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30120130405010
30120130405010
30120130405010
30120130405010
30120130405010
30120130405010
30120130405010
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30120130405010

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  • 1. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 5, September - October (2013) © IAEME 81 DESIGN, ANALYSIS AND OPTIMISATION OF BODY FLANGE AND COVER FLANGE USING FINITE ELEMENT ANALYSIS P. M. Desai1 , B. C. Pathak2 , V. A. Patel3 , P. B. Rana4 1 (Mechanical Engineering, SVIT, Vasad, INDIA) 2,3,4 (Mechanical Engineering, Government Engineering College, Bharuch, INDIA) ABSTRACT Most of the researchers have worked upon weight optimization of metal to metal contact flange. Also research has been done on sealing ability criteria for bolted joints with gasket and on safe operating condition for gasket joint under pressure and temperature. Optimization of body flange and cover flange of steam condenser used in thermal power plant and improving the ability of gasket has not been carried out yet and is under the area of research. This paper will provide an exposure to design, analysis and optimization of body flange & cover flange by using FEM approach and its validation by analytical as per ASME. Keywords: Cover Flange, Finite Element Analysis, Optimization. I. INTRODUCTION A flanged joint may be made with flanges cast integral with the pipes or loose flanges welded or screwed. The flange faces are machined to ensure correct alignment of the pipes. The joint may be made leak proof by placing a gasket of soft material, rubber or canvas between the flanges. The flanges are made thicker than the pipe walls, for strength. The flange is the most essential part of Pressure vessel, Condenser, Heat Exchanger and Storage Tank. Flanges are used on the shell of a vessel or an exchanger to permit to disassembly and removal or cleaning of internal parts. Flanges are also used for making piping connections and any other nozzle attachment at opening. In the case of the ASME, Appendix Y, the bending stress value in three directions longitudinal, radial and tangential can be determined directly using an analytical approach. The equation for the maximum longitudinal hub bending stress given in the code does not indicate the location of this stress but only the magnitude. The radial flange bending stress can either be determined at the bolt circle or at the inside diameter. The tangential Flange bending Stress was INTERNATIONAL JOURNAL OF MECHANICAL ENGINEERING AND TECHNOLOGY (IJMET) ISSN 0976 – 6340 (Print) ISSN 0976 – 6359 (Online) Volume 4, Issue 5, September - October (2013), pp. 81-87 © IAEME: www.iaeme.com/ijmet.asp Journal Impact Factor (2013): 5.7731 (Calculated by GISI) www.jifactor.com IJMET © I A E M E
  • 2. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 5, September - October (2013) © IAEME 82 determined from the Appendix Y procedure at the inside diameter of the flange and so is compared directly with the FEA predictions. [1] The analysis of bolted flanged joint with gaskets is due to the nonlinear behavior of the gasket material combined with permanent deformation. The material undergoes permanent deformation under excessive stresses. The degree of elasticity is a function of the compressive stresses which act on the gasket during assembly and after it is put into service. Gasket stiffness has a predominant effect on the behavior of the joint because of its relatively low stiffness. [2] II. DESIGN OF FLAT HEAD Here the Design of Flange is based on the ASME Codes Section-8, Div. I and the dimensions obtained are Thickness of shell = 12 mm Thickness of Body Flange = 102 mm Thickness of Cover Flange = 60 mm Hexagonal Bolt = M30 x 172 Hexagonal Nut = M30 Material for shell, cover flange and body Flange is SA 516 Gr 70. Material for Hexagonal Bolt and Hexagonal Nut is SA 193Gr B7. The dimensions obtained by the calculations are used to model the part by using commercial modeling software. 2.1 Modelling and Simulation Methodology For carrying out analysis 3D model as shown in figure 1 has been prepared in commercial software creo 1.0 using dimension obtained from ASME section-8, Div.-I. Fig.1. 3D Model of Flange Assembly 2.2 Simulation Methodology Model has been simplified using commercial software creo 1.0 for analysis. The simplified model hasshown in Figure 2.
