In our daily life, according to different operation methods, stainless steel pickling and passivation treatment mainly includes 6 kinds of dipping method, paste method, brushing method, spraying method, circulation method, electrochemical method, etc. three methods.

Stainless steel pipes, elbows, small parts, etc. are more suitable for this method, and the treatment effect is very good. Because the treated parts can be fully immersed in the pickling passivation solution, the surface reaction is thorough, and the passivation film is fine and uniform. This method is suitable for continuous Intermittent operation, but as the reaction concentration of the solution decreases, a new solution needs to be replenished. Its defects are limited by the shape and capacity of the acid tank, and it is not suitable for large-capacity equipment and pipelines whose shape is too long and wide. For a long time, it is not necessary to reduce The effect of evaporation of the solution requires special premises, acid pools and heating equipment.

Stainless steel pickling passivation paste is widely used in China, and provides a series of products, its main components are nitric acid, hydrofluoric acid, corrosion inhibitor, adhesive and so on. It is suitable for welding seam treatment, welding discoloration, deck top, corner dead angle, reverse side of escalator, large-scale transformation and passivation of storage tank. Washing and passivation is completed once, with strong independence, passivation paste has a long shelf life, and a new passivation paste must be used for each replacement treatment. Due to the limitation of subsequent flushing time, passivation can be strengthened in weak links such as welds. The defects are poor operating environment, high labor intensity, high cost, poor processing effect, etc. It is necessary to combine other methods.

It is suitable for pickling and passivation of single product or equipment with simple internal structure in fixed places and closed environments. The advantages are that the continuous operation speed is fast, the method is simple, the corrosion effect on workers is small, the pipeline can be pickled again during the liquid transportation process, and the utilization rate of the solution is higher. This method has many restrictions, such as: all scaffolding in the tank should be Removed, the tanks and pipelines should be clean, and there should be no residues or impurities in the pipelines; all deep well pumps, valves, tank washing machines and other liquid cargo systems on the whole ship should be debugged for standby; if the pickling solution stays in the tank for too long, it will A reaction occurs, causing excessive corrosion of stainless steel, which requires continuous operation. The shipyard must be highly cooperative and prepare a large amount of clean water at any time. In case of power failure, water failure, or strike, it will cause serious consequences; waste acid and waste water should be placed in larger containers It should be neutralized and discharged as soon as possible to avoid corrosion of the cabin; with the increase of reaction time and impurities in the solution, the useful components of the pickling solution gradually decrease, and the concentration of the solution needs to be checked at any time, and a new solution should be prepared in time ;The residence time of the spray liquid on the deck, the four walls, the dead corner, the reverse side of the escalator, etc. is short, and the pickling effect is slightly worse than that of the bottom plate.

Pickling passivation pretreatment: If there is grease and other dirt on the stainless steel surface, it will affect the quality of pickling passivation. Generally speaking, the inner wall of the water tank should be cleaned with an alkaline detergent, and the concentration of chloride ions in the pickling solution/paste and cleaning water should be Control: If the chloride ion content exceeds the standard, it will damage the stainless steel passivation film. Some stainless steel pickling solutions/pastes use corrosive media containing chloride ions such as hydrochloric acid and perchloric acid as the main agent or auxiliary agent to remove the surface oxide layer. It is unfavorable to avoid corrosion, so it is necessary to control the inspection