502 Relationship between sealing performance and gasket contact stress of pipe flange connections

2004 ◽  
Vol 2004 (0) ◽  
pp. 127-128
Author(s):  
Kouji SATOU ◽  
Tomohiro TAKAKI ◽  
Yuki YAMANAKA ◽  
Toshimichi FUKUOKA
Keyword(s):  
Contact Stress ◽  
Sealing Performance

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.

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.

On the Effect of External Bending Loads in Bolted Flange Joints

2007 ◽  
Author(s):  
Abdel-Hakim Bouzid ◽  
Yves Birembaut ◽  
Hubert Lejeune
Keyword(s):  
Analytical Model ◽  
Contact Stress ◽  
Analytical Approach ◽  
Bolted Joint ◽  
Acceptable Solution ◽  
Sealing Performance ◽  
Circumferential Distribution ◽  
Bending Loads ◽  
Minimum Stress ◽  
Bolted Flange

Most current flange design methods use an equivalent pressure to treat bolted flange connections subjected to external bending loads. This oversimplified approach together with the lack of a proper assessment of the actual affected tightness make these methods inadequate for modern flange design. The substitution of the external applied moment by an equivalent pressure is excessively conservative and not realistic since it assumes that the achieved tightness is that of a gasket unloaded entirely to a minimum stress whereas in reality only a small section of it is, the rest of it is actually at a much higher stress. The successfulness of a valid analytical approach in yielding to an acceptable solution resides in its ability to account for the circumferential distribution of the gasket contact stress and its effect on leakage. This paper presents an analytical model based on the flexibility of the flange to treat flanges subjected to bending loads such as those produced by external moments and misalignments and capable of integrating leakage around the gasket circumference. The bolted joint sealing performance in the presence of such loads is evaluated using the new PVRC gasket constants Gb, a and Gs obtained from ROTT tests. The analytical results including leakage predictions are validated by comparison to those obtained numerically by FEA and experimentally on different size flanges. The over-conservatism of the equivalent pressure is demonstrated.

An Analysis of Circular Bolted Flanged Joints on Solid Round Bars Subjected to External Bending Moments

2000 ◽  
Author(s):  
Toshiyuki Sawa ◽  
Tsuneshi Morohoshi ◽  
Akihiro Shimizu
Keyword(s):  
Stress Distribution ◽  
Contact Stress ◽  
Three Dimensional ◽  
Bending Moment ◽  
Theory Of Elasticity ◽  
Load Factor ◽  
Bending Moments ◽  
Sealing Performance ◽  
Contact Stress Distribution ◽  
Good Agreement

Abstract In designing bolted joints, it is important to know the contact stress distribution which governs the clamping effect or the sealing performance and to estimate the load factor (the ratio of an increment in axial bolt force to an external load) from bolt design standpoint. The clamping force by bolts and the external bending moment are axi-asymmetrical loads and not many investigations have seen reported which treat axi-asymmetrical. In this paper, the clamping effect, and the load factor for the case of solid round bars with circular flanges, subjected to external bending moments, are analyzed as an axi-asymmetrical problem using the three-dimensional theory of elasticity. Experiments were carried out concerning the contact stress distribution, and the load factor for the external bending moment (a relationship between an increment in axial bolt force, and external bending moment). The analytical results were in fairly good agreement with the experimental ones.

Fluid Dynamics and Contact Stress on Hard Sealing Surface Analysis of LNG Cryogenic Ball Valve

2021 ◽  
Author(s):  
Zhen-Hao Lin ◽  
Jia-Jie Lu ◽  
Jun-Ye Li ◽  
Jin-Yuan Qian
Keyword(s):  
Fluid Dynamics ◽  
Contact Stress ◽  
Fluid Pressure ◽  
Reference Value ◽  
Ball Valve ◽  
Normal Operation ◽  
Pipeline System ◽  
Complex Flow ◽  
Tightening Force ◽  
Sealing Performance

Abstract LNG (liquefied natural gas) cryogenic ball valve (CBV) is an important flow control device in LNG receiving stations. Its reliability directly affects the stability of the pipeline system, especially its damage or leak in the seat seal will seriously threaten the normal operation and the safety of LNG receiving stations. When LNG flows through the CBV, due to the interaction between fluid pressure and the valve structure, the hard sealing at the valve seat is not only subjected to the pre-tightening force of saucer spring, but also affected by the fluid pressure of the complex flow. Therefore, it is necessary to study the flow characteristics in the CBV and the hard sealing performance affected by the LNG. In this paper, the fluid dynamics and the contact stress on hard sealing performance in the CBV are analyzed. The pressure drop, pressure, and velocity distributions were analyzed, respectively. The contact stress on the hard sealing surfaces of the CBV with fluid pressure was analyzed by the fluid-structure coupling method. This work has a certain reference value for researching and mastering the hard sealing performance of cryogenic ball valves.

