Book

This book highlights the relevance of the Crack Tip Opening Angle (CTOA) for analysing ductile crack propagation and arrest in pressurized pipelines. The study shows that CTOA provides a practical criterion for characterizing fracture resistance and predicting crack propagation and arrest, while its value remains influenced by mechanical, geometrical, and environmental conditions.The coupling of fracture-mechanics analysis with consequence modelling extends the approach from structural integrity assessment to safety evaluation. In particular, the CTOA–ALOHA methodology makes it possible to relate pipeline or tank failure to the resulting hazardous-gas release and associated safety distance. For ammonia, the safety distance is particularly sensitive to internal temperature and wind speed, whereas the comparison with hydrogen demonstrates that the nature of the released substance and its associated hazards strongly affect the required safety perimeter.Overall, this approach provides a useful framework for linking ductile fracture mechanics with risk assessment and for improving the definition of safety zones around pressurized systems containing hazardous gases.