Search

A complete subsea production system (SPS) is assembled by interconnecting subsea manufacturing facilities through subsea connectors. To ensure the reliability and longevity of the SPS, it is imperative to thoroughly investigate the mechanical behavior and sealing performance of the subsea connector's core-sealing components. In this study, the loading conditions of the subsea clamp connector are examined to analyze the load transfer relationship between its components under different modes. A mathematical model for the load transfer between locking torque and sealing contact pressure is developed for the preloading mode, and the concept of mechanical transfer efficiency is introduced. Another mathematical model for the load transfer between the locking torque and the design pressure is developed for the operation mode. Furthermore, a three-dimensional full-size finite element model of the subsea clamp connector is established to analyze the effects of complex loads on the mechanical behavior and sealing performance of its core-sealing components. The simulation results indicate that internal pressure loading positively affects the sealing of the subsea connector, and that the stress distribution in the core-sealing components under bending moment loading exhibits significant asymmetric characteristics. Additionally, the superposition of axial tensile loads reduces the effect of the bending moment on the strength of the core seal member but further weakens the seal. Finally, an experimental system is designed to validate the simulation results. [ABSTRACT FROM AUTHOR]

In order to explore the effect of piston cup structure on its sealing characteristics and mechanical properties, a numerical simulation model of the piston cup in the BW-160 mud pump was established. Effects of work load, friction coefficient and cup structure parameters on the sealing and mechanical properties of the piston were discussed under mud discharge condition. The results show that stress concentration on the root and lips of the cup is becoming more and more obvious with the working load increases. The average contact pressure increases with the friction coefficient increases, but an excessive friction coefficient accelerate the wear of the cup and the heat generation. Effect of the piston lip interference and thickness on the sealing performance of the cup is greater than that of the inner wall width. The piston with groove structure can effectively improve the sealing performance of the piston. The mechanical properties of triangular groove cup are better than that of semicircular and trapezoidal groove cup.

A model based on a three-dimensional fractal function is developed and used in conjunction with experiments to analyze the evolutionary pattern of sealing performance during the start-up process of dynamic pressure seals, and the influence of end-face microscopic features on the evolution law is discussed. It is found that the opening state of the seal is divided into three stages: the non-opened stage, transition stage, and full-opened stage. The isotropic dimensions of the cavities have a coupling effect on the leakage, and they diminish as the speed increases. In order to enhance the sealing performance during start-up, it is suggested that the seal faces have a fractal dimension of 2.4 to 2.6, and a characteristic factor of less than 1 × 10−9 m.

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 China Rubber Industry is the property of Editorial Office of China Rubber Industry 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 China Rubber Industry is the property of Editorial Office of China Rubber Industry 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 Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) 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 Coal Geology & Exploration is the property of Xian Research Institute of China Coal Research Institute 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 the whole working process of scroll compressor, the working environment and stress of dynamic and static scroll plates are complicated, which easily leads to the deformation of dynamic scroll teeth, which leads to the deterioration of radial clearance sealing performance and the increase of axial clearance, which affects the working efficiency and reliability of scroll compressor. Therefore, based on the finite element theory, the real stress situation of scroll compression motor scroll was simulated by applying various loads, and the distribution law of stress and strain was obtained. Firstly, by improving the solution of the temperature load of the scroll plate, the average temperature function of the fluid domain on the scroll wall was calculated, and the steady-state temperature distribution model of the scroll solid domain was established. Then, temperature load, gas pressure load, inertial force load, temperature-gas pressure load and multi-load coupling were applied to the scroll teeth respectively. Finally, the stress and strain distribution of the orbiting scroll plate under different loads was analyzed. The research results show that the radial deformation law under temperature-gas pressure load is similar to that under gas pressure load. The law of axial deformation is similar to that of temperature load. Under multi-load coupling, the maximum deformation and stress of the scroll tooth are greatly affected by the inertial force. The maximum deformation and stress value of the scroll tooth increase by 7.97 μm and 52.5 MPa respectively compared with the temperature-gas pressure load. In different working chambers, the deformation of the inner wall of the scroll tooth is greater than that of the outer wall, and the maximum difference is 1.11 μm. Between different working chambers, the deformation amplitude of the inner and outer walls gradually decreases with the gas compression process. [ABSTRACT FROM AUTHOR]

