The Difference Between Hot-dip Galvanized Steel Pipe and Pre Galvanized Pipe

Ⅰ. The structure of hot dip galvanized steel pipe and pre galvanized pipe

1. Hot-dip galvanized steel pipe structure: 

Hot-dip galvanized steel pipe is to make the molten metal react with the iron matrix to produce an alloy layer so that the matrix and the coating are combined. The steel pipe is pickled first. In order to remove the iron oxide on the surface of the steel pipe, after the pickling, it is cleaned in an ammonium chloride or zinc chloride aqueous solution or a mixed aqueous solution of ammonium chloride and zinc chloride and then sent to the hot dip plating tank.

Hot-dip galvanizing has the advantages of uniform coating, strong adhesion, and long service life. The matrix of the hot dip galvanized pipe undergoes a complex physical and chemical reaction with the molten plating solution to form a corrosion-resistant zinc-iron alloy layer with a compact structure. The alloy layer is integrated with the pure zinc layer and the steel pipe matrix. Therefore, its corrosion resistance is strong. 

2. Galvanized steel pipe structure: 

The pre galvanized pipe adjusts the production process of hot dip galvanized steel pipe. The strip steel used for pipe making is first pickled. In order to remove the iron oxide on the surface of the strip steel, after pickling, it is cleaned in a tank with ammonium chloride or zinc chloride aqueous solution or a mixed aqueous solution of ammonium chloride and zinc chloride and then Sent into the hot dip plating tank. It is then air-dried and then made into tubes. The coating layer is uniform and bright, and the amount of zinc coating is small, which is lower than the cost of producing hot-dip galvanized steel pipes. Its corrosion resistance is slightly worse than that of hot-dip galvanized steel pipes.

There is also a kind of JIS G3444 pipe mainly used in construction and infrastructure, which is also popular in the construction field.

Ⅱ. The difference between hot dip galvanized pipe and pre galvanized pipe

1. Hot-dip galvanized steel pipe

(1) The color of the hot-dip galvanized steel pipe is a bit whitish, and the weight: 6 meters long and 6.5 kg (strong corrosion resistance, long service life, slightly higher price);

(2) The hot-dip galvanized steel pipe is snow white but not shiny or reflective, with a lot of snowflakes on the surface, and zinc tumors (condensed zinc) on both ends.

2. Pre-galvanized pipe

(1) The color of the pre-galvanized pipe is a bit blue, and the weight: 6 meters long and 5.5 kilograms (strong corrosion-resistance, slightly worse than the hot-dip galvanized steel pipe, the service life is shorter than the hot-dip galvanized steel pipe, and the price is low).

(2) The pre-galvanized pipe is shiny white and reflective, with very few snowflakes, and the two ports are clean and free of zinc tumors.