What are the methods of surface passivation treatment, and which one is the most commonly used?

In the production of galvanized steel pipes, the main passivation treatment methods currently applied worldwide are chromate passivation and phosphating treatment. The former is primarily used when no additional coatings are required on the surface of the galvanized steel pipe after passivation. The latter is mainly used when galvanized steel parts still need to be painted. Chromate passivation treatment is cheaper and more effective, and therefore it is more widely used in the passivation treatment of galvanized steel sheets and galvanized steel pipes.