In pipes of energy plants, sometime, the local wall thinning may result from severe erosion- corrosion damage. However, effect of local wall thinning on strength and fracture behavior of pipe system were not well studied, systematically. And alsoallowable limit of the local wall thinning has not been developed for the pipe system.In this paper, effect of depth, shape and location of local wall thinning on strength and failure mode of pipe subjected to bending were studied, systematically. The main results obtained are followings1 ) Observed failure modes were elephant foot type local buckling, ovalization, buckling + ovalization and cracking.2) When M{sub}po≥M{sub}Y, maximum moment M{sub}max was evaluated by using new flow stressρ{sub}tf proposed in this paper, conservatively.3) When M{sub}po≥M{sub}Y, except for craking, pipes with local wall thinning showed enough plastic rotation angle.4) Generally speaking, fracture behavior of pipes with local wall thinning is different from that of cracked pipes.
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