Finite Element Analysis of Gasketed Flange Bolted Joint

IJSRD - International Journal for Scientific Research & Development| Vol. 4, Issue 03, 2016 | ISSN (online): 2321-0613

Finite Element Analysis of Gasketed Flange Bolted Joint Pushpak Patel1 Bhavin Mehta2 Hardik Patel3 1,2,3 Assistant Professor 1,2,3 Department of Mechanical Engineering 1,2,3 Charotar University of Science and Technology, Changa, Gujarat, India Abstract— Gaskets play an important role in the sealing performance of bolted flange joints. The use of gasket factors plays an essential role in calculations for flanged joints. In this paper, a three-dimensional finite element analysis (FEA) of gasketed flange Bolted joint has been carried out. Finite element analysis results are also verified with the available ASME method and discussed. Key words: Bolted Flange Joints, Gasket Factors, Finite Element Analysis

A. Finite Element Model

I. INTRODUCTION Flanged joints with gaskets are very common in pressure vessel and piping systems, and are designed mainly for internal pressure. These joints are also used in special applications such as in nuclear reactors and space vehicles. Prevention of fluid leakage is the prime requirement of flanged joints. Gaskets are used to create a static seal between two stationary members of a mechanical assembly and to maintain that seal under operating conditions which may vary dependent upon changes in pressures and temperatures. The investigation of flanged joints for ASME Boiler and Pressure Vessel Code (BPVC) Section VIII (1) allowable stress compliance, flange rigidity and additional investigation for gasket contact stress under all loading conditions is necessary to confirm the leak tightness of the assembly. In order to ensure the maintenance of the seal throughout the life expectancy of the assembly, sufficient stress must remain on the gasket surface to prevent leakage. The residual bolt load on the gasket should at all times be greater than the hydrostatic end force acting against it. The hydrostatic end force is the force produced by the internal pressure which acts to separate the flanges. Internal Pressure is exerted against both the flange and the gasket.

Fig. 1: Forces acting on a gasket Flange joint II. SELECTION OF SOFTWARE FOR MODELING AND STRESS ANALYSIS

The accurate result of the software analysis depends upon the effectiveness and simplicity of analysis software together with its speed and simple user interface. There for among many options. Pro/ENGINEER is selected for modeling and ANSYS is selected for stress analysis of gasketed flange Bolted joint.

Fig. 2: Geometry of Flange Joint B. Flange B = Inside diameter of the flange = 406.4 mm A = Outside diameter of the flange = 558.8 mm t = Flange thickness = 44.45 mm r = Hub radius = 9.525 mm g0 = thickness of the hub at the small end = 19.05 mm C. Gasket GOD = Gasket OD = 450.85 mm GID = Gasket ID = 412.75 mm D. Bolting C = bolt-circle diameter = 514.35 mm Number of bolts = 16 For finite element modeling the simulation module of program is used. Finite element programme divides the element into a grid of ‘element’, which form a model of real structure. A finite model is complete idealization of the entire structural problem, including the node locations, the elements, physical and materials properties, loads and boundary condition. The model is supposed to be defined differently for different types of analysis: static structural loads, dynamic or thermal analysis. The goal of finite element model is not to make a model look like structure. The purpose of finite element modeling is to make a model that behaves mathematically like the structure modeled, not necessarily one looks like real structure. III. FINITE ELEMENTS MODELING AND STRESS ANALYSIS It consists of three steps. Which are:  Pre-processing  Solution  Post processing. A. Pre-processing This includes the entire process of developing the geometry of a finite element model, entering physical and material properties, describing the boundary conditions and loads and

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Finite Element Analysis of Gasketed Flange Bolted Joint (IJSRD/Vol. 4/Issue 03/2016/410)

checking the model. ‘CAD model’ generated with the help of Pro/ENGINEER shown in fig.3.

B. Solution The solution phase can be performed in the model solution task of the simulation application, or an external finite element analysis program. C. Post processing The post processing task of simulation application provides tools to display and interpret the results after the solution is finished. Results of Nodal Stress Joint Assembly for post processing which is shown in fig.6.

