There is also the other possibility that the neoprene rubber between the retaining straps and bottles was either missing or worn very badly allowing chaffing of the retaining strap and the bottle. High vibrations, metal rubbing against metal, metal wearing thinner, then too thin to retain the 1600-1700psi pressurised oxygen = KABOOM!
Yes, but there aren't any restraining straps in the area where the bottle failed. It's held at the bottom (in a cup like fitting) and at the top (by a strap). It's believed to have failed about 30% of the way up from the base....nowhere near any restraint.