Bolted flange joints are widely used in engineering structure. The evolution of leakage is studied using detailed contact finite element analysis. The distribution of stress at the gasket is analyzed using a contact condition based on slide-line elements using ABAQUS, a commercial finite element code. Slide-line elements also take into account pressure penetration as contact that is lost between flange and gasket. Results are presented for a particular flange, a raised face flange sealed by a mild steel gasket. Although a lot of pipe flange connections are exposed to elevated temperature during long-term plant operation, a sealing performance of the pipe flange connections at elevated temperature is not well understood because of the experimental difficulty and the analytical problems due to the lack of the materials properties of gaskets at elevated temperature. The authors have been evaluating the effect of the material properties of spiral wound gaskets (SWG) and the sealing performance of the pipe flange connections at elevated temperature.

1. International Journal of Engineering and Techniques - Volume 1 Issue 6, Nov – Dec 2015
ISSN: 2395-1303 http://www.ijetjournal.org Page 87
Analysis of Leakage in Bolted-Flanged Joints with Gasket and
Under Thermal Condition, a Critical Review
Wasim B. Patel*1
, Pundlik N. Patil2
, Raghunath Y. Patil3
, Prasad P. Patil4
1(
PG Scholar,Department of Mechanical Engineering, North Maharashtra University, Jalgaon.
Email: wpwasimpatel@gmail.com)
2,3,4
(Assi. Prof. Department of Mechanical Engineering, North Maharashtra University, Jalgaon.
Email: pnp09@rediffmail.com)
I. INTRODUCTION
In a flanged joint, it is always required to select a
suitable gasket depending on the kind of fluid, the
pressure and the temperature. However, even
though suitable gaskets are chosen, their sealing
performance usually deteriorates over the years.
Therefore, maintenance to repair leaks and/or
replace gaskets is required. Bolted joints are very
often the weak link between pressure vessels as
they are very prone to leakage. This is especially
true when these joints are subjected to high
temperature. A comprehensive survey _1_
conducted in 1985 showed that high operational
temperature and thermal transients are one of the
major sources of flanged joint failure. In the piping
industry, there are several problems that continue to
receive a considerable amount of research attention,
particularly in the area of bolted-flanged joint
design. Two problems that are critical in bolted
flanged joint design are strength of the joint and
leakage. The first problem has been studied since
the 1920s for metallic joints with a general
consensus on the available solution well established
[3]. The second problem has been studied for
almost an equally long period yet leakage analysis
continues to be the subject of much study, as
evident by the number of articles published in the
past quarter century [4],[5],[2].
Pipe flange connections with gaskets in chemical
plants, electric power plants and other plants are
usually exposed to internal pressure under elevated
temperature environment. Even a plant operated at
lower temperature like room temperature, pipe
flange connections are exposed to a change in
ambient temperature.
In many studies the sealing performance of the
pipe flange connections has been investigated and
evaluated by analyzing the contact stress at the
interfaces, a variation of the axial bolt force and
creep behavior of gaskets [6],[7],[1]. These studies
evaluated the sealing performance of the pipe
flange connections under elevated temperature and
Abstract:
Bolted flange joints are widely used in engineering structure. The evolution of leakage is studied using
detailed contact finite element analysis. The distribution of stress at the gasket is analyzed using a contact
condition based on slide-line elements using ABAQUS, a commercial finite element code. Slide-line elements
also take into account pressure penetration as contact that is lost between flange and gasket. Results are presented
for a particular flange, a raised face flange sealed by a mild steel gasket. Although a lot of pipe flange connections
are exposed to elevated temperature during long-term plant operation, a sealing performance of the pipe flange
connections at elevated temperature is not well understood because of the experimental difficulty and the
analytical problems due to the lack of the materials properties of gaskets at elevated temperature. The authors have
been evaluating the effect of the material properties of spiral wound gaskets (SWG) and the sealing performance
of the pipe flange connections at elevated temperature
Keywords — Flanged joints Bolted Joint, Stress Analysis, Sealing Performance, Gasketed Joint, Thermal
Conduction Condition
RESEARCH ARTICLE OPEN ACCESS

2. International Journal of Engineering and Techniques - Volume 1 Issue 6, Nov – Dec 2015
ISSN: 2395-1303 http://www.ijetjournal.org Page 88
the difficulty of detail evaluation of the connections
due to the uncertain behavior of the gasket under
thermal conditions was revealed.
