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FE Analysis : Pressure Vessel
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INDEX
1. INTRODUCTION
2. OBJECTIVE
3. ASSUMPTIONS
4. CAD MODEL
5. MESHED MODEL
6. FE MODEL INFORMATION
7. MATERIAL PROPERTIES
8. LOADS AND BOUNDARY CONDITIONS
9. PROCEDURE
10. RESULTS – DEFLECTIONS AND STRESSES
11. RESULTS SUMMARY
12. OBSERVATIONS AND CONCLUSION
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1. INTRODUCTION
This Report consists of Results and Conclusions for FE Structural Stress Analysis of Vessel carried out to evaluate the Design adequacy for various loads like Design Pressure, Hydro Test Pressure & Nozzles External Loads.
Based on the Inputs, Vessel dish end from flange with 9 Nos. Nozzles, 2 Stiffener Rings and 2 Sliding Saddles are considered for the Analysis.
Analysis is carried out for 3 Load Cases :Load Case-1 - First is for Internal Pressure, Temperature and Nozzles Loads; Load Case-2 – Second is for Nozzle Loads NO Internal Pressure;Load Case-3 - Third is for Hydro Test for the Pressure of 7.2 Bars.
2.0 OBJECTIVE
To evaluate the design of Vessel Nozzles, Saddles and Stiffeners under various Loads.
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3.0 ASSUMPTIONS
1. Material Properties are correct as per ASME Sec-II D.
2. Linear Material of Steel are taken for the Analysis Purpose.
3. Loads and Boundary Conditions applied as per the Supplied Inputs.
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4. CAD MODEL : Assembly considered for FEA
S4
S1A
S2A
S3
Nozzles S3, S4, S5, S8, S9, S1A , S6A, S2A are areas of interest.
S6A S5
S8
S9
SLIDING
SADDLE
STIFFNER RING-1
FIXED
SADDLE
STIFFNER RING-2
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5. MESHED MODEL : Assembly considered for FEA
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The Vessel with nozzles is meshed with 2nd Order Tetrahedral Elements.
No. of Nodes in the Model = 3,73,787 No. of Elements in the Model =
1,98,188
The quality of elements is qualifying following criteria:-
From all the components in the FE Model Assembly, 99% of elements
Qualify for :-
Achieved
6. FE MODEL INFORMATION :
Tetra Collapse > 0.1 (0% failed)
Skew < 60 (0% failed)
Jacobian > 0.5 (0% failed)
Vol. Aspect Ratio < 9.75 (0% failed)
Min. Angle Tria Faces > 15 (0% failed)
Max. Angle Tria Faces < 130 (0% failed)
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7. MATERIAL PROPERTIES :
Properties of SA 516 Gr 65, as per ASME Sec-II, Part-D, Table-5A
•Thermal conductivity : 0.0479 W/mm/oC
•Thermal Expansion : 12.4 E-6 / oC
•Elongation : 19% min in 8” 23% min in 2”
•Max. Allowable Stress (Sm) : 144 MPa
2010 ASME Boiler and pressure vessel code, Section II, Part D
MATERIAL Young’s Modulus
(MPA)
Poisson's
Ratio
Yield Strength
(MPa)
Tensile Strength (MPa)
SteelSA 516 Gr 65
198,000 0.29 240 450
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8. Loads and Boundary Conditions
Design pressure applied on all the
No external loads on S3 & S4
inner surface of vessel and nozzles
Hydro Test Pressure = 7.2Bar,
Design Temp. 159Deg. C
S4
S1A
S2A
S3
S6AS5
S8S9
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9.0 PROCEDURE
• 2D drawing is converted to 3D model as per the drawings.
• The model is imported into Hyper mesh and meshed using solid tetra elements.
• These elements were imported to ANSYS and assigned the Material Properties to each
component as specified in drawings.
• The boundary conditions are applied as per Section-8 in this report.
• Design pressure of 5.5 Bars is applied over the inner surfaces of vessel and nozzles.
• Nozzle loads were applied as per nozzle loads table.
• For load cases, temperature of 159oC is applied over the inner surfaces of vessel.
• Model is solved for 3 different load cases as specified in Introduction section in this report.
