1st Hungarian-Ukrainian Joint Conference on SAFETY-RELIABILITY AND RISK OF ENGINEERING PLANTS AND...
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1st Hungarian-Ukrainian Joint Conference on SAFETY-RELIABILITY AND RISK OF ENGINEERING PLANTS AND
COMPONENTS”
BAY-LOGI
1
Fatigue calculations on benchmark tasks according to ASME code,
experiences, results
Bay Zoltán Foundation for Applied ResearchVEIKI Power Research Institute
Szávai SzabolcsPálfi TamásTóth László
1st Hungarian-Ukrainian Joint Conference on SAFETY-RELIABILITY AND RISK OF ENGINEERING PLANTS AND
COMPONENTS”
BAY-LOGI
2
Benchmark tasks for the Paks License Renewal Project
Created by Mechanical Components Scientific Committee
Solution made by different research institutes, solution methodology accepted by MC-SC
Conflict the ASME interpretation of different experts
Compare the result of different solution methods and tools
Develop verification cases for the applied methodologies of the project
Create a general solution method which can also be used for more complicated problems
1st Hungarian-Ukrainian Joint Conference on SAFETY-RELIABILITY AND RISK OF ENGINEERING PLANTS AND
COMPONENTS”
BAY-LOGI
3
Analysis of pipeline and its elements
Evaluation of flange for structural integrity, stiffness, and leak tightness
Structural and fatigue analysis of a thick walled pressure vessel with openings
Benchmark tasks for the Paks License Renewal Project
1st Hungarian-Ukrainian Joint Conference on SAFETY-RELIABILITY AND RISK OF ENGINEERING PLANTS AND
COMPONENTS”
BAY-LOGI
4
Applied codes and regulations
ASME BPV CODE SECTION. III. (2001)
Procedure for actions related to the life
time extension of equipment operating in
nuclear plants
Directives for structural analysis of
pressure vessels. OAH NBI 3.3
1st Hungarian-Ukrainian Joint Conference on SAFETY-RELIABILITY AND RISK OF ENGINEERING PLANTS AND
COMPONENTS”
BAY-LOGI
5
Simple problems require mainly numerical methods (e.g. FEM) however analytical solutions are also acceptable
ASME based, PNAE material properties
Class I. components Design and operational
conditions Coupled thermo-mechanical
static and cyclic analysis
Benchmark tasks for the Paks License Renewal Project
1st Hungarian-Ukrainian Joint Conference on SAFETY-RELIABILITY AND RISK OF ENGINEERING PLANTS AND
COMPONENTS”
BAY-LOGI
6
Benchmark tasks
Task Elements Type
Analysis of pipeline and its elements
Pipes, welds, elbows, curved pipes, branch connections, welded transitions
StructuralFatigueTightness
Load conditions:Level A Pressure testCyclic loads
Structural and fatigue analysis of a thick walled pressure vessel with openings
Vessel, nozzle, openings
Evaluation of flange for structural integrity, stiffness, and leak tightness
Flange connection, leak tightness, bolts.
1st Hungarian-Ukrainian Joint Conference on SAFETY-RELIABILITY AND RISK OF ENGINEERING PLANTS AND
COMPONENTS”
BAY-LOGI
7
Analysis types
Test problem Structural analysis Fatigue leakage
Pipeline and its elements
Stress indexes Critical point of the pipe elements (branch connections, welds, etc.)
