In this study, three steel pipes from the Existing Enbridge Network were studied to evaluate their hydrogen compatibility. The pipes were selected based on the grade and installation year and were titled as Vintage, Legacy, and modern pipes. These pipes were machined to prepare lab-scale test coupons and then characterized to determine their baseline properties. After that, the samples were exposed to hydrogen in a closed chamber for varying durations. Tensile tests were performed on the exposed samples to evaluate ductility. Subsequently, fracture mechanical behavior was assessed using the crack tip opening displacement test to characterize crack propagation phenomena. The study provides a fundamental understanding of the diverse effects of hydrogen and evaluates the fitness of steel pipes from different grades and eras for hydrogen service.
Hydrogen is being considered as a valuable alternative energy source that can play a significant role in the decarbonization of energy systems (NRCan, 2020), (USDA, 2023), (HyBlend, 2022), (COAG Energy Council, 2019), (IEA), (Federal Ministry for Economic Affairs and Energy, Germany, 2020), (HM Government, 2021). It is considered as an excellent energy carrier and produces no carbon dioxide when burned. Therefore, blending hydrogen into natural gas can effectively reduce emissions from homes and industries (USDA, 2023).
The natural gas network comprises gathering, feeder, transmission, and distribution pipelines. Transmission pipelines, primarily steel-based construction and designed to operate at pressures typically ranging from 450 psi to 2,200 psi, transport gas over long distances. These pipelines are designed to function at more than 30% of the Specified Minimum Yield Strength (SMYS) (CGA, 2021). On the other hand, distribution pipelines, largely structured by polyethylene (PE) and steel, operate at lower pressures, usually 0.5 psi to 500 psi, for shorter distances, such as from the city gate to neighborhoods and individual homes. They typically operate at a hoop stress that is less than 30% of SMYS (National Resources Canada (NRCan), 2020), (Canada Energy Regulator, 2020). It is important to note that, regardless of the network or pipeline type, safety is of utmost importance.
