<p>When flaws are detected in pressure retaining components, assessments have to be done in order to demonstrate the fitness-for-service (FFS) of the component for continued operation. This FFS demonstration is performed in accordance with FFS Codes providing by flaw assessment procedure and acceptance standards. The first step of the flaw assessment is the flaw characterization which aims at determining the flaw geometry to be used for the analyses. This key step is done according to flaw characterization rules provided in the FFS Codes and hence appears as essential for the rest of the assessment.</p><p>According to the flaw characterization rules of ASME B&amp;PV Code Section XI, a nonplanar flaw (i.e., oriented in two or more intersecting inclined planes, curvilinear geometry, or combinations of nonplanar geometry) shall be resolved into two planar flaws by projection of the flaw area into planes normal to the maximum principal stresses. This approach allows simplifying the flaw assessment but should remain conservative. Therefore, the conservatisms due to the simplified projection approach for nonplanar flaws are investigated in this paper. Current computational tools have been clearly improved such that the modelling of nonplanar flaws does not present any significant difficulty. In this frame, this paper compares the stress intensity factors of projected nonplanar flaws and the mixed mode stress intensity factor of actual nonplanar flaws. This is carried out for multiple flaw sizes, flaw shapes, flaw orientations and different load cases. The final scope is to quantify how the flaw projection into planes normal to the maximum principal stresses is conservative and how this conservatism could be improved, if need be.</p>

Assessment of the Resolution of Nonplanar Flaws in Pressure Retaining Components in Terms of Stress Intensity Factors

Paper Proceedings: https://asmedigitalcollection.asme.org/PVP/PVP2021/volume/85314

ASME 2021 Pressure Vessels & Piping Conference (PVP2021)

Supporting the need among researchers worldwide for additional online and multimedia content, ASME now offers the ASME Conference Video Collection. This platform will collect and provide long-term access to conference presentation videos, encompassing all technology areas within ASME's technical conference and events program. About 30,000-40,000 engineers across all mechanical engineering and related disciplines participate in ASME conferences each year. This includes authors of approximately 6,000 to 8,000 technical papers published by ASME, the majority of whom also submit video presentations for our virtual conferences. The video collection will be available as an add-on to existing product packages or as a separate subscription.