FEM Stress Analysis and Sealing Performance Evaluation in Bolted Flange Connections With Metal Flat Gasket Subjected to Bending Moment and Internal Pressure

2014 ◽  
Author(s):  
Koji Kondo ◽  
Yuya Omiya ◽  
Shota Tsubaki ◽  
Toshiyuki Sawa
Keyword(s):  
Plastic Deformation ◽  
Internal Pressure ◽  
Bending Moment ◽  
Leak Rate ◽  
Stress Distributions ◽  
Bolt Preload ◽  
Sealing Performance ◽  
Higher Temperature ◽  
Contact Surfaces ◽  
Bolted Flange

Bolted flange connections with metal gasket have been used at higher pressure under higher temperature condition. Assembly procedures and tightening methods the connections including some types of metal gasket is empirically. Generally, it is known that the bolt preload which is required for satisfying an indicated leak rate in the connections including the metal gasket is not higher than that of the connections including sheet gaskets and spiral wound gaskets. However, no research for the evaluating the sealing performance in the bolted flange connections with metal gaskets has been conducted. In this paper, the leakage tests for the bolted flange connections with the metal flat gasket were conducted in the case where the maximum internal pressure of 7MPa and a bending moment are applied, where the leak rate is measured using the pressure drop method. Then, the sealing performance of the connections with the metal flat gasket was evaluated. In addition, using the FEM stress calculations, the flange stress distributions between the flange surface and the gasket were examined as the evaluation. As the result, it is found that the stress distribution at the contact surfaces between the metal flat gasket and the flange surface under the bending moment and the internal pressure. In the leakage tests, it was observed that the amount of the leakage (He gas) depends on the stress distributions and the plastic deformation of the gasket.

The Mechanical Characteristics and Sealing Performance Evaluation of Bolted Pipe Flange Connections With Metallic Flat Gaskets Subjected to Internal Pressure

2016 ◽  
Author(s):  
Koji Kondo ◽  
Koji Sato ◽  
Satomi Takahashi ◽  
Toshiyuki Sawa
Keyword(s):  
Plastic Deformation ◽  
Mechanical Characteristics ◽  
Experimental Results ◽  
Leak Rate ◽  
Effect Of Temperature ◽  
Load Factor ◽  
Stress Distributions ◽  
Bolt Preload ◽  
Sealing Performance ◽  
Higher Temperature

Bolted pipe flange connections with metallic gaskets have been used under higher pressure as well as higher temperature. However, a few researches on the mechanical characteristics in connections with metallic gaskets have been carried out. It is necessary to examine the mechanical characteristics such as the contact gasket stress distributions which govern the sealing performance, the deformation of the metallic gaskets, changes in axial bolt forces and the hub stress under higher pressure and temperature. In the present paper, the objectives are to examine the changes in axial bolt forces, the hub stress and the contact gasket stress distributions and the sealing performance of the pipe flange connections with metallic flat gaskets. Firstly, the mechanical characteristics of the connections under higher pressure are analyzed using FEA. Then, experiments were carried out to measure the load factor, the hub stress and the leak rate (the sealing performance). The relationship between the average contact gasket stress and the leak rate was measured using platen device at room temperature. The FEA results are fairly coincided with the experimental results. It is shown that the leak rate decreases as the contact gasket stress increases and when the plastic deformation of gaskets occurs, the sealing performance increases. The leak rate was measured in the range of 10−4∼10−7 [Pa·m3/s]. It is found that the sealing performance increases as the gasket width increase in the elastic deformation range while it is independent of the gasket width when the plastic deformation occurs. The effect of temperature on the mechanical characteristics of the connection is also examined. The FEA results are in a fairly good agreement with the experimental results. It is found that the sealing performance increases as the temperature increases. In addition, a method how to determine the bolt preload for increasing the sealing performance is proposed.