Fig. 3: CAD Model (Pro/ENGINEER) 1) Meshing Nodes and elements are generated by one of the two methods, mapped mesh or free mesh. Here the free mesh is used for meshing because of more flexibility in defining mesh areas; it will automatically create by an algorithm, which tries to minimize element distortion which is shown in fig. 4. Fig. 6: Equivalent Stress IV. RESULTS AND DISCUSSION

Fig. 4: Meshing 2) Boundary Condition The boundary condition is applied to build analysis cases containing loads and restraint of the model in finite element analysis, which is shown in fig.5. 3) Operating Condition Internal Pressure = 0.6894 Mpa

Table 1 presents calculated flange stresses as per ASME Section - VIII Div I. Flange Flange Calculated Seating Operating Flange Symbol Stresses Stresses Stresses (N/mm2) (N/mm2) Longitudinal SH 197.08 41.03 Hub Stress Radial Flange SR 58.31 12.14 Stress Tangential ST 47.35 9.92 Flange Stress Combined 0.5 127.70 31.085 Stresses (SH + SR) Combined 0.5 122.22 25.475 Stresses (SH + ST) Table 1:- Calculated flange stresses Allowable flange stress (Sf) = 137 Mpa As per ASME Section - VIII Div I: The longitudinal-hub stress: SH < 1.5 Sf The tangential-flange stress: ST < Sf The radial-flange stress: SR < Sf The combined stresses: 0.5(SH + SR) < Sf 0.5(SH + ST) < Sf V. CONCLUSION

Fig. 5: Boundary Condition

By Finite element analysis, the stress at the Gasketed Flange joint has studied. From the comparison of design calculations as per ASME codes and Stress results obtained from the F.E.A. analysis indicated that the flanged joint is within acceptable levels.

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Finite Element Analysis of Gasketed Flange Bolted Joint (IJSRD/Vol. 4/Issue 03/2016/410)

REFERENCES [1] Jaroslav Bartonicek, Manfred Schaaf, Friedrich Schoeckle; “Use of gasket factors in flange calculations ”; ASME PVP Conference; 2000. [2] Muhsen Al-Sannaa and Abdulmalik Alghamdi; “Two dimensional finite element analysis for large diameter steel flanges”; December 2002. [3] Brett C Taylor ; “Assessment of Appropriate Pressure Vessel Flange Bolt Tension by Finite Element Modelling ” [4] Muhammad Abid; “Determination of safe operating conditions for gasketed flange joint under combined internal pressure and temperature: A finite element approach”; 2005. [5] M. Abid and D.H. Nash; “Structural strength: Gasketed vs non-gasketed flange joint under bolt up and operating condition”; International Journal of Solids and Structures; March 2005. [6] Muhammad Abid; “Stress Variation in the Flange of a Gasketed Flanged Pipe Joint during Bolt up and Operating Conditions”; 2006. [7] M. Murali Krishna, M.S. Shunmugam, N. Siva Prasad; “A study on the sealing performance of bolted flange joints with gaskets using finite element analysis ”; International Journal of Pressure Vessels and Piping. [8] Pushpak M. Patel, Piyush P. Gohil; “Stress Variation in Gasketed Flange Joint during Bolt up and Operating Condition”; Indian Journal of Technical Education; 2012. [9] “Gasket Handbook”; Lamons Gasket Company. [10] “Gasket Design Criteria”; Flexitallic. [11] Catalogue of Intermech Sealing Solutions Ltd. [12] Chapter: 22 Seal Technology; “Mechanical Engineers' Handbook,”; By Myer Kutz; Second Edition; John Wiley & Sons;1998. [13] Catalogue of Pressure Vessel Engineering Ltd (ASME Vessel Code Calculations - Finite Element Analysis ). [14] ASME Boiler and Pressure Vessel Code Section - VIII, Div 1, Appendix 2. [15] Jordan Christopher Baker; “Analysis of Bolting in Flanged Connections”; April 2009. [16] “Guidelines for safe seal usage Flanges and Gaskets ”;ESA / FSA Publication; September, 1998. [17] William J. Koves; “Bolted-Flange Joints And Connections”; 2009.

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