GB/T 14092.4-2025 "Environmental Conditions for Mechanical Products - Part 4: Marine" applies to mechanical products used in offshore fixed and mobile facilities, replacing the 2009 edition and optimizing the classification system. It establishes a six-dimensional classification of environmental conditions, including climate, special climate, and chemically active substances, and refines parameters and severity levels for the four major sea areas: the Bohai Sea, Yellow Sea, East China Sea, and South China Sea. Key indicators such as salt spray concentration, vibration and shock intensity, and biological fouling are specified. A new chapter on special climatic environments has been added, while content related to mechanically active substances has been removed. The standard references relevant international standards and provides a basis for the design, material selection, protection, and environmental condition standardization of marine mechanical products, ensuring suitability for service requirements in different sea areas.