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 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.

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

2005 ◽  
Author(s):  
Masahide Katsuo ◽  
Toshiyuki Sawa ◽  
Yuki Kikuchi
Keyword(s):  
Internal Pressure ◽  
Stress Analysis ◽  
Bending Moment ◽  
Fem Analysis ◽  
Bending Moments ◽  
3 Dimensional ◽  
Leakage Test ◽  
Sealing Performance ◽  
Flange Thickness ◽  
Good Agreement

This study deals with the stress analysis and the estimation of sealing performance of the pipe flange connections with an adhesive under an internal pressure and an external bending moment are analyzed by using the 3-dimensional elastic finite element method (FEM). The experiment of the leakage test of the connections with an adhesive was carried out by applying the above loads to the connections. From the FEM analysis, the following results were obtained; (1) when an internal pressure is applied to the flange connections, the compressive stress at the interface between a flange and an adhesive increases proportionally from the inner side of the interface to outside, and (2) when an internal pressure and a bending moment apply to the flange connections, the stress distribution at the half part of the interface increases as the external bending moments increase and also Young’s modulus of the adhesive increases. From the experiments, the following results were obtained: (1) sealing performance of the pipe flange connections with an adhesive under an internal pressure and an external bending moment increases as the flange thickness and an initial clamping force of bolts increases and (2) the sealing performances were not found between the connections with an adhesive and that with a gasket combining an adhesive. Furthermore, the numerical results are in fairly good agreement with the experimental results.

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 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).

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.

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.

Finite Element Stress Analysis for Leak Tests of Pipe Flange Connections Subject to Internal Pressure and Bending Moment

2011 ◽  
Author(s):  
Satoshi Nagata ◽  
Toshiyuki Sawa ◽  
Takashi Kobayashi ◽  
Hirokazu Tsuji
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Internal Pressure ◽  
Bending Moment ◽  
Strain Gages ◽  
Element Analysis ◽  
Element Simulation ◽  
Sealing Performance ◽  
Gas Leak ◽  
Helium Gas

This paper reports the results of finite element analysis representing the sealing performance tests on the slip-on type pipe flange connections for 8 inch and 16 inch. The flange connections are subjected to internal pressure and bending moment. Internal pressure is applied by helium gas and the bending moment is loaded through 4 points bending equipment. Gas leak rates are measured by pressure decay method. During the test, the variations in the axial bolt force are monitored for all the bolts by strain gages. The pipe stress at the junction of pipe and flange is also measured. Finite element analysis simulates the tests and the simulated results are compared with the measured data. Then the behaviors of the slip-on type flange connections under internal pressure and bending moment as well as the sealing performance are clarified by the experiment and the finite element simulation.

scholarly journals Assessment of internal pressure effect, causing additional bending of the pipeline

2020 ◽  
Vol 242 ◽  
pp. 160
Author(s):  
Ramil BAKTIZIN ◽  
Rail ZARIPOV ◽  
Gennadii KOROBKOV ◽  
Radik MASALIMOV
Keyword(s):  
Internal Pressure ◽  
Pressure Effect ◽  
Extreme Values ◽  
Bending Moment ◽  
Extreme Value ◽  
Bending Moments ◽  
Temperature Stresses ◽  
Working Pressure ◽  
Trunk Pipeline ◽  
Bending Stresses

Article justifies accounting for internal pressure effect in the pipeline, causing additional bending of the pipeline. According to some scientists, there is an erroneously used concept of the equivalent longitudinal axial force (ELAF) Sx, which depends on working pressure, temperature stresses, and joint deformations of pipelines with various types of soils. However, authors of the article use ELAF Sx concept at construction of mathematical model of stress-strain state (SSS) for complex section of the trunk pipeline, and also reveal it when analyzing the results of calculating the durability and stability of the pipeline. Analysis of SSS for calculated section of the pipeline was carried out for two statements of the problem for different values of operation parameters. In the first statement, effect of internal pressure causing bending of the pipeline is taken into account, and in the second it is neglected. It is shown that due to effect of ELAF Sx at p0 = 9.0 MPa, Dt = 29 °C extreme value of bend increases by 54 %, extreme values of bending stresses from span bending moment increase by 74 %, and extreme value of bending stresses from support bending moment double with regard to corresponding SSS characteristics of the pipeline. In case of neglecting the internal pressure effect causing additional bending of the pipeline (second statement of the problem), error in calculating the extreme value of bend is 35 %, extreme value of bending stresses from span bending moments is 44 %, and extreme value of bending stresses from support bending moments is 95 %.

Limit Load Solutions of the Orthotropic Thick-Walled Pipe Subjected to Internal Pressure, Bending Moment and Torsion Moment

2019 ◽  
Author(s):  
Min Xu ◽  
Yujie Zhao ◽  
Binbin Zhou ◽  
Xiaohua He ◽  
Changyu Zhou
Keyword(s):  
Analytical Solution ◽  
Yield Strength ◽  
Internal Pressure ◽  
Yield Criterion ◽  
Bending Moment ◽  
Limit Load ◽  
Pure Bending ◽  
Pure Torsion ◽  
Torsion Moment ◽  
The Difference

Abstract Based on the Hill yield criterion, the analytical solutions of the limit load of orthotropic thick-walled pipes under pure internal pressure, bending moment and torsion are given respectively. The simplified Mises analytical solution and finite element results of limit load for isotropic thick-walled pipe are obtained. The solution verifies the reliability of the analytical solution. The paper discusses the difference of limit load of isotropic and orthotropic pipes under the conditions of pure internal pressure, pure bending moment and pure torsion moment. It is concluded that the influence of material anisotropy on the limit load is significant. The limit load of pipe under pure internal pressure is mainly determined by circumferential yield strength, pure bending is only related to axial yield strength and pure torsion moment is related to the yield strength in the 45° direction and radial yield strength.

FEM Stress Analysis and Leakage Behavior of Pipe-Socket Threaded Joints Subjected to Bending Moment and Internal Pressure

2020 ◽  
Author(s):  
Satoshi Nagata ◽  
Shinichi Fujita ◽  
Toshiyuki Sawa
Keyword(s):  
Finite Element ◽  
Internal Pressure ◽  
Bending Moment ◽  
Experimental Tests ◽  
Element Analysis ◽  
Contact Conditions ◽  
Sealing Performance ◽  
Bending Load ◽  
Threaded Joints ◽  
Thread Root

Abstract This paper is a report of the studies on the mechanical behaviors and leakage characteristics of pipe-socket threaded joints subjected to bending moment as well as internal pressure by means of experimental tests and finite element simulations. The paper dealt with the 3/4″ and 3″ joints, and the joints for both sizes have two different combinations of thread types in the pipe and socket, i.e. taper-taper thread combination or taper-parallel one, respectively. Experimental bending leak tests showed that the taper-taper joints could retain internal pressure under bending load up to nearly plastic collapse. The taper-parallel joints, however, could hardly keep internal pressure against bending moment even the sealing tape was applied to enhance the sealing performance. Finite element analysis was carried out to simulate those bending tests, especially to clarify the deformation and the stress distribution in the engaged threads in detail. The analysis demonstrated that the sealing performance of the joints highly depend on the contact conditions not only at the thread crest to thread root but also in between flank surfaces. A complicated leak path across the engaged threads under bending moment was identified by the simulation.

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