Thermal Stress Analysis and the Sealing Performance Evaluation of Bolted Flange Connection at Elevated Temperature

2009 ◽  
Author(s):  
Yuya Omiya ◽  
Toshiyuki Sawa
Keyword(s):  
Heat Conduction ◽  
Thermal Stress ◽  
Elevated Temperature ◽  
Internal Pressure ◽  
Theory Of Elasticity ◽  
Gas Leakage ◽  
Sealing Performance ◽  
Helium Gas ◽  
Reliable Design ◽  
Bolted Flange

In designing bolted flange connections under heat conduction conditions and internal pressure, the characteristics such as the contact gasket stress are important factors from reliable design standpoint. They must be examined analytically and experimentally. In this paper, in order to examine the above characteristics, thermal stress of bolted flange connections subjected to internal pressure and heat conduction conditions is analyzed using the theory of elasticity and FEM calculations. The effects of gasket properties and nominal diameter of flanges on the above characteristics are examined numerically. In the experiments, the amount of helium gas leakage in the connection was measured. Using the obtained gasket stress at elevated temperature, a method for estimating the amount of gas leakage is proposed. The analytical results of the above characteristics are compared with the experimental results, with reasonable agreements. The results reveal that the sealing performance increases due to the gasket properties as the temperature increases in this study.

The Sealing Performance Evaluation of Bolted Flexible Box-Shaped Flange Joints Under Thermal Conduction Conditions

2009 ◽  
Author(s):  
Ryou Kurosawa ◽  
Toshiyuki Sawa ◽  
Yuya Omiya ◽  
Kentaro Tenma
Keyword(s):  
Elevated Temperature ◽  
Internal Pressure ◽  
Thermal Conduction ◽  
Stress Distributions ◽  
Flange Joint ◽  
The Finite Element Method ◽  
Gas Leakage ◽  
Bolt Preload ◽  
Sealing Performance ◽  
Helium Gas

Bolted joints with gaskets such as flexible box-shaped flange joints have been used in mechanical structures. The joints are usually used under internal pressure as well as other loadings such as thermal, impact loadings and so on. In designing the bolted flexible box-shaped flange joint with gaskets, it is important to evaluate the sealing performance of the joints under internal pressure and thermal conduction conditions. In this paper, the contact gasket stress distributions and changes in bolt load in the bolted flexible box-shaped flange joint with joint sheet gaskets subjected to internal pressure and thermal conduction condition are analyzed using the finite element method (FEM). The leakage tests were conducted using an actual box-shaped flange connection with a joint sheet gasket. Using the contact gasket stress distributions under internal pressure at an elevated temperature (Helium gas) obtained from the FEM calculations and the amount of the gas leakage measured in the experiment, the sealing performances are evaluated experimentally and numerically. In addition, the effect of the thermal conduction condition on the sealing performance is examined. Furthermore, a method how to determine the bolt preload of the flexible box-shaped flange joint at an elevated temperature for a given tightness parameter is demonstrated. Discussion is made on the sealing performance.

Thermal Stress Analysis and Evaluation of Sealing Performance in Pipe Flange Connections With Spiral Wound Gaskets Under Elevated Temperature and Internal Pressure

2005 ◽  
Author(s):  
Toshiyuki Sawa ◽  
Yoshio Takagi ◽  
Teruhisa Tatsuoka
Keyword(s):  
Thermal Stress ◽  
Elevated Temperature ◽  
Internal Pressure ◽  
Theory Of Elasticity ◽  
Stress Distributions ◽  
The Finite Element Method ◽  
Analysis And Evaluation ◽  
Sealing Performance ◽  
Effects Of Temperature ◽  
Spiral Wound

In this paper, the thermal stress distributions at the interfaces between pipe flanges and the gasket under elevated temperature and internal pressure were calculated by using the theory of elasticity and the finite element method (FEM) taking into account hysteresis in the stress-strain curves of spiral wound gasket. Leakage tests were performed using helium gases. In addition, the effects of temperature on the sealing performance were examined by using an actual pipe flange connection with spiral wound gasket under elevated temperature. By using the calculated contact stress distributions and the results of the leakage tests, the sealing performance was evaluated.

