Compact flange
Assessment of oval compact Assessment of oval compact flange according to EN13445-3 annex B
P. SchreursSintra-2009-019-03
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
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
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)
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
Assessment
Load case Assessment criteria
GPD - DCDesign conditions
Maximum allowable strain
Gross plastic deformation design/test case
• Maximum plastic deformation is in welding neck area
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2.5% plastic strain
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.
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 [-]
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
Location of assesment of contactpressure
Secondary seal on
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seal on gasket
Primairy
seal on heel
surface
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]
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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