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Electroless nickel phosphor coating is an important technology in the field of industrial coatings which is widely used in many technical applications. The electroless nickel phosphorus layer has high hardness and corrosion resistance, making it ideal for multiple applications for example, automotive, aerospace and electronics industries. Sulfuric acid is an essential agent in many industrial processes. The corrosive and abrasive nature of sulfuric acid results in rapid wear of mechanical parts, resulting in frequent replacement, increased maintenance costs, and may cause environmental and safety issues. The purpose of this work is to investigate the effect of the different conditions such as heat treatment temperature, coating time and coating bath temperature on wear rate and microhardness by employed electroless Ni-P coating, which was effectively assigned to mechanical seal models. The Taguchi design array L9 was used to conduct the experimental work. The coating thickness was measured using an optical microscope. The results showed that the hardness increased reaching peak as 653 HV at 400 °C and coating time 4 hours. As for wear rate, it was recorded the lowest value as 0.00060 g/m under same conditions. Through SEM and XRD, the formation of NiP and Ni3P were found. ANOVA demonstrated that heat treatment temperature was the most effected factor that contributed to enhance both hardness and wear resistance, followed by coating time. [ABSTRACT FROM AUTHOR]

Aiming at the problem of mechanical seal failure due to serious wear and tear in operation, the numerical model of the thermal–solid coupling wear of the seal ring is established by taking the friction sub-material as the research object, and the hardness, wear coefficient, and friction coefficient of different soft-ring materials are obtained by a test to verify the accuracy of the numerical model of wear. Additionally, the temperature field and deformation field of the seal ring of different materials are calculated, and the effects of the material parameters, such as elasticity modulus and thermal conductivity, on the temperature, relative deformation, and axial deformation trend are reported. The wear relation of the mechanical seal was optimized, and the correction coefficients of several materials were calculated. The results show the following: the main wear of the seal ring is due to adhesive wear leading to particle shedding and extrusion, adhesive wear causes material transfer, which alters the composition of the worn surface.in turn leading to cratering, which also causes the wear of the seal ring; the friction performance is better when the soft-ring material is graphite (C); the temperature, as well as the deformation, is smaller when the soft-ring material is silicon carbide (SIC); the correction coefficients for the life of SIC are calculated to be 0.23, for C, to be 0.14, and for stainless steel (Ss), to be 0.31, and the corrected equations can more accurately predict the corresponding material. The corrected equation can more accurately predict the service life of the corresponding material. [ABSTRACT FROM AUTHOR]

The main cause of failure in sealing friction pairs, friction wear, has presented analytical challenges due to rapidly changing and complex friction frequency characteristics. This has led to a focus on surface morphology treatment rather than direct measurement techniques in research. In this context, the present study adopted Acoustic Emission (AE) technology for direct monitoring of friction pairs, aiming to identify friction response signals during their transient contact and abrasion stages. Employing time–frequency analysis, the research delineated the state evolution of AE characteristics during the entire operational cycle of the friction pair, from start to stop. It has established the time–frequency information of AE signals in relation to the surface state of the sealing friction pair and deciphered the correlation between the friction AE signals and the surface state alterations of the friction pair. The study showed that the frequency of friction-induced signals in seals is 270 ± 40 kHz. The transition speeds for the friction pair's state, moving from boundary lubrication to mixed lubrication and then to fluid dynamic lubrication, were identified as 200 rpm and 1000 rpm, respectively. Additionally, an escalation in signal activity was observed in dry friction scenarios and when surface defects were present in the friction pair, markedly exceeding the activity in conditions of no wear. This relationship between the friction signals and the operational state of the seal facilitates precise assessments of wear and operational integrity, underpinning the theoretical aspects of periodic wear in seal tribology. [ABSTRACT FROM AUTHOR]