The structure of caprocks is often greatly altered by different scales of faults or fissures in long-term geological tectonic evolution, and the sealing performance may be deteriorated. In this paper, a simplified geological model characterized as multilayered sandstone and fault-bearing caprocks extracted from the Shuang 6 underground gas storage located in the Liaohe oilfield was established. Different fault geometry (e.g., fault length, fault dip angle, and fault type) and seepage attributes (porosity and permeability) were considered to illustrate their impacts on natural gas migration during the cyclic high rate of injection and production of natural gas. The results showed that the seepage anisotropy and the natural gas front are strongly affected by the formation properties and, especially, are hindered by the low permeability sandstone layers. The difference in the lateral migration distance of natural gas in different layers can reach 110 m at the end of the injection period, with an annual injection volume of 108 m3. The migration of natural gas along the fault zone is mainly controlled by the permeability of faults, followed by fault scale, fault dip angle, and fault type. The sealing failure of caprocks in the fault zone does not occur based on the simulated gas migration distribution, showing that a very limited amount of natural gas migrates into the caprocks. [ABSTRACT FROM AUTHOR]

As a crucial component for temporary blocking of layer segments in the segmental fracturing process, bridge plugs are difficult to unseal by conventional methods and may cause major downhole accidents if not handled properly. In this paper, a nanofluidic self-heating unsealing rubber cylinder is designed, which is equipped with a nanofluidic self-heating unsealing sandwich inside the conventional rubber cylinder, consisting of a nanofluidic system and an annular flexible heater. When unsealing, the nanofluidic self-heating unsealing sandwich is heated by the annular flexible heater, and the nanofluidic system can help the bridge plug rubber cylinder shrink in volume and unseal smoothly by the characteristics of heat shrinkage and cold expansion. The nanofluidic system, consisting of porous carbon with an exceptionally large specific surface area and glycerol, serves as a prime example for filling the sandwich layer, and the design parameters calculation was carried out. The sealing performance of the designed nanofluidic self-heating unsealing rubber cylinder was analyzed based on the Mooney–Rivlin principal structure by finite element modeling. The results show that the maximum contact stress between the nanofluidic self-heating unsealing rubber cylinder and the casing wall increases by 9.73%, the compression distance reduces by 24.47%, and the maximum equivalent force decreases by 12.17% on average compared with a conventional rubber cylinder under the same seating load. The designed nanofluidic self-heating unsealing rubber cylinder can satisfy the requirements of pressure-bearing capacity and sealing performance and performs better than a conventional rubber cylinder. [ABSTRACT FROM AUTHOR]

Wet‐assembly hybrid bonded/bolted (WHBB) joint is a kind of sealing fastener that contains sealant both in bolt‐hole clearance and between CFRP laminates, which is increasingly applied in composite aircraft fuel tanks. As the guarantee of tensile strength and sealing performance, the thickness and interface characteristics of bolt‐hole sealant layer are investigated by a newly developed comprehensive evaluation method in this paper. The results indicate that the tensile strength of WHBB joint is positively correlated with the bolt‐hole clearance. As for the sealing property of WHBB joints, the leakage rates of WHBB joints with bolt‐hole adhesive layer (0.01, 0.03 and 0.05 mm) is three orders of magnitude less than that of joints with 0 mm adhesive layer. Moreover, the rising slope of leakage rates of the WHBB joints decreases with the increase of bolt‐hole clearance under tensile fatigue loads, which means the WHBB joint with higher bolt‐hole clearance shows better tensile fatigue resistance. The micro‐morphology of bolt‐hole interface indicates that the sealing property of WHBB joints is increased significantly due to the effectively enhanced interface behavior. [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.)

Radial seals are sensitive to axial overload failure and may cause leaks. This paper presents two semi-analytical methods for the joint strength and sealing performance of the subsea pipeline compression connector under axial overload failure. The method for the joint strength consists of two parts: One is the analytical model for the joint strength of the connection and seal under axial tension and compression conditions. The models are based on membrane theory, considering the hardening and bending effects. The other is a two-dimensional, axisymmetric finite element model for the joint strength of the radial metal seal. The semi-analytical method for the overload sealing performance is derived using a finite element model and the Reynolds equation of the laminar flow. The effects of critical parameters on the joint strength and the overload sealing performance are analyzed. The experiments are carried out with specimens and prototypes to evaluate the evolution of the sealing interface and the joint strength. The results show that both the internally turned sealing surface and the deflection of the pipe can improve the joint strength. In addition, the compression-type connector can remain sealed under the maximum axial overload. The proposed methods allow the prediction and identification of the overload joint strength and the sealing condition of the compression-type connector and provide a better understanding of the radial metal seal under the axial overload condition. [ABSTRACT FROM AUTHOR]

