Automated FE Analysis Applications in Energy Industry · General Primary Bending stresses General...

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Automated FE Analysis Applications in Energy IndustryAutomated FE Analysis Applications in Energy Industry

M. Afzali, B. BarakatCetim, France


1. Introduction

2. Industrial applications

3. Codes & Standards Design Procedures

4. Damage Analysis

5. Design procedures applied to a chemical reactor

6.Concluding remarks


Pressure Equipments are used in different petrochemical & energy industries:

Thermal power plantsNuclear power plantsRefineriesChemical plants,…

The Industries has to insure the safety & environmental conditions

1. Introduction


Design of Pressure Equipment has to respect the Codes & Standards

The FE stress analysis should respect a specific procedure

An automated procedure allows to insure the analysis quality & to reduce the analysis time

1. Introduction (Cont’)


Thermal power plantNuclear power plantsRefineriesChemical plants,ShipyardCar industry ( with Natural Gas as fuel),…

2. Industrial applications


Code & Standard organization :- General procedure- Material- Design- Fabrication- Control

Codes & Standards–ASME (USA), EN13445 (EU), CODAP (F), PD5500 (GB), ADM (D)

The codes constitute a set of homogeneous rules taking into account the different risk & damage depending the use of Pressure Equipment

3. Codes & Standards Design procedures


Design of Pressure Equipment:Design by Formula (DBF)Design by Analysis (DBA)

Limitation of DBFOnly linear analysisSimple forms are coveredNot include all possible loading casesDo not take into consideration the interaction between

adjacent nozzles,…DBA is an alternative & more general purpose tool for design of PE. The stress analysis should respect the Codes requirements

3. Codes & Standards Design procedures (Cont’)


Stress analysis should take into account the damage analysis:Large deformationHomogenous & large deformation before thickness

reduction

Plastic Instability Increase of deformation without loading evolution

4. Damage Analysis


Progressive deformationPlastic deformation under cyclic loading

Rupture under creep deformationRupture under creep at high temperature

4. Damage Analysis (Cont’)


Stress Analysis according to Codap (F), European standard or ASME code

5. Design Procedure applied to a chemical reactor


Stress Analysis according to European standard or ASME code1. Stress analysis (by FE)2. Decomposition of stress into Membrane & Bending

components3. Classify the stress (Primary, Secondary, Local et General)4. Addition each type of stress for all load cases 5. Evaluate each type of stress6. Calculate the principal stress associated to each type of

stress7. Calculate the equivalent stress8. Evaluate the equivalent stress according to design criteria

5. Design Procedure applied to a chemical reactor (Cont’)


Stress analysis & decomposition

Total stressStress analysis is carried on locally

Membrane stressAverage stress through the thickness

Bending stressAverage of total stress linearly distributed through the thickness



Membrane & bending stresses



Classification of the stresses

Primary membrane stresses are used to study the damages as large deformation or plastic instability

General Primary Membrane stresses are calculated in a standard part of the equipment(Ex. Stress in a cylindrical part)

Local Primary Membrane stressesStress components calculated in a singularity zone (high

gradient stress distribution : nozzle, opening,…)



General Primary Bending stressesGeneral Primary Bending stresses are calculated in a “general” part of the equipment(Ex. Stress in a cylindrical part under internal pressure)

Secondary stresses Part of stress component to assure the deformation compatibility between elements(Ex. Thermal expansion )

Classification of the stresses (Cont’)



Major stress discontinuities Stress discontinuity through the thickness due to shape or

material Ex : head-cylinder junction, change of thickness or material

Minor stress discontinuitiesStress discontinuities in a local or limited zoneEx : fillet with small radius, Seam or Girth welded zone

Local Zone Zone close to the major stress discontinuities or loading

Classification of the stresses (Cont’)



Major stress discontinuities

Local zone

Minor stress discontinuities

General Zone

General ZoneHomogeneous stress distribution (far from stress discontinuities)



PEA Module : Visualization of equivalent stress

Primary membrane stress

Total primary stress(Membrane + Bending)Total stress (Primary + Secondary)



Stress evaluationDetermination of nominal stress

Security factors depend on following parameters :

MaterialsLevel of inspection,Welding control

Security factors are applied to yield or rupture stress

The design nominal stress is « f »



Stress evaluation according to ASME, EN13445 or CODAP®



General membrane primary equivalent stress < f

Local membrane primary equivalent stress < 1.5 f

Total primary stress < 1.5 f

Sum of General membrane primary equivalent stress & bending < 1.5 f

Sum of Primary & secondary stress < 3 f Criteria to avoid the accumulated plastic deformation




CODAP®General membrane primary equivalent stress: C10.1.7.1.aLocal membrane primary equivalent stress : C10.1.7.1.b1Total primary stress : C10.1.7.1.cTotal stress (primary + secondary) : C10.1.7.2.a

EN 13445 :Equivalent stress Tresca or Von Mises criteria : C.4.1General membrane primary equivalent stress: C7.2-1Local membrane primary equivalent stress : C7.2-2Total primary stress : C7.2-3Total stress (primary + secondary) : C7.3-1

ASME :General membrane primary equivalent stress : 4-131Local membrane primary equivalent stress : 4-132Total primary stress : 4-133Total stress (primary + secondary) : 4-134




PEA Module : Verification of the criteria

Verified Criteria

Non-verified criteria



Verification of the criteria

Visualization of maximum shear stress

Tresca/2Stress Criteria



PEA Module : An adapted FE model preparation & design in Ansys workbench

Geometry preparationCreating “local” & “General” areaAdapted FE preparationStress calculation

Stress evaluation according to Code & Standard criteria

VisualizationReporting


3 operations are done automatically

1. Grouping of all the surface bodies under the same part

2. Creating of joints (ensure meshing continuity)

3. Creating of General_area and Local_area named selections, consisting of sets of faces



Verify Criteria admissibility

Nominal stress selection



The Design of Pressure Equipment has to respect the specific requirements from best practice rules, design Codes & Standards

The use of an automated procedure within an FE environment assures the design quality taking into account the requirements & safety

The automated procedure helps the QA activities

Many industrial applications are involved

This allows time & cost reduction in the design process

6. Concluding remarks

Automated FE Analysis Applications in Energy Industry · General Primary Bending stresses General...

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