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Core conclusion: Depending on the strength of the corrosive medium, stainless steel exhibits varying corrosion resistance against different media: conventional stainless steel is primarily resistant to weakly corrosive agents such as the atmosphere, water vapor, and water； Higher-grade stainless acid-resistant steel can withstand strong corrosive agents such as acids, alkalis, and salts. Material selection recommendations for different scenarios: For normal mildly corrosive media such as ordinary water, oil, and common gases, 304 stainless steel is sufficient to meet the requirements; it offers the best cost-performance ratio and is suitable for most general industrial applications. Media containing chloride ions/corrosive substances: seawater, brine, acid and alkali solutions, chemical reagents. 316/316L stainless steel containing molybdenum should be used, as it offers better resistance to pitting and intergranular corrosion; in particularly demanding applications, alloy materials can be customized to further enhance corrosion resistance. Media with high purity requirements: gases/liquids for use in the food, pharmaceutical, and semiconductor industries require a design free from dead corners; seals should preferably be made of food-grade PTFE/PCTFE materials to meet the cleanliness standards of these industries. High-temperature corrosive media: High-temperature sulfur-containing flue gases and industrial furnace conditions – 446 high-chromium ferritic stainless steel can be used; it offers stable oxidation resistance at temperatures of 800–1000°C, excellent resistance to sulfidic corrosion, and a better cost-performance ratio compared to nickel-based alloy steels.