Segment lining structure is one of the choices to be used for low-to-vacuum maglev tunnels in the future. The airtightness at the joints of the lining structures is one of the critical problems that need to be addressed. However, little attention has been devoted to this problem until now. In this paper, a new apparatus was invented and used to study the mechanical behavior and airtightness sealing capacity of the gasket-in-groove, and a finite element analysis (FEA) model, validated by the test, was developed and used to further investigate thoroughly the sealing performance and sealing failure mechanism of the gasket-in-groove. The results obtained by the above two methods were discussed and compared, and a series of findings were presented. The results showed that the initial pressure distribution on the gasket–gasket contact surface is not uniform due to the presence of the inner holes in the gasket and the grooves between the gasket legs and an approximate "W" shape distribution in this study. The effect of vacuum pressure on the contact pressure distribution is very significant and shows an overall decreasing trend with increasing vacuum pressure. A higher initial maximum contact pressure would provide a better sealing effect but a lower sealing safety factor. Airtightness failure induced by evacuation is a contact surface separation process in which the maximum contact pressure shows a tendency to rise sharply with vacuum pressure increases, followed by a slow drop, and then declines dramatically to zero. [ABSTRACT FROM AUTHOR]

The dynamic characteristics of the complex relationship among the sealing system, excitation, and response have a considerable impact on the operational reliability of hydrodynamic mechanical seals, which is a critical issue in the field of sealing theory and technology. Scholars at home and abroad have established dynamic models and calculated the displacement responses of dynamic and static rings in the time domain based on the force on these rings so that the response results can be used for system stability analysis. Neither are the excitation characteristics of cavitation load extracted, nor are the distance response and system leakage rate of the dynamic and static rings analyzed under coupled cavitation and random excitation. In this study, under different operating conditions of the hydrodynamic mechanical seal system, the liquid film evaporation load and seismic load are applied to study the frequency domain response of the distance between the dynamic and static rings and the system leakage rate. The following conclusions have been obtained: Assuming that the chamber pressure is 0.5 MPa and the spring specific pressure is 0.055 MPa, during stable operation, the distance between the moving and stationary rings at 1500 rpm~3000 rpm speeds is 1.12 μm~3.05 μm. For a specific spring pressure of 0.055 MPa, medium pressures of 0.2 MPa~1.0 MPa, and spindle speeds of 1500 rpm~3000 rpm, the excitation force is 30 N, and the frequency is 30 Hz, And the seismic load is assumed to be sinusoidal, the excitation force is 6 N, the fundamental frequency is 120 Hz, and the system leak rate is in 0.1 mL/min~1.3 mL/min. Under multi-frequency excitation coupling, the distance between the dynamic and static rings will decrease as the pressure of the medium in the sealing cavity increases, and this will increase with the increase in the rotating speed. The leakage rate of the system will increase with the increase in the rotating speed and the pressure of the medium, and the test value is largely consistent with the theoretical value. [ABSTRACT FROM AUTHOR]

A new type of sealing device is designed for the temporary venting and nitrogen injection of the natural gas long-distance pipeline station under the current emergency condition. The finite element analysis and laboratory test of the device are carried out, and the results of the two are compared and analyzed; furthermore, to meet the higher bearing pressure requirements, the device was structurally improved and again subjected to finite element analysis. The above results show that the pressure-bearing capacity of the designed sealing device can reach 5 MPa, which meets the field work requirements; after the improvement, the von Mises stress of the O-ring is evenly distributed, and the value is only 36% of that before the improvement, while the contact stress is 181% of that before the improvement, and the sealing performance of the O-ring is enhanced. [ABSTRACT FROM AUTHOR]

