Effect of External Bending Moment on the Sealing Performance of Pipe Flange Connection

2010 ◽  
Author(s):  
Yoshio Takagi ◽  
Hiroyasu Torii ◽  
Toshiyuki Sawa ◽  
Yuya Omiya
Keyword(s):  
Stress Distribution ◽  
Internal Pressure ◽  
Deformation Characteristic ◽  
Bending Moment ◽  
Displacement Curve ◽  
Linear Deformation ◽  
Flange Connection ◽  
Sealing Performance ◽  
Non Linear ◽  
The Difference

Since an external bending moment affects the sealing performance of pipe flange connection, it is important to investigate this effect. This paper analyzed the contact gasket stress distribution of pipe flange connections and evaluates the effect of external bending moment on the sealing performance from the viewpoint of changes in contact gasket stress. The study includes the FE analyses and the experimental leakage tests. The FE analyses suggested the large decrease of contact gasket stress at tension side and small increase at compression side. The difference in change in contact gasket stress was caused by the non-linear hysteresis characteristics of stress-displacement curve of gasket. The FE analyses also suggested that the loading order, internal pressure and external bending moment, also affected the sealing performance due to the non-linear deformation characteristic of the gasket. The sealing performance when the external bending moment applied prior to the internal pressure was degraded more than when the internal pressure was applied prior to the external bending moment. The experimental leakage tests using helium (He) gas were analyzed by the finite element method and discussed. This paper also evaluated the stress distribution in the pipe flange under external bending moment. The results suggested that the hub stress dominated the flange structure and the most important factor in designing the flange.

FEM Stress Analysis and Mechanical Characteristics of Bolted Pipe Flange Connections With PTFE Blended Gaskets Subjected to External Bending Moments and Internal Pressure

2017 ◽  
Author(s):  
Koji Sato ◽  
Toshiyuki Sawa ◽  
Riichi Morimoto ◽  
Takashi Kobayashi
Keyword(s):  
Stress Distribution ◽  
Internal Pressure ◽  
Mechanical Characteristics ◽  
Bending Moment ◽  
Leak Rate ◽  
Bending Moments ◽  
Four Point Bending ◽  
Sealing Performance ◽  
The Difference ◽  
Good Agreement

In designing of pipe flange connections with gaskets, it is important to examine the mechanical characteristics of the connections subjected to external bending moments due to earthquake such as the changes in hub stress, axial bolt forces and the contact gasket stress distribution which governs the sealing performance. One of the authors developed the PTFE blended gaskets and the authors examined the mechanical characteristics of the connections with the PTFE blended gaskets under internal pressure. However, no research was done to examine the mechanical characteristics of the connections with the newly developed PTFE blended gasket subjected to external bending moment due to earthquake. The objectives of the present study are to examine the mechanical characteristics of the connection with PTFE blended gasket subjected to external bending moment and internal pressure and to discuss the difference in the load order to the connections between the internal pressure and the external bending moments. The changes in the hub stress, the axial bolt force and the contact gasket stress distribution of the connection are analyzed using FEM. Using the obtained the gasket stress distribution and the fundamental data between the gasket stress and the leak rate for a smaller test gasket, the leak rate of the connection with the gasket is predicted under external bending moment and internal pressure. In the FEM calculations, the effects of the nominal diameter of pipe flanges on the mechanical characteristics are shown. In the experiments, ASME class 300 4 inch flange connection with 2m pipes at both sides is used and the test gasket is chosen as No.GF300 made by Nippon Valqua Industries, ltd. Four point bending moment is applied to the connection. The FEM results of the hub stress and the axial bolt forces are in a fairly good agreement with the experimental results. In addition, the FEM results of the leak rate are fairly coincided with the measured results.

Evaluation of Sealing Performance of Pipe Flange Connection Subjected to External Bending Moments

2009 ◽  
Author(s):  
Yoshio Takagi ◽  
Hiroyasu Torii ◽  
Toshiyuki Sawa ◽  
Kensuke Funada
Keyword(s):  
Bending Moment ◽  
Bending Moments ◽  
Stress Strain ◽  
Flange Connection ◽  
Strain Behavior ◽  
Leakage Test ◽  
Bolt Preload ◽  
Sealing Performance ◽  
Non Linear

The sealing performance of pipe flange connection subjected to an external bending moment was evaluated with the FEM and the experiments. The experimental leakage test using water revealed that the bending moment had an important effect on the sealing performance. The FE analyses suggested that the contact gasket stress, which was a function of the bolt preload, determines the leakage. The changes in contact gasket stress at tension side and compression side when the external bending moment applied were not symmetrical. The reduction in the contact gasket stress of tension side was larger than that of compression side due to the non-linear stress-strain behavior of the gasket. In addition, the hub stress of the flange when external bending moment applied, was evaluated from FE result and the discussion for optimizing the flange design subjected to external bending moment was done in this paper.

