-
Returning ChallengesPipeline Components
Carlos SiciliaPipeline Innovation Forum 2014Hvik, 27/03/14
-
Limit State Design for Submarine Pipelines
Good design codes DNV-OS-F101
Recommended Practices
JIPs
Company Guidelines
Even framework for problem specific reliability
assessment, e.g. used for UHB
Introduction
-
What about elements within pipeline system that
are not pipes?
Pipeline Components
Present in all systems
Introduction
-
PIP systems:
Bulkheads
Swaged joints
Inner pipe pull collars
General:
J-lay collars
Riser hang off
Flanges
Connectors
Corrosion monitoring
spools
Introduction
Other:
Tees
Wyes
Hot tap
Bends?
In-line structures?
-
Introduction
-
Introduction
J-lay Collar
End Bulkhead
In-line Pull-out Collar
-
What does DNV-OS-F101 say about this?
Design according to recognized codes with some
additional requirements
Pipeline Code
-
What does DNV-OS-F101 say about this?
At least same safety as the connecting pipeline/riser
section
The component shall be designed to accommodate
the loading from the connected pipeline section and
vice versa with appropriate safety
But how to even agree on Design / Test pressure?
Pipeline Code
-
ASME VIII, PD5500, EN13445-3
Background to Pressure Vessel Design Codes
Pressure Vessel Codes
S = min (SMTS/3.5, SMYS/1.5)
-
Basic approach:
Linear elastic stress analysis with factored loads
Linearize stresses
Separate Primary and Secondary stresses
Check against allowable values
Pressure Vessel Codes
-
Based on actual limit states:
Plastic collapse (gross plastic deformation)
Local failure (limit potential for fracture)
Collapse from buckling
Cyclic loading fatigue
Cyclic loading ratcheting
Sensible and all relevant aspects covered
Conceptually consistent with pipeline code
Pressure Vessel Codes
-
But is safety level consistent?
Material factor ~ 1.3 Load factor ~ 1.5
Is this too conservative?
Pressure Vessel Codes
Straight pipe Bending moment with design pressure
ScenarioDNV
LCC
EN-13445
Limit Moment Allowable Moment
No material
factor
With material
factor
No material
factor
With material
factor
Moment [kN/m] 542 580 446 387 297
Ratio to DNV 1.00 1.07 0.82 0.71 0.55
-
More advanced options:
Elastic perfectly plastic analysis
Full non-linear analysis with material hardening
Based on strain limits
Pressure Vessel Codes
Maximum Plastic Strain
-
Is the non-linear option enough?
Pressure Vessel Codes
High Loads (Buckle?)
-
Pressure Vessel Codes
-
Pressure Vessel Codes
S = min (SMTS/3.5, SMYS/1.5)