Vessel Membrane and bending stresses Primary, bending and peak stresses
Critical FEM elements
Take into consideration the FSRF of welds
Flange Membrane and bending stresses Primary, bending and peak stresses for bolts
Bolt, thread Seals
1st Hungarian-Ukrainian Joint Conference on SAFETY-RELIABILITY AND RISK OF ENGINEERING PLANTS AND
COMPONENTS”
BAY-LOGI
8
Loadcases
Design Load: p=13,7 MPa T=325ºC
Test pressure: p=16,4 MPa, T=140ºC
Load on the nozzle:N=300kN, M=200kNm T=100kNm
T [˚C] T [˚C]
T [˚C]T [˚C]
p [MPa] p [MPa]
p [MPa]p [MPa]
A. Cycle (1x) B. Cycle (2x)
C. Cycle (5x) D. Cycle (5x)
t [h] t [h]
t [h]t [min]
130 13019,5 16
300 30012 12
60 60
290 60
0,1 0,1
11 0,1
1,4 1,4
10 40 60
0 0
0 0
1,65 3,4 1,65 3,4
1446 1454
2 month
6
Cyclic load:
1st Hungarian-Ukrainian Joint Conference on SAFETY-RELIABILITY AND RISK OF ENGINEERING PLANTS AND
COMPONENTS”
BAY-LOGI
9
Structural and fatigue analysis of a pressure vessel
Structural analysis for design conditions
– Critical points (2. and 3.)– Nozzle
Fatigue evaluation at 3.Thermal stress calculation in the cylindrical wall
1st Hungarian-Ukrainian Joint Conference on SAFETY-RELIABILITY AND RISK OF ENGINEERING PLANTS AND
COMPONENTS”
BAY-LOGI
10
Structural analysisof the nozzle
Material properties based on PNAE Analysis of the nozzle based on WRC107
1st Hungarian-Ukrainian Joint Conference on SAFETY-RELIABILITY AND RISK OF ENGINEERING PLANTS AND
COMPONENTS”
BAY-LOGI
11
Axysymmetrical FEM model to get sufficient results for the critical points. Derive the primary, secondary and peak stresses from the calculated stress distribution Determination of the membrane and membrane+bending stressesFatigue evaluation
– Calculation of the stress intensities– Rainflow analysis for determining the stress cycles– FSRF determination for the analyzed points– CUF calculation – Critical point evaluation
Structural analysisof pressure vessel
1st Hungarian-Ukrainian Joint Conference on SAFETY-RELIABILITY AND RISK OF ENGINEERING PLANTS AND
COMPONENTS”
BAY-LOGI
12
Results, Experiences
Calculations were done by 2 independent research institutes
– VEIKI Rt., Budapest– BAY-LOGI and Univ. of Miskolc, Miskolc
Good agreement between the stresses and the location of critical elementsWRC107: COADE interpolated and „manual” diagram reading of the parameters caused different results in the nozzle
1st Hungarian-Ukrainian Joint Conference on SAFETY-RELIABILITY AND RISK OF ENGINEERING PLANTS AND
COMPONENTS”
BAY-LOGI
13
Results, Experiences
1st Hungarian-Ukrainian Joint Conference on SAFETY-RELIABILITY AND RISK OF ENGINEERING PLANTS AND
COMPONENTS”
BAY-LOGI
14
Wall temperature distributions Cycle „A”Cycle „A” Cycle „C”Cycle „C”
1st Hungarian-Ukrainian Joint Conference on SAFETY-RELIABILITY AND RISK OF ENGINEERING PLANTS AND
COMPONENTS”
BAY-LOGI
15
Fatigue analysis
Stress differences were calculated considering varying principal stress directions:
– At the principal stress calculation the difference of each stress components in the two time steps was used
1st Hungarian-Ukrainian Joint Conference on SAFETY-RELIABILITY AND RISK OF ENGINEERING PLANTS AND
COMPONENTS”
BAY-LOGI
16
Analysis of pipeline and its elements
Structural analysis– Design condition– Level A– Pressure test
Fatigue analyses– Primary, secondary
and thermal stresses
1st Hungarian-Ukrainian Joint Conference on SAFETY-RELIABILITY AND RISK OF ENGINEERING PLANTS AND
COMPONENTS”
BAY-LOGI
17
Material properties – based on PNAE
CAEPIPE model for– Stiffness calculation – Determination of the Moments for each element
ASME Class 1 stress indexes– Pipes, welds, curved pipes, branch connections, welded
transitions
Structural analysisFatigue analysis
– Determination of the stress amplitudes– CUF calculation
Required steps for analysisof pipeline and its elements
1st Hungarian-Ukrainian Joint Conference on SAFETY-RELIABILITY AND RISK OF ENGINEERING PLANTS AND
COMPONENTS”
BAY-LOGI
18
Stresses were calculated also using shell elements in Msc Nastran4W
In each cross-section:– Stress transformations needed to determine stresses in the
local coordinate system– Parametric calculations needed to calculate the highest
bending stress
Finite element solution
1st Hungarian-Ukrainian Joint Conference on SAFETY-RELIABILITY AND RISK OF ENGINEERING PLANTS AND
