Tactical Depressurization of Hydrogen and CNG Tanks Using Rifles and Other Projectiles

After a tank has been exposed to crash violence, or an external fire, it might, in some situations, be judged dangerous to move the vessel due to the risk of a sudden tank rupture. Therefore, Swedish rescue services have a long history of using rifles to penetrate and therefore depressurize the vessels. In this paper, some first steps on providing guidance on the selection of ammunition and required stand back distance are presented. The results indicate that a stand back distance on the order of 100 m is required and that the standard 7.62 Ball should only be used for composite CNG-tanks, while stronger ammunitions are needed for steel and composite hydrogen tanks. However, more research is required to provide a more solid scientific underpinning of the tactic guidance.