  • 3. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 5, September - October (2013) © IAEME 83 Fig.2. Symmetry Model of Flange To simplify the model only half portion has taken for the analysis. The model is further simplified by removing manholes, nozzle and filling by cut out III. FINITE ELEMENT ANALYSIS 3.1 Material Properties Material properties for flange model are given as per the table 1 shown below. Table1. Material Properties For Linear Analysis Young Modulus 195 GPa Poisson Ratio 0.3 Density 7850 Kg/ m3 For Nonlinear Material Young Modulus 300 GPa Poisson Ratio 0.45 3.2 Boundary Conditions Assemble flange model is imported in Ansys 14.0. So different contact between assemble model has been defined as given in table 2. Graphical representation is shown in the figure 3. Table2. Boundary Conditions For Linear Analysis Young Modulus 195 GPa Poisson Ratio 0.3 Density 7850 Kg/ m3 For Nonlinear Material Young Modulus 300 GPa Poisson Ratio 0.45
  • 4. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 5, September - October (2013) © IAEME 84 Fig.3. Boundary Condition 3.3 Meshing Model Model is meshed with tetrahedral elements as shown in the figure 4. Total number of nodes and elements are 130847 and 52075 respectively. Fig.4. Meshing Model 3.4 FEM validation of Flange Assembly The initial validation of the simulation has been done by comparing its results obtained from analytical calculation (ASME Code, Sec-8, Div.-I). Figure 5 shows the finite element analysis of cover flange. Table3. Comparative Stress Analysis Sr .No Allowable Limit Analytical Stress Simulation Stress % Deviation 1 138 MPa 127.9 MPa 125.44 MPa 1.9 % Fig.5. Finite Element Analysis of Cover Flange
  • 5. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 5, September - October (2013) © IAEME 85 Thus result is obtained indicates that numerical simulation result is well within limit. The deviation between simulation and analytical solution is approximately 1.9%. 3.4 Design modification The model provided by company had certain modification with respect to analytical design model. Henceforth simulation has been carried out for this new model. Figure 5.2 3D Symmetric model There was addition of two plates in the model which cause change in value of stress which can be seen in the figure 5.4. Figure 5.3 Total Deformation Figure 5.4 Equivalent Stress (Von-misses) It can be seen from the above result that stress value has increased as compared with design model. There is addition of two stiffeners in this new model which cause increasing in stress value. But these stiffeners cannot be removed as it may cause buckling of flange. IV. OPTIMISATION Now in order to further optimized design, two more stiffeners of dimension 56×130×1200 are added on the outside surface of flange as shown in Figure.
  • 6. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 5, September - October (2013) © IAEME 86 Figure 5.5 Flange With additional stiffener (102 x 60) The finite element analysis results of this modified design are shown in figure 5.6 and 5.7. Figure 5.6 Total deformation Figure 5.7 Von-misses stress The above stress shows that the new value of stress is 91.421. Hence the dimension of flange can be decreased further. A new model has been prepared by reducing thickness of cover flange from 60 mm to 56 mm and body flange from 102 to 96 mm. The result obtained for this new design (96×56 with additional Stiffener) is shown in figure 5.8 and 5.9. Figure 5.8 Total deformation Figure 5.9 Von-misses stress
  • 7. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 5, September - October (2013) © IAEME 87 The value of stress obtained from new model is 106.27 MPa as against the allowable limit of 138 MPa. But still that is large difference between design stress and allowable stress value. This indicates there is further possibility of decreasing dimension. A new model has been prepared by decreasing the dimension of cover flange and body flange from the 56 to 52 mm and 96 to 92 mm respectively. The results obtained from new model (92×52 with additional Stiffener) shown in figure 5.10 and 5.11. Figure 5.10 Total deformation Figure 5.11 Von-misses stress The value of stress obtained from new model is 114.13MPa as shown in the figure 5.10 which is far away from allowable stress limit of 138MPa. A new model has been prepared by decreasing the thickness of cover flange and body flange from the 52 to 48 and 92 to 90 respectively. The stress obtained for the above model is 129.21MPa as shown in figure 5.11 which is within the allowable limit. V. CONCLUSION Numerical Simulation techniques can be effectively used for analysis of ring type flange. The result of numerical simulation overcomes the limitation of analytical approach which can be valuable as seen from the results of suggested model. The optimum Value of thickness of Cover Flange and Body Flange are 48 mm and 90 mm respectively. VI. REFERENCE [1] M.Abid and D.H.Nash, “ A Parametric study of metal to metal contact flanges with optimised geometry for safe stress and no leak condition”-International Journal of Pressure vessels and Piping 81 , 2004, pp 67-74. [2] M.Murlikrishna, M.S.Shunmugam And N.Siva Prasad, “A study of the sealing performance of bolted flanged joints with gaskets using finite element analysis”- International Journal of Pressure Vessels and Piping 84,2007,pp-349-357. [3] ASME Boiler And Pressure Vessel Code,Section-8,Div-1,2010 edition, Rulesof construction for Pressure vessel. [4] ASME B16.5, 2003 edition, Pipe Flanges and Flanged Fittings. [5] I.M.Jamadar, S.M.Patil, S.S.Chavan, G.B.Pawar and G.N.Rakate, “Thickness Optimization of Inclined Pressure Vessel using Non Linear Finite Element Analysis using Design by Analysis Approach”, International Journal of Mechanical Engineering & Technology (IJMET), Volume 3, Issue 3, 2012, pp. 682 - 689, ISSN Print: 0976 – 6340, ISSN Online: 0976 – 6359.

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