The Ultimate Guide to Galvanized Round Steel Pipe Manufacturing

The galvanized round steel pipe is widely used in various industries due to its excellent corrosion resistance and durability. One of the most efficient methods for producing galvanized round steel pipe is sulfate zinc plating, which offers unique advantages in terms of deposition rate and current efficiency.

High Current Efficiency and Fast Deposition Rate

The sulfate zinc plating process boasts a current efficiency of up to 100%, with a deposition rate that surpasses other galvanizing techniques. However, due to its relatively coarse crystalline structure and poor throwing power, it is mainly suitable for simple geometric shapes like pipes and wires.

To enhance performance, the sulfate zinc-iron alloy plating process was developed. This method retains only zinc sulfate as the main salt while eliminating other components. By adding an appropriate amount of iron salt, the traditional single-metal zinc coating is transformed into a zinc-iron alloy coating.

This innovation not only preserves the high current efficiency and fast deposition rate but also significantly improves throwing power and deep plating capability. Previously, only simple components could be plated, but now both simple and complex parts can be processed. Additionally, the protective performance of the coating is 3–5 times better than that of single-metal zinc plating.

Production tests confirm that when used for continuous plating of wires and galvanized round steel pipes, the coating exhibits finer and brighter grains with a rapid deposition rate. The desired thickness can be achieved within just 2–3 minutes.

Superior Protective Performance

The sulfate zinc-iron alloy plating process maintains a 100% current efficiency and an unmatched deposition speed. For thin-walled pipes, the production speed reaches 8–12 m/min, with an average coating thickness of 2 µm/min—a result that is difficult to achieve with conventional continuous galvanizing methods.

The coating is bright, smooth, and aesthetically pleasing. According to the GB/T10125 standard (salt spray test), the coating remains intact after 72 hours, with only minor white rust appearing after 96 hours.

Environmentally Friendly Production Process

The manufacturing of galvanized round steel pipe using the sulfate zinc-iron alloy process follows a unique clean production approach. The plating tanks are interconnected, allowing solutions to flow directly without spillage or overflow.

The entire production line operates on a closed-loop system, where all solutions (including acid, plating, brightening, and passivation baths) are recycled without external discharge. Only five cleaning tanks are required, and wastewater generation is minimized—especially since no rinsing is needed after passivation.

Specialized Electroplating Equipment

Like wire electroplating, galvanized round steel pipe production utilizes continuous plating but with different machinery. Wire plating tanks are long, wide, and shallow, allowing wires to pass through holes while maintaining spacing.

In contrast, galvanized round steel pipe plating requires a more complex tank design. The tank consists of upper and lower sections: the upper part is the plating chamber, while the lower part serves as a solution storage and circulation tank. The trapezoidal-shaped tank ensures smooth movement of pipes during plating, with two openings at the bottom connecting to the storage tank and forming a closed-loop system with a submerged pump.

Unlike wire plating, where only the workpiece moves, galvanized round steel pipe plating involves dynamic movement of both the pipe and the plating solution, ensuring uniform coating distribution.

Conclusion

The sulfate zinc-iron alloy plating process offers unparalleled efficiency, superior corrosion resistance, and eco-friendly production for galvanized round steel pipe. Its advanced technology and specialized equipment make it a leading choice in the industry.