Study on Radial Clearance Sealing Performance of Graphite Ring

2020 ◽  
Vol 143 (3) ◽  
Author(s):  
Zhou Xianjun ◽  
Chen Chunlei ◽  
Li Jianhua ◽  
Wu Yanze
Keyword(s):  
Contact Stress ◽  
Pipe Wall ◽  
Leakage Rate ◽  
Radial Clearance ◽  
Sealing Performance ◽  
Porous Media Model ◽  
Packing Rings ◽  
Ring Seal ◽  
Packing Ring ◽  
Deformation Test

Abstract Firstly, the suitable forming method of graphite ring was screened according to compression deformation test, considering the characteristics of radial clearance seal. Then, the compression resilience, radial contact stress and axial sealing performance of graphite packing rings with different density were researched by testing. Research shows: 25% compressibility is the limit of radial clearance compensation ability of graphite packing ring; And the radial contact stress of graphite packing ring on the pipe wall is linearly positively correlated with the axial load, density has little effect on it. Based on the porous media model of gaskets, axial leakage models of three kinds of graphite rings with different density were obtained by experimental fitting and the influence of external working conditions on leakage mode was analyzed, which provide a theoretical basis for the design of graphite ring seal based on leakage rate.

Prediction of Time-Correlated Leakage Rates of Bolted Flanged Connections by Considering the Maximum Gasket Contact Stress

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
Z. G. Sun ◽  
B. Q. Gu
Keyword(s):  
Finite Element ◽  
Stress Relaxation ◽  
Contact Stress ◽  
Prediction Method ◽  
Leakage Rate ◽  
Leakage Model ◽  
Rate Prediction ◽  
Sealing Performance ◽  
Gasket Material ◽  
Maximum Contact

The leakage rates of bolted flanged connections change with service time due to the gasket contact stress relaxation and degradation of gasket material. The nonuniform distribution of gasket contact stress has significant influence on the leakage behavior of the connections. In order to predict the time-correlated leakage rates accurately, both appropriate approaches to dealing with the gasket residual contact stress and a corresponding time-correlated leakage model of sealing elements are needed. In this paper, an analytical model has been developed to determine the maximum contact stress at gasket outer diameter in consideration of creeps of flanges, bolts and gasket coupled to the axial deformation compatibility equation. The analysis was verified against the finite element numerical simulation considering the nonlinear behavior of gasket and material creep. The analytical results of the maximum contact stress of gasket and its change over time compared well with those obtained by finite element method. A time-correlated leakage model of nonmetallic gasket sealing connections based on the porous medium theory was established, in which the effects of the gasket material degradation and contact stress relaxation on the sealing performance were taken into consideration. Furthermore, a leakage rate prediction method was proposed. Some long-term sealing performance tests were performed on two types of gaskets to obtain the coefficients in the leakage model. The leakage rate prediction method proposed in this paper was also validated against the experimental data presented by other researchers, and the errors between the predicted values and the experimental results were within 18%.

Analytical and Numerical Evaluation of the Axial Stress Distribution of Two Soft-Packed Stuffing-Box Configurations

2014 ◽  
Author(s):  
Mehdi Kazeminia ◽  
Abdel-Hakim Bouzid
Keyword(s):  
Contact Stress ◽  
Axial Stress ◽  
Design Procedure ◽  
Operating Conditions ◽  
Analytical Models ◽  
Fe Method ◽  
Sealing Performance ◽  
Packing Rings ◽  
Valve Sealing ◽  
Axial Stress Distribution

Stuffing-box packed valves which confine high-pressure fluids are often subjected to leakage failure. The lack of a design procedure and the vulnerability of packing ring sealing materials to withstand different operating conditions are the root cause of the problem. The sealing performance of valves with packed stuffing-box depends on the ability of the assembly to maintain a minimum threshold contact pressure between the packing and the stem and the packing and the housing throughout service operation. The distribution of the contact stresses in the packing materials is a key parameter to efficient sealing performance. This study presents a contact stress modeling study of two different design configurations that are helpful to produce a uniform distribution of the contact stress. The first model is based on the introduction of a variable gap between the packing and the side walls. The second model is based on a multistage loading of the packing rings. The two developed analytical models are validated by comparison with the numerical simulation using FE method and the results show a good agreement. The two design configurations can be used to improve valve sealing performance.

