A Potential Method for the Fatigue Assessment at a Corrosion Pitted Surface

摘要

Pressure vessels are commonly used in nuclear and non-nuclear plant for a variety of applications. Some applications require the vessels to contain highly corrosive substances during operation. These vessels are therefore subject to corrosion causing general, local wall thinning and corrosion pitting. The local thinning of the vessel walls, for example such as corrosion pitting, can lead to fatigue crack initiation during the operation of the plant. This paper reports the results of work aimed at investigating fatigue crack initiation procedures for the assessment of pressure vessels subject to local wall thinning such as corrosion pitting. A companion paper reporting the results investigating the effect of local wall thinning on the collapse and buckling of thin walled pressure vessels is also presented at this conference. Guidance is based on the use the R5 Sigma-d method. Although this procedure does not specifically address corrosion pits, the R5 method does consider fatigue crack initiation at the tip of a slender notch. This coupled with the BS7910 quality curve approach provides a pragmatic assessment route for the fatigue assessment of corrosion pitting in pressure vessels.