In order to solve the problem of clutch slip caused by excessive pressure loss of rotary joint seal in marine field, a mechanical seal with V-shaped groove in end face which can reduce the pressure loss was proposed. This proposed seal can enhance the sealing performance of rotary joint, ensure the normal operation of rotary joint, and reduce the rotating machinery failure caused by the failure of rotary joint seal. In this research, the numerical model of the flow field of the rotary joint mechanical seal was firstly constructed, and then the accuracy of the model was verified by the pressure loss test bench of the rotary joint. Finally, the V-shaped groove type, micro-pit type and arc-shaped groove type of the rotary joint mechanical seal proposed in this research were compared and analyzed. The results show that compared with the original grooveless rotary joint mechanical seal, the pressure loss of the V-shaped groove type rotary joint mechanical seal can be reduced by about 10 %, the pressure loss of the micro-pit type rotary joint mechanical seal can be increased by about 4 %, and the pressure loss of the arc-shaped groove type rotary joint mechanical seal can be increased by about 21%. [ABSTRACT FROM AUTHOR]

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION ENGINEERING and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION ENGINEERING and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION ENGINEERING and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In view of the problems that the mechanical seal for the water pump is prone to deformation, friction and wear, and loss of sealing performance in the process of use, taking the temperature change of end surface as the research entry point, the temperature distribution, stress and strain diagram of rotating ring, and stationary ring are obtained by thermal-stress coupling simulation. The temperature change of stationary ring is studied by the experiments, and the friction state of end surface of rotating ring and stationary ring are observed. The results indicate that the test temperature of stationary ring is slightly lower than simulation temperature, which is related to the thermocouple fixed on the side of the stationary ring for temperature measurement. In addition, comparing the micro morphology of end surface of rotating ring before and after the experiment, it is found that there is significant plastic deformation on the inner diameter of rotating ring, which is related to the stress generated by the thermal-mechanical coupling of inner diameter of rotating ring exceeding the material limit, consistent with the simulation results. [ABSTRACT FROM AUTHOR]

The air film sealing device is one of the most widely used sealing technologies in the industrial field, its reliable sealing performance is essential for the normal operation of the equipment. The relative movement of the contact end faces of the dynamic and static sealing rings of the gas film sealing device will produce friction, and the friction process will produce complex acoustic emission signals, which often imply important information about the operation status of the sealing end faces. It is often difficult to accurately identify and classify these weak characteristic signals by traditional methods. Therefore, it is necessary to develop fault diagnosis methods with higher precision. In order to solve the problem that it was difficult to identify the friction state of the dynamic and static ring end faces of mechanical seals, taking the air film sealing device as the research object, a method for identifying the end face of air film seals based on the deep fusion model was proposed. Firstly, the acoustic emission signal of the sealed end face was collected by the acoustic emission sensor and acquisition equipment. Secondly, the wavelet packet transform method was used to filter the collected signal and extract the weak features in the time domain and frequency domain, and then the deep random forest (DRF) was integrated into the convolutional neural network (CNN) as a classification layer. Finally, according to the leakage amount of the experiment, the confusion matrix and the receiver operating curve were used to analyze the feature extraction ability of the two models. The research results show that the accuracy of the CNN-DRF fusion model for the two features of the sealed end-face acoustic emission signal is respectively 96% and 98%, which can fully extract the signal feature information and has better fault diagnosis ability than the traditional CNN model. [ABSTRACT FROM AUTHOR]

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION ENGINEERING and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We proposed a numerical method to investigate the thermo-fluid–structural coupled characteristics of a mechanical seal of a reactor coolant pump (RCP), especially during extended loss of AC power (ELAP) operation. We developed a finite element program for the general Reynolds equation, including the turbulence effect to calculate the pressure, opening force, and leakage rate of fluid lubricant and the two-dimensional energy equation to calculate the temperature distribution of the fluid lubricant. We verified the accuracy of the developed program by comparing the simulated temperature distribution and leakage rate of this study with those of previous research. Heat conduction and elastic deformation due to pressure and temperature changes at the seal structure were analyzed using an ANSYS program. The results showed that temperature more significantly affected the elastic deformation of the seal structure near clearance than pressure both under normal and ELAP operating conditions. High temperature and pressure of the coolant under ELAP operating conditions deform the seal structure, resulting in a much smaller clearance of the fluid film than normal operating condition. However, even with a small clearance under ELAP operation, the leakage rate slightly increases due to the high internal pressure of the coolant. This research will contribute to the development of robust mechanical seals for RCPs by accurately predicting the characteristics of mechanical seals, especially when the RCP is operating under ELAP. [ABSTRACT FROM AUTHOR]

