This document discusses the design, analysis, and optimization of body flanges and cover flanges for steam condensers used in thermal power plants using finite element analysis. The researchers modeled flanges based on ASME code dimensions and analyzed stress levels, validating results against analytical calculations. Additional stiffeners were added through optimization, reducing flange thicknesses from 102mm to 90mm for the body flange and 60mm to 48mm for the cover flange while maintaining stress below allowable limits. Finite element analysis was found to overcome limitations of analytical methods and determine optimal flange dimensions within safety factors.

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
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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
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2. International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –
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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
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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
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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
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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 –
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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 –
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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.