FEM Stress Analysis and the Sealing Performance Evaluation in Bolted Flange Connections With Ring Joint Gasket Subjected to Internal Pressure: Effect of Scatter in Bolt Preloads

2012 ◽  
Author(s):  
Koji Kondo ◽  
Shota Tsubaki ◽  
Toshiyuki Sawa ◽  
Tsutomu Kikuchi ◽  
Yuya Omiya
Keyword(s):  
Internal Pressure ◽  
Leak Rate ◽  
Stress Distributions ◽  
Sealing Performance ◽  
Torque Wrench ◽  
Helium Gas ◽  
Higher Temperature ◽  
Bolted Flange ◽  
Better Than ◽  
Good Agreement

Bolted flange connections with ring joint gaskets have been used to seal the inner fluid under higher internal pressure and higher temperature conditions where soft gaskets such as compressed sheet gaskets cannot be applied. Bolted flange connections are frequently tightened using torque wrench, and it is known that the values of bolt preloads are scattered. The effect of the scatter on the sealing performance for bolted flange connections with compressed sheet gasket or semi-metal gasket has been examined. However, no research on the characteristics for the bolted flange connections with ring joint gasket has been found. It is necessary to know the effect of the scattered bolt preloads on the sealing performance and mechanical behavior of the connection with ring joint gasket. In addition, it is important to know an optimum method for determining the bolt preloads taking account of the scatter in bolt preloads. In this paper, leakage tests for bolted flange connections with octagonal ring joint gaskets were conducted for cases where the bolt preloads are uniform and scattered. The sealing performance of these connections with ring joint gaskets was measured and evaluated. In addition, the leak rate was estimated using the contact gasket stress distributions of the connections when the bolt preloads were uniform and scattered using 3-D FEM. Finally, the measured leak rate for the connection using helium gas was compared with the estimated results. The estimated results are in fairly good agreement with the measured values. It is found that the sealing performance of the connections tightened with the uniform bolt methods is better than that with scattered bolt preloads.

Evaluation of Sealing Performance and FEM Calculations in Bolted Flange Connections With Ring Joint Gasket Subjected to Internal Pressure

2011 ◽  
Author(s):  
Kentaro Tenma ◽  
Tsutomu Kikuchi ◽  
Toshiyuki Sawa ◽  
Kazuhide Horiuchi
Keyword(s):  
Pressure Drop ◽  
Stress Distribution ◽  
Maximum Pressure ◽  
Metal Ring ◽  
Stress Distributions ◽  
Bolt Preload ◽  
Sealing Performance ◽  
Higher Temperature ◽  
Contact Surfaces ◽  
Bolted Flange

The bolted flange connections with ring joint gasket have been used to seal the inner fluid at higher pressure under higher temperature condition. Assembly procedures and tightening methods for the type of gasket have typically been empirically determined. Generally, it is known that the bolt preload which is required to seal the inner fluid in the connections using the ring joint gasket is not higher than that of the connections using sheet gaskets and spiral wound gaskets. However, no research for the evaluation of sealing performance in the bolted flange connections with metal ring gasket has been conducted. In this paper, the leakage tests for the bolted flange connections with the ring joint gasket were conducted in the case where the maximum pressure is 10MPa. Measuring the leak rate of inner fluid using the pressure drop method, the sealing performance of the connections with the ring joint gasket was evaluated. In addition, using the FEM stress calculations, the flange hub stress distributions and the flange groove stress distributions were examined as the evaluation for the flange strength. As the result, it is found that the stress distribution at the contact surfaces between the ring joint gasket and the flange groove depends on the bolt tightening procedure. In the leakage tests, it was observed that the amount of the leakage (He gas) depends on the stress distributions at the groove stress which is affected due to the bolt tightening method.

