Hot dipped galvanizing manufacturing technology

Hot dipped galvanized steel pipe is very popular among users because of its cost-effective performance in various applications today. Nevertheless, few of users have a good knowledge of this special type of galvanized steel products in the market. Today we would like to help you know much about how to manufacture hot dipped galvanized steel pipe in a mill.

DongPengBoDa Steel Pipe Group is a famous steel pipe manufacturer in China. Here we would talk more about the hot dipped galvanizing process in a mill as follows：
Generally speaking, the hot dipped galvanizing process consists of three basic steps: surface preparation, galvanizing, and inspection.
1. Surface Preparation
Surface preparation is one of the important steps in the application of any coating. In most cases, incorrect or inadequate surface preparation is the cause of a coating failure before the end of its expected service lifetime. As a rule, the surface preparation step in the galvanizing process has its own built-in means of quality control because zinc will not react with unclean steel surface. Take black steel pipe for an example. Any failures or inadequacies in surface preparation will immediately be apparent with the steel is withdrawn from the molten zinc, because the unclean areas will remain uncoated and immediate corrective action must be taken.
2. Galvanizing
In the true galvanizing step of the process, the material is completely immersed in a bath of molten zinc. The bath contains at least 98% pure zinc and is heated to approximately 840F (449C). In general, while immersed into the kettle, the zinc reacts with the iron in the steel to form a series of zinc/iron intermetallic alloy layers. Once the fabricated items coating growth is finished, they are withdrawn slowly from the galvanizing bath, and the excess zinc is removed by draining, vibrating, and or centrifuging. Furthermore, hot dipped galvanizing is a factory-controlled process performed under any climate conditions. Most brush and spray-applied coatings depend upon proper climate conditions for correct applications. With reference to galvanized steel pipe, the toughness of galvanized coating is extremely important, for the barrier protection is dependent upon coating integrity. Other coatings damage easily during shipment or through rough handling on the job site.
3. Inspection
The inspection of hot dipped galvanized steel pipe is simple and fast. The two properties of the coating closely scrutinized are coating appearance and coating thickness. In the modern times, variety of simple physical and laboratory tests are performed to determine thickness, uniformity, adherence, and appearance in a mill.