To study the effect of soft segments of thermoplastic polyurethane elastomer (TPU) material on the sealing performance of hydraulic cylinders, a series of TPU materials were synthesized by polybutylene adipate diol (PBA),polycarbonate diol (PCDL), polycaprolactone diol(PCL), polytetrahydrofuran ether diol ( PTMEG ), diphenyl methane-4, 4'--diisocyanate (MDI) and hydroquinone dihydroxyethyl ether (HQEE).The effects of soft segment types on physical and mechanical properties, friction and wear properties, hydraulic oil aging properties and sealing properties of TPU materials were studied. The results show that the four kinds of TPU materials synthesized by four soft segments have good physical and mechanical properties. PBA-type TPU material has the best wear resistance, and the friction coefficient of the TPU materials synthesized by four soft segments under the condition of hydraulic oil lubrication is 0. 05, indicating a lower friction coefficient. PCDL--type TPU material has the best tolerance to hydraulic oil and sealing performance. PCDL--type TPU material is an ideal material for manufacturing hydraulic cylinder seals. [ABSTRACT FROM AUTHOR]

Based on the bolt preload equation, the relationship between tightening moment and preload of the pipeline connection structure was deduced, the finite element model of the pipeline connection structure was established, and the relationship between torque and preload of composite pipeline connection structure was simulated and calculated theoretically. The relative error of the calculation results between the established finite element model and the theoretical formula is small, which verifies the validity of the finite element model. Based on the tightening model of the pipeline joint structure, the influence of the angle error on the tightening process and sealing performance was studied. The results show that the tightening process with angle error is divided into nonlinear fitting period and linear tightening period. With the increase of the angle error, the width of the sealing ring decreases, and the width of the sealing ring of the large ball decreases faster than that of the small ball. As the angle error increases, the preload of the composite pipeline joint structure decreases, and its assembly cannot achieve the expected effect. [ABSTRACT FROM AUTHOR]

Combining the finite element method of global network reconstruction with the numerical calculation model under lubrication, the variation trends of sealing performance parameters such as lip profile, contact pressure, maximum contact pressure, pumping rate and friction torque during the wear process of oil seal under lubrication were analyzed. The simulation results show that the wear of oil seal can be divided into two stages. The first stage is the initial wear stage, in which the wear rate of lip is large, and the maximum contact pressure also shows a large downward trend. The second stage is the stable wear stage, in which the wear rate is small, the wear amount is small, and the variation trend of maximum contact pressure tends to be flat. The wear degree of lip contour tends to be gentle with the increase of wear time, and the wear degree on the air side is more serious than that on the oil side. The pumping rate shows a trend of decreasing first and then increasing, indicating that the wear will lead to the loss of lip tip material and the instability of oil seal sealing performance. The friction torque shows an upward trend due to the combined influence of the radial force caused by wear and the shear action of lubricating oil. [ABSTRACT FROM AUTHOR]

The multi-lip combined seal has the advantages of multi-lip coupling, large supporting force, and can withstand high-pressure shocks. It is an irreplaceable structure for single-lip seals. However, most of the seal wear analysis focuses on the simulation method of the single-lip seal under the influence of macro factors, and very little involves the wear characteristics of multi-lip seals. In this paper, a micro numerical method is established, which combines the elastohydrodynamic lubrication theory with the modified Archard equation. The performance of a multi-lip combined seal under different working conditions is analyzed through simulation, including macro and micro factors. It is found that some of the characteristics of single-lip seals are also reflected in multi-lip seals, and there is a critical speed that makes the sealing behavior of each seal lip different. [ABSTRACT FROM AUTHOR]

The static metallic joints' sealing performance is deeply impacted by the plastic deformation and the interfacial separation of the contact surfaces with self-affine roughness. The yield hardening effect, unavoidable at the contact interface, is of vital importance to the plastic deformation and the distribution of the interfacial separation. However, most of the previous research ignores the effect of yield hardening, assuming that the contact surfaces are elastic-perfectly plastic. To address the problem, a novel analytic model for investigating the sealing performance under the effect of yield hardening has been developed in this paper. The upper boundary of contact stress in the conventional Persson model has been enlarged from a constant nominal yield stress to a maximum yield stress that varies with contact strain, making the model adaptable to actual scenarios with yield hardening effects. Utilizing the measured data of contact surfaces as input, the corresponding leakage rates are calculated. Besides, the contact stress distribution as well as the real contact area at the interface is also discussed. The sealing experiments are carried out accordingly, verifying that the proposed model owns the ability to predict the leakage rate under the effect of yield hardening. [ABSTRACT FROM AUTHOR]

