Effects of Scatter in Bolt Preload on the Sealing Performance of Pipe Flange Connections Under Internal Pressure (Case Where the Nominal Diameter of Pipe Flange Connection is 20″)

2010 ◽  
Author(s):  
Yoshio Takagi ◽  
Toshiyuki Sawa ◽  
Hiroyasu Torii ◽  
Yuya Omiya
Keyword(s):  
Stress Distribution ◽  
Internal Pressure ◽  
Control Method ◽  
Torque Control ◽  
Stress Distributions ◽  
Flange Connection ◽  
Nominal Diameter ◽  
Bolt Preload ◽  
Sealing Performance ◽  
Contact Stress Distribution

It has been well known that a scatter in axial bolt forces in pipe flange connections tightened by the torque control method is substantial. In practice, pipe flange connections with the large nominal diameter tightened by the torque control method have been used in chemical industry, and so on. In our study, the characteristics of the connections with smaller nominal diameter (less than 8″) have been shown. So, in an optimum design of pipe flange connections with gaskets, it is necessary to understand the characteristics of the pipe flange connections with large nominal diameter under internal pressure and the contact gasket stress distributions due to the scatter in axial bolt forces in the connections tightened by the torque control method. In this paper, the experimental and FE analyses were done to evaluate the effect of scatter in axial bolt force on the gasket stress distribution and the sealing performance of pipe flange connections with 20″ nominal diameter. Two types of torque controlled assembling procedures, that is, ASME PCC-1 and JIS B 2251 procedures, are evaluated as an assembling procedures and an effect of scatter in the axial bolt forces obtained from the above methods is examined. Then, the effect of scatter in the axial bolt forces on the sealing performance of the connection is evaluated. The contact stress distribution in the larger pipe flange connection with 20″ nominal diameter under internal pressure is analyzed using FEM by taking into account a non-linearity and a hysteresis. The measured scatter in the axial bolt forces is applied in the FEM calculations.

Effects of Scatter in Bolt Preload of Pipe Flange Connections With Gaskets on Sealing Performance

2003 ◽  
Author(s):  
Toshiyuki Sawa ◽  
Mitsuhiro Matsumoto ◽  
Satoshi Nagata
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Internal Pressure ◽  
Control Method ◽  
Torque Control ◽  
Stress Distributions ◽  
Flange Connection ◽  
Gas Leakage ◽  
Bolt Preload ◽  
Sealing Performance

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 intemal 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. This paper deals with the leakage of the pipe flange connections with a spiral wound gasket and that with a compressed sheet gasket tightened by the torque control method. The scatter in the axial bolt forces was measured in the experiments. The contact gasket stress distributions at the interfaces of the pipe flange connections with the gaskets were calculated under the measured axial bolt forces by using elasto-plastic finite element method (FEM) taking into account hysteresis and non-linearity in the stress-strain curves of the gaskets. 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. As the result, a difference in an amount of gas leakage measured was found to be substantial between our study and PVRC procedure. By using the calculated contact gasket stress distributions under the internal pressure 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 Scatter in Bolt Preload of Pipe Flange Connections With Spiral Wound Gaskets Under Internal Pressure: In Case of Larger Pipe Flange Connection With 20" Nominal Diameter

2004 ◽  
Author(s):  
Toshiyuki Sawa ◽  
Wataru Maezaki
Keyword(s):  
Internal Pressure ◽  
Contact Stress ◽  
Control Method ◽  
Torque Control ◽  
Stress Distributions ◽  
Gas Leakage ◽  
Nominal Diameter ◽  
Bolt Preload ◽  
Sealing Performance ◽  
Helium Gas

It has been well known that a scatter in axial bolt forces of pipe flange connections tightened by the torque control method is substantial. In practice, pipe flange connections with the larger nominal diameter tightened by the torque control method have been used, frequently. So, in an optimum design of pipe flange connections with gaskets, it is necessary to understand the characteristics of the pipe flange connections with larger nominal diameter under internal pressure and the contact gasket stress distributions due to the scatter of the axial bolt forces in the connections tightened by the torque control method. In this paper, the leakage tests were performed in the actual larger pipe flange connections with 20” nominal diameter using helium gas. Then, 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 calculated contact stress distributions and the results of the leakage tests, the sealing performance was evaluated.

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.

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.

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.

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.

