1. Bay Zoltán Foundation for Applied Research Institute for Logistics and Productgion Systems BAY-LOGI Evaluation system for corrosion defects in pipelines Dr. Gyöngyvér B. Lenkey, Dr. László Tóth, Zsolt Balogh

2. Bay Zoltán Foundation for Applied Research Institute for Logistics and Productgion Systems BAY-LOGI Objectives of the work  Evaluation of the applicability of FEM for predicting the failure pressure and the safe operation pressure for corroded pipelines  Development of safety diagrams  Development of evaluation system for corrosion defects

3. Bay Zoltán Foundation for Applied Research Institute for Logistics and Productgion Systems BAY-LOGI Previous projects  Development of FEM model with real defect geometry  Development of simplified defect geometries and comparative assessment  Comparison of FEM results with pressure tests and with engineering methods  Development of failure criteria for failure pressure

4. Bay Zoltán Foundation for Applied Research Institute for Logistics and Productgion Systems BAY-LOGI Mapping the real 3D defect geometry Sample (negative) Laser distance measurment

5. Bay Zoltán Foundation for Applied Research Institute for Logistics and Productgion Systems BAY-LOGI Boundary conditions for FEM model Modelling the pressure test:  Quarter modell  Increasing internal pressure  Increasing axial tension (proportional with the pressure)

6. Bay Zoltán Foundation for Applied Research Institute for Logistics and Productgion Systems BAY-LOGI Parameters of FEM calculations  Elastic-plastic material law (determined from tensile tests, R eH =350 MPa, R m =480 MPa)  Von-Mises yield criteria, isotropic hardening  Large deformation option

7. Bay Zoltán Foundation for Applied Research Institute for Logistics and Productgion Systems BAY-LOGI Transfer the real defect geometry into the FEM modell

8. Bay Zoltán Foundation for Applied Research Institute for Logistics and Productgion Systems BAY-LOGI Development of simplified defect geometries Parabolic modellRectangular modell6th order surface modell

9. Bay Zoltán Foundation for Applied Research Institute for Logistics and Productgion Systems BAY-LOGI Predicting the failure pressure

10. Bay Zoltán Foundation for Applied Research Institute for Logistics and Productgion Systems BAY-LOGI Criterion:  eq = R m ' 0 5 10 15 20 25 01234567 Defect depth, mm Pressure, MPa Real defect Rectengular modell Parabolic modell Measured failure pres. 6 th order modell Validation of failure criterion and applicability of simplified geometries

11. Bay Zoltán Foundation for Applied Research Institute for Logistics and Productgion Systems BAY-LOGI Comparison of measured and predicted failure pressure values – with engineering methods Pressure, MPa Defect depth, mm Meas. fail. pres.

12. Bay Zoltán Foundation for Applied Research Institute for Logistics and Productgion Systems BAY-LOGI Objectives of the present project  Performing large number of FEM calculations with simplified defect geometry (parabolic)  Development of safety diagrams and defect evaluation system

13. Bay Zoltán Foundation for Applied Research Institute for Logistics and Productgion Systems BAY-LOGI Basic data for the FEM calculations  Different pipe geometry (diameter, wall thickness)  Different materials  Different defect sizes (d, L, b)

14. Bay Zoltán Foundation for Applied Research Institute for Logistics and Productgion Systems BAY-LOGI Definition of critical pressure values (p ys, p yf, p F )

15. Bay Zoltán Foundation for Applied Research Institute for Logistics and Productgion Systems BAY-LOGI Development of safety diagrams  Different representation possibilities (as a function of L/D, d/t, L or d)  E.g. normalisation of critical pressure values: for pF-flawless=2.Rm'.t/(D-t), 1. norm - pys= pys/ pF- flawless, 2. norm - pyf= pyf/ pF- flawless, 3. norm - pF= pF/ pF- flawless, 4. norm - pü= pü/ pF- flawless.

16. Bay Zoltán Foundation for Applied Research Institute for Logistics and Productgion Systems BAY-LOGI Normalised pressure values vs. L/D – comparison with the operation pressure

17. Bay Zoltán Foundation for Applied Research Institute for Logistics and Productgion Systems BAY-LOGI Final safety diagrams For P ys

18. Bay Zoltán Foundation for Applied Research Institute for Logistics and Productgion Systems BAY-LOGI For P yf

19. Bay Zoltán Foundation for Applied Research Institute for Logistics and Productgion Systems BAY-LOGI For P F

20. Bay Zoltán Foundation for Applied Research Institute for Logistics and Productgion Systems BAY-LOGI Definition of safety factors  For the critical pressure values: –n 1 =P ys /P ü  for the beginning of plastic deformation –n 2 =P yf /P ü  for the localisation of the plastic deformation (contraction) –n 3 =P F /P ü  for the failure (plastic instability)  Operational safety? – combination of n 1, n 2, n 3 – application possibility of risk based approaches – owner’s responsibility!

21. Bay Zoltán Foundation for Applied Research Institute for Logistics and Productgion Systems BAY-LOGI Summary and conclusion  FEM calculations gave more accurate prediction for the failure pressure than engineering methods.  The predicted failure pressure (based on FEM calculations) were in good agreement with the pressure test results.  Simplified defect geometries could be applied for predicting the failure pressure, so it gives opportunity to perform large number of FEM calculations and development of safety diagrams.  With the application of the safety diagrams a proper safety evaluation system can be developed together with the owner.  Possibility for more complex safety assessment system and application of risk based principles.

22. Bay Zoltán Foundation for Applied Research Institute for Logistics and Productgion Systems BAY-LOGI Köszönöm a figyelmüket!