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Combining the three core influencing factors of polythionic acid corrosion mentioned previously, its impact can be reduced from three dimensions: material selection, environmental control, and process operation.: 1. Material optimization and selection: Prioritize the use of stabilized stainless steel containing titanium and niobium (such as 321, 347) or low-carbon "L-grade" austenitic stainless steel to avoid grain boundary chromium deficiency and reduce the risk of sensitization from the source. When welding, a small current and fast multi-pass welding process is used to shorten the residence time in the sensitization range of 500°C to 800°C, reduce the heat affected zone, and reduce welding residual stress. 2. After the environmental condition control device is shut down, the equipment pipelines that are not temporarily under maintenance should be filled with slightly positive pressure and oxygen-free nitrogen to seal them, isolate oxygen and moisture, and destroy the conditions for the generation of polythionic acid. Keep the equipment temperature above the dew point throughout the process to maintain internal dryness and eliminate the liquid water environment required for the formation of polythionic acid. 3. For process operation protection, equipment that needs to be disassembled for maintenance should be neutralized and alkaline washed with 1.5% to 2% sodium carbonate alkaline solution to directly neutralize the generated polythionic acid, and then rinsed with pure water and dried. Ammonia-containing nitrogen gas protection can also be used to neutralize acidic media and form an inert environment to isolate corrosive conditions.