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10. RESULTSLoad Case-1 : Internal pressure, Temperature & nozzles loads
CONSTRAINTS ON SLIDING SADDLE
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9.1 Stress Analysis Results : Load Case-1Deflection Plot (mm) Internal pressure, temperature, nozzles loads
Max. Deflection = 18mm
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9.2 Stress Analysis Results : Load Case-1Deflection Plot (mm)
Max. Deflection = 18mm
Internal pressure, temperature, nozzles loads
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9.3 Stress Analysis Results : Load Case-1Deflection Plot (mm)
Max. Deflection = 18mm
Internal pressure, temperature, nozzles loads
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9.4 Stress Analysis Results : Load Case-1Deflection Plot (mm)
Max. Deflection = 18mm
Internal pressure, temperature, nozzles loads
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9.5 Stress Analysis Results : Load Case-1Stress Plot (MPa) : Von-Mises Stresses
S4
S1A
S2A
S3
S6A S5
S8
S9
Stress linearization
Stress (Pl+Pb+Q) = 358 MPa
Stress (Pl+Pb+Q) = 50 MPa
S5
S2A
Stress (Pl+Pb+Q) = 291 MPaFor reference only
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S4
S1A
S2A
S3
S6A S5
S8
S9
Stress linearization
Stress (Pl+Pb+Q) = 396 MPa
Stress (Pl+Pb+Q) = 73 MPa
S6A
S8
9.6 Stress Analysis Results : Load Case-1Stress Plot (MPa) : Von-Mises Stresses
Stress (Pl+Pb+Q) = 302 MPaFor reference only
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9.7 Stress Analysis Results : Load Case-1
S4
S1A
S2A
S3
S6A
S8
S9Stress linearization
Stress Plot (MPa) : Von-Mises Stresses
S4
S5
Stress (Pl+Pb+Q) = 58 MPa
Stress (Pl+Pb+Q) = 101 MPa
S9
Stress (Pl+Pb+Q) = 95 MPa
Stress (Pl+Pb+Q) = 31 MPa
Stress (Pl+Pb+Q) = 129 MPa
For reference only
07/10/2011
Stress (Pl+Pb+Q) = 35 MPa
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S4
S1A
S2A
S3
S6A S5
S8
S9
Stress linearization
Stress Plot (MPa) : Von-Mises Stresses
S3
S1A
Stress (Pl+Pb+Q) = 345 MPa
Stress (Pl+Pb+Q) = 248 MPa
9.8 Stress Analysis Results : Load Case-1
For reference only
S4
S1A
S2A
S3
S6AS5
S8
S9
R1
9.9 Stress Analysis Results : Load Case-1
Stress Plot (MPa) : Von-Mises Stresses
R2
R2R1
Stress (Pl+Pb+Q) = 342 MPa Stress (Pl+Pb+Q) = 91 MPa 20
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9.10 Stress Analysis Results : Load Case-1
Stress Plot (MPa) : von-Mises Stresses
Stress (Pl+Pb+Q) = 1055 MPa Stress (Pl+Pb+Q) = 985 MPa
Sliding Saddle Fixed Saddle
After masking localized stress areas
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10. RESULTSLoad Case-2 : Nozzles loads, NO Internal Pressure & Temperature
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10.1 Stress Analysis Results : Load Case-2Deflection Plot (mm)
Max. Deflection = 3 mm
Nozzles loads only
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10.2 Stress Analysis Results : Load Case-2Deflection Plot (mm)
Max. Deflection = 0.87mm
Nozzles loads only
Top View Bottom View
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10.3 Stress Analysis Results : Load Case-2
Stress Plot (MPa) : Von-Mises Stresses
S4
S1A
S2A
S3
S6A S5
S8