C5F10O is a promising insulating medium in the manufacturing of environmentally friendly gas-insulated switchgears (GISs). The fact that it is not known whether it is compatible with sealing materials used in GISs limits its application. In this paper, the deterioration behaviors and mechanism of nitrile butadiene rubber (NBR) after prolonged exposure to C5F10O are studied. The influence of C5F10O/N2 mixture on the deterioration process of NBR is analyzed through a thermal accelerated ageing experiment. The interaction mechanism between C5F10O and NBR is considered based on microscopic detection and density functional theory. Subsequently, the effect of this interaction on the elasticity of NBR is calculated through molecular dynamics simulations. According to the results, the polymer chain of NBR can slowly react with C5F10O, leading to deterioration of its surface elasticity and loss of inside additives, mainly ZnO and CaCO3. This consequently reduces the compression modulus of NBR. The interaction is related to CF3 radicals formed by the primary decomposition of C5F10O. The molecular structure of NBR will be changed in the molecular dynamics simulations due to the addition reaction with CF3 on NBR's backbone or branched chains, resulting in changes in Lame constants and a decrease in elastic parameters. [ABSTRACT FROM AUTHOR]

The sealant flow and rim seal at the periphery of cavities formed between rotor and stator disks prevent the high-temperature gas from ingesting into disk cavities and reduce the use of secondary air bleeding from a compressor. The unsteady sealing performance of rim seal and the cooling characteristics of sealant flow on endwall of a 1.5-stage axial turbine are studied by solving the three-dimensional unsteady Reynolds-averaged Navier-Stokes (URANS) equations via shear stress transfer (SST) turbulence model. Besides, mass transfer analogy is introduced to predict the sealant distribution which makes the numerical sealing effectiveness in front and aft cavities agree well with experimental data. The accuracy of the numerical method is verified. The sealing effectiveness in cavities and the flow field in rim seal clearance are analyzed, and the film cooling performance on endwall is explored. The results show that, compared with Φ0 =0.0170, the area-averaged sealing effectiveness εc on stator face is increased by 19.05% when Φ0 =0.500 in the front cavity, and compared with Φ0 =0.0042, the area-averaged sealing effectiveness εc on stator face is increased by 9.82% when Φ0 =0.096 in the aft cavity. The nonaxisymmetric pressure on the endwall near rim seal and Kelvin Helmholtz unstable vortices arise due to the circumferential velocity difference between main flow and cavity flow. The flow field in the rim seal clearance is jointly affected by these two factors. The flow pattern in the front rim seal clearance is mainly affected by unstable vortex while the flow pattern in the aft rim seal clearance depends on the circumferential pressure distribution. According to FFT, the most significant frequency of flow field variety is about 1200 Hz and 400 Hz (corresponding to two and six blades passing periods) in front and aft rim seals, respectively. The time-averaged cooling effectiveness increases with the increase of sealant flow on endwall and decreases gradually in the axial direction. The unsteady flow behavior of cooling effectiveness on endwall is also discussed in detail. [ABSTRACT FROM AUTHOR]

Top seal failure of ram blowout preventer (BOP) is one of the main factors leading to well control risk. The constitutive model and parameters of nitrile butadiene rubber (NBR) were optimized by compression and tensile tests, and the failure analysis model of the contact seal of the ram BOP top seal was built. The nonlinear contact mechanical behavior of the connection part of the BOP top seal was analyzed by the finite element method. Then, the influence of corrosion and wear defects at the top seal position of the 2FZ35-70 BOP under rated working pressure on the contact seal were studied, and the results showed that the overall contact pressure distribution of the top seal corrosion defects was uniform, the local contact pressure of the corrosion pit edge increased, and the top contact pressure decreased. The overall contact pressure of the wear defect of the top seal decreased linearly, the contact pressure at the maximum depth of the wear defect was the smallest, and the contact pressure gradually decreased to both sides. Ultimately, to guarantee the safety and reliability of the ram BOP, it is suggested that the acceptable depths of the seal corrosion pit and the wear at the top of the ram BOP are 4.0 mm and 0.2 mm, respectively, thus the reliability evaluation problem of the quantitative seal of the ram BOP top seal is solved. [ABSTRACT FROM AUTHOR]