A. Flange description
The flange geometry and dimensions used in the
analysis were extracted from [8],[2] and are shown
in fig. 1. The characteristics of the gasket and
number of bolts are also from [8], all of which are
summarized in table 1. The flange is constructed of
steel with Young’s modulus of 200 GPa and
Poisson’s ratio of 0.3. the ASME code assumes
flange failure when the material yields. the stress-
strain diagram of the gasket is assumed to be
trilinear as shown in fig. 2 [9],[2].
Fig. 1 Flange geometry and dimensions.
Fig. 2 Gasket stress-strain diagram.
Sr.
No.
Characteristics Value
1 Nominal flange size (mm) 300
2 Gasket material type Soft flat mild steel
3 Gasket width (mm) 15
4 Inside diameter of the gasket 315
5 Effective gasket width (mm) 6.9
6 Gasket factor m 5.5
7 Gasket yield factor, y (Pa) 124,100
8 Number of bolts 16
9 Size of bolts M48
TABLE 1 BOLT AND GASKET CHARACTEISTICS
II. FINITE ELEMENT MODEL
We used PATRAN [2] to create the finite
element mesh depicted in Fig. 3, and ABAQUS
[10],[2] to perform the analysis. Second order
axisymmetric elements, CAX8 are used throughout
the mesh of the flange and gasket.
A. Gasket Contact
Contact between gasket and flange face has been
modeled using ISL22A elements on the gasket and
a sideline that is attached to the flange face. Also,
since the gasket is not rigidly attached to the flange,
it can be blown out by the internal pressure (this can
happen in cases where softer gaskets are used and
flange faces are very smooth). To model this, we
had used a standard Coulomb friction model. We
assume a coefficient of static friction of 0.8, a very
rough surface.
B. Bolt Holes
The material of flange is not homogeneous
because of the presence of the bolt holes. This is
handled by smearing the material properties used in
the bolt hole area of the mesh. That is, using
material properties of weaker material in the bolt
hole area. Guidelines can be found in the ASME
code for determining effective material properties
for perforated plates. For the model given here, the
effective material properties are calculated using an
elasticity moduli reduction factor. This factor is
equal to one minus the ratio of the volume of the
bolt holes to the volume swept by the bolt diameter
along the entire circumference of the flange along
the bolt circle diameter. Hence, the reduction factor
is 0.6. The effective in-plane moduli of elasticity
are obtained by multiplying the reduction factor
times the flange modulus. The in-plane Poison’s
ration is left unchanged. The modulus in the hoop
direction should be very small and the hoop

3. International Journal of Engineering and Techniques - Volume 1 Issue 6, Nov – Dec 2015
ISSN: 2395-1303 http://www.ijetjournal.org Page 89
Poison’s ration should be zero. The effective shear
modulus is computed from its respective modulus
of elasticity and Poison’s ratio. These lead to the
following material properties for the bolt hole area:
Er = Ez = 120 GPa, Eθ = 0.12 MPa, νrz = 0.3, νzθ =
νrθ = 0, Grz = 46.1 GPa, and Grθ = Gzθ = 0.06
MPa. These Poison’s ratios and elasticity moduli
are specified for the bolt hole part of the mesh. The
material properties for the gasket and the rest of the
flange are shown in Table 1[2].
C. Boundary Conditions
We specify axisymmetric boundary conditions
on the symmetric plane of the gasket. That is, the
axial displacement in the middle of the gasket is
zero (Fig. 3).
D. Bolt Load
The bolt load computed using Eq. (4) is smeared
over the bolt hole upper surface as a normal
pressure, as shown in Fig. 3. These are the load
applied at the beginning of the analysis, the seating
condition. In this case, there could be no contact
loss during the loading and the reacting gasket
pressure should be larger than the minimum
effective seating pressure, y.
E. Internal Pressure
The internal pressure loading can be divided into
three loads: (1) the internal pressure, which acts on
the internal surface of the vessel; (2) the hydrostatic
end load, which is the membrane stress acting far
from the joint in the pipe due to the internal
pressure and is computed using the first term of Eq.
(2); (3) the penetrating pressure as the contact
between the flange face and the gasket is lost. The
PPENn sub-option of the distributed load option is
used to simulate pressure penetration between
surfaces in contact. This fluid pressure shall
penetrate into the mating surface interface until
some area of the surfaces is reached where the
contact area pressure between the abutting surfaces
exceeds the fluid pressure, cutting off further
penetration. The pressure penetration loads start
from the inside of the vessel, left side in Fig. 5, and
penetrate between the surfaces continuously from
this side. The pressure penetration path can be
specified in ABAQUS. The pressure penetration
option in ABAQUS is only supported in plane
stress and axisymmetric elements, not 3-D, which is
the reason why we solved the problem using an
axisymmetric model.