A dry gas seal (DGS) is one of the key basic components of natural gas transmission pipeline compressors, and the sealing performance of a DGS dealing with complex multi-component pipeline natural gas is different from that dealing with conventional nitrogen medium. In this paper, a spiral groove DGS of the compressor in natural gas transmission pipeline systems is taken as the research object. The thermal hydrodynamic lubrication model of the DGS is established considering turbulence effect and choking effect. Based on the finite difference method, the temperature and pressure distributions and the steady-state performance of the DGS are obtained by simulating. The influence of unitary impurity compositions such as light hydrocarbon, heavy hydrocarbon, non-hydrocarbon, and their contents on the steady-state performance of the DGS is analyzed. The steady-state performance of the DGS dealing with multi-impurity natural gas such as in the West-East gas transmission is investigated under different operating conditions. The results show that turbulence had a significant effect on the DGS, while choking had a weak effect. Increasing the content of light hydrocarbon such as C2H6 and heavy hydrocarbon such as C5H10 resulted in an increase in the gas film stiffness, leakage rate, and the temperature difference between the inlet and outlet, while non-hydrocarbon, such as N2, reduced the temperature difference between the inlet and outlet. The greatest impact on seal performance was produced by the heavy hydrocarbon, followed by the light hydrocarbon, and the least was produced by the non-hydrocarbon. [ABSTRACT FROM AUTHOR]

The cavitation effect of lubricating film has a significant impact on the seal performance of hydrodynamic pressure mechanical seals.Kerosene-based magnetic fluid lubrication upstream pumping mechanical seal with inclined groove was taken as the research object.By considering the cavitation heat effect as well as the viscous temperature effect, the calculation model of lubricating fluid film was established to study the influences of working conditions and structural parameters on the seal performances using the volume fraction of gas phase in the liquid film as an indicator, and the results were compared with those based on the model only considering the viscous temperature effect. It is found that, due to the cavitation heat model considering the variation of saturated vapor pressure of liquid film medium with temperature,the opening force, leakage rate and volume fraction of vapor phase when considering the thermal effect of cavitation are smaller than the corresponding results when considering the viscosity-temperature effect only, but the variation regularity of each parameter is basically the same under the two conditions. The cavitation effect is enhanced by increasing the rotational speed and the groove diameter ratio, while the cavitation effect is weakened by increasing the inlet pressure, film thickness, radial angle and number of grooves. An increase in rotational speed, groove depth, radial angle, and groove diameter ratio will lead to an increase in leakage rate, while an increase in inlet pressure and groove number can improve sealing performance. [ABSTRACT FROM AUTHOR]

Copyright of Petroleum Refinery Engineering is the property of Petroleum Refinery Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to reduce the dry frictional wear of the end face of the mechanical seal used in the start and stop stage and under severe vibration conditions, the dry frictional wear simulation and experimental study of the textured face of the mechanical seal used in the pump were carried out. Firstly, the transient finite element model of the end face of dynamic and static ring seal with surface texture was established by ANSYS software. Based on Archard wear theory, the wear law of static ring ( graphite ring) under different texture spacing angle, edge length and rotation angle was analyzed, and the wear volume distribution of graphite ring was obtained. Then, the wear test of seal ring with different texture parameters was carried out by friction and wear testing machine under dry friction condition, and the surface morphology and wear mass of seal ring were obtained. Finally, The effects of different texture parameters on the wear mass of graphite ring and the mechanism of texture wear reduction were discussed. The experimental results show that the texture grooves are capable of hosting abrasive particles and generating a graphite transfer film to minimize wear; to minimize wear on the face of sealing ring, it is necessary to have a suitable texture area that can accommodate abrasive particles without causing excessive surface roughness; on average, with every 5 ° increase in texture spacing angle and 0. 1 mm decrease in edge length, the wear mass of graphite ring respectively decreases by approximately 7. 83% and 7. 35% . The wear mass of the graphite ring increases by 4. 25% on average when the rotation angle increases by 15 °. These findings can offer enhanced theoretical support towards surface texture design for pump mechanical seals, thereby bolstering their wear resistance. [ABSTRACT FROM AUTHOR]