Copyright of China Rubber Industry is the property of Editorial Office of China Rubber Industry 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 Tunnel Construction / Suidao Jianshe (Zhong-Yingwen Ban) is the property of Tunnel Construction 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 improve the safety performance of well control semi sealed ram blowout preventer(BOP), failure analysis and sealing performance evaluation were carried out for the semi sealed ram BOP in service, and the characterization test of ram body and material tensile and impact tests were completed. Based on the stress analysis of semi sealed ram during overflow shut in, and the stress and strain test data of ram body material, a full size semi sealed ram BOP model was established. The mechanical properties of ram and sealing rubber core were simulated under the combined load of downhole high-pressure fluid and cylinder pressure. The results show that when the cylinder pressure exceeds 9. 4 MPa, the groove root of the ram body just enters the yield deformation, and the maximum equivalent stress occurs at the groove root of the ram body, leading to premature fracture failure of the ram body. The stress concentration in the contact area between the rubber core and the upper end of the ram is the most obvious. It is concluded that the upper part of the rubber core is squeezed due to the combined load, thus losing the sealing ability. Finally, measures to reduce ram stress concentration were proposed. The research results provide guidance for safe operation of semi sealed ram BOP under overflow. [ABSTRACT FROM AUTHOR]

Ethylene–propylene–diene monomer (EPDM) rubber is one of the rapidly developing synthetic rubbers for use as a gasket material in proton exchange membrane (PEM) fuel cell applications. Despite its excellent elastic and sealing properties, EPDM faces challenges such as molding processability and recycling ability. To overcome these challenges, thermoplastic vulcanizate (TPV), which comprises vulcanized EPDM in polypropylene matrix, was investigated as a gasket material for PEM fuel cell applications. TPV showed better long-term stability in terms of tension and compression set behaviors under accelerated aging conditions than EPDM. Additionally, TPV exhibited significantly higher crosslinking density and surface hardness than EPDM, regardless of the test temperature and aging time. TPV and EPDM showed similar leakage rates for the entire range of test inlet pressure values, regardless of the applied temperature. Therefore, we can conclude that TPV exhibits a similar sealing capability with more stable mechanical properties compared with commercialized EPDM gaskets in terms of He leakage performance. [ABSTRACT FROM AUTHOR]

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) 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.)

Blowout preventer reliability is important for safe drilling operation. In order to study the sealing mechanism and failure mechanism of conical blowout preventer, a numerical model of conical blowout preventer was established based on the theory of large deformation of rubber, and the deformation law, stress distribution and sealing performance of rubber core in well shut-in operation were studied. The results show that there are stress concentrations in the contact area between the rubber core and the piston, the grooves in the middle of the adjacent support ribs, and the chamfered corner of the inner wall of the rubber core, the main form of failure at these locations is rubber cracking. Higher stress is present in the neck region of the upper plate and the back region of the lower plate of the support ribs. The inner wall surface of the rubber core gradually produces stripes of wrinkles, and the smaller the size of the sealed drill pipe, the more obvious the wrinkles are. When the drill pipe joint is sealed by the rubber core, there is a sealing buffer zone at the shoulder, and the contact pressure change abruptly. The lower portion of the rubber core's inner wall serves as the primary sealing area. Increasing the piston displacement appropriately can enhance the sealing performance of the rubber core. The results can provide a theoretical basis for the optimization design of the conical blowout preventer. [ABSTRACT FROM AUTHOR]

Globe-cone joint as a common connection form is the weakness to cause leakage in pipeline system of satellite or rocket product. Manufacturing and assembly uncertainties exist extensively, which causes the uncertainty of sealing performance inevitably and thus decreases the reliability of pipeline system under harsh environment. This study proposes a novel method for the robust optimization design of key structural sizes in globe-cone joint considering manufacturing and assembly uncertainties. First, an accurate three-dimensional finite element model of globe-cone joint is built, including size error and surface micro-topography. Based on assembly simulation, it is convenient to achieve sufficient sample data. Second, the second-order polynomial response surface model is built for establishing the relationship between uncertain parameters, optimized structural parameters, and sealing performance. Third, the combination of the interval possibility method, penalty function method and improved particle swarm optimization algorithm are proposed to optimize the structural parameters including cone angle and spherical radius for improving the robustness of sealing performance. The experimental results based on simulation indicated that not only the globe-cone joints with the optimized cone angle and spherical radius had the better sealing performance, but also the sensibility of sealing performance to various manufacturing and assembly uncertainties was greatly decreased. [ABSTRACT FROM AUTHOR]