Stress Analysis and Sealing Performance Evaluation of Bolted Pipe Flange Connections With Smaller and Larger Nominal Diameter Under Repeated Temperature Changes

2014 ◽  
Author(s):  
Yuya Omiya ◽  
Toshiyuki Sawa
Keyword(s):  
Internal Pressure ◽  
Thermal Condition ◽  
Power Plants ◽  
Thermal Exposure ◽  
Flange Connection ◽  
Gas Leakage ◽  
Nominal Diameter ◽  
Other Hand ◽  
Sealing Performance ◽  
Helium Gas

Pipe flange connections with gaskets in chemical plants, electric power plants and other industrial plants are usually exposed to elevated internal pressure with cyclic thermal condition. It is important to investigate the sealing performance of pipe connections under long term severe thermal exposure swings to ensure operational safety. In this study, the effects of cyclic thermal conditions on the sealing performance and mechanical characteristics in larger and smaller nominal diameter of pipe flange connection are examined using FEM calculations. Helium gas leakage is predicted using the contact gasket stress obtained from the FEM results. On other hand, the leakage tests using the smaller nominal diameter of pipe flange connection were conducted to measure the amount of helium gas leakage and to compare with the predicted amount of gas leakage. As the results, the contact gasket stress distributions were changed dramatically under cyclic thermal condition and elevated internal pressure. In the pipe flange connections with smaller nominal diameter, the contact gasket stress was the smallest in the restart condition. On other hand, the minimum contact gasket stress in the pipe flange connection with larger nominal diameter was depending on the materials of connection. In the pipe flange connection with larger nominal diameter, the contact gasket stress distributed and changed in the radial direction due to the flange rotation. A fairly good agreement was found between the experimental leakage result and predicted leakage results.

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.

FEM Analysis and Evaluation of the Sealing Performance in Flexible Box-Shape Flanged Bolted Joints With Gaskets Subjected to Internal Pressure: Effect of the Bolt Pitch

2007 ◽  
Author(s):  
Toshiyuki Sawa ◽  
Ryo Kurosawa ◽  
Yasuaki Tatsumi
Keyword(s):  
Internal Pressure ◽  
Fem Analysis ◽  
Bolted Joints ◽  
Stress Distributions ◽  
The Finite Element Method ◽  
Analysis And Evaluation ◽  
Flange Connection ◽  
Sealing Performance ◽  
Helium Gas ◽  
Bolted Flange

Bolted joints with gaskets such as non-circular flange connections have been widely used in mechanical structures, nuclear and chemical industry, and so on. They are usually used under internal pressure as well as other loadings such as thermal, impact loadings and so on. In designing the non-circular flange connections with gaskets, it is important to evaluate the sealing performance of the non-circular flange connections with gaskets subjected to internal pressure. An important issue is how to evaluate the sealing performance in the box-shape bolted flange connections by using the contact gasket stress distributions at the interfaces, how to reduce a number of bolt and nuts, that is, how to enlarge the bolt pitch, and how to determine the initial clamping bolt force (preload) by using the new gasket constants. In this paper, the stresses of box-shape flange connection with gaskets subjected to an internal pressure are analyzed using the finite element method (FEM), taking account a hysteresis in the stress-strain curves of the gasket. The contact gasket stress distributions when the internal pressure is applied to the connection are analyzed. The leakage tests were conducted using an actual box-shape flange connection with a gasket Using the contact gasket stress distributions at the interfaces under an internal pressure (Helium gas was used) and the amount of the leakage measured in the experiment, the sealing performances are evaluated experimentally and theoretically by changing the bolt pitch in the connections. Discussion is made on the effect of the bolt pitch on the sealing performance in the above connections.

