The Effect of Corrosion Patch Geometry on Stress Intensity Factors for External Surface Cracks in Cast Iron Water Mains

Abstract

Stress intensity factors play a vital role in predicting the failures of cast iron water mains which are being utilised as buried water mains since several decades in many countries including Australia. The corrosion patterns which can vary from uniform, pitting and/or patch, may result uneven pipe thickness affecting the prediction of stress intensity factors. An inaccurate prediction of stress intensity of the corroded pipes can lead to false judgements by water managers regarding failure predictions, which may result in high economic losses in asset management process. The objective of this paper is to study the effect of external corrosion geometry on stress intensity factors for external surface cracks in cast iron water mains using 3D finite element models. In this study, spherical patch geometry is adopted using a 3D model to characterise externally corroded pipes. Results from the study revealed that external corrosion geometry has a significant effect from on the stress intensity factors for a considered external surface crack. The findings from this study can be used to evaluate the behaviour of stress intensity factor of an external surface crack with variation of corrosion geometry.