Abstract
The lower volumetric energy density of hydrogen compared to natural gas requires cost-effective transport solutions. Compressed hydrogen transport via pipelines has been considered the most economical for distances under 3000 km. Retrofitting existing natural gas pipelines is crucial for efficiently delivering hydrogen since it is expected to penetrate and decarbonize several sectors. However, its interaction with most metallic materials makes this approach challenging. Pipelines are often subject to cyclic loads due to pressure fluctuations, which can result in accelerated fatigue crack growth in hydrogen environments. This enhanced degradation reduces the expected lifetime of the infrastructure. Ensuring rigorous maintenance and inspection protocols is essential to detect potential structural defects and prevent failures. This study investigates further the issue of retrofitting pipelines for hydrogen transportation. Combining a physical model and the Markov state model, which helps consider the variable and stochastic nature of the pressure fluctuations, provides an inspection and maintenance plan for an existing pipeline connecting Norway and the United Kingdom. Copyright © 2025, AIDIC Servizi S.r.l.