What Is a Zinc Spray System in an ERW Tube Mill?

What Is a Zinc Spray System?

A Zinc Spray System, also called a Tube Internal Zinc Coating Machine or Internal Weld Seam Zinc Spraying Unit, is used in an ERW Tube Mill to protect the inside weld seam from corrosion.

During the ERW welding process, the steel strip edges are heated to a very high temperature and fused together. This heat can damage or burn away the original zinc coating at the weld area, leaving the weld seam vulnerable to rust.

The Zinc Spray System restores zinc protection by spraying molten zinc onto the internal weld seam immediately after welding.

🔹 Improve corrosion resistance
🔹 Extend pipe service life
🔹 Restore zinc protection at the weld area
🔹 Meet galvanized pipe quality requirements

Where Is the Zinc Spray System Installed?

In a typical ERW tube mill, the Zinc Spray System is installed immediately after the welding section.

Typical ERW Tube Mill Process

Coil Loading➡️ Uncoiling➡️ Strip Forming➡️ HF Welding➡️ Outside Bead Removal➡️ Zinc Spray System➡️ Cooling➡️ Sizing Section➡️ Flying Saw Cutting➡️ Pipe Collection

The system applies zinc to the inside weld seam before the pipe enters the sizing section.

How Does a Zinc Spray System Work?

The Zinc Spray System uses electric arc spraying technology to apply a protective zinc coating to the internal weld seam of ERW pipes.

Step 1: Zinc Wire Feeding

Two zinc wires are continuously fed into the spray gun through the wire feeding system.

Step 2: Electric Arc Generation

When the two zinc wires contact each other at the gun tip, an electric arc is generated. The arc instantly melts the wire ends and creates molten zinc.

Step 3: Zinc Atomization

Compressed air blows the molten zinc into fine particles, forming a high-speed zinc spray stream.

Step 4: Internal Weld Seam Spraying

The spray gun is positioned to direct the zinc particles onto the internal weld seam immediately after welding, where the original zinc coating has been damaged by welding heat.

Step 5: Coating Formation

The zinc particles rapidly cool and solidify on the weld seam surface, forming a uniform protective layer that restores corrosion resistance.

Main Components of Zinc Spray System

✔ Spray Machine Mainbody

✔ Spray Gun

✔ Connecting Cable

✔ Cable Lug

✔ Spare Parts Package

The system mainly consists of a spray machine mainbody, spray gun, connecting cable, cable lug, and spare parts package. During operation, zinc wire is melted inside the spray gun and sprayed onto the internal weld seam of the pipe, restoring the zinc coating damaged during HF welding and improving corrosion resistance.

Typical Technical Parameters

Parameters can be customized according to tube mill specifications.

Is a Zinc Spray System Necessary in Every Tube Mill?

No.

A Zinc Spray System is not a mandatory machine for every ERW tube mill.

Whether it is required depends on the final pipe application.

Usually Required For

✅ Galvanized water pipes

✅ Construction pipes

✅ Greenhouse pipes

✅ Scaffolding pipes

✅ Fence pipes

✅ Fire protection pipes

✅ Outdoor structural pipes

Usually Not Required For

❌ Black steel pipes

❌ Mechanical tubes

❌ Furniture tubes

❌ Automotive tubes without galvanizing requirements

If your products do not require corrosion protection at the internal weld seam, the Zinc Spray System may not be necessary.

How to Select the Right Zinc Spray System?

When choosing a Zinc Spray System, consider the following factors:

1. Pipe Diameter Range

Different spray guns and lances are designed for different tube sizes.

Verify the minimum and maximum pipe diameter of your tube mill.

2. Mill Production Speed

Higher production speeds require greater zinc spraying capacity and more stable control.

3. Tube Material

The coating performance may vary depending on galvanized strip specifications and steel grades.

4. Coating Requirement

Different markets may require different zinc coating thickness levels.

5. Available Installation Space

The system should match the layout and available space of the existing tube mill.

6. Automation Level

Modern systems equipped with PLC and HMI provide easier operation and more stable production.

Frequently Asked Questions (FAQ)

Q1: Why does the weld seam lose zinc coating?

The high temperature generated during HF welding burns away or damages the original zinc layer near the weld area.

Q2: Can the system be added to an existing tube mill?

Yes.

Most Zinc Spray Systems can be retrofitted to existing ERW tube mills with proper installation space.

Q3: What zinc wire is normally used?

High-purity zinc wire with 99.9% purity is commonly used.

Q4: Does the system affect tube mill speed?

No.

When properly selected, the Zinc Spray System operates synchronously with the tube mill and does not reduce production speed.

Looking for a Zinc Spray System for Your Tube Mill?

At AIS Machinery, we provide customized Zinc Spray Systems that can be integrated into both new and existing ERW tube mills. Our engineers can recommend the most suitable solution based on your production parameters and project requirements.

✅ Custom design for different tube sizes

✅ Stable operation for high-speed production

✅ Technical support and installation guidance

Whether you are building a new galvanized pipe production line or upgrading an existing tube mill, our team is ready to help.

📩 Send us your tube specifications and production requirements today, and we will recommend the most suitable Zinc Spray System for your project.