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

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

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

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

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)

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

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

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

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

Bay Zoltán Foundation for Applied Research Institute for Logistics and Productgion Systems BAY-LOGI Criterion:  eq = R m ' 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

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.

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

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)

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 )

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.

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

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

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

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

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!

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.

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