Tube Wear Research Articles

Impact and tangential composite fretting wear of Zr-4 alloy tubes under random loading conditions

The fuel rod casing tube is a crucial component in pressurized water reactor (PWR) nuclear power plants. Flow-induced vibrations in the circulating water can result in complex alternating fretting wear between the casing tube and the positioning lattice frame. Existing research on fretting wear has primarily focused on unidirectional wear, with limited investigation into composite fretting wear under complex working conditions. This study conducted impact and tangential composite fretting wear tests on Zr-4 alloy tubes under varying constant and random impact loads to examine fretting wear behavior. The findings show that the peak friction coefficients in the impact and tangential composite fretting wear tests were consistent across the three constant load conditions, with higher peak friction coefficients observed under random load conditions and a longer time required to reach these peaks during micromotion tests. Comparative analysis revealed that random impact and tangential composite fretting wear caused the most severe damage. Under constant load conditions, wear damage became more severe with increasing load, transitioning from oxidized and adhesive wear to a peeling layer as the load intensified in the impact and tangential composite fretting wear tests.

Design and application of portable eddy current inspection device for thimble tubes of nuclear power plant

Abstract The Thimble tube is an important piece of equipment in the nuclear power plant; its role is to provide a neutron flux detector with a channel for the reactor fuel assembly. Eddy current detection is the main way to evaluate and track the wear of the thimble tube. In order to conduct more efficient detection of the thimble tube, this paper has carried out a series of studies on the mechanical device of the eddy current detection of the thimble tube and the software control system. The inspection system is compact, portable, and does not require an external power supply or gas source, making it easy to carry and operate. It is well-suited for promotion in various nuclear power plants.

Fretting wear behaviors of Cr-coated Zr–1Nb alloy cladding tube mated with Zr-4 alloy dimple under different tangential displacements

The fretting wear behaviors and wear mechanism of the Cr-coated Zr–1Nb alloy cladding tube mated with Zr-4 alloy dimple were investigated under different tangential displacements. With the increasing tangential displacement, the fretting running status changes from mixed fretting regime to gross slip regime, the friction coefficient increases first and then decreases, and the removed material volume, maximum wear depth, and wear coefficient of the Cr-coated Zr–1Nb alloy cladding tube increase. Fouvry's criteria were used to verify the correctness of the fretting running status. The primary wear mechanisms in the mixed fretting regime are adhesive wear and oxidative wear, while those in the gross slip regime are delamination wear and oxidative wear. The wear mechanism of the dimple is mainly delamination wear. Cr coating inhibits the wear of the cladding tube. After the coating is completely removed, the volume of material removed from the cladding tube increases dramatically, eventually exceeding the volume of material removed by dimple.

Assessment of increased tube life in boiler convection banks through commercially available tube coatings

The replacement cost of a boiler convection bank due to wear (erosion) is approximately AUD1mn, with a tube life of approximately 10–15 years using current protection technology (tube shields). Computational fluid dynamics (CFD) modelling has been used extensively to redesign convection banks to reduce tube wear and predict where tube shields should be located for new convection bank geometries. Tube coatings have been successfully applied in other industries to protect against erosion. They can also be applied in areas such as the superheater loops where the higher temperatures can cause problems for tube shields. The erosion performance of commercially available coatings applied by laser and thermal spray (high velocity oxy-fuel (HVOF) and twin-wire arc spray (TWAS)) processes was compared to that of bare tubes and tube shields, in both laboratory scale tests at the CSIRO Clayton facility and factory trials at Mulgrave Mill. The testing was supported by financial analyses at each stage of the project. A WearPro 62 (tungsten carbide) coating applied by laser was the best performer, with an expected coating life of approximately 18 years. The data were extrapolated to predict the coating life for convection banks with different gas velocities. There were also significant issues with the early failure of tube shields by mechanisms other than erosion. Such failures are of concern as many shielded locations in convection banks are difficult, costly or impossible to access once installed. Further assessment and improvement of the attachment of tube shields to tubes are required.