COMPONENTS”
BAY-LOGI
19
Results using finite element solution was in good agreement with the results using CAEPIPE model and ASME stress indexes
– Large deformation calculation needed, because the pressure caused deformation at the curved sections essentially affects stiffness
– Special spring elements had to be used to model the support
Finite element solution
1st Hungarian-Ukrainian Joint Conference on SAFETY-RELIABILITY AND RISK OF ENGINEERING PLANTS AND
COMPONENTS”
BAY-LOGI
20
Analysis of flange joint for structural integrity, stiffness
and leak tightnessStructural analysis for:
– Level A – Pressure test
Leak tightness evaluation– seating load– stiffness
Fatigue analysis of bolts and threads
1st Hungarian-Ukrainian Joint Conference on SAFETY-RELIABILITY AND RISK OF ENGINEERING PLANTS AND
COMPONENTS”
BAY-LOGI
21
Material properties: – based on PNAE
Elastic model including:– bolts – sealing
Analysis of flange joint for structural integrity, stiffness
and leak tightness
1st Hungarian-Ukrainian Joint Conference on SAFETY-RELIABILITY AND RISK OF ENGINEERING PLANTS AND
COMPONENTS”
BAY-LOGI
22
Required steps of the evaluation
Required bolt area verification
Analysis of bolts for level A condition
Stiffness calculation of the joint
– Determination of the displacements
– Examination of the leak tightness
Analysis of flange joint for structural integrity, stiffness
and leak tightness
1st Hungarian-Ukrainian Joint Conference on SAFETY-RELIABILITY AND RISK OF ENGINEERING PLANTS AND
COMPONENTS”
BAY-LOGI
23
Required steps of the evaluation:
Analysis of the bolts for test pressure
Calculation of the gasket force
Examination of the thread
Fatigue analysis for bolts and threads
Analysis of flange joint for structural integrity, stiffness
and leak tightness
1st Hungarian-Ukrainian Joint Conference on SAFETY-RELIABILITY AND RISK OF ENGINEERING PLANTS AND
COMPONENTS”
BAY-LOGI
24
The finite element model
Spring elements were used to model the seal and the bolts
Rigid elements were used for the washers
The active bolt length=unconstrained length+2x3 threads
1st Hungarian-Ukrainian Joint Conference on SAFETY-RELIABILITY AND RISK OF ENGINEERING PLANTS AND
COMPONENTS”
BAY-LOGI
25
Results
Calculations were done in 2 independent research institutes
– VEIKI Rt., Budapest: • Finite element model including bolts and sealing
– BUTE, Budapest• Finite element model for the flanges + semi analytical model for
stiffness calculations
Good agreement between the stiffness values and the stresses
1st Hungarian-Ukrainian Joint Conference on SAFETY-RELIABILITY AND RISK OF ENGINEERING PLANTS AND
COMPONENTS”
BAY-LOGI
26
Some of the stress calculations were done also by using analytical methods, and got higher stresses then by FEM calculations, because more complex analytical model required
Results
1st Hungarian-Ukrainian Joint Conference on SAFETY-RELIABILITY AND RISK OF ENGINEERING PLANTS AND
COMPONENTS”
BAY-LOGI
27
Check points for future participants
Task Check points
Analysis of pipeline and its elements
–Stiffness–Moments at different load cases stress indexes–Stresses–Fatigue cycles, CUF
Structural analysis of a nozzle of the pressure vessel
–WRC107 parameters for nozzle analysis, stresses and categorization
–Stresses for the operational conditions, membrane and membrane+bending stresses
–Critical points from the fatigue calculation, fatigue cycles, stress amplitudes, CUF
–Temperature distribution and thermal stresses
Analysis of flange joint for structural integrity, stiffness and leak tightness
–Stress components from the structural analysis, membrane and membrane+bending stresses
–Stiffness of the flange–Bolt loads and gasket seating condition.–Fatigue evaluation, CUF calculation
1st Hungarian-Ukrainian Joint Conference on SAFETY-RELIABILITY AND RISK OF ENGINEERING PLANTS AND
COMPONENTS”
BAY-LOGI
28
Summary and conclusions
The developed benchmark tasks are suitable for:
– Demonstrating the ASME methodology in accordance
with the Hungarian directives
– Comparing the result of different solution methods and tools
– Providing verification points for the applied
methodologies
– Act as a general solution method, can also be used for
more complex problems