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Quantitative NDT with probabilistic fracture mechanics for the assessment of fracture risk in pipelines and pressure vessels

: Kurz, J.H.; Cioclov, D.; Dobmann, G.; Boller, C.

Japan Welding Society -JWS-; Univ. Karlsruhe; Fraunhofer-Institut für Werkstoffmechanik -IWM-, Freiburg/Brsg.:
German-Japan Seminar "Materials, Processes and Components" 2010. CD-ROM : 8.-10.07.2010, Karlsruhe
Karlsruhe, 2010
10 S.
Seminar "Materials, Processes and Components" <6, 2010, Karlsruhe>
Fraunhofer IZFP ()
fracture risk assessment; failure assessment diagram (FAD)

In the context of probabilistic paradigm of fracture risk assessment in structural components a computer simulation rationale is presented which has at the base the integration of Quantitative Non-destructive Inspection and Probabilistic Fracture Mechanics. In this study the static failure under static loading is assessed in the format known as Failure Assessment Diagram (FAD). The key concept in the analysis is the stress intensity factor (SIF) which accounts on the geometry of the component and the size of a pre-existent defect of a crack nature. FAD assessments can be made in deterministic sense, which yields the end result in dual terms of fail/not-fail. The fracture risk is evaluated in probabilistic terms. The superposed probabilistic pattern over the deterministic one (in mean sense) is implemented via Monte-Carlo sampling. The probabilistic fracture simulation yields a more informative analysis in terms of probability of failure. An important feature of the PVrisk software is the ability to simulate the influence of the quality and reliability of non-destructive inspection (NDI). It is achieved by integrating, algorithmically, probabilistic FAD analysis and the Probability of Detection (POD). The POD information can only be applied in a probabilistic analysis and leads to a refinement of the assessment. By this means, it can be ascertained the decrease of probability of failure (increase of reliability) when POD-characterized NDI is applied. Therefore, this procedure can be used as a tool for inspection based life time conceptions. In this paper results of sensitivity analyses of the fracture toughness are presented with the aim to outline, in terms of non-failure probabilities, the benefits of applying NDI, in various qualities, in comparison with the situation when NDI is lacking.