Prediction of Sucker Rod-tubing Wear Depth in Surface Drive Screw Pump Production Wells

With the wide application of ground drive screw pump in the process of oil production, the wear problem of screw pump sucker rod-tubing is becoming more and more prominent. In order to systematically study the wear of the rod and tube of the screw pump production well and quantify the wear of the rod and tube, this paper establishes a calculation model of the contact force of the screw pump sucker rod by analyzing the force of the rod and tube string in the three-dimensional wellbore trajectory. Based on the indoor rod and tube wear simulation experiment, combined with the wear efficiency theory, a prediction model of sucker rod-tubing wear under different working conditions was established, and an example well calculation was carried out. The results show that the force of sucker rod is mainly affected by sucker rod size, submergence degree and other factors, and the wear of sucker rod and tubing is mainly affected by working time, rotational speed and wear efficiency. The research results can not only accurately carry out accurate quantitative calculation of downhole rod and tube wear, but also provide theoretical and technical basis for prediction of rod and tube wear depth.

A Framework for Tool Condition Monitoring of Abrasive Waterjet Systems

The study presents an innovative method for developing a waterjet mixing tube process monitoring system, leveraging aluminium oxide abrasives for accelerated data collection. A novel method of recording data during the jet dwell cycle is proposed, which eliminates abrasive from the data collection step and allows for the mixing tube wear state to be predicted before machining takes place. Airflow sensors were shown to be capable of detecting changes in mixing tube exit diameter. The performance of machine learning models, utilizing airflow data, was compared against simpler models using wear time as a sole parameter. Both approaches were tested in their ability to predict the exit diameter and to classify the state of the tool. Although wear time-based models outperformed machine learning models in this study, their ability to adapt to process changes may be limited. Machine learning models, given a larger dataset, may be required for accurate wear detection. The research lays a promising foundation for developing a robust mixing tube monitoring system. Future work should focus on collecting more data, investigating the effect of mixing chamber and orifice wear on the airflow signal, and evaluating model performance trained with accelerated wear data, on tubes worn in a regular wear trial.

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.

Simulation of blast propagation and structural effects of accidental hydrogen-air-mixture explosion in a two-stage light-gas gun laboratory for hypervelocity impact experiments

Two-stage light-gas guns allow to accelerate projectiles up to velocities of several kilometers per second to conduct impact experiments. The projectile acceleration is obtained through a mechanism that relies on the expansion of a light gas, such as helium or hydrogen. Hydrogen allows to employ higher projectile velocities and masses than helium, together with lower wear of the launch tube. However, its use requires a thorough assessment of potential risks of explosion. In this work, we present a combined blast and structural numerical analysis to evaluate the effects of hydrogen deflagration as a consequence of accidental leakage scenarios during the operation of a two-stage light-gas gun. As a test case, we study the Large Gun operated at Fraunhofer EMI in Freiburg, Germany. The possible failure of non-structural elements, such as doors and windows, and the subsequent blast propagation into areas adjacent to the room hosting the facility are also accounted for. The simulation procedure presented in this work is scalable to similar and larger facilities for impact research as well as to other contexts involving analogous risks of gas explosions.

The effectiveness of protective layer in reducing fretting wear of Alloy 690TT tubes/ 405 stainless steel plates

Fretting experiments of Alloy 690TT tubes against 405 stainless steel (405 SS) plates were carried out to evaluate the influence of temperature on fretting performance of Alloy 690TT tubes in air. The results indicated that an adhesive and smooth protective third body layer was generated on Alloy 690TT tubes above a certain temperature, between 150 ℃ and 200 ℃ for given conditions. The protective layer was a mixture of oxides and transferred 405 SS, which was directly associated with fretting conditions. Thus, a wear transition map of Alloy 690TT was established. Besides, the results of this work also revealed that the plastic deformation of 285 ℃ was slighter than that of 150 ℃.

