Performance evaluation of life-saving equipment for ice-class ships under simulated extreme cold conditions

Polar environments pose a severe threat to maritime safety, as extreme cold and ice accretion drastically increase the risk of equipment malfunction. Life-saving appliances (LSAs) are the final line of defense for personnel evacuation and survival. However, current marine LSAs frequently suffer from material embrittlement, mechanical blockage, and operational failure when exposed to extreme cold, leaving evacuees highly vulnerable. Despite the strict operational requirements mandated by the IMO Polar Code, there remains a critical lack of systematic, high-fidelity experimental frameworks for verifying the operating performance of LSA under extreme cold conditions. This study addresses this deficiency by developing a comprehensive environmental simulation and testing methodology to identify the specific failure mechanisms of polar LSA, thereby providing essential data to facilitate the polar-specific adaptation of maritime safety equipment.

Testing was conducted at the Far East Anti-Cold Laboratory using a large-scale environmental chamber capable of regulating temperatures down to −70 ℃, with a maximum cooling rate of 0.88 ℃/min and a temperature control accuracy of ±1 ℃. The test matrix included lifebuoys, lifejackets, fully enclosed lifeboats, immersion suits, and individual and group survival kits. To replicate dynamic equipment icing, the platform integrated a custom dual-path servo-driven subsystem that decoupled the supply temperature, pressure, and spray flow to generate precise supercooled water droplet conditions. The experimental protocol consisted of an 8 h deep-cold thermal equilibrium pre-treatment, followed by in-situ material evaluations (including a 2 m drop test), functional verification under 5 mm dynamic icing, and post-experiment recovery inspections. A multisource thermodynamic sensing network comprising 14 measurement points was used to continuously track spatial temperature gradients inside the equipment.

Experimental data revealed distinct failure patterns across different LSA categories at −50 and −60 ℃. While primary structural LSA such as lifebuoys maintained mechanical integrity without macroscopic cracking, emergency survival kits experienced severe systemic failures. Polymer packaging exhibited cold embrittlement, making unsealing extremely difficult; liquid contents (e.g., hand sanitizers) froze; mechanical switches seized due to thermal contraction. Crucially, the freezing of nonmetallic zippers on immersion suits and lifejackets prevented unassisted donning. Under dynamic icing conditions, lifeboat doors and release hooks operated normally only after manual de-icing. Furthermore, the thermodynamic sensing network identified steep spatial temperature gradients within immersion suits and lifeboats, indicating significant heat distribution imbalances between localized heat sources and distal extremities.

The developed simulation platform and multisource measurement architecture successfully isolate the underlying material and functional failure mechanisms of LSA in polar conditions. The findings confirm that extreme cold and icing severely compromise the operational readiness of auxiliary survival gear and emergency donning mechanisms. Additionally, the internal heating strategies currently employed in LSA exhibit critical thermodynamic limitations. This study provides a robust methodological foundation and the necessary experimental evidence to guide material upgrades, thermal redesign, and system-level polar adaptation of maritime LSA.