A fail safe container and container insert are disclosed. A flexible container insert may convert energy from a catastrophic event, including but not limited to collisions, accidents, impacts, pressure container failures or explosions such as detonations, or other catastrophic incidents, into a stretching of an internal structure of a fail-safe container insert to minimize or prevent failure of the container insert and/or the container. The stretchability of the container insert may accommodate both temperature and shape changes to protect a container, including but not limited to a pressure vessel, from rupture or other failure. Accordingly, a container insert may be considered self-healing in that it may absorb the effects of catastrophic events to prevent failure, may return to a generally previous condition, and/or may seal or otherwise reduce or minimize breaches when they do occur.