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION ENGINEERING and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The John Crane 48 V mechanical seal is a long-distance oil transfer pump station shaft end seal; its sealing effect directly affects pipeline production safety. However, it has been found that there is oil leakage at the shaft end of the pump station. In order to explore the oil transfer pump mechanical seal abnormal leakage failure causes, to ensure the safety and stability of production, the end face of the 48 V mechanical seal was analyzed by white light interference and scanning electron microscope technology. The failure mechanism of the 48 V mechanical seal was explored from the perspective of the wear mechanism of moving and stationary rings. Results showed that the wear mechanism of the 48 V mechanical seal stationary ring was mainly abrasive wear, and substantial furrows, bulges, and depressions existed on the wear surface. The material removal mechanism was brittle spalling, and the roughness of the wear surface increased with the increase in wear depth and decreased with the increase in wear average width. Uneven wear occurred on the end face of the stationary ring of the mechanical seal, resulting in the leakage of the sealing medium from the end cover of the mechanical seal. The working condition could be improved by adding a spring compensation device to the stationary ring or increasing the gap between the stationary ring and the shaft sleeve. [ABSTRACT FROM AUTHOR]

The friction coefficient and wear rate of pretreated graphite with liquid nitrogen were obtained by using a ball-on-disk tester, and the wear of GCr15–graphite seal pairs with the low-temperature time-dependent pretreatment was discussed by comparing the wear morphology. The results show that liquid nitrogen pretreatment can affect the hardness and interlayer spacing of graphite. The range of the friction coefficients of pretreated graphite changes from 0.17 to 0.22. With the increase of liquid nitrogen pretreatment time, the wear mechanism of graphite would change from dominated three-body wear to adhesion wear. The experimental results of the mechanical seal with liquid nitrogen pretreatment show that the wear rate of stator is less than 0.00165 mm3·N−1·m−1, and the graphite shows a good low-temperature compatibility. [ABSTRACT FROM AUTHOR]

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION ENGINEERING and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Portable hydrolysis reactors for hydrogen storage material reactions are extremely important for the application of hydrogen energy since hydrolysis is a facile path to provide hydrogen. The strain and sealing components are extremely important for a hydrogen reactor. However, most researchers are focusing on the hydrogen storage materials for hydrolysis instead of the hydrolysis reactors. Herein, the structure of a hydrolysis reactor has been designed based on the strain distribution and sealing efficiency. The stress concentration on the threaded connection part and sealing effects have been analyzed using finite element analysis method. The stress concentration has been effectively reduced by increasing thread turns and wall thickness of thread. The stress concentration was also found to be affected by the thread types. Double sealing connection was adopted, where the sealing performance was found to increase with increase pressure in the reactor. This study provides a feasible design of a portable hydrolysis reactor for solid-state hydrogen storage materials. [Display omitted] • The structure of hydrolysis reactor has been designed based on the strain distribution and sealing efficiency. • The stress concentration on the threaded connection part and sealing effects have been analyzed using finite element analysis method. • The sealing performance of the reactor was found to increase with increase pressure in the reactor. • This study provides a feasible structure design scheme for a portable hydrolysis reactor. [ABSTRACT FROM AUTHOR]

