1. Pipe Integrity Check using Finite Element Analysis
Energy TechSea

2. Objective Scope Energy TechSea Structural Integrity Checks for
~104-ft long pipe connected with 216’dia Tank
~84-ft long pipe connected with 155’dia Tank
~66-ft long pipe connected with 100’dia Tank
Computational science tool, Finite element analysis, i.e. ABAQUS is utilized
Checks performed as per B31.3 Process Piping Code
Appropriate remediation is recommended
Pipe with 216’OD Tank
Pipes with 155’OD and 100’OD Tank
Energy TechSea

3. Pipe Configuration and Geometry
216’OD Tank Bottom
3D Bend
Ring Wall
72’
20’ 9’
7.5’
Pipe Data
DESCRIPTION
Pipe
Outer diameter (OD)
30 in
Wall thickness
0.5 in
Material
X60
Specified minimum yield strength at 20oC
60 ksi
Specified minimum tensile strength at 20oC
75 ksi
Modulus of Elasticity at -170oC
30.0 x 106 psi
Mean coefficient of thermal expansion
6.6 x 10-6 /oF
155’OD Tank Bottom
3D Bend
Ring Wall
51’ 8”
20’ 9’
100’OD Tank Bottom
3D Bend
Ring Wall
33’ 4”
20’ 9’
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4. Acceptability Criteria as per B31.3
B31.3 Code stress check
A pipe stress verification as per the design code ASME B31.3 was performed.
Axial stresses are compared for Sustained load and Displacement stresses specified in ASME B31.3 section
Sustained Load < 25ksi
Pressure
Other sustained load (load due to settlement)
Displacement Stress < 45 ksi
Thermal load
Other displacement load (load due to settlement)
Combined Stress <45 ksi (for conservative analysis)
Sustained load +Displacement Stress
Combined Stress is checked instead of Displacement stress due to a conservative estimation.
Energy TechSea

5. Finite Element Analysis: Geometry
Finite Element Modeling
Finite element software ABAQUS was used
Pipe31H Hybrid beam element was used
Appropriate Mesh sensitivity was checked maintaining numerical solution requirement.
Element size
6-in for pipe straight section
3-in for pipe bend section
Thick wall pipe section was assumed
Element
Ring Wall
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6. FEA: Boundary Condition
Pipe Connection at the Tank was assumed Fixed
To simulate settlement due to burial between the ring wall and the Tank end Linear vertical displacement was applied
To simulate settlement due to the burial between the ring wall and the free end, Linear vertical displacement was applied
For settlement displacement 3.5”, 3.0”, 2.5”, 2” and no displacement were considered for pipes
Ring Wall
Fixed BC
Displacement BC
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7. FEA: Boundary Condition
u1=0,u2=-3.5,u3=0
Rot=0
u2=-2”
Free End 1 2 3
u2=-2.3”
u2=-2.5”
u2=-2.8”
u2=-3.0”
u2=-3.3”
u2=-3.4”
u2=-3.5”
Ring Wall
Burial
u2=-1.25”
u2=-.5”
Pipe with 216’ft OD Tank
155’OD Tank Bottom
Ring Wall
u2=-2.3”
u2=-2.8”
u2=-3.0”
u2=-3.2”
u2=-3.4”
u2=-3.5”
u2=-1.8”
u2=-1.3”
u2=-2.5”
Pipe with 155’ft OD Tank
155’OD Tank Bottom
Ring Wall
u2=-2.7”
u2=-2.9”
u2=-3.2”
u2=-3.4”
u2=-3.5”
u2=-1.7”
u2=-2.2”
Pipe with 100’ft OD Tank
Energy TechSea

8. FEA: Load Cases: Total 19 Analyses
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9. Summary Result: Sustained Load
Observation for Sustained Load
Pipe with 216’OD Tank capable of taking 3” settlement Load
Pipe with 155’OD Tank not capable of taking 3.5” settlement Load
Pipe with 100’OD Tank capable of taking 3.5” settlement Load

10. Summary Result: Combined Load
Observation for Combined Load
All 3 pipe capable of taking 3.5” settlement Load+Max Temp+Pressure.
Maximum Axial Stresses are within the Allowable stress 45 ksi
Energy TechSea

11. Result: 216’-OD Tank: Sustained Load for 3.5” Settlement
Axial Stress Contour Along the Pipeline
31.3 ksi
Ringwall
26.7 ksi
Observation
Maximum Axial Stress 31.3 ksi near the Tank end > Allowable stress is 25 ksi (B31.3)
For 3 “ Settlement Axial Stress is ksi.
For No Settlement Max. Axial Stress is 5.5 ksi
1.5” Differential settlement between the Ring Wall and the Tank End governs the high axial stresses.
Energy TechSea

12. Result: 216’-OD Tank: Combined Load for 3.5” Settlement, T=160F
Observation
Maximum Axial Stress 37.5 ksi near the Tank end < Allowable stress 45 ksi (B31.3)
For T=100F the axial stress is 32.8ksi
For No Settlement Axial Stress is ksi
1.5” Differential settlement between the Ringwall and Tank End governs the high axial stresses.
Axial Stress Contour Along the Pipeline
37.5 ksi
Ringwall
25.5 ksi
Energy TechSea

13. Result: 155’-OD Tank: Sustained Load for 3.5” Settlement
Axial Stress Contour Along the Pipeline
30.5 ksi
Ringwall
25.5 ksi
Observation
Maximum Axial Stress 30.5ksi near the Tank end > B31.3 Allowable stress 25 ksi
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14. Result: 155’-OD Tank: Combined Load for 3.5” Settlement, T=160F
Observation
Maximum Axial Stress 37.4 ksi near the Ringwall < B31.3 Allowable stress 45 ksi
For T=100F the max. axial stress is 24.5ksi
1.2” Differential settlement between the Ringwall and Tank End governs the high axial stresses.
Axial Stress Contour Along the Pipeline
36.6 ksi
Ringwall
37.4 ksi
Energy TechSea

15. Result: 100’-OD Tank: Sustained Load for 3.5” Settlement
Observation
Maximum Axial Stress 25.0 ksi near the Tank end = B31.3 Allowable stress is 25 ksi
Axial Stress Contour Along the Pipeline
25.0 ksi
Ringwall
21.7 ksi
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16. Result: 100’-OD Tank: Combined Load for 3.5” Settlement, T=160F
Observation
Maximum Axial Stress 31.2 ksi near the Tank end < B31.3 Allowable stress 45 ksi
For T=100F the max. axial stress is 26.6ksi near the Tank.
Axial Stress Contour Along the Pipeline
31.2 ksi
Ringwall
21.2 ksi
Energy TechSea

17. Recommendations Energy TechSea
Swivel flange or other type of connector can be used to connect the at the tank end to allow rotation.
Minimize the differential settlement between the Ring Wall and the Tank end
Energy TechSea