<p>Vapor cloud explosions in liquefied natural gas facilities can compromise containment-critical components and initiate cascading environmental consequences through subsequent cryogenic release. This study presents a mechanically conditioned structural–environmental assessment of a representative horizontal LNG vessel connected to piping, saddle supports, flanged joints, and bolts. A nonlinear finite element model was developed to evaluate the coupled response of the vessel–pipe–flange assembly under two VCE loading levels: a baseline scenario with 0.43&#xa0;bar applied to the vessel and 0.07&#xa0;bar to the connected piping, and an intensified scenario with three-times-higher loading. Equivalent plastic strain was used as a post-processing screening metric for connection-critical deformation, with a 5% threshold adopted for welded and bolted connection regions. The results show that the baseline VCE case produces localized plasticity below the screening threshold, whereas the intensified case shifts the assembly into a connection-critical response regime. The vulnerable regions are not the general vessel shell, but the flanged connections, saddle-supported zones, and pipe–vessel transition regions, where stiffness discontinuity, contact interaction, bolt-load redistribution, and support reactions concentrate plastic deformation. These structural hotspots are then used to define credible cryogenic-spill initiation regions and to interpret the environmental consequence pathway, including LNG pool spreading, vaporization, cold dense vapor-cloud formation, oxygen displacement, methane-emission relevance, cryogenic exposure of surrounding materials, and domino escalation. The findings demonstrate that LNG blast safety should be assessed as a coupled structural–environmental problem and that mitigation should prioritize connection-level reinforcement, improved support detailing, local blast shielding, gas detection, emergency isolation, cryogenic spill impoundment, and post-event inspection.</p>