Mechanical seals are used in a wide range of industrial applications, including pumps, compressors etc., in order to avoid leakage of the working fluid. The design construction, and the operation of the mechanical seals continue to evolve to meet the demands of new technologies and industries. These developments are the increase of operating parameters, in the condition of strictly respecting the environment protection. A mechanical seal consists of two rings, one being static and the other one dynamic, which are actioned by one or two fluid pressure, and an elastic force (or magnetic) which keeps the two faces of the rings in permanent contact. A direct contact between the frontal face of the rings will increase the surface temperature and the rings wear, so a small fluid film, as a lubricant and coolant, it is kept between the two face sealings. At modern mechanical seal are used also a secondary fluid. The tightening force in the seal, which it is very important, depends on seal construction, materials used, working fluid type, pressure and temperature, rotational speed, secondary fluid type, pressure, and temperature. Paper aims to present the studies made by the authors on a mechanical seal of the AESSEAL, cartridge seal type CDSA of a 1” in order to obtain the correct sealing pressure between seal rings. Calculation was made analytical, with the respect of regulations of the standards, and by FEA method. Was obtained a CFD model, to simulate the pressure inside the chamber of secondary fluid at different inlet/outlet pressures to determine the real value of it. The obtained results by CFD analyses were integrated in FEM analyses by ANSYS Static Structural to calculate the contact pressure on the rings faces and to calculate the minimum spring force for internal and external sealing cartridges for different working and secondary fluid pressure, also considering the seal construction design, materials, and rotational speed of 3000rpm. The results are very important in operation of the mechanical seal because the graphs presented in the paper give the operators the correct value of the spring tightening in the seal depending on the different ranges of fluids pressures.

Aiming at the problem of mechanical seal failure due to serious wear and tear in operation, the numerical model of the thermal–solid coupling wear of the seal ring is established by taking the friction sub-material as the research object, and the hardness, wear coefficient, and friction coefficient of different soft-ring materials are obtained by a test to verify the accuracy of the numerical model of wear. Additionally, the temperature field and deformation field of the seal ring of different materials are calculated, and the effects of the material parameters, such as elasticity modulus and thermal conductivity, on the temperature, relative deformation, and axial deformation trend are reported. The wear relation of the mechanical seal was optimized, and the correction coefficients of several materials were calculated. The results show the following: the main wear of the seal ring is due to adhesive wear leading to particle shedding and extrusion, adhesive wear causes material transfer, which alters the composition of the worn surface.in turn leading to cratering, which also causes the wear of the seal ring; the friction performance is better when the soft-ring material is graphite (C); the temperature, as well as the deformation, is smaller when the soft-ring material is silicon carbide (SIC); the correction coefficients for the life of SIC are calculated to be 0.23, for C, to be 0.14, and for stainless steel (Ss), to be 0.31, and the corrected equations can more accurately predict the corresponding material. The corrected equation can more accurately predict the service life of the corresponding material.

Abstract The friction coefficient and wear rate of pretreated graphite with liquid nitrogen were obtained by using a ball-on-disk tester, and the wear of GCr15–graphite seal pairs with the low-temperature time-dependent pretreatment was discussed by comparing the wear morphology. The results show that liquid nitrogen pretreatment can affect the hardness and interlayer spacing of graphite. The range of the friction coefficients of pretreated graphite changes from 0.17 to 0.22. With the increase of liquid nitrogen pretreatment time, the wear mechanism of graphite would change from dominated three-body wear to adhesion wear. The experimental results of the mechanical seal with liquid nitrogen pretreatment show that the wear rate of stator is less than 0.00165 mm3·N−1·m−1, and the graphite shows a good low-temperature compatibility.

