Principle and purpose of pickling passivation process for stainless steel pipe surface

      Principle and purpose of pickling passivation process on stainless steel pipe surface Pickling is a method of using chemical reaction to dissolve rust, oxide film and other products on the surface of the workpiece without affecting the base metal. Its purpose is to decontaminate the surface of the workpiece and achieve purification.

      Passivation is a method of using a chemical reaction to form a dense oxide film on the surface of the workpiece. The purpose is to prevent the progress of electrochemical corrosion by establishing an oxide film or an oxygen adsorption layer on the surface of the workpiece, thereby improving the corrosion resistance (anti-electrochemical corrosion) performance of the metal. Before pickling and passivation, the welding coating, splash, burr, dirt, etc. on the pipe surface must be cleaned up.

      For safety reasons, large areas of oil stains can be cleaned with steam or 3~5% caustic soda (NaOH) solution, then rinsed with clean water and dried. Note that the CL-concentration of the water used should not exceed 25mg/l.

Pickling, passivation solution preparation and construction precautions

    (1) Be sure to wear work clothes, work caps, boots, gloves and glasses;

    (2) When preparing pickling and passivation solutions, be sure to follow the principle of pouring water first and then injecting acid;

    (3) Pickling, passivation liquid or pickling and passivation liquid paste should be prepared according to the formula requirements, and the formula should not be changed at will.