Sealing Performance Evaluation in Bolted Flange Connections With Ring Joint Gasket Subjected to Internal Pressure

2013 ◽  
Author(s):  
Koji Kondo ◽  
Koji Sato ◽  
Toshiyuki Sawa ◽  
Shota Tsubaki ◽  
Yuya Omiya
Keyword(s):  
Plastic Deformation ◽  
Performance Evaluation ◽  
Metal Ring ◽  
Stress Distributions ◽  
Ring Type ◽  
Bolt Preload ◽  
Sealing Performance ◽  
Higher Temperature ◽  
Sealing Mechanism ◽  
Bolted Flange

Bolted flange connections with ring type joint gaskets have been used to seal the inner fluid under higher pressure and higher temperature conditions when soft gaskets cannot be used in the connections. However, few researches on the characteristics and the sealing performance evaluation for the bolted flange connections with metal ring gasket have been conducted. Therefore, assembly procedures and tightening methods of the connection with ring type joint gaskets is empirically and not fully elucidated. It is important to know the characteristics such as the contact gasket stress distribution which governs the sealing performance prediction, the sealing performance and the sealing mechanism in the bolted flange connections for determining optimum tightening methods and the bolt preload. In this paper, the differences of the sealing performance for the bolted flange connections (3″) by the re-use octagonal and oval type ring gaskets are examined. In the FEM calculations the contact gasket stress distributions and the range of plastic deformation are examined and the sealing mechanism is discussed. It is found that the basic sealing mechanism is caused by the plastic deformation at the contact area of the gasket. In addition, the leakage tests for the bolted flange connections with the nominal diameter of 20″ with the octagonal ring type joint gaskets being inserted are conducted, where the bolt tightening for the connection is carried out according to both ASME PCC-1 and JIS B2251, respectively. Using these results, the optimum tightening methods for the connection with ring type joint gaskets are discussed.

Stress Analysis and the Sealing Performance Evaluation of Pipe Flange Connections With Gaskets Subjected to Internal Pressure and External Bending Moment: Effects of Scatter in Bolt Preload

2004 ◽  
Author(s):  
Toshiyuki Sawa ◽  
Wataru Maezaki ◽  
Satoshi Nagata
Keyword(s):  
Finite Element Method ◽  
Internal Pressure ◽  
Control Method ◽  
Bending Moment ◽  
Torque Control ◽  
Stress Distributions ◽  
Gas Leakage ◽  
Bolt Preload ◽  
Sealing Performance ◽  
Spiral Wound

It has been well known that a scatter in axial bolt forces of pipe flange connections tightened by the torque control method is substantial. It is necessary for evaluating the sealing performance of the pipe flange connections with the gaskets subjected to internal pressure and external bending moment to know the contact gasket stress distributions due to the scatter of the axial bolt forces in the connections tightened by the torque control method. This paper deals with the leakage of the pipe flange connections with a spiral wound gasket subjected to internal pressure and external bending moment tightened by the torque control method. The scattered axial bolt forces were measured in the experiments. The contact gasket stress distributions at the interfaces between pipe flanges and the gasket were calculated under the measured axial bolt force by using elasto-plastic finite element method (FEM) taking into account hysteresis and non-linearity in the stress-strain curves of spiral wound gasket. The effects of the scatter in the axial bolt forces tightened by the torque control method on the gas leakage were also examined by using the actual pipe flange connections under internal pressure and external bending moment. By using the calculated contact stress distributions and the results of the leakage tests, the sealing performance was evaluated. It is found that the sealing performance is worse in the actual pipe flange connection than that evaluated by PVRC procedure.