In order to study the effects of deep-sea complex and severe working conditions on the power device of deep-sea wading equipment, taking the contacting mechanical seal for deep-sea propeller as the research object, a two-dimensional axisymmetric finite element model is established. The influence of alternating conditions on the temperature rise of seal face is explored. The pseudo-real condition test of the mechanical seal is conducted on a self-built test rig, and the temperature rise of seal face is monitored. The surface morphology and wear characteristics are measured and analyzed. The results show that the alternating conditions have a significant influence on the temperature field of the seal ring, and the temperature rise of seal face shows an obvious alternating transient characteristic. After the alternating condition test, the end face roughness of the rotating ring increases significantly. The transient working condition makes the contact state between the seal faces unstable. Abrasive wear occurs on the end face, with obvious pits and densely distributed furrows of different depths. The alternating speed has a greater influence on the temperature rise and wear of the end face than that of the alternating medium pressure. The numerical simulation results are in good agreement with the experimental results, which provides a necessary theoretical guidance and experimental basis for the structural design of the mechanical seal of the deep-sea propeller.

Copyright of Journal of China University of Petroleum is the property of China University of Petroleum and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION ENGINEERING and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION ENGINEERING and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The paper includes a theoretical approach to the frontal mechanical seals with rubber bellows, used in the conveyance of fluids in centrifugal pumps, in terms of friction coefficients, balancing and possible fluid losses. The study also presents an experimental study for a mechanical seal with rubber bellows and a shaft diameter of 35 mm, operating at different speeds at the pump shaft and different pressures of the transported fluid. At higher pressure the seal is balanced and at lower pressures is discharged. [ABSTRACT FROM AUTHOR]

Aimed at the operating failure problem of a shaft end mechanical seal of the oil-gas multiphase pump on the offshore platform, the causes were analyzed, and the structure was improved. Through the performance test of the improved mechanical seal, the change of sealing performance with pressure the wear condition of sealing end face under different spring specific pressure conditions were compared and analyzed, and the change of sealing performance with pressure and rotational speed under different end face widths was compared and analyzed. The results show that reducing the spring specific pressure can slightly reduce the friction power of the seal end face, but it will increase the risk of leakage, and reducing the end face width can effectively improve the sealing performance under poor lubrication conditions. The optimal design parameters of the seal were determined, and the 100 h qualification test of the domestic sealing prototype was carried out. The stability of the friction power of the sealing end face and the leakage index during its operation were examined. The experimental results show that the friction power of the improved sealing end face is basically stable, with small fluctuations, and the leakage meets the standard index requirements. This verifies the rationality of the improved sealing structure, the effectiveness and the adaptability of operating conditions of optimizing design parameters. [ABSTRACT FROM AUTHOR]

To improve the reliability of the end faces of high-temperature mechanical seals, a high-performance composite material that introduces carbon nanotubes (CNTs) into the laser-melted Cr coating is proposed. In this study, for high-temperature and high-speed mechanical seals under actual working conditions, friction and wear tests were conducted under different working conditions and using different end face materials. The high-temperature tribological properties of the Cr-CNTs coatings were analyzed, and the strengthening mechanism of the Cr-CNTs coatings on end faces was investigated. The results indicate that the wear resistance of the Cr-CNTs coating at high temperatures is first enhanced and then weakened with the increase in the CNTs content. The composite coating end face performance is optimal when the CNTs content is 10 wt%. The presence of CNTs between the end faces when grinding against the graphite ring favors the generation of a graphite film. The coefficient of friction of the Cr-CNTs coating is reduced by at least 12.46% compared to the Cr coating at a temperature of 483 K. This study provides reference examples for the application of carbon nanotubes in high-performance mechanical seals and new research ideas for improving the performance of mechanical seal end faces. [ABSTRACT FROM AUTHOR]