S9
Stress linearization
Stress (Pl+Pb+Q) = 227 MPa
Stress (Pl+Pb+Q) = 7 MPa
Stress (Pl+Pb+Q) = 154 MPa
S5
S2A
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Stress (Pl+Pb+Q) = 2.5 MPa
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10.4 Stress Analysis Results : Load Case-2
Stress Plot (MPa) : Von-Mises Stresses
S4
S1A
S2A
S3
S6A S5
S8
S9
Stress linearization
Stress (Pl+Pb+Q) = 227 MPa
Stress (Pl+Pb+Q) = 321 MPa
S6A
S8
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10.5 Stress Analysis Results : Load Case-2
Stress Plot (MPa) : Von-Mises Stresses
S4S4
S9
S1A
S2A
S3
S6A S5
S8Stress linearization
S9
Stress (Pl+Pb+Q) = 17 MPaStress (Pl+Pb+Q) = 4 MPa
Stress (Pl+Pb+Q) = 1 MPa
Stress (Pl+Pb+Q) = 14 MPa 27
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10.6 Stress Analysis Results : Load Case-2
Stress Plot (MPa) : Von-Mises Stresses
S4
S1A
S2A
S3
S6A S5
S8
S9Stress linearization
Stress (Pl+Pb+Q) = 125 MPa
Stress (Pl+Pb+Q) = 209 MPa
S1A
S3
Stress (Pl+Pb+Q) = 12 MPa
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S4
S1A
S2A
S3
S6AS5
S8
S9
R1
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10.7 Stress Analysis Results : Load Case-2
Stress Plot (MPa) : Von-Mises Stresses
Stress (Pl+Pb+Q) = 72 MPa Stress (Pl+Pb+Q) = 32 MPa
S1A
R2
R2R1
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10.8 Stress Analysis Results : Load Case-2
R1
S1A
R2
After masking localized stress areas
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Stress Plot (MPa) : Von-Mises Stresses
Sliding Saddle
Stress (Pl+Pb+Q) = 28 MPa
Fixed SaddleStress (Pl+Pb+Q) = 15 MPa
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11. RESULTS Load Case-3 : Hydro Test
Hydro Pressure=7.2 bar
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11.1 Deflection Analysis Results : Load Case-3Deflection Plot (mm)
Max. Deflection = 19mm
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11.2 Deflection Analysis Results : Load Case-3Deflection Plot (mm)
Max. Deflection = 19mm
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11.3 Deflection Analysis Results : Load Case-3Deflection Plot (mm)
Max. Deflection = 19mm
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11.4 Deflection Analysis Results : Load Case-3Deflection Plot (mm)
Max. Deflection = 19mm
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Stress (Pl+Pb+Q) = 257 MPa
11.5 Stress Analysis Results : Load Case-3Stress Plot (MPa) : Von-Mises Stresses
S4
S1A
S2A
S3
S6A S5
S8
S9
Stress linearization
Stress (Pl+Pb+Q) = 335 MPa
S2A
S5
Stress (Pl+Pb+Q) = 106 MPa 36
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11.6 Stress Analysis Results : Load Case-3Stress Plot (MPa) : Von-Mises Stresses
S4
S1A
S2A
S3
S6A S5
S8
S9Stress linearization
Stress (Pl+Pb+Q) = 164 MPa
Stress (Pl+Pb+Q) = 207 MPa
Stress (Pl+Pb+Q) = 76 MPa
S6A
S8
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11.7 Stress Analysis Results : Load Case-3
S4
S1AS3 S8
S9
Stress Plot (MPa) : Von-Mises Stresses
S4
S2AS6A S5
Stress linearization
Stress (Pl+Pb+Q) = 137 MPa
Stress (Pl+Pb+Q) = 69 MPa
Stress (Pl+Pb+Q) = 157 MPa
S9
Stress (Pl+Pb+Q) = 137 MPa
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Stress (Pl+Pb+Q) = 254 MPa
