Correction on stress intensity factor of root within pipeline girth weld considering various geometric parameters

Abstract

The study focuses on the stress intensity correction factor (Mk) for internal surface cracks located at the girth pipe root toe. To assess the impact of various parameters on Mk, three-dimensional finite element models are developed. These models take different types of misalignment, a range of variable-wall-thickness ratios, and initial crack depths into account. The findings reveal that the stress intensity correction factor Mk tends to increase with the rise in misalignment and variable-wall-thickness ratio. Conversely, an increase in the initial crack depth leads to a decrease in Mk. The study demonstrates that the Mk values, when accounting for different geometric factors, are significantly higher than those calculated using BS 7910. This suggests that the BS 7910 standard may provide overly optimistic predictions. As a result, a revised Mk formula is proposed, which generally maintains an error margin of less than 10 %. This modified formula offers a significant enhancement to prevailing codes and standards, furnishing a more dependable benchmark for the assessment of structural integrity in pipeline laying procedures.