The paper presents T-stress solutions developed to characterize constraint levels in large-scale cracked pipes and elbows. Stress intensity factor, KI, solutions for pipes and elbows are normalised by material fracture toughness to define the Kr parameter in fitness-for-service procedures, such as R6. Adding knowledge on levels of T-stress allows more advanced analysis through a normalised constraint parameter βT.

The paper presents analyses for 6 pipes and 8 elbows. Values of the normalised constraint parameter βT are calculated for each pipe and elbow at the experimentally measured crack initiation point. Comparison of constraint levels in the pipes and elbows with those in various types of fracture toughness specimen are used to predict the initiation loads using the R6 method and to provide guidelines for transferability.

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