Assessing and Managing Individual and Societal Risk in Hydrogen Pipeline Design

The design of hydrogen pipelines presents unique safety challenges that require a re-evaluation of traditional risk assessment approaches. While extensive data and well-established methodologies support the evaluation of natural gas pipelines, hydrogen introduces new uncertainties due to its distinct physical properties, alternative ignition behaviour, and the limited availability of operational and incident data.

This paper presents a probabilistic method developed to assess risk associated with delayed ignition of hydrogen following a loss of containment event. Unlike immediate ignition scenarios, delayed ignition represents a complex hazard influenced by the presence and density of ignition sources, time-to-ignition, and evolving dispersion behaviour. Additionally, a generalised risk framework is presented, applicable for all hazard types, with a focus on addressing individual and societal risk in pipeline design.

The framework was applied to the design of a hydrogen pipeline. The risk of fatalities and injuries were superimposed across a range of loss-of-containment scenarios along the pipeline route. Results showed that although explosion events had the potential for higher consequences, thermal radiation from ignited jet fires often represented the dominant risk driver, particularly in areas with lower population and ignition source density. These insights have important implications for route selection, emergency response planning, and stakeholder engagement.

The methods presented offer structured guidance for evaluating and mitigating hydrogen pipeline risks, contributing to the development of safe design practices as best-practice frameworks continue to evolve.