Study on the Compression-Resilience and Sealing Performance of New Metal-to-Metal Contact Gasket

2018 ◽  
Vol 140 (2) ◽  
Author(s):  
Zhou Xianjun ◽  
Zhai Haodong ◽  
Wen Weipeng ◽  
Wu Yanze
Keyword(s):  
High Temperature ◽  
Internal Pressure ◽  
Contact Stress ◽  
Temperature Stability ◽  
Leakage Rate ◽  
Metal Contact ◽  
Stable Range ◽  
High Temperature Stability ◽  
Sealing Performance ◽  
Different Temperatures

The compression-resilience performance of new metal-to-metal contact (MMC) gasket at different temperatures was studied by compression-resilience test, and the influences on sealing performance of gasket caused by internal pressure of medium and assembly stress were studied by sealing test. Then the influences on performance of gasket caused by internal pressure of medium, bolt pretightening force, and temperature were studied through finite element method of ANSYS. According to the results of test and numerical analysis, conclusions are as follows: The new MMC gasket has good high-temperature stability from results of tests at different temperatures. When the MMC occurs between flange and gasket, the contact stress of new MMC gasket is about 50 MPa. When applying loads, the limiting ring of gasket is able to bear parts of bolt loads, and when reducing loads, its resilience can compensate loss of gasket stress. In this case, the stress on sealing surface of gasket remains stable so that the leakage rate can keep in a stable range. Because of its unique structure in design, the inner contact stress of new MMC gasket increases with the rise of internal pressure of medium so that in a certain range, the leakage rate changes gently, which shows that the gasket has a certain self-sealing ability. Besides, the new MMC gasket is able to adapt to high temperature and fluctuation of internal pressure of medium.

Nonlinear Analysis of Rotary Sealing Performance of Rubber O-Ring

2013 ◽  
Vol 470 ◽  
pp. 371-375 ◽  
Author(s):  
Shao Hua Chen ◽  
Guo Zhang Jiang ◽  
Gong Fa Li ◽  
Liang Xi Xie ◽  
Wen Qiang Qian
Keyword(s):  
Contact Stress ◽  
Element Model ◽  
Rotating Shaft ◽  
Medium Pressure ◽  
Maximum Contact Stress ◽  
Sealing Performance ◽  
Two Factors ◽  
Ring Seal ◽  
Von Mises ◽  
Maximum Contact

The two-dimensional O-ring seal nonlinear axisymmetric finite element model are established which is used for swinging hydraulic cylinder. Some factors influencing rubber O-ring sealing performance were taken into account, such as rotating shaft diameter, O-ring seal section diameter. The results indicate that when medium pressure is zero, the two factors influence Von Mises and maximum contact stress of sealing face greatly. Under medium pressure (P=10Mpa), the two factors have a little influence to Von Mises and maximum contact stress.

Analysis of Packer Rubber Mechanics Properties

2014 ◽  
Vol 971-973 ◽  
pp. 380-389
Author(s):  
Jian Ning Wang ◽  
Gang Wu ◽  
Wei Yi Xie ◽  
Xin De Han ◽  
Ming Chao Gang
Keyword(s):  
Finite Element ◽  
Elastic Modulus ◽  
Constitutive Model ◽  
Contact Stress ◽  
Theoretical Basis ◽  
Element Model ◽  
Rubber Material ◽  
Bottom Hole ◽  
Sealing Performance ◽  
The Finite Element Model

Abstract: The packer rubber stress in the bottom hole is more complex. Based on constitutive model of the packer rubber material, this paper determines such parameters as model constants, Poisson's ratio of rubber materials and elastic modulus by using experimental method, to build up the finite element model of center tube-rubber cylinder-casing for the purpose of stress analysis. Finally, the distribution regularity of rubber cylinder-casing contact stress and packer setting travel distance with varying loads is concluded. The results can provide the theoretical basis for further analysis of packer rubber sealing performance.

Tubing String Thread Sealing Surfaces Damage Evaluation Based on Acoustic Elasticity Theory

2019 ◽  
Vol 944 ◽  
pp. 828-834 ◽  
Author(s):  
Jian Jun Wang ◽  
Jian Hua Sun ◽  
Shang Yu Yang ◽  
Yao Rong Feng ◽  
Kai Lin
Keyword(s):  
Surface Roughness ◽  
Elasticity Theory ◽  
Contact Stress ◽  
Surface Characterization ◽  
Surface Damage ◽  
Center Frequency ◽  
Sealing Performance ◽  
Tubing String ◽  
Acoustic Elasticity

During the processing of tubing premium threaded made up, the degree of the thread sealing surface intactness will directly affect the sealing performance of the string. Nevertheless, there are some difficulties to detect the damage of the engaged sealing surface effectively. In the present study the sealing surface damage was judged by the sealing surface contact stress’s relative changes according to the acoustic elasticity theory,. At the same time, the wear defects generated at the tubing sealing surface, during the tubing made up, contrasted with the wear and unworn surface roughness of coupling ultrasonic detected about the sealing surface. The results showed that with the acoustic amplitude evaluated the sealing contact stress was susceptible to the influence of surface roughness of coupling. But the reflection wave with the center frequency on the sealing surface characterization of the contact stress could avoid this problem effectively.