= πGy (1)
=pB2
/4 + p(G2
– B2
)/4 + 2πbGmp (2)
Am = max (Wm1 / Sb , Wm2/Sa ) (3)
W = ½ (Ab + Am ) Sa (4)
Fig. 3 Axisymmetric finite element mesh.
III. EXPERIMENTAL METHOD
A. Leakage Test
This paper also study about the leakages of
flanged joints. The leakage tests using pipe flange
connection were also conducted to evaluate the
sealing performance of the SWG. The pipe flange
and the bolts both are made of stainless steel
SUS304 (Japan Industrial Standard, JIS). The SWG

4. International Journal of Engineering and Techniques - Volume 1 Issue 6, Nov – Dec 2015
ISSN: 2395-1303 http://www.ijetjournal.org Page 90
sealing element is made of non-asbestos filler. The
inner and outer rings are also made of the stainless
steel SUS304 (JIS). The nominal diameter of bolts
used is M20 (JIS) and the size of the gasket taken is
ASME/ANSI Class 600 [11].
Figure 4 gives a schematic diagram of the
experimental setup [1] taken for study. Two pipe
flanges including a gasket were clamped by the
torque control method with the target torque T. The
axial bolt forces are measured by two calibrated
strain gauges attached on the shank of the bolts in
the tightening process. The internal pressure was
applied by using Helium gas, and the magnitude of
the internal pressure was measured by the pressure
transducer. The amount of gas leakage evaluated by
the change in the internal pressure over some time
interval. The pipe flange was heated by using an
electric heater shown in Fig. 4. The outputs of set
up were recorded by the analysing recorder through
dynamic amplifiers. The tightening procedure, JIS
B2251 [12], was applied to tighten the pipe flanges
in the experiments. The target torque T (=k･Ff･d)
was determined from the torque coefficient "k", the
target initial clamping bolt force (bolt preload) Ff
and the bolt nominal diameter "d". The torque
coefficient "k" was previously obtained in
tightening test using one bolt. The lubricating oil
was applied at the contact surfaces in the
experiments, and the torque coefficient "k" was
obtained as k=0.1465. After the target initial
clamping bolt force Ff was determined, the values
obtained by R.O.T.T. (Room Temperature
Operational Tightness Test) were used to obtain the
new gasket constants [13],[14]. The target initial
clamping bolt force Ff determined for a given
tightness parameter Tp under an internal pressure P
by the PVRC procedure, and the assembly
efficiency that was 0.85 [15]. In addition, the
leakage tests with heat and inner pressure cycle
condition were conducted and the change of the
sealing performances was evaluated.
Fig. 4 Schematic of experimental setup for helium gas leakage test
IV. RESULTS AND DISCUSSIONS
A. Material Properties of Gasket
Figure 5 shows the stress-strain curves of new
SWG measured in compression test at each
temperature. Stress-strain curve shifted to the
higher strain side as increasing the temperature. In
other words, the result showed that the deformation
resistance, that is the modulus of stress-strain curve,
became lower as increasing the temperature[1].
Figure 6 shows the stress-strain curve measured
in cyclic compression test at room temperature.
Figure 6 suggested that the hardening effect was
observed as increasing the cyclic number.
Figure 7 shows the result of stress-strain curves
of new, aged and used SWG. The elastic moduli
were calculated from the slope of stress-strain
curves in 35-45MPa. The elastic modulus of the
aged SWG in the unloading process was a lower
compared with that of the new SWG. On the other
hand, the elastic modules of the aged SWG and the
new SWG in the loading process didn’t show a
significant difference. It is suggested that the
decrease of the gasket stress in the new SWG is
larger than that of aged SWG and the new SWG is
more sensitive in inner pressure loading.
Figure 8 shows the thermal expansion coefficient
evaluated [16],[1]. The gasket expanded as
increasing the temperature and the thermal
expansion coefficient evaluated from the slope of
the curve changed at 210℃. The thermal expansion
coefficient was 218.1x10-6/℃ up to 210℃ and it
decreased 29.0x10-6/℃ more than 210℃.

5. International Journal of Engineering and Techniques - Volume 1 Issue 6, Nov – Dec 2015
ISSN: 2395-1303 http://www.ijetjournal.org Page 91
Fig. 5 Stress-strain curves of new SWG
Fig. 6 Stress-strain curves of cyclic compression test of new SWG at room
temperature
Fig. 7 Stress-strain curves of new, aged and used SWG
Fig. 8 The result of TG/DTA of a filler material in SWG
V. CONCLUSIONS
The material and thermal properties of SWG
were experimentally evaluated and the effect of
those properties on the sealing performance of
bolted flange connections under thermal condition
and internal pressure were analyzed. The method
presented in this paper can be used to study leakage
behavior and validate the ASME code formulation
for other gasket materials and joint configurations.
