Assessment of a gouge and dent defect in a pipeline

This paper pubished in Engineering Failure Analysis, deals with A37 steel pipelines containing a gouge and dent defect. The influence of the dent depth on the burst pressure of pipelines is evaluated for a given geometry of the gouge. Experimental burst tests are performed and finite element analysis is used in order to compare the numerical and experimental results. Experimental results showed that a combined gouge and dent defect does not reduce the burst pressure of A37 steel pipelines. These results contradict established research conclusions and the bulk of the literature on the subject. A combined criterion based on volumetric method and stress triaxiality is proposed for assessment of pipelines containing a gouge and dent defect.

Analysis of notch effect in the apparent fracture toughness and fracture micromechanisms

This paper, reported by Sciencedirect.com, presents an analysis of the notch effect on two ferritic-pearlitic steels operating within their corresponding lower shelf, and develops an experimental programme, composed of 28 CT characterisation specimens and 72 CT validation specimens, together with finite elements analysis with the aim of validating the apparent fracture toughness predictions provided by the Theory of Critical Distances. The results have shown how this theory provides reasonable predictions of the apparent fracture toughness of the material .

The research is completed with the analysis of the evolution of fracture micromechanisms when the notch radius increases, revealing a direct relation between this evolution and the apparent fracture toughness observations.

Analyse de défaillance d’une vanne à tiroir de centrale nucléaire

Présentation d’un cas d’analyse de défaillance d’une vanne à tiroir de centrale nucléaire publié par la revue « Engeneering Failure Analysis ».

Il s’agit de l’étude d’une vanne à tiroir dont le « BeltEye » est défaillant bien avant qu’il est atteint sa durée de vie prévue. Le processus de ruine s’est avéré être de la corrosion-érosion-cavitation. Ce n’est pas la forme en venturi qui en est responsable mais le décalage entre le réducteur et le « Belt Eye » qui a provoqué l’érosion-cavitation. La cavitation a amplifié la corrosion accélérée par l’écoulement (FAC).