Thinning of Carbon steel pipe subjected to water flow has been observed in many piping systems. The feeder pipes in CANDU® reactors have been found susceptible to this degradation mechanism. In response, an industry program has been initiated to investigate the effect of local thinning on structural integrity. A CANDU® feeder pipe bend specimen was thinned locally to about 70% of pressure based thickness near the weld at the onset of the bend. The test specimen was subjected to severe pressurized cyclic bending for over 1600 cycles, and was subsequently pressurized to failure under a constant applied bending deformation. The failed specimen was subjected to metallurgical examination. The present paper reports the results of a finite element analysis of the cyclic part of the test and an elastic plastic analysis for failure under pressurization. The results are compared with the experimental outcomes. The conclusions address specifically the test, more generally the failure of thinned pipe and the use of elastic-plastic finite element analysis to predict failure due to pressurization.

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