What is Hot-dip Galvanized Steel Pipe

Created on 08.18

Hot-dip galvanized steel pipes are commonly used in playground equipment. Because of the special galvanizing process, the anti-corrosion of steel pipe greatly enhanced and the service life of steel pipe extended a lot. In this article, This article will introduce the definition, core difference, cost comparison, application in playground equipment, advantage comparison of hot-dip galvanized steel pipes in detail. I hope all these contents will be helpful to you.

1.Hot-dip galvanized steel pipes and cold galvanized steel pipes.

Hot-dip galvanizing steel pipe is a kind of steel pipe coated with anti-corrosion by metallurgical reactions at high temperature. The specific process is to put the rust-removed steel pipes into the molten zinc at about 440-460℃. The zinc and iron will have chemical reactions at high temperature to form the zinc-iron alloy layer, and then coated with pure zinc layer by physics. Finally, the zinc-iron alloy layer and pure zinc layer form the composite coating on the surface of the steel pipe. The anti-corrosion ability of the steel pipe is enhanced. The steel pipe will not rust and corrode by the principle of sacrificial anode. While the cold galvanized steel pipe (also called electro-galvanized steel pipe) adopts the principle of electrolysis to prevent steel pipe from rusting. The specific operation is to take the steel pipe as the cathode and put it into the electrolyte containing the zinc ion. Then deposit the zinc ion on the steel pipe surface by applying the external electric current to form the pure zinc coating on the surface of the steel pipe. This kind of coating is only a simple physical attachment and has poor protection effect. What's more, the cold galvanized steel pipe is prohibited in many countries because it will cause heavy metal pollution in production and use.

2.Core difference.

In terms of process principle, hot-dip galvanizing is based on metallurgical reactions and immersion galvanizing process at high temperature, and the coating combines with the surface of the steel pipe in the form of chemical bonding; while the cold galvanizing process is based on electrolytic deposition, and the coating on the steel pipe surface is mainly adhered by physics. So the bonding strength of hot-dip galvanizing coating is much stronger than that of cold galvanizing.Secondly, in terms of coating thickness and structure, the thickness of composite coating of hot-dip galvanizing steel pipe is generally controlled between 60-150μm, and the thickness is relatively uniform as a whole, and there is no pinhole phenomenon. The thickness of cold galvanizing coating is relatively thin, generally controlled between 5-30μm, and the structure is single. The coating is prone to pinhole or missed plating due to uneven plating. There is a weak anti-corrosion effect. In addition, the adhesion and durability are also very different. The zinc-iron alloy layer of hot-dip galvanizing is tightly combined with the base of the steel pipe, the adhesion is ≥70N/cm and will not fall off. The adhesion of cold galvanized coating is relatively weak, generally ≤30N/cm and is prone to falling off or falling off when impacted, rubbed or temperature change.In addition, in terms of appearance, the surface of hot-dip galvanized steel pipe is grayish white, with zinc flowers or slight undulations. The surface of cold-galvanized steel pipe is uniform and smooth, and the surface is bright silver.

3.Cost performance comparison.

From the perspective of unit cost, hot-dip galvanizing steel pipe is significantly higher than cold galvanizing steel pipe because hot-dip galvanizing process is complicated, energy consumption is high, and zinc coating is thicker. However, from the perspective of total life cycle cost, the advantage of durability is very obvious: the anti-corrosion life of hot-dip galvanizing steel pipe is usually 20 to 50 years, while cold galvanizing steel pipe needs to be replaced or recoated after 5 to 10 years.

4. Application in playground equipment.

Hot dip galvanizing steel pipe is widely used in the field of children's playground equipment, especially in the field of safety and environmental protection.Children's playground equipment, such as slides, children's climbing frames and swings, which are placed outdoors for a long time, will be corroded by rain, moisture and ultraviolet rays, and have extremely high requirements for the anti-corrosion performance of steel pipes. Hot dip galvanizing steel pipes have a thick galvanized layer and strong anti-corrosion ability. They can effectively resist the erosion of these corrosive media, ensure the stability of equipment, and prevent the equipment from breaking or deforming due to rust and deformation.

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