Mechanical seals are used in a wide range of industrial applications, including pumps, compressors etc., in order to avoid leakage of the working fluid. The design construction, and the operation of the mechanical seals continue to evolve to meet the demands of new technologies and industries. These developments are the increase of operating parameters, in the condition of strictly respecting the environment protection. A mechanical seal consists of two rings, one being static and the other one dynamic, which are actioned by one or two fluid pressure, and an elastic force (or magnetic) which keeps the two faces of the rings in permanent contact. A direct contact between the frontal face of the rings will increase the surface temperature and the rings wear, so a small fluid film, as a lubricant and coolant, it is kept between the two face sealings. At modern mechanical seal are used also a secondary fluid. The tightening force in the seal, which it is very important, depends on seal construction, materials used, working fluid type, pressure and temperature, rotational speed, secondary fluid type, pressure, and temperature. Paper aims to present the studies made by the authors on a mechanical seal of the AESSEAL, cartridge seal type CDSA of a 1" in order to obtain the correct sealing pressure between seal rings. Calculation was made analytical, with the respect of regulations of the standards, and by FEA method. Was obtained a CFD model, to simulate the pressure inside the chamber of secondary fluid at different inlet/outlet pressures to determine the real value of it. The obtained results by CFD analyses were integrated in FEM analyses by ANSYS Static Structural to calculate the contact pressure on the rings faces and to calculate the minimum spring force for internal and external sealing cartridges for different working and secondary fluid pressure, also considering the seal construction design, materials, and rotational speed of 3000rpm. The results are very important in operation of the mechanical seal because the graphs presented in the paper give the operators the correct value of the spring tightening in the seal depending on the different ranges of fluids pressures. [ABSTRACT FROM AUTHOR]

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION ENGINEERING and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION ENGINEERING and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We proposed a numerical method to investigate the thermo-fluid–structural coupled characteristics of a mechanical seal of a reactor coolant pump (RCP), especially during extended loss of AC power (ELAP) operation. We developed a finite element program for the general Reynolds equation, including the turbulence effect to calculate the pressure, opening force, and leakage rate of fluid lubricant and the two-dimensional energy equation to calculate the temperature distribution of the fluid lubricant. We verified the accuracy of the developed program by comparing the simulated temperature distribution and leakage rate of this study with those of previous research. Heat conduction and elastic deformation due to pressure and temperature changes at the seal structure were analyzed using an ANSYS program. The results showed that temperature more significantly affected the elastic deformation of the seal structure near clearance than pressure both under normal and ELAP operating conditions. High temperature and pressure of the coolant under ELAP operating conditions deform the seal structure, resulting in a much smaller clearance of the fluid film than normal operating condition. However, even with a small clearance under ELAP operation, the leakage rate slightly increases due to the high internal pressure of the coolant. This research will contribute to the development of robust mechanical seals for RCPs by accurately predicting the characteristics of mechanical seals, especially when the RCP is operating under ELAP.

A dry gas seal (DGS) is one of the key basic components of natural gas transmission pipeline compressors, and the sealing performance of a DGS dealing with complex multi-component pipeline natural gas is different from that dealing with conventional nitrogen medium. In this paper, a spiral groove DGS of the compressor in natural gas transmission pipeline systems is taken as the research object. The thermal hydrodynamic lubrication model of the DGS is established considering turbulence effect and choking effect. Based on the finite difference method, the temperature and pressure distributions and the steady-state performance of the DGS are obtained by simulating. The influence of unitary impurity compositions such as light hydrocarbon, heavy hydrocarbon, non-hydrocarbon, and their contents on the steady-state performance of the DGS is analyzed. The steady-state performance of the DGS dealing with multi-impurity natural gas such as in the West-East gas transmission is investigated under different operating conditions. The results show that turbulence had a significant effect on the DGS, while choking had a weak effect. Increasing the content of light hydrocarbon such as C2H6 and heavy hydrocarbon such as C5H10 resulted in an increase in the gas film stiffness, leakage rate, and the temperature difference between the inlet and outlet, while non-hydrocarbon, such as N2, reduced the temperature difference between the inlet and outlet. The greatest impact on seal performance was produced by the heavy hydrocarbon, followed by the light hydrocarbon, and the least was produced by the non-hydrocarbon.

