What is the difference between hot-dip galvanizing flanges that are galvanized first and those that are galvanized later?

"Pre-galvanizing" (galvanizing the plate before forming) for hot-dip galvanized flanges can lead to damage to the zinc coating during subsequent processing, reducing corrosion resistance, and the weak bonding between the zinc coating and the flange body, resulting in complex processes and high costs. "Post-galvanizing" (galvanizing the entire flange after forming) is the standard process, where the zinc coating is metallurgically bonded to the flange substrate, covering all surfaces comprehensively. It has excellent corrosion resistance, high reliability, can withstand mechanical damage, has a long maintenance cycle, and low overall cost. It is the preferred solution to ensure long-term corrosion resistance and stable use of flanges.