FEM Stress Analysis and the Sealing Performance Evaluation of Pipe Flange Connections Subjected to External Bending Moments and Internal Pressure

2011 ◽  
Author(s):  
Kazuhide Horiuchi ◽  
Yoshio Takagi ◽  
Toshiyuki Sawa
Keyword(s):  
Tensile Strength ◽  
Internal Pressure ◽  
Design Method ◽  
Bending Moment ◽  
Initial Contact ◽  
Bending Moments ◽  
Loading History ◽  
Pipe Length ◽  
Sealing Performance ◽  
The Difference

In previous study, the characteristics of the pipe flange connections such as the contact gasket stress distribution and the sealing performance of the connection subjected to bending moments are examined. The result suggests that the leakage increases as the bending moment increases. However, a design method for the connection subjected to bending moment is not taken into consideration. The sealing performance of the connection for the different loading history is changed due to non-linearity and hysteresis of non-asbestos gasket. After the pipe flange connections are tightened, bending moment prior to internal pressure is applied due to misalignment of the connections with bolts and nuts. So, it is necessary to examine the difference in the sealing performance due to different loading history and to establish a design method for the connections subjected to bending moment and internal pressure. In this study, the difference in the sealing performance due to different loading history is examined and pipe length in each usage condition is determined for the two loading histories using tensile strength of hub side and allowable leak rate of soppy bubble method to establish a design method of flange subjected to bending moment. The result suggests the average contact gasket stress for the different loading history is changed due to non-linearity and hysteresis of non-asbestos gasket and pipe length in each initial contact gasket stress is determined for the two loading histories.

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.

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.

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

2006 ◽  
Author(s):  
Toshiyuki Sawa ◽  
Ryo Kurosawa ◽  
Wataru Maezaki
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Internal Pressure ◽  
Stress Analysis ◽  
Stress Distributions ◽  
The Finite Element Method ◽  
Flange Connection ◽  
Bolt Preload ◽  
Sealing Performance ◽  
The Difference

The contact gasket stress distributions of a non-circular flange connection with a compressed sheet gasket subjected to internal pressure were analyzed taking into account of the hysteresis behavior of the gasket by using the finite element method (FEM). Leakage tests were also conducted using an actual non-circular flange connection with a compressed sheet gasket under internal pressure. Using the 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 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.

FEM Stress Analysis and Sealing Performance in Pipe Flange Connections With Gaskets Subjected to Internal Pressure and External Bending Moment

2002 ◽  
Author(s):  
Toshiyuki Sawa ◽  
Mitsuhiro Matsumoto
Keyword(s):  
Internal Pressure ◽  
Strain Curve ◽  
Bending Moment ◽  
Stress Distributions ◽  
Stress Strain Curve ◽  
Flange Connection ◽  
Leakage Test ◽  
Sealing Performance ◽  
Calculated Average ◽  
Good Agreement

This paper deals with the characteristics of a pipe flange connection with a compressed asbestos sheet gasket (JIS) subjected to an internal pressure and a bending moment. The contact gasket stress distributions at the interfaces between pipe flanges and a gasket are calculated by the elasto-plastic finite element method taking account a hysteresis and a non-linearity in the stress-strain curve of the compressed asbestos sheet gasket. In addition, measurements of a change in axial bolt force and leakage test were conducted using an actual pipe flange connection with the gasket subjected to the internal pressure and the bending moment. The new gasket constants are calculated by using the results of the leakage test and the calculated average contact gasket stress. The values of the new gasket constants obtained by the present study are in a fairly good agreement with those from ROTT (PVRC). It is found that the value of the tightness parameter is increased as the bending moment is increased. This is because the average contact gasket stress under the bending moment is increased, while it is decreased under the internal pressure.

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.

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