The transformation of fretting corrosion mechanism of zirconium alloy tube mating with 304 stainless steel in high temperature high pressure water

Studying the fretting wear mechanism of zirconium alloy in high temperature high pressure water is of great importance for understanding the failure behavior of fuel assembly. In this work, the tangential fretting wear of zirconium alloy tube at different displacement amplitudes (40 µm and 80 µm) and normal forces (6 N and 12 N) was investigated in high temperature high pressure water. The results show that the wear depth and wear volume of zirconium alloy tested at 6 N-80 µm are the highest among all the tests. When the testing condition is 6 N-80 µm, the fretting is located in the gross slip regime. Oxidation and abrasive wear dominate the fretting wear behavior. The increase in normal force and decrease in displacement reduces the relative sliding distance between the contact interfaces, which reduces the ejection of wear debris and changes the wear mechanism. When the test conditions are 6 N-40 µm and 12 N-40 µm, the fretting regime is located in the partial slip regime, and the dominant wear mechanisms are adhesive wear and oxidation. Under the synergistic effect of mechanical wear and high-temperature water corrosion, a dual-layer structure oxide scale is formed on the worn area. The mixed oxide layer with loose and porous structure is formed by the accumulation of granular wear debris, while the dense inner oxide layer is mainly formed by oxidation of the matrix alloy. Fretting wear accelerates material corrosion by wear debris refinement and cracking. The integrity of the oxide layer is negatively correlated with its thickness. As the thickness of the oxide layer increases, more cracks can be observed in the oxide layer.

MODELS AND METHODS FOR IMPROVING THE OPERATION OF THE ENERGY FACILITY CONTROL SYSTEM

This article is devoted to improving methods and models for a computer-integrated control system (CICS) that monitors the wear of heat exchange surfaces of pipes in steam boilers at coal-fired thermal power stations (TPP), in particular for coal with unknown abrasive composition. The system uses real-time coal quality data to 1manage the abrasive, optimize coal distribution, and verify coal quality to reduce costs. It is described that the difficulties faced by the global coal industry are related to quality, price and environmental issues, and the transition to sustainable energy is complicated by this diversity. Efficient power generation depends on accurate identification of fuel composition and minimizing damage from abrasive impurities in the fuel of heat exchangers. Despite the existing analytical methods, there is a need for improved diagnostic technology, which involves the integration of automated systems to improve efficiency and sustainability. The paper presents a mathematical model that calculates the effect of different types of coal and impurities on the wear of heat exchange tubes, maximizing service life and minimizing costs. It includes a Cochran sampling rule to improve coal quality control. An automated coal quality management method was also developed to reduce wear from abrasive coal impurities. It includes a stepwise supplier selection and stock utilization method, enhancing wear control using the Cochran stepwise sampling method. In addition, a fuzzy logic-based control device distributes the flow in such a way as to ensure satisfactory coal quality, emphasizing the need for continuous system monitoring. A model-based CICS has been developed that controls coal flow based on real-time impurity identification, resulting in significant cost savings and extended overhaul intervals. Computational experiments confirm that the CICS can more than double the service life of heat exchange tubes by maintaining a satisfactory thickness, thereby postponing repairs and reducing operating costs. Overall, this article presents a comprehensive approach to managing and optimizing heat exchanger tube wear at TPP using modelling, real-time data analysis, and automated control systems to improve efficiency and sustainability.

High Temperature Tribological Performance of Steel/Copper Friction Pairs Lubricated with a Modified C-WS2-(Fe3O4 + TiN) Nanoadditives in Non-Copper Coated Solid Wires.

In this study, four kinds of nanoparticles, graphite, WS2, Fe3O4, and TiN, were used as lubricating additives for steel/copper friction pairs to solve the problem of welding contact tube wear with non-copper-coated solid wire at high temperature. The single and composite nanoparticles have excellent dispersion stability in absolute ethanol under the action of the compound surfactant NaSTA + OA + PVP (i.e., sodium stearate, oleic acid, and polyvinylpyrrolidone). The tribological test results showed that the maximum decrement, with reference to the average coefficient of friction and wear volumes, were measured with nanoparticle concentration in 1:1:1 ratio at 300 °C. Compared with dry friction, the average friction coefficient and wear volume are reduced by 74.3% and 84.8%, respectively, which may be attributed to the formation of a stable tribo-film mainly composed of C–O, Fe2O3, WO3, TiO2, TiNxOy composite on the worn surface. Therefore, it is considered that the combined lubrication effects of the ball-bearing effect, repairing of worn surfaces, and the tribo-film resulted in the lowest friction and wear.