The stress-strain curve of SWG shifted to the high
strain side while becoming a high temperature. The
deformation resistances of the SWG increased as
increasing the cyclic load/unload. In conclusion, the
ASME code method for designing bolted joints,
although not theoretically exact, is sufficiently
accurate for most practical purposes, and is simpler
to implement than the finite element formulation.
ACKNOWLEDGMENT
I acknowledge the support of Shri Gulabrao
Deokar College of Engineering, Jalgaon. Central
college liberary facility providing support. I also
like to express my deep and sincere gratitude to my
Project guide Prof. P. N. Patil and Head of
Mechanical Engineering Department Prof. R. Y.
Patil without their support it could not happen.
REFERENCES
1. Yuya Omiya *1, Toshiyuki Sawa. “ Sealing
Performance Evaluation of Pipe Flange Connection
with Spiral Wound Gasket under Cyclic Thermal
Condition.” International journal of Mechanic
Systems Engineering, Volume 3, 102-110
2. Hector Estrada “ Analysis of Leakage in Bolted-
Flanged Joints Using Contact Finite Element
Analysis.” journal of Mechanics Engineering and
Automation, Volume 5, 135-142
3. Waters, E. O., Wesstrom, D. B., Rossheim, D. B.,
and Williams, F. S. 1937. “Formulas for Stresses in
Bolted Flanged Connections.” Transactions of the
ASME 59: 161-9.
4. Bertini, L., Beghini, M., Santus, C., and Mariotti, G.
2009. “Metal to Metal Flanges Leakage Analysis.”
Presented at the ASME 2009 Pressure Vessels and
Piping Division Conference, Prague, Czech
Republic.
5. Estrada, H., and Parsons, I. D. 1999. “Strength and
Leakage Finite Element Analysis of a Fiber
Reinforced Plastic Stub Flange Joint.” International
Journal of Pressure Vessels and Piping 76: 543-50.

6. International Journal of Engineering and Techniques - Volume 1 Issue 6, Nov – Dec 2015
ISSN: 2395-1303 http://www.ijetjournal.org Page 92
6. Sawa T., Takagi Y. and Torii H., “Sealing
Performance Evaluation of Pipe Flange Connection
Under Elevated Temperatures”, Proceedings of
ASME PVP2007/Creep 8 Conference, 2007
7. Abid M., “Determination of safe operating conditions
for gasketed flange joint under combined internal
pressure and temperature: A finite element
approach”, Vol. 83, 6, pp. 433- 441, 2006
8. Nishioka, K., Morita, Y., and Kawashima, H. 1979.
“Strength of Integral Pipe Flanges (No. 2 Gasket
Seating Stress and the Influence of Number of
Bolts).” Bulletin of the JSME 22 (174): 1705-11.
9. Flinn, R. A., and Trojan, P. K. 1990. Engineering
Materials and Their Apparitions. 4th ed. Boston:
Houghton Mifflin Company.
10. Hibbitt, Karlsson & Sorensen, Inc., ABAQUS
User’s Manual.
11. ASME/ANSI B16.5, Section Ⅷ, Division Ⅷ, 1988
12. JIS B2251, “Bolt Tightening Guidelines for Pressure
Boundary Flanged Joint Assembly”, 2008
13. Payne, J.R., Bazergui, A. and Leon, G.F., “A New
Look at Gasket Factors,” Proc. 10th International
Conference on Fluid Sealing, BHRA, H1, pp. 345-
363, 1984
14. Bickford J., Gaskets and Gasketed Joints, Marcel
Dekker Inc, New York, 1998
15. Leon, G.F. and Payne, J.R., “An Overview of the
PVRC Research Program on Bolted Flanged
Connections,” Proc, 6th International Conference on
Pressure Vessel Technology, Vessel Technology, 1,
pp. 217, 1989
16. Takagi Y., Torii H., Sawa T. and Kawasaki N.,
“Stress Analysis Sealing Performance Evaluation of
Pipe Flange Connection At Elevated Temperature”,
Proceedings of ASME PVP2008 Conference, 2008S.
M. Metev and V.P. Veiko, Laser Assisted
Microtechnology, 2nd ed.,R. M. Osgood, Jr., Ed.
Berlin, Germany: Springer-Verlag, 1998.