Evaluation of the Sealing Performance in Bolted Flange Connection Under Heat Condition and Internal Pressure: The Effect of Scatter in Bolt Preloads

2006 ◽  
Author(s):  
Toshiyuki Sawa ◽  
Yoshio Takagi ◽  
Katsuhiro Yamada
Keyword(s):  
Internal Pressure ◽  
Control Method ◽  
Torque Control ◽  
Stress Distributions ◽  
Heat Condition ◽  
Flange Connection ◽  
Gas Leakage ◽  
Sealing Performance ◽  
Torque Wrench ◽  
Bolted Flange

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 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. Especially, when gases are used in the pipe flange connections with gaskets at a high temperature, it is necessary to evaluate the amount of gas leakage. In this study, when bolts and nuts in a pipe flange connection were tightened using a torque wrench, the axial bolt forces were measured and then the amount of gas leakage in the pipe flange connection at 50,100,150 and 200 °C was measured under internal pressure. Leakage tests were performed using Helium gases. In addition, the thermal stress distributions at the interfaces between pipe flanges and the gasket under heat condition (temperature 50,100,150 and 200 °C) and internal pressure were calculated by using the finite element method (FEM) taking into account hysteresis in the stress-strain curves of a spiral wound gasket. By using the calculated contact stress distributions and the results of the leakage tests, the sealing performance was evaluated.

Sealing Performance Evaluation of Pipe Flange Connection Under Elevated Temperatures

2007 ◽  
Author(s):  
Toshiyuki Sawa ◽  
Yoshio Takagi ◽  
Hiroyasu Torii
Keyword(s):  
Elevated Temperature ◽  
Stress Distribution ◽  
Internal Pressure ◽  
Elevated Temperatures ◽  
Flange Connection ◽  
Gas Leakage ◽  
Sealing Performance ◽  
Nominal Size ◽  
Operational Temperature ◽  
Contact Stress Distribution

Since a lot of pipe flange connections are exposed to elevated temperature during operation, it is important to evaluate the sealing performance of the connections under operational temperature. In this study, the sealing performance of pipe flange connection was experimentally evaluated by measuring the amount of gas leakage at room temperature (RT), 100 °C and 200 °C in addition to internal pressure. Non-asbestos graphite gaskets were used in the experiment. The nominal size of the pipe flange used during the experimental study was 3 inch. The eight bolts and nuts were tightened according to ASME PCC-1 and the Japanese method (HPIS). During assembly, the axial bolt force was individually measured with strain gauges attached to each bolt. The scatter in the axial bolt force during the assembling process was examined and compared between the ASME and the HPIS. In addition, the gasket contact stress distribution of each assembly process was calculated by finite element method under elevated temperature and internal pressure. In the FE study, experimentally measured physical properties such as elastic modulus and thermal expansion were used. ηhe amount of leakage was estimated from the contact gasket stress distribution obtained by FE analysis. The estimated axial bolt forces were compared with those of experimental ones.

The Effect of Clamping Force and Material Properties on the Tightness Performance a Flexible Box-Shaped Flange Bolted Joint

2008 ◽  
Author(s):  
Ryou Kurosawa ◽  
Toshiyuki Sawa ◽  
Satoshi Nagata ◽  
Yasuaki Tatsumi
Keyword(s):  
Internal Pressure ◽  
Bolted Joints ◽  
Clamping Force ◽  
Stress Distributions ◽  
The Finite Element Method ◽  
Flange Connection ◽  
Sealing Performance ◽  
Helium Gas ◽  
Bolted Flange ◽  
Cover Material

Bolted joints with gaskets such as non-circular flange connections have been widely used in mechanical structures, nuclear and chemical industry, and so on. They are usually used under internal pressure as well as other loadings such as thermal, impact loadings and so on. In designing the non-circular flange connections with gaskets, it is important to evaluate the sealing performance of the non-circular flange connections with gaskets subjected to internal pressure. An important issue is how to evaluate the sealing performance in the box-shaped bolted flange connections by using the contact gasket stress distributions at the interfaces, how to reduce the weight and how to determine the initial clamping bolt force (preload) by using the new gasket constants. In this paper, the stresses of box-shaped flange connection with gaskets subjected to an internal pressure are analyzed using the finite element method (FEM), taking account a hysteresis in the stress-strain curves of the gasket. The reduced contact gasket stress distributions are analyzed when the internal pressure is applied to the connection. The leakage tests were conducted using an actual box-shaped flange connection with a gasket. Using the reduced contact gasket stress distributions at the interfaces under an internal pressure (Helium gas was used) and the amount of the leakage measured in the experiment, the sealing performances are evaluated experimentally and theoretically by changing the initial clamping force and cover material in the connections. In addition, the sealing performance of the connection with raised face is also examined. Discussion is made on the effects of the initial clamping force, cover material and the types of facing on the sealing performance in the above 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.

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