Transcript Final Presentation.pptx

Chris Wowk
MANE 6970
Master’s Project

The objective of this project was to evaluate
the behavior of flat faced cover plate/flange
joints using:
◦ Radial Beam Theory (Analytic Solution)
◦ Solid Element Finite Element Models
◦ Shell/Beam Element Finite Element Models

The effect of the following design variables
on joint behavior were also investigated:
◦ Bolt pre-stress
◦ Cover plate thickness
◦ Nominal pipe size

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ASME B16.5
standard
flange/cover plate
sizes were used
Typical flange
(steel) and bolting
(CRES) materials
were used

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Analytical solution
developed by considering
the annular portion of the
flange and cover plate as
a collection of radial
beams
Moment diagram allowed
for expressions for flange
rotations and deflections
be determined through
integration
Separation of the joint
was then calculated
Solid Element Model
Shell/Beam Element Model
4"
NPS Size
Analysis
Method
Cover Thickness
Bolt Pre-Stress
Joint
Separation
Along Length
Radial Beam Theory
Solid Element FEA
Shell Element FEA
Radial Beam Theory
Radial
Location of
Contact
Appendix Y Equations
Solid Element FEA
Shell Element FEA
Radial Beam Theory
Stress In
Center of
Cover
Appendix Y Equations
Solid Element FEA
Shell Element FEA
Maximum
Joint
Separation
Radial Beam Theory
Solid Element FEA
Shell Element FEA
t1
0
Pressure
Load
16"
0.5*t1
25%
Yield
80%
Yield
0
Pressure
Load
25%
Yield
2*t1
80%
Yield
0
Pressure
Load
t2
25%
Yield
80%
Yield
0
Pressure
Load
25%
Yield
80%
Yield

Differences exist in the joint behaviors predicted by the
different analysis types
◦ Shell/beam FEA predicted joint separations typically smaller than
other methods
 Bolt modeling method is the expected causes
◦ RBT not able to predict complete separation between cover plate
and flange at zero pre-stress

General conclusions that the different analysis types were in
agreement on:
◦ Joint separation decreases as bolt pre-stress and/or cover plate
thickness increase
◦ Radial location of contact moves closer to the bolt circle as bolt prestress increases

Results from smaller pipe size could not be scaled for larger
pipe size (non-linear)
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Radial and tangential stresses in the center of
the cover plate generally decreased as bolt
pre-stress and/or thickness increases
Values differed between the analysis types
FEA results showed increases in stress at 80%
yield pre-stress
◦ Cause is unknown – potential element distortion
issue
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Analysis type matters in evaluating flat faced
bolted flange joints
High bolt pre-stress is required to limit
separation of flange components and reduce
leak potential
Separation can also be reduced by increasing
cover plate thickness
Be wary of how you model bolts in FEA
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ASME Boiler and Pressure Vessel Code, Section VIII – Rules for
Construction of Pressure Vessels, 2013 Edition, Appendix Y.
Galai, H and Bouzid, A.H, “Analytical Modeling of Flat Face
Flanges with Metal-to-Metal Contact Beyond the Bolt Circle,”
Journal of Pressure Vessel Technology, Vol 132, 2010.
Schneider, R.W, “Flat Face Flanges with Metal-to-Metal
Contact Beyond the Bolt Circle,” Transactions of the ASME, Vol
90, 1968, pgs 82-88.
Waters, E.O and Schneider, R.W, “Axisymmetric, Nonidentical,
Flat Face Flanges with Metal-to-Metal Contact Beyond the
Bolt Circle,” Journal of Engineering for Industry, Vol 91, 1969,
pgs 615-622.