New brittle fracture model for the European pressure vessel standard

Abstract

A model for design against brittle failure based on recent fracture mechanics findings is proposed. The procedure is an update of that in the recent European pressure vessel standard EN 13445. The thickness dependence of the maximum permissible crack has been analysed with the help of research on non-destructive testing. Cracks with a quarter thickness depth are assumed to be readily detectable for larger gauges. For thinner gauges the cracks have to cover a larger fraction of the thickness to be safely observed. The model is verified by comparison to fracture mechanics test data for high strength steels. Results from individual wide plate tests are successfully reproduced by the model. Furthermore, T 100 values (the temperature where K JC=100 MPa m 1/2) for test series are conservatively predicted by the model. The model adequately describes the influence of thickness and heat treatment on the T 100 values.