Development of engineering codes of practice for corrosion fatigue

The recognition that time dependent effects of aqueous corrosion can have a large influence on fatigue failure in structural steels for nuclear reactor pressure vessels is having an important influence on the continuing process of revision and improvement of design and inspection codes. The contrasting requirements of engineering codes for design purposes or for in-service inspection purposes are discussed. The critical assumptions in each are highlighted and illustrated with examples incorporating recent improvements in the mechanistic understanding of the development of corrosion fatigue failure. The consequences of adopting a crack tolerant approach in the design phase, as distinct from the evaluation of defects found in-service, are also critically examined.