EXPERIMENTAL RESEARCH INTO MARBLE CUTTING BY ABRASIVE WATER JET

The article presents research on the erosion of the metamorphic rock - marble by the Abrasive Water Jet (AWJ). The fragmentation of abrasive grains during the erosion process is demonstrated. The effect of the cutting process's most important parameters as traverse speed, nozzle ID, and abrasive mass flow rate, on the maximum cutting depth, is shown. To create a mathematical-statistic model of the erosion process, the methodology of the response surface (RSM) was used for modeling. The polynomial equation of the second degree is chosen for developing the regression model. Studies have shown the optimal parameters of the process, to reach the highest depth of the cut. Additionally, the erosion wear of a focusing tube under different process conditions is presented.

Simulation of eddy current testing of steam generator tubes with wear and secondary side magnetite deposits

The steam generator (SG) tubes of pressurised water reactors are prone to degradation and are periodically inspected using eddy current testing (ECT) techniques. SGs provide a safety barrier between the radioactive primary side and the non-radioactive secondary side. Historically, a major degradation issue was stress corrosion cracking of tubes made of alloy 600. In modern SGs, better resistance to stress corrosion cracking is observed with the replacement of alloy 600 by alloy 690. However, this alloy does not prevent tubes from wear at support locations or wear resulting from fretting with loose parts. Long-term operation of SGs also leads to non-volatile species accumulation in the secondary side of the SGs, mainly magnetite. Magnetite deposits may build up as a dense and solid material on top of the tubesheet (hard sludge) and also in the flow slots of tube support plates, therefore modifying the general flow pattern and velocity of the secondary fluid. This has detrimental effects on the safe operation of SGs. The clogging-up ratio of the flow slots therefore needs to be assessed. The development of an ECT simulation model to address tube wear and magnetite deposits in SGs is presented. This model is based on the CIVA NDT platform. A bobbin coil signal is simulated and its performance for tube wear and magnetite deposit evaluation is discussed.

Erosion wear performance of HVOF and cold spray coatings deposited on T-91 boiler steel

Erosion wear in boiler tubes in coal based boilers is one of the serious problem and often results in downtime. After studying the literature, it was observed that thermal spray coatings are one of the effective solutions in reducing the erosion wear of boiler tubes. In this research work, the comparative erosion wear study of uncoated, HVOF coated and Cold spray coated samples of T-91 steel in simulated coal fired boiler conditions were performed. The Ni powder coatings were deposited on the substrate and impacted at 30°, 60° and 90° impingement angles with alumina erodent employing an air jet erosion tester. The erosive wear with respect to weight loss was maximum at 30° impingement angle, that was reduced at an impingement angle 60° and minimum at an impingement angle of 90°. This is erosive wear behavior of ductile materials. The erodent discharge rate was fixed at 2 g/min and air temperature at 800 °C. The cold spray coatings can reduce the weight loss from 40 to 60%.

