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 Research VEIKI Power Research Institute Szávai Szabolcs Pálfi Tamás Tóth 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 TaskElementsType Analysis of pipeline and its elements Pipes, welds, elbows, curved pipes, branch connections, welded transitions  Structural  Fatigue  Tightness Load conditions:  Level A  Pressure test  Cyclic 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 problemStructural analysisFatigueleakage Pipeline and its elements Stress indexesCritical point of the pipe elements (branch connections, welds, etc.) VesselMembrane and bending stresses Primary, bending and peak stresses Critical FEM elements Take into consideration the FSRF of welds FlangeMembrane and bending stresses Primary, bending and peak stresses for bolts Bolt, threadSeals

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   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 analysis of 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 stresses   Fatigue 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 analysis of 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 elements   WRC107: 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 „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 analysis   Fatigue analysis – –Determination of the stress amplitudes – –CUF calculation Required steps for analysis of 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 tightness   Structural 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 TaskCheck 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