Effects of Scattered Bolt Preload on the Sealing Performance of Pipe Flange Connection With Gaskets Under External Bending Moment and Internal Pressure

2012 ◽  
Author(s):  
Toshiyuki Sawa ◽  
Yoshio Takagi ◽  
Koji Sato ◽  
Yuya Omiya ◽  
Hayato Doi
Keyword(s):  
Internal Pressure ◽  
Bending Moment ◽  
Experimental Result ◽  
Chemical Plants ◽  
Stress Distributions ◽  
Bolt Preload ◽  
Sealing Performance ◽  
Torque Wrench ◽  
History Of ◽  
Good Agreement

Bolted pipe flange connections have been widely used in mechanical structures such as oil, chemical plants and so on. Sometimes leakage accidents occur from the connections. In assembling the pipe flange connections, the bolt preloads are scattered and then the connections are subjected to external bending moment due to earthquake as well as internal pressure. In the present paper, the changes in the axial bolt forces are measured in assembling. The bolts are tightened with torque wrench. Using the history of the bolt force changes, the gasket stress distributions on the connection with gaskets are analyzed using FEM. Then the gasket stress distributions on the connections under external bending moment and internal pressure are analyzed. Using the gasket stress distributions, the amount of leakage of the connections is estimated while the basic gasket characteristics have been measured according to JIS B 2251. The amount of leakage of the connection was measured for the various gasket stresses. The estimated results are in a fairly good agreement with the measured results. It is found that the effect of the scatter of bolt preload is substantial on the sealing performance of the connections. Discussion is made on the sealing characteristics of the connections. The change of axial bolt force obtained from experimental result and FEM result are fairly good agreement.

FEM Stress Analysis and Sealing Performance in Pipe Flange Connections With Gaskets Subjected to External Bending Moment: Case Where Internal Fluid is Liquid

2003 ◽  
Author(s):  
Toshiyuki Sawa ◽  
Mitsuhiro Matsumoto ◽  
Fumio Ando
Keyword(s):  
Finite Element Method ◽  
Internal Pressure ◽  
Liquid Water ◽  
Bending Moment ◽  
Bending Moments ◽  
Stress Distributions ◽  
Bolt Preload ◽  
Sealing Performance ◽  
Internal Fluid ◽  
Practical Design

The leakage evaluation when gas is used is more severe than that when liquid is used in pipe flange connections. In a practical design, it is also necessary to examine the leakage in the connection under liquid internal pressure. This paper deals with the contact gasket stress distributions in the pipe flange connections with a spiral wound gasket and a compressed sheet gasket by using elasto-plastic finite element method (FEM) taking account hysteresis and non-linearity in the stress-strain curves of the gaskets, when bending moments as well as internal pressure are applied to the connections. In the FEM calculations, the effects of the gaskets and the initial clamping bolt force (bolt preload) on the contact gasket stress distributions are examined. The leakage tests for the connections under bending moments were also conducted by using liquid (water). By using the results of the leakage tests and the calculated contact gasket stress distributions, the sealing performance of the connections is evaluated. It is found that the sealing performance of the connection under the bending moment can be estimated when internal fluid is liquid (water).

Stress Analysis and Sealing Performance Evaluation in Rectangular Box-Shape Bolted Flange Connection With Gasket Subjected to Internal Pressure

2011 ◽  
Vol 133 (2) ◽  
Author(s):  
Toshiyuki Sawa ◽  
Ryo Kurosawa ◽  
Wataru Maezaki
Keyword(s):  
Finite Element Method ◽  
Internal Pressure ◽  
Research Council ◽  
Stress Distributions ◽  
The Finite Element Method ◽  
Flange Connection ◽  
Bolt Preload ◽  
Sealing Performance ◽  
The Difference ◽  
Bolted Flange

The contact gasket stress distributions in a rectangular box-shape bolted flange connection with a compressed sheet gasket subjected to internal pressure were analyzed using the finite element method. Leakage tests were also conducted for an actual rectangular box-shape bolted flange connection with a compressed sheet gasket under internal pressure. Using the obtained contact gasket stress distributions and the results of the leakage tests, the new gasket constants were calculated. The difference in the new gasket constants between the values obtained from the present study and those from the Pressure Vessel Research Council (PVRC) procedure was substantial. In addition, a method to determine the bolt preload for a given tightness parameter was demonstrated and the difference in the determined bolt preload was shown between the present study and the PVRC procedure. The characteristics of the rectangular box-shape bolted flange connection were demonstrated by comparing those of circular bolted flange connections.