Mechanical seals ensure the internal sealing of centrifugal pumps from the surrounding environment. They are one of the most critical components in a centrifugal pump. For this reason, the condition of mechanical seals should be monitored during operation. Mechanical seal friction power is an important component of mechanical losses in centrifugal pumps and is used as an indicator of wear and therefore seal condition. The soft sensor described in this paper is based on temperature measurements at the seal and can be used for determining the frictional power performance. A major factor in determining frictional power performance is the heat transfer between the mechanical seal and the medium inside the pump. For calculating the heat transfer, the stationary temperature fields in the rings of the mechanical seal are described by transmission efficiencies. The root mean squared error was determined for steady-state operating conditions to assess the quality of the soft sensor calculation. The frictional power performance can be determined by recording the temperature at the mechanical seal mating ring and the medium. The algorithm detects when the steady-state operating conditions change but does not map the dynamic changes between the stationary operating conditions.

Taking the mechanical seal of the submersible as the object, a transient coupled heat transfer model was established, and the deformation of the seal face under stable and alternating conditions was investigated by considering the thermal–mechanical coupling effect. The deformation characteristics of the seal face under two different alternative forms of amplitude and period were analyzed. The morphology and wear characteristics of the seal face were measured and discussed based on the pseudo-real test of the mechanical seal under alternating loads. The results showed that the seal face tended to be squeezed near the inner diameter and a tapered convergent gap appeared at the outer diameter of the seal face under alternating loads. The deformation of the seal face presented obvious alternating transient characteristics under alternating loads, and the deformation under alternating rotational speed was greater than that of alternating medium pressure. The deformation of the seal face increased with the amplitude of the alternating loads, while the period of the alternating loads had little influence on it. The wear mechanism of the seal face under alternating conditions was mainly abrasive wear, and the wear caused by alternating rotational speed is more significant. [ABSTRACT FROM AUTHOR]

This research investigated the effect of lubricant's non-Newtonian properties on dynamic characteristics of a herringbone grooved liquid film seal (HG-LFS) considering cavitation. A modified steady-state perturbation Reynolds equation of the non-Newtonian was derived. Visualized experiments were conducted to verify the accuracy of calculations. The non-Newtonian effect on stiffness, cavitation, damping coefficients, and other sealing performance of the liquid film seal at different velocity, pressure and film thickness were discussed and analyzed. The results indicate that the seal has larger stiffness and damping coefficients with the dilatant lubricant, the cavitation can be inhibited by the shearing-thinning lubricant, and the impact of non-Newtonian on the seal stability decreases with the increase of film thickness. This study would contribute to the design and theoretical research of liquid film seals. [ABSTRACT FROM AUTHOR]

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION ENGINEERING and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION ENGINEERING and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Shanghai Jiao Tong University (1006-2467) is the property of Journal of Shanghai Jiao Tong University Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The fluid flow in the small pore throat is a nonlinear flow, and the microscopic force between the fluid and the wall cannot be ignored. However, the previously established theories about the leakage between sealing interfaces have not considered the influence of microscopic forces. Based on contact mechanics and percolation theory, the void characteristics of the sealing interface were clarified, and the influence of microscopic force on fluid flow in porous medium was analyzed. Combined with the capillary force, the concept of a critical void radius between the mechanical seal interfaces is proposed. The fluid flow resistance model and leakage rate calculation equation of the sealing interface considering the van der Waals force are established, and the leakage judgment criterion of the sealing interface is provided. Through numerical calculation and experiments, the effect of microscopic force is verified in terms of the fluid flow law and macroscopic leakage rate. The results show that van der Waals forces have an important influence on the fluid flow between the sealing interfaces. As the microchannel size decreases, the van der Waals forces between solid and liquid increase, and the influence of these van der Waals forces on the fluid flow between the sealing interfaces cannot be ignored. The calculation model of the sealing interface leakage rate proposed in this paper shows little difference with the results of the Persson model, and is in good agreement with the experimental results; the maximum relative error is 8.7%, the minimum relative error is only 3.8%. [ABSTRACT FROM AUTHOR]