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Compact flange
Assessment of oval compact Assessment of oval compact flange
according to EN13445-3 annex B
P. SchreursSintra-2009-019-03
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Project description
• Design of a compact flange• Project in cooperation with PLT
Pipe Line Technology
Netherlands
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Principle of compactflange
• Contact pressure between heel of both flanges ensures leak
tightness
• Seal ring is secondary sealing• Due to angle of flange face, a
high contact pressure • Due to angle of flange face, a high contact
pressure
is established in sealing surface
• High tolerance for cyclic loading with respect to leak
tightness.
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Principle of compactflange
Before assembly
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After assembly
designloads
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FEA model
• ¼ model of flange• 1st order brick elements• Contact between
flanges and sealring• Pretension elements in bolts• Tie between
bolts and flanges
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FEA model
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Boundary conditionsBlocked displacements in axial direction
Axial force due to internal pressure
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Symmetrie boundary conditions
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Loadcases (1)
• According EN13445-3 annex B– Gross plastic deformation design
check– Gross plastic deformation testconditions check– Progressive
plastic deformation (Shakedown)
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– Progressive plastic deformation (Shakedown)
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Loadcases (2)
Load case Loadsteps
Bolt pretension(per bolt)
Pressure[Barg]
Temp[°C]
External loading from piping system
[N]GPD - DC
Design conditions
1 800.000N - - -2 Bolt fixed
in positionpdesignx1,2
Tdesign External loading x1,2
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conditions in position x1,2GPD - DC
Testconditions
1 800.000N - - -2 Bolt fixed
in positionptest - -
PPD-DCDesign
conditions
1 800.000N - - -2 Bolt fixed
in positionpdesign Tdesign External loading
3 0 0 04 pdesign Tdesign External loading
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Assessment
Load case Assessment criteria
GPD - DCDesign conditions
Maximum allowable strain
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Gross plastic deformation design/test case
• Maximum plastic deformation is in welding neck area
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2.5% plastic strain
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Progressive plastic deformation (1)
• 5 critical locations:– Heel– Wedge– Neck
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– Neck– Bolts– Seal
• Goal is to prove that construction shakes down to lineair
elastic behaviour.
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Progressive plastic deformation (2)
0.04%
0.05%
0.06%
0.07%
Pla
stic
str
ain
[%]
Plastic strain in the compact flange
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0.00%
0.01%
0.02%
0.03%
0.04%
Pla
stic
str
ain
[%]
cycle step [-]
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Progressive plastic deformation (3)
• After 1st cycle no additional plastic deformation occures
• Flange connection shakes down to linear elastic behaviour
after 1 cycle
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behaviour after 1 cycle
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Location of assesment of contactpressure
Secondary seal on
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seal on gasket
Primairy
seal on heel
surface
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Contact pressure between components
350
400
450
500
con
tact
pre
ssu
re [
MP
a]
contact pressure on heel surface
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0
50
100
150
200
250
300
350
0 5 10 15 20 25
con
tact
pre
ssu
re [
MP
a]
radial distance over heel surface [mm]
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Conclusion
• Plastic strain in design and test conditions are lower than
5%
• Connection shakes down to lineair elastic behaviour• Contact
pressure is always higher then 2x internal • Contact pressure is
always higher then 2x internal
pressure, thus sealing is established.
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