Fracture analysis of a pressure vessel made of high strength steel (HSS)

The application of design methods based on finite element analysis “Design by Analysis – Direct Route” as an alternative to the recommendations based on the experience and formulas “Design by Formula” allows removing the unnecessary conservatism of the current design codes. A finite element analysis (FEM) was used to calculate the behaviour of a pressure vessel (PV) made of high strength steel (P500) subject to the design loads and assuming the existence of the “worst case” crack allowed by the European standards in order to demonstrate the safe use of these steels and the too conservative design rules currently applied by the PV manufacture codes. It was demonstrated that the presence of cracks on pressure vessels made of high strength P500 steel non-detected during non-destructive tests, do not endanger the safety of the vessel, so its application can be fully successful and safe even under the worst allowed conditions, given way to significant reductions of wall thicknesses, weights and costs.