The walls are 3mm thick steel, they're very likely to buckle and tear when it tips over, the residual methane vapor gets out and there are plenty of sources of heat to ignite it.

They don't claim to have any plans of recovering the wreckage, but they have previously fished up wreckage for study, so it's still possible they decide to do that.

generally 4mm for the barrel sections, plus all the stringers that add rigidity to that 4mm.