The existing seal is not designed with a special sand retaining structure, and it is difficult to discharge the mud particles after entering, resulting in serious wear of the seal and premature failure. Therefore, a special-shaped sealing structure for sand blocking of roller cone bits is proposed to solve the problem of sealing wear. Starting from the structural principle, the structural parameters of the special-shaped seal of the sand-retaining flap are designed based on the O-ring, and the sealing principle is analyzed, the formula of grease leakage is derived, and the simulation and optimization analysis are completed with the aid of APDL. This proved the feasibility of the design. The influence law of structural parameters on contact pressure and leakage is obtained, and the formula of leakage is verified; The influence of structural parameters on the contact gap of the sand flap is obtained. Under the condition of optimal combination of structural parameters, the grease leakage is 43 mg/h, a decrease of 85%. Theoretically, it takes 580 h to exhaust the grease, and the contact gap of the sand flap is 0.00019479 mm, a decrease of 95%, which can greatly reduce the wear of the main seal. This study opens up a new idea for seal design. [ABSTRACT FROM AUTHOR]

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

By applying the dynamic mesh technology of FLUENT software to the numerical simulation of internal flow field in mechanical seal clearance, the problem of unpredictable liquid film thickness in the simulation process can be solved, and a more actual internal flow field characteristic can be obtained. The flow of sealing fluid between the end faces of moving and stationary rings is affected by the superposition of differential pressure flow and shear flow. The clearance seal performance is studied by using computational fluid dynamics (CFD), and the influence of pressure difference, axial seal length and rotor speed on the sealing performance is analyzed. The experimental results show that the leakage of the seal gap increases with the increase of the pressure difference, changes linearly with the rotation speed, and is inversely proportional to the rotation speed. The larger the speed, the smaller the leakage. The longer the axial length of the seal, the smaller the leakage of the seal clearance. The numerical simulation value obtained by the dynamic grid method is close to the experimental value under three different speeds. It is feasible to apply the dynamic grid technology to the simulation of the internal flow field of mechanical seals, and good results can be achieved. [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.)

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.)

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.)

Balance valve is a core component of the 11000-meter manned submersible “struggle,” and its sealing performance is crucial and challenging when the maximum pressure difference is 118 MPa. The increasing sealing force improves the sealing performance and increases the system’s energy consumption at the same time. A hybrid analytical—numerical—experimental (ANE) model is proposed to obtain the minimum sealing force, ensuring no leakage at the valve port and reducing energy consumption as much as possible. The effects of roundness error, environmental pressure, and materials on the minimum sealing force are considered in the ANE model. The basic form of minimum sealing force equations is established, and the remaining unknown coefficients of the equations are obtained by the finite element method (FEM). The accuracy of the equation is evaluated by comparing the independent FEM data to the equation data. Results of the comparison show good agreement, and the difference between the independent FEM data and equation data is within 3% when the environmental pressure is 0–118 MPa. Finally, the minimum sealing force equation is applied in a balance valve to be experimented using a deep-sea simulation device. The balance valve designed through the minimum sealing force equation is leak-free in the experiment. Thus, the minimum sealing force equation is suitable for the ultrahigh pressure balance valve and has guiding significance for evaluating the sealing performance of ultrahigh pressure balance valves. [ABSTRACT FROM AUTHOR]

The compression packer is an important downhole oil production tool, and its failure is mainly attributed to the degradation of its embedded rubber cylinders under the action of high temperatures. In the present study we have made a comprehensive investigation on the mechanical response of the sealing packer based on two rubber materials at high temperatures. Firstly, by measuring the material parameters under different temperatures, we established the constitutive relationships of the two rubber materials (Aflas and Kalrez) in consideration of the temperature effect, in the light of the Mooney-Rivlin model. Next, the sealing performances of two optimized packers were analyzed including Aflas and Kalrez rubber cylinders. The effects of high temperature and the initial setting pressure on the sealing effects of these two optimized packers were probed based on the finite element analysis (FEA), and the ranges of temperature and initial setting pressure for best sealing were determined. This study can provide some ideas for the material selection and structural optimization for sealing packers, aiming to ensure the safe operation of the packers in severe environments.