Fatigue life prediction and crack growth analysis of weld zones in API X60 steel using Weibull distribution and Monte Carlo simulations

The integrity of welded joints in API X60 steel pipelines , critical for oil and gas transportation, is crucial for ensuring the reliability and safety of pipeline infrastructure. This study investigates crack propagation and fatigue life in three distinct zones of welded joints: the base metal (BM), the Melted Metal (MM), and the heat-affected zone (HAZ). Experimental crack propagation tests under cyclic loading were conducted to evaluate the fatigue resistance of these zones. The results indicate that the HAZ is the most susceptible to crack initiation and propagation due to its microstructural transformations during welding, with the BM exhibiting the highest fatigue resistance. To predict the fatigue life of welded joints, a probabilistic approach integrating Weibull distribution modeling and Monte Carlo simulations was employed. Additionally, Bayesian updating was applied to refine the failure predictions based on experimental data. The findings emphasize the need for targeted inspection and maintenance strategies, particularly for the HAZ, to mitigate the risk of premature failures . This study contributes to improving the reliability assessment of pipeline welds by combining experimental data with advanced probabilistic modeling , offering a more accurate estimation of fatigue life and enhancing the understanding of crack propagation mechanisms in welded structures.