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11.8 Stress Analysis Results : Load Case-3
Stress Plot (MPa) : Von-Mises Stresses
S3 S4
S1A
S2A
S3
S6A S5
S8
S9Stress linearization
Stress (Pl+Pb+Q) = 271 MPa
Stress (Pl+Pb+Q) = 71 MPa
S1A
For reference only
S4
S1A
S2A
S3
S6AS5
S8
S9
R1
11.9 Stress Analysis Results : Load Case-3
Stress Plot (MPa) : Von-Mises Stresses
R2
R2R1
Stress (Pl+Pb+Q) = 342MPa Stress (Pl+Pb+Q) = 114 MPa
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11.10 Stress Analysis Results : Load Case-3
Stress Plot (MPa) : Von-Mises Stresses
Stress (Pl+Pb+Q) = 1104 MPa Stress (Pl+Pb+Q) = 861 MPa
R2
Sliding SaddleFixed Saddle
After masking localized stress areas
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12.0 Result Summary:-
Stress Categories
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43Stress Sm = 144 MPa
12.1 Stress Result Summary:-
Nozzle No. Stress Category Load Case No. Stresses Baseline
Iteration (MPa)
S3 Pl+Pb <1.5*Sm (207 MPa) LC-2 209
Pl+Pb+Q <3*Sm (414 MPa) LC-1 38
Pl+Pb+Q <3*Sm (414 MPa) LC-3 254
S4 Pl+Pb <1.5*Sm (207 MPa) LC-2 17
Pl+Pb+Q <3*Sm (414 MPa) LC-1 58
Pl+Pb+Q <3*Sm (414 MPa) LC-3 137
S5 Pl+Pb <1.5*Sm (207 MPa) LC-2 7
Pl+Pb+Q <3*Sm (414 MPa) LC-1 50
Pl+Pb+Q <3*Sm (414 MPa) LC-3 106
S8 Pl+Pb <1.5*Sm (207 MPa) LC-2 321
Pl+Pb+Q <3*Sm (414 MPa) LC-1 396
Pl+Pb+Q <3*Sm (414 MPa) LC-3 207
For reference only
Stress Sm = 144 MPa
12.2 Stress Result Summary:-
Nozzle No. Stress Category Load Case No. Stresses Baseline
Iteration (MPa)
S6A Pl+Pb <1.5*Sm (207 MPa) LC-2 2.5
Pl+Pb+Q <3*Sm (414 MPa) LC-1 73
Pl+Pb+Q <3*Sm (414 MPa) LC-3 76
S9 Pl+Pb <1.5*Sm (207 MPa) LC-2 1
Pl+Pb+Q <3*Sm (414 MPa) LC-1 31
Pl+Pb+Q <3*Sm (414 MPa) LC-3 69
S1A Pl+Pb <1.5*Sm (207 MPa) LC-2 12
Pl+Pb+Q <3*Sm (414 MPa) LC-1 35
Pl+Pb+Q <3*Sm (414 MPa) LC-3 71
S2A Pl+Pb <1.5*Sm (207 MPa) LC-2 227
Pl+Pb+Q <3*Sm (414 MPa) LC-1 358
Pl+Pb+Q <3*Sm (414 MPa) LC-3 335
For reference only
Stress Sm = 144 MPa
12.3 Stress Result Summary:-
Nozzle No. Stress Category Load Case No. Stresses Baseline
Iteration (MPa)
Sliding
Saddle
Pl+Pb <1.5*Sm (207 MPa) LC-2 28
Pl+Pb+Q <3*Sm (414 MPa) LC-1 1055
Pl+Pb+Q <3*Sm (414 MPa) LC-3 1104
Fixed
Saddle
Pl+Pb <1.5*Sm (207 MPa) LC-2 15
Pl+Pb+Q <3*Sm (414 MPa) LC-1 985
Pl+Pb+Q <3*Sm (414 MPa) LC-3 861
Stiffener
Ring R1
Pl+Pb <1.5*Sm (207 MPa) LC-2 32
Pl+Pb+Q <3*Sm (414 MPa) LC-1 91
Pl+Pb+Q <3*Sm (414 MPa) LC-3 114
Stiffener
Ring R2
Pl+Pb <1.5*Sm (207 MPa) LC-2 72
Pl+Pb+Q <3*Sm (414 MPa) LC-1 342
Pl+Pb+Q <3*Sm (414 MPa) LC-3 342
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12.4 OBSERVATIONS AND CONCLUSION
1. Stresses in all the Nozzles are below respective Allowable Stresses as per the
Stress Categories of ASME Section-II D for all load cases, hence design is safeto carry these loads.
2. Stresses in both Saddles exceeds respective Allowable Stresses, hence
Saddle Design needs the modification to carry various loads.
3. Stresses in both Stiffener Rings are below respective Allowable Stresses,
hence Stiffener Ring Design is safe to carry various loads.
For reference only
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