Numerical Simulation Study on Battery-Casing Sealing Considering Rubber Aging

2020 ◽  
Vol 36 (6) ◽  
pp. 955-969
Author(s):  
Yijie Huang ◽  
Fei Guo ◽  
Yuchao Ke ◽  
Fangyong Wu ◽  
Xiaohong Jia ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Porous Media ◽  
Circular Arc ◽  
Sealing Material ◽  
Sealing Performance ◽  
Porous Media Model ◽  
New Energy ◽  
Key Factor ◽  
Grid Independence ◽  
New Energy Vehicles

ABSTRACTBattery-casing sealing is the key factor for secure travel of new energy vehicles. We constructed a relatively accurate mechanical-simulation model by selecting a constitutive model, analyzing the influence of thermal elongation, verifying the grid-independence and comparing numerically by the pressure-measurement film on the basis of studying the physical performance of a certain type of sealing material that had been used in battery-casings after aging. Based on a porous-media model and combined with changes of macroscopic and microscopic contact characteristics of materials at different times after aging, the evolution rule of sealing performance with time was analyzed quantitatively by calculating the leakage. By analyzing the structure of circular arc bulge on the surface of sealing material, the radius of circular arc bulge with better sealing performance was obtained, which could reduce the leakage of sealing structure during the material’s lifecycle.

Comparison on Mechanical Behavior of Bolted Flanges Per Old and New Section VIII Division 2

2011 ◽  
Author(s):  
Susumu Terada ◽  
Tatsuo Nishihara ◽  
Tomohiro Suzuki
Keyword(s):  
Stress Level ◽  
Contact Stress ◽  
Outer Edge ◽  
Main Concern ◽  
Symmetric Model ◽  
Large Size ◽  
Sealing Performance ◽  
Internal Fluid ◽  
Section Viii ◽  
As Stress

The allowable stress for 2.25Cr 1Mo 0.25V steel per ASME Section VIII Div.2 2007 edition (hereinafter called New Div2) becomes higher than that per old Div.2. Therefore the thickness of flange can be thinner than that per old Div.2. The internal fluid leakage is main concern as well as stress level especially for large size flanges per New Div.2. In this paper the analysis method using axi-symmetric model are investigated and the numerical analyses using axi-symmetric models for two types of flange design are performed in order to compare the flange rotation, gasket contact stress and stress level of flange and bolts. The contact stress of New Div.2 flange was lower than that of Old Div.2 flange totally. However the maximum gasket contact stress of New Div.2 flange which occurred at outer edge of the gasket is almost same as that of Old Div.2. Therefore it is expected that the sealing performance of flange connections per both Old Div.2 and New Div.2 is almost same.

scholarly journals Analysis of Sealing and Leakage Performance of the Subsea Collet Connector with Lens-Type Sealing Structure

2020 ◽  
Vol 8 (6) ◽  
pp. 444
Author(s):  
Feihong Yun ◽  
Gang Wang ◽  
Zheping Yan ◽  
Peng Jia ◽  
Xiujun Xu ◽  
...  
Keyword(s):  
Structural Characteristics ◽  
Gain Coefficient ◽  
Leakage Rate ◽  
One Dimensional ◽  
Mechanics Model ◽  
Sealing Performance ◽  
Width Measurement ◽  
Pressure Experiment ◽  
The One ◽  
The Relationship

The contact mechanics model of the metal lens-type sealing gasket is established on the basis of Hertz theory on the macroscopical scale in this paper. The relationship among sealing width, contact pressure, and preload is solved. Based on the structural characteristics of the subsea collet connector, the self-locking characteristics are analyzed to determine the gain coefficient of the sealing structure for the loading thrust. On the microscopic scale, the contact characteristics of the turning lens-type sealing gasket and the hub structure are analyzed by the equivalent replacement of the peak cut coefficient of the one-dimensional sinusoidal wave. The influence of different leakage forms on sealing performance is discussed from both radial and circumferential leakage, and the leakage rate of the lens-type sealing structure is calculated. The hydrostatic pressure experiment of the subsea collet connector with lens-type sealing gasket is carried out, and the correctness of the theoretical analysis is verified from the results of the pressure maintaining, sealing width measurement, and preload conversion.

Structure Characteristics and Improvement of Oil Seal of Turbo-Supercharger

2013 ◽  
Vol 779-780 ◽  
pp. 1130-1133
Author(s):  
Hui Gan ◽  
Kun Yu Yang
Keyword(s):  
High Speed ◽  
High Reliability ◽  
Great Influence ◽  
Pressure Change ◽  
Exhaust Gas ◽  
Test Results ◽  
Chamber Volume ◽  
Sealing Performance ◽  
Complementary Action ◽  
Ring Seal

Through the analysis of the sealing mechanism of the oil seals in exhaust gas turbo supercharger and the comparative test of different oil seals with the pressure change in the oil-return chamber, a seal that uses a caulking ring with reverse threads is designed, and an optimum combination of oil seal is selected. The combination of caulking ring and the oil-return thread structure has better complementary action on oil sealing, because for the seal with oil-return reverse thread there is better dynamic and static seal effect on ring seal and has good sealing performance and high reliability at high speed. The test results of screening selection of combination seals show that different combinations of caulking ring and the oil-return threads have great influence on the pressure of the oil-return chamber. The combination of caulking ring outside and oil-return threads inside is recommended to be used. In addition, the smooth return of the oil can be ensured as far as possible by increasing the supercharger oil-return chamber volume. The improved structure of the oil seal has effectively enhanced the reliability of the whole unit of the exhaust gas turbo supercharger.

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