment was established based on a circular cross-section short pipe model. To calculate the CHTC, an analytical calculating method named Fourier equation method based on experimental data and a numerical simulation method were introduced. To further investigate the influence of different factors including inlet fluid mass flow rate, inlet fluid temperature, inlet fluid turbulence intensity, pipe diameter, surface roughness and the furnace temperature on the CHTC, more numerical simulations were implemented, together with the ANOVA analysis. And results showed that the obtained simulation temperature field was in good agreement with the experiment, and the calculated CHTC values distilled from the simulation results were matched well with that of experiment, too. Moreover, all the investigated factors were found to have significant influence on the CHTC value, and the top three factors are inlet fluid mass flow rate, inlet fluid temperature and inner pipe surface roughness. Finally, a novel threaded pipe applied in hot stamping die was introduced derived from the ideal of improving inner pipe surface roughness, which was found to have much higher CHTC, the turbulence intensity along the cooling pipe could be promoted, which could help increase the heat transfer intensity as well.

A wheel-type in-pipe robot for grinding weld beads

To improve the safety and efficiency of polishing operations in circular boiler headers, a new type of wheel-drive polishing robot was developed in this study. The robot was designed to grind weld beads on the inner walls of pipes in diameter between 550 mm and 714 mm. The robot consists of a moving structure, a positioning structure, and a polishing structure. Charge coupled device (CCD) cameras and line lasers are used in the robot's vision system, thus the robot can be manually controlled to move, locate, and grind quickly and accurately. The experimental results showed that the robot performed well in practical applications.

Study of water quality in the distribution network of the centralized water supply system in the city of Lviv

The problem of water quality change in the distribution network of the centralized water supply system in the city of Lviv is considered, and some results of our research in this area are presented. The main purpose of the research is identifying the main factors of water quality change in the distribution network of the city. During the research, collection, analysis and synthesis of data on technological parameters of the distribution network were carried out, and the data of the analysis of eight water samples taken from residents in different districts of the city of Lviv were used. The results suggest that the increase in total hardness and alkalinity of water is caused by mixing of water from different water intakes in the distribution network; water oxidability growth - by probable accidents with entry of organic pollutants into the pipeline; increase in the concentration of total iron - by corrosion of long-life and great-length sites of the distribution network; reduction of free residual chlorine - by its spending on oxidation of chemicals contained in water and elimination of pathogenic microorganisms of biofilms on the inner walls of pipes. In some water samples, an excess of requirements of physiological full value of the mineral composition of drinking water by total hardness and probable value of solids, due to their increased values in the source water was observed. However, the values of water quality indices in the studied sites do not exceed the norms applicable to drinking water. To prevent the deterioration of the drinking water quality, and, therefore, the health of residents, the introduction of modern systems of monitoring and modeling of water quality change in the distribution network is recommended.

A novel radial anode layer ion source for inner wall pipe coating and materials modification--hydrogenated diamond-like carbon coatings from butane gas.

We report a new ion source development for inner wall pipe coating and materials modification. The ion source deposits coatings simultaneously in a 360° radial geometry and can be used to coat inner walls of pipelines by simply moving the ion source in the pipe. Rotating parts are not required, making the source ideal for rough environments and minimizing maintenance and replacements of parts. First results are reported for diamond-like carbon (DLC) coatings on Si and stainless steel substrates deposited using a novel 360° ion source design. The ion source operates with permanent magnets and uses a single power supply for the anode voltage and ion acceleration up to 10 kV. Butane (C4H10) gas is used to coat the inner wall of pipes with smooth and homogeneous DLC coatings with thicknesses up to 5 μm in a short time using a deposition rate of 70 ± 10 nm min(-1). Rutherford backscattering spectrometry results showed that DLC coatings contain hydrogen up to 30 ± 3% indicating deposition of hydrogenated DLC (a-C:H) coatings. Coatings with good adhesion are achieved when using a multiple energy implantation regime. Raman spectroscopy results suggest slightly larger disordered DLC layers when using low ion energy, indicating higher sp(3) bonds in DLC coatings. The results show that commercially interesting coatings can be achieved in short time.