Comparative Behavior of Type I and IV High Pressure Gaseous Hydrogen Tanks During Ballistic Testing

Decarbonized energy use is now both an economic and an ecological imperative. Hydrogen plays a crucial role in achieving this objective for both mobility and stationary applications. While the safe handling and use of hydrogen in industries stems from extensive experience, there is limited data available in the open literature for military applications. Specifically, the unique challenges of battlefield aggression must be considered in risk assessments. To address this gap, SID-EPN (Service d’Infrastructure de la Défense Expertise et Production Nationale) and CEA (Commissariat à l’Energie Atomique et aux Energies Alternatives) have conducted an experimental program to investigate the safety issues arising from high-pressure hydrogen tanks being hit by ballistic rounds of 12.7 × 99 mm (caliber 50) APHEI (Armor-Piercing, High Explosive and Incendiary) ammunitions. This article reviews the main challenges in hydrogen risk assessment on the battlefield, compiles available results from the open literature, and presents new experimental findings. Two types of hydrogen storage tanks were tested: Type I and Type IV. For Type I tanks, the effects of ballistic aggression are highly reproducible, typically resulting in a jet fire. In contrast, Type IV tanks exhibit more varied and less predictable behavior. Hydrogen leaks may or may not ignite, and the leak may temporarily disappear locally during the transient phase (self-sealing behavior), or even generate a secondary deflagration if congested. These findings highlight the complexities involved in ensuring the safe use of hydrogen in military applications and underscore the need for further research and robust safety protocols.