FEM Stress Analysis and Sealing Performance in Bolted Flange Connections With Cover of Pressure Vessel Subjected to Internal Pressure

2003 ◽  
Author(s):  
Toshiyuki Sawa ◽  
Rie Higuchi
Keyword(s):  
Internal Pressure ◽  
Contact Stress ◽  
Pressure Vessel ◽  
The Finite Element Method ◽  
Flange Connection ◽  
Bolt Preload ◽  
Sealing Performance ◽  
Bolted Flange ◽  
Contact Stress Distribution ◽  
Spiral Wound

The stresses of a bolted flange connection with a cover of pressure vessel (CPV) in which a spiral wound gasket is inserted, under internal pressure are analyzed taking account a hysteresis of the gasket by using the finite element method (FEM). The leakage tests were also conducted using an actual bolted flange connection with a CPV with a spiral wound gasket. Using the contact stress distribution of the bolted flange connection with a CPV under internal pressure and the tightness parameter, the values of the new gasket constants were obtained by taking into account the changes in the contact stress. A difference in the new gasket constants between the estimated values obtained from the actual bolted flange connection with a CPV and the values obtained by the PVRC procedure was small. In addition, a method to determine the bolt preload for a given tightness parameter was demonstrated. The obtained results of the bolt preload for the bolted flange connection with a CPV were in a fairly good agreement with those obtained by the PVRC procedure under a lower pressure application. However, a difference in the bolt preload was about 7% when the internal pressure was increased.

scholarly journals Structural Design and Sealing Performance Analysis of Biomimetic Sealing Ring

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Chuanjun Han ◽  
Han Zhang ◽  
Jie Zhang
Keyword(s):  
Friction Coefficient ◽  
Contact Stress ◽  
Von Mises Stress ◽  
Stress Increase ◽  
Medium Pressure ◽  
Sealing Performance ◽  
Sealing Ring ◽  
Hardness Increase ◽  
Dynamic Seal ◽  
Von Mises

In order to reduce the failure probability of rubber sealing rings in reciprocating dynamic seal, a new structure of sealing ring based on bionics was designed. The biomimetic ring has three concave ridges and convex bulges on each side which are very similar to earthworms. Bulges were circularly designed and sealing performances of the biomimetic ring in both static seal and dynamic seal were simulated by FEM. In addition, effects of precompression, medium pressure, speed, friction coefficient, and material parameters on sealing performances were discussed. The results show that von Mises stress of the biomimetic sealing ring distributed symmetrically in no-pressure static sealing. The maximum von Mises stress appears on the second bulge of the inner side. High contact stress concentrates on left bulges. Von Mises stress distribution becomes uneven under medium pressure. Both von Mises stress and contact stress increase when precompression, medium pressure, and rubber hardness increase in static sealing. Biomimetic ring can avoid rolling and distortion in reciprocating dynamic seal, and its working life is much longer than O-ring and rectangular ring. The maximum von Mises stress and contact stress increase with the precompression, medium pressure, rubber hardness, and friction coefficient in reciprocating dynamic seal.

scholarly journals Research on Key Factors of Sealing Performance of Combined Sealing Ring

2022 ◽  
Vol 12 (2) ◽  
pp. 714
Author(s):  
Heming Cheng ◽  
Xinyuan Chen ◽  
Xiaolan Chen ◽  
Hucheng Liu
Keyword(s):  
Contact Force ◽  
Working Conditions ◽  
Contact Stress ◽  
Compression Ratio ◽  
Cylinder Wall ◽  
Seal Ring ◽  
Key Factors ◽  
Working Pressure ◽  
Sealing Performance ◽  
Sealing Ring

In this study, the mechanical properties of a combined seal ring under different loads were numerically calculated using ANSYS. The effect of the working pressure and pre-compression ratio of a rubber O-ring on the contact stress of the combined seal ring was studied. The influence of the wear ring’s chamfer, thickness, and width on the contact stress and contact force of the combined seal ring was analyzed. Studies have shown that it is particularly important to select a compression ratio that is suitable for the working conditions. Under the same conditions of working pressure and compression ratio, upon increasing the wear ring chamfer, the contact pressure is decreased due to the decreasing contact bandwidth between the wear ring and the cylinder wall. This has little effect on the contact stress of the combined seal ring as well as the contact force, while the width of the wear ring is proportional to the latter.

Stress Analysis of Bolted Joints of Flat Cover With Tap Bolts in a Pressure Vessel

1999 ◽  
Author(s):  
Toshiyuki Sawa ◽  
Akihiro Karasawa ◽  
Akihiro Shimizu
Keyword(s):  
Contact Stress ◽  
Pressure Vessel ◽  
Three Dimensional ◽  
Bending Moment ◽  
Theory Of Elasticity ◽  
Contact Stresses ◽  
Ultrasonic Waves ◽  
Bolted Joints ◽  
Load Factor ◽  
Sealing Performance

Abstract Bolted joints with gaskets have been designed empirically, and the sealing performance is not made clear by theoretical analyses because the contact stress distribution between the gasket and the flanges are not clarified when an internal pressure is applied to the joint. The present paper, discusses the distribution of contact stresses in the bolted joints fastened with tap bolts, when a clamped part with a gasket is the cover of a pressure vessel and is a circular flange. The distribution of contact stresses is analyzed as a three-body contact problem, using the three-dimensional theory of elasticity. Moreover, the contact stress is measured by means of ultrasonic waves. In addition, the load factor (the ratio of an increment of the axial bolt force to an external load) and the maximum stress caused in bolts are analyzed taking into account the bending moment. For verification, experiments are carried out, and the analytical results are found in fairly good agreement with the experimental ones. It was found that the sealing performance was improved when Young’s modulus of the gaskets was decreased and the gasket thickness was increased.

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