Validation of the European FITNET Fitness-for-Service Fracture Assessment Procedure Available to Purchase

The new European fitness-for-service procedure FITNET includes a hierarchy of different approaches for fracture assessment, designated Option 0 to Option 5. The choice of Option depends on the information available to the user, and can include direct calculation of crack driving force by FEA, allowance for weld strength mismatch and allowance for crack-tip constraint. The fracture assessment procedures have been extensively validated by analysing the results of large-scale fracture tests and engineering failures in accordance with the procedure, and comparing actual with predicted behaviour. This paper presents a selection of the many hundreds of analyses carried out, with particular emphasis on the more advanced Options incorporating weld strength mismatch and crack-tip constraint. Failure of the testpieces was correctly predicted by the FITNET procedure in all cases (ie, the analysis point corresponding to failure of the specimen lay outside the failure analysis line of the FAD). The safety factor associated with the analysis is, however, shown to decrease as the more advanced Options are invoked, ie the analysis becomes more accurate and less conservative, as intended.