Hydrogen is vital to a successful global energy transition due to its potential to decarbonise hard-to-electrify sectors such as steelmaking, transportation, and power generation. In the near future, steel pipelines are expected to play a vital role in enabling efficient, large-scale distribution of high-pressure hydrogen gas – however, a set of engineering challenges exists. Repurposing natural gas pipelines for hydrogen transport requires understanding how external defects, like dents and gouges, affect structural integrity under hydrogen exposure. To address this, we combine experiments with a new hydrogen embrittlement model aimed at large plastic straining scenarios, which integrates: (i) multi-trap hydrogen transport, (ii) finite-strain plasticity, and (iii) a hydrogen- and triaxiality-dependent damage law. Each of these model ingredients is validated with experiments on pipeline steels: (i) hydrogen permeation, (ii) full-scale denting of a pipe, and (iii) mechanical testing at different hydrogen and triaxiality levels. The validated model is used to study passive (indentation before hydrogen exposure) and active (indentation with hydrogen) dents and gouges, revealing that active denting is more detrimental than passive denting, but also that hydrogen brings a very small increase in the level of damage induced by these defects; i.e., dents and gouges considered safe in natural gas transmission are likely harmless in hydrogen transport pipelines too.