Effect of Scatter in Axial Bolt Force on the Sealing Performance of 20” Inch Pipe Flange Connections With CSG Under Internal Pressure

2015 ◽  
Author(s):  
Yuya Omiya ◽  
Koji Itano
Keyword(s):  
Internal Pressure ◽  
Large Diameter ◽  
Axial Direction ◽  
Stress Distributions ◽  
Flange Connection ◽  
Large Diameter Pipe ◽  
Bolt Preload ◽  
Sealing Performance ◽  
Diameter Pipe ◽  
Experimental Analyses

Since a scatter in axial bolt force exists in assembling the pipe flange connections, it is important to evaluate the effect of scatter in axial bolt force on the sealing performance of pipe flange connection. The FE and experimental analyses were done to evaluate the effect of scatter in axial bolt force on the sealing performance of pipe flange connection with 20 “nominal diameter. The results revealed that the large diameter pipe flange connection was sensitive to the scatter in axial bolt force. Besides, the large diameter pipe flange affected more by flange rotation when internally pressurized. As a result, a larger diameter pipe flange connection with scattered bolt preload showed poor sealing performance. The experimentally obtained scatter in axial bolt force as assembled was taken into account in FE analyses and the effect of the scatters on the contact gasket stress distributions was shown numerically. FE results show that the sealing performance is reduced due to the distributed gasket stress and bolt force scatter in the axial direction.

FEM Stress Analysis and Sealing Performance in Non-Circular Flange Connections With Gaskets Subjected to Internal Pressure

2003 ◽  
Author(s):  
Toshiyuki Sawa ◽  
Wataru Maezaki
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Internal Pressure ◽  
Stress Analysis ◽  
Stress Distributions ◽  
Flange Connection ◽  
Bolt Preload ◽  
Sealing Performance ◽  
Element Method

The contact gasket stress distributions of a non-circular flange connection with a compressed asbestos sheet gasket subjected to internal pressure were analyzed taking account a hysteresis of the gasket by using finite element method (FEM). Leakage tests were also conducted using an actual non-circular flange connection with a compressed asbestos sheet gasket under internal pressure. By using the contact gasket stress distributions and the results of the leakage tests, the new gasket constants were calculated. A difference in the new gasket constants between the values obtained from the present study and those by the PVRC procedure was substantial. In addition, a method to determine the initial clamping bolt force (bolt preload) for a given tightness parameter was demonstrated. abstract text here.

FEM Stress Analysis and Mechanical Characteristics of Bolted Pipe Connections With Larger Nominal Diameter Inserting PTFE Blended Gasket Under Internal Pressure

2018 ◽  
Author(s):  
Koji Sato ◽  
Toshiyuki Sawa ◽  
Xing Zheng
Keyword(s):  
Stress Distribution ◽  
Internal Pressure ◽  
Performance Prediction ◽  
Mechanical Characteristics ◽  
Leak Rate ◽  
Load Factor ◽  
Flange Connection ◽  
Nominal Diameter ◽  
Sealing Performance ◽  
Good Agreement

The sealing performance prediction of bolted pipe flange connections with gaskets is important factor. However, it is known that the sealing performance of the larger nominal diameter connection is worse than that with smaller nominal diameter connection due to the flange rotation. Furthermore, recently PTFE blended gaskets were developed newly and the excellent sealing performance in the bolted pipe flange connection with smaller nominal diameter is found. So, it is necessary to examine the sealing performance and the mechanical characteristics of pipe flange connections with larger nominal diameter under internal pressure. The objectives of present study are to examine the mechanical characteristics of the pipe flange connection with PTFE blended gasket under internal pressure such as the load factor, the contact gasket stress distribution and the sealing performance using FEM and experiments. Using the obtained contact gasket stress distribution and the fundamental leak rate for smaller PTFE gasket, the leak rate of the connection is predicted under internal pressure. In the FEM calculation, the effects of the nominal diameter of pip flange connections on the mechanical characteristics are shown. In the experiments, ASME class 300 24” pipe flange connections is used and the gasket is chosen as No.GF300 in PTFE blended gaskets. The FEM results of the axial bolt forces are in a fairly good agreement with the experimental results. In addition, the leak rate obtained from the FEM calculations are fairly coincided with the measured results. The mechanical characteristics of pipe flange connection with PTFE blended gasket are compared with those with spiral wound gasket.

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.

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