Inspection of hydrogen transport equipment: A data-driven approach to predict fatigue degradation

Hydrogen is an environmentally friendly fuel that can facilitate the upcoming energy transition. The development of an extensive infrastructure for hydrogen transport and storage is crucial. However, the mechanical properties of structural materials are significantly degraded in H2 environments, leading to early component failures. Pipelines are designed following defect-tolerant principles and are subjected to periodic pressure fluctuations. Hence, these systems are potentially prone to fatigue degradation, often accelerated in pressurized hydrogen gas. Inspection and maintenance activities are crucial to guarantee the integrity and fitness for service of this infrastructure. This study predicts the severity of hydrogen-enhanced fatigue in low-alloy steels commonly employed for H2 transport and storage equipment. Three machine-learning algorithms, i.e., Linear Model, Deep Neural Network, and Random Forest, are used to categorize the severity of the fatigue degradation. The models are critically compared, and the best-performing algorithm is trained to predict the Fatigue Acceleration Factor. This approach shows good prediction capability and can estimate the fatigue crack propagation in low-alloy steels. These results allow for estimating the probability of failure of hydrogen pipelines, thus facilitating the inspection and maintenance planning.