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Hot Dipped Galvanized Pipe | GI Pipes | ERW Tubes Factory

Standard ASTM A53/ API 5L/ ISO 65
Certification API, ISO
Grade Gr.B
Out Diameter All Outside Diameter
Wall Thickness All Thickness
Length 6M/ 12M or Customized
Usage Construction
The Thickness of Zinc 200 – 550 g/㎡

ASTM A53/ API 5L Hot Dipped Galvanized ERW Steel Pipe

Hot-dip galvanising is an effective anti-corrosion treatment for a wide range of steel products. Hot-dip galvanised pipes are manufactured by dipping the descaled steel pipe into a zinc solution at around 500°C. The galvanised layer enhances the anti-corrosion properties of the steel pipe and extends the service life of the pipe. Hot dipped galvanized steel pipe is mostly utilized in the transmission of coal, gas, and steam, also used for construction, such as scaffolding, greenhouse, and structure.

Application for Hot Dipped Galvanized Pipe

Pre-Galvanized Steel Pipe Used for Greenhouse Frame
Hot Dipped Galvanized Pipe Used in Highway Guardrail

Advantage of hot dipped galvanized coating

Hot Dipped Galvanized Process

The hot-dip galvanized 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.

1. Hot-dip galvanizing is to pickle the steel pipe first. It is cleaned in the tank of ammonium chloride or zinc chloride aqueous solution or mixed aqueous solution of ammonium chloride and zinc chloride.
2. Pipe is sent to the hot dip coating tank.
3. The passivation solution is then sent to protect the zinc layer.
4. The final step is cooling.

Hot Dipped Galvanized Process

What's the different between of Pre-Galvanized and Hot Dipped Galvanized?

Hot dipped galvanization is an economical choice for anticorrosion. It is often used on objects that have been fabricated beforehand but yet to be galvanized and the hot-dipped galvanization plays as the last step.

Meanwhile, pre-galvanizing, as its name implies, is performed at the first stage of production. Hence, it mainly occurred at the mills, and the results of the process will be cut into size and fabricated later.

a. Coating thickness
Both methods result in a uniform thickness for the coating. However, the hot-dipped galvanization produces a thicker layer of protection than the pre-galvanization does. The minimum average thickness of hot-dip galvanized steel is of 200 – 550g/㎡ while it is between 40 -100g/㎡ for the pre-galvanized products.

b. Coating bond
The first steps of these hot dipped galvanzied processes of making galvanized steel is cleaning the surface, hence, the bond between the steel and the protective coating is metallurgical and strong.

Because the pre-galvanized steel pipe is directly welded, the hot-dip galvanized steel pipe needs to be processed on the basis of the bare pipe. Therefore, the processing cost is much higher than that of the pre-galvanized steel pipe.

Example Size

Note: Some of the main specifications are shown below, please contact us for more details.

Outside Diameter
Wall Thickness

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