Effects of Scatter in Bolt Preload on the Sealing Performance in Bolted Flange Connections With Cover of Pressure Vessel Under Internal Pressure

2006 ◽  
Author(s):  
Satoshi Nagata ◽  
Toshiyuki Sawa ◽  
Seiichi Hamamoto
Keyword(s):  
Internal Pressure ◽  
Pressure Vessel ◽  
Torque Control ◽  
Control Methods ◽  
Stress Distributions ◽  
Flange Connection ◽  
Gas Leakage ◽  
Bolt Preload ◽  
Sealing Performance ◽  
Bolted Flange

It has been well known that the scatter in axial bolt forces of bolted flange connections tightened by torque control methods is substantial. In evaluating the sealing performance of a bolted flange connection with a gasket subjected to internal pressure, it is necessary to know the contact gasket stress distributions due to the scatter of the axial bolt forces in the flange connections tightened by torque control methods. This paper deals with the leakage of a bolted flange connection with a cover of pressure vessel including a spiral wound gasket tightened by a torque wrench. The scatter in the axial bolt forces was measured using strain gauges attached at the shank of bolts. The amount of leakage from the bolted flange connection with cover of pressure vessel was measured by so-called pressure decay method. The gas employed was Helium. From the measured leakage, the actual assembly efficiency is examined. The eight bolts and nuts were tightened according to the ASME PCC-1 method and Japanese method developed by High Pressure Institute (HPI). The difference in the bolt preload was shown between the ASME method and the HPI method. The contact gasket stress distributions at the interface of the flange connection with the gasket were calculated under the measured axial bolt forces by means of finite element analysis. Using the calculated gasket contact stress distribution, the amount of gas leakage was estimated. The estimated gas leakage was compared with the measured results.

Stress Analysis and Sealing Performance Evaluation in Bolted Flange Connections With Ring Joint Gasket Subjected to Internal Pressure

2012 ◽  
Author(s):  
Koji Kondo ◽  
Shota Tsubaki ◽  
Toshiyuki Sawa ◽  
Koji Sato ◽  
Yuya Omiya
Keyword(s):  
Performance Evaluation ◽  
Metal Ring ◽  
Stress Distributions ◽  
Pressure Condition ◽  
Bolt Preload ◽  
Sealing Performance ◽  
Metal Metal ◽  
Higher Temperature ◽  
Sealing Mechanism ◽  
Bolted Flange

Bolted flange connections with ring joint gaskets have been used to seal the inner fluid under higher pressure and higher temperature condition when soft gasket cannot be used in the connection. The ring joint gaskets are assumed that they can seal inner fluid by the metal-metal contact between the ring joint gasket and the grooves of flanges under higher pressure condition. However, no research on the characteristics and sealing performance evaluation for the bolted flange connections with metal ring gasket has been conducted. Therefore, assembly procedures and tightening methods of the connection with ring joint gaskets is empirically. It is important to know the characteristics such as the contact gasket stress distribution, the sealing performance and the sealing mechanism in the bolted flange connections for determining optimum tightening methods and the bolt preload. In this paper, the leakage tests for the bolted flange connections (3″) with the octagonal ring joint gaskets are conducted. Measuring the leak rate of inner fluid from the connections using the pressure drop method, the sealing performance of the connections with the ring joint gaskets is evaluated. In addition, using the 3-D FEM stress calculations, the gasket contact stress distributions for the connections with the octagonal ring joint gaskets are examined. Using these results, the optimum bolt preload of the connection with octagonal ring joint gaskets are discussed. Furthermore, the leakage tests for the bolted flange connections (20″) with the octagonal ring joint gaskets are conducted in the case where the bolt tightening is carried out according to both ASME PCC-1 and JIS B 2251, respectively. The optimum tightening methods for the connection with octagonal ring joint gaskets are discussed.

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