Керування газо-масопотоками в струминному обладнанні

Based on a numerical simulation of gas flows in an ejector unit and an analysis of grinding chamber acoustic signals, this paper shows ways to increase the efficiency of jet grinding. To prevent ejector speed-up tube wear and to obtain a ground product without impurities, the effect of feeding an additional energy carrier flow on the flow pattern in the speed-up tube of a jet mill was studied. A comparative analysis of the ejector flow pattern as a function of the presence of an additional feed and the speed-up tube shape was carried out. It was shown that the use of a conical nozzle offers a more uniform flow at the ejector outlet. The additional energy carrier feed provides a uniform increase in flow speed and reduces speed-up tube wall wear. The acoustic signals of the mill working zones were related to the jet grinding process parameters, around which a ground product quality control method was developed. The paper presents a technique for determining the material particle size in the energy carrier flow from the results of acoustic monitoring of the process. The technique uses the established relationship between the dispersion of the acoustic signal characteristic frequency and the mass of the corresponding fracture of the mixture in in-flow material transportation. The technique speeds up material particle size determination and improves the finished product quality. An automatic system was developed to control the grinding process by controlling the loading process according to the characteristics of the grinding zone acoustic signals. An operating model of a controlled hopper of a gas jet mill was made. The operability of the control system was verified on a simulation model, which includes a control objet (mill) model and a control system model. It was shown that the system of mill loading automatic control by the characteristics of the grinding zone acoustic signals offers an up to 10 percent increase in mill capacity, which was verified in industrial conditions at Vilnohorsk Mining and Metallurgical Plant.

PSL zoning and material selection of tubing pipes at Ozenmunaigas JSC fields

The relevance of this work is caused by the need to reduce operating costs in the group of companies of NC KazMunayGas JSC in general and in Ozenmunaigas JSC in particular by increasing the service life of the tubing used. In this regard, the purpose of research and testing was to select the optimal tubing material for each group of wells. Correct grouping of wells (PSL zoning) is also important for the selection of the optimal tubing material. The article indicates the methodology and characteristics for the distribution of wells into groups (PSL zoning). analysis of the causes (wiping, corrosion) contributing to the rapid wear of tubing in the fields of JSC Ozenmunaigas, and recommendations for their solution.

Numerical research on multi-particle movements and nozzle wear involved in abrasive waterjet machining

Multi-particle velocities and trajectories in abrasive waterjet machining are of great value to understand the particle erosion mechanism involved in the cutting process. In this paper, the whole-stage simulation model is established from the high-pressure water and abrasive particles entering the nozzle to the mixed abrasive jet impacting the workpiece based on the SPH-DEM-FEM method. Comparing the simulation results with the experimental results under different process parameters, the capability of the proposed model is systematically validated. The model is applied to study the mixing and accelerating process of abrasive particles, and the results show that a speed difference is existed between the water and abrasive particles after being ejected from the nozzle. In addition, the nozzle wear pattern is also analyzed carefully. It is discovered that the most serious wear happened at the junction of the mixing chamber and the focusing tube. And the focusing tube wear is uneven and spreads downward.

A study on the wear allowance of a railway vehicle hydraulic damper

Railway vehicle hydraulic dampers are usually subject to wear-induced premature failures, so it is meaningful to evaluate the wear allowance of the hydraulic damper. Mathematical modelling of damping characteristics of a railway vehicle hydraulic damper under wear conditions is carried out, the model describes the functions of main damping characteristics indices vs. inner tube wear M1 and rod wear M2 . Simulation is then performed using the model, and indicates that increase of M1 would lead to significant drop of the maximum extension damping force, fading of the damping coefficient and significant rising of the damping force asymmetry rate, but the maximum compression damping force keeps to be constant, while increase of M2 would lead to significant drop of almost all of the indices except for the asymmetry rate. A wear allowance line for the damper is finally obtained when both of M1 and M2 work in real situations, the area enclosed by the wear allowance line and two axles is a safe area, any dot with a combination of M1 and M2 outside the safe area means the damper has exceeded its wear allowance and should be maintained or replaced. The mathematical model and the wear allowance line obtained in this work can be used for health status evaluation and design optimization of railway hydraulic dampers.

Obtaining the Dependences of the Contact of the Composite Abrasive Material with the Nozzle Walls, which Reduces the Wear of the Focusing Tube of the Waterjet Installation

To solve the problem of obtaining an effective composite abrasive material that allows preserving the focusing tube and increasing the cutting capabilities of the water jet, the authors obtained theoretical dependences that establish the relationship between the strength of the abrasive-polymer compound and its production modes