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After pickling static equipment such as stainless steel towers and heat exchangers, passivation treatment must be carried out in accordance with specified procedures to form a dense chromium-rich oxide protective film on the surface, thereby significantly enhancing corrosion resistance. I. Key preliminary processes: Multiple stages of rinsing with clean water: Immediately after acid cleaning, the workpiece is rinsed repeatedly with plenty of flowing clean water, focusing on cleaning the welds and hard-to-reach areas, in order to completely remove any remaining acid and prevent further corrosion of the substrate by the acid. Optional neutralization treatment: For parts with high requirements, weakly alkaline solutions are used to neutralize any residual acidic substances, followed by rinsing with pure water until the pH value approaches neutrality. II. Core operations for passivation: Immersion method: Immerse the clean workpiece in a 5%~20% nitric acid passivation solution at room temperature to 40°C for 20~60 minutes, thereby promoting the accumulation of chromium to form a passivation film; this method is suitable for small components. Circulating spray method: For large-scale equipment such as towers and heat exchangers, the passivation pre-coating agent is circulated and sprayed via a pumping system, with the temperature maintained at 30–50°C; this process is repeated for 1–3 hours to ensure complete coverage of the inner surfaces. Passivation paste application method: Apply the specialized stainless steel passivation paste evenly onto the surface of the equipment, then let it sit and react for 15 to 30 minutes; this method is suitable for both local repairs and large-scale applications on site. III. Completion and Quality Inspection: After blunting, rinse thoroughly with clean water, then dry it with clean compressed air or low-temperature drying to avoid water stains. The integrity of the passivation film is checked using the blue dot method; the absence of blue spots indicates compliance. Meanwhile, the chloride content in the rinsing water is kept at ≤25 ppm to prevent damage to the passivation film.