What Is the Tube Mill Process?
The Tube Mill Process is the industrial method used to produce metal tubes and pipes from flat metal strips (usually steel, stainless steel, aluminum, or other alloys). This is done using a tube mill line, which forms, welds, sizes, and cuts the strip into a final pipe or tube.
Overview: From Coil to Tube
Flat Metal Strip (coil) → Formed into Tube → Welded → Sized → Cut → Final Tube
Step-by-Step Tube Mill Process
1. Uncoiling
A coil of metal strip is loaded onto a decoiler.
The strip is straightened and flattened using a leveling machine.
2. End Shearing & Welding (Optional)
Ends of two coils can be joined by butt welding to allow continuous operation.
3. Forming
The strip is passed through a series of forming rolls.
Gradual bending transforms the flat strip into a round (or square) open tube.
4. Welding
The open edges are heated using high-frequency current (Electric Resistance Welding – ERW).
Pressure rolls press the heated edges together to form a continuous longitudinal weld.
For stainless steel or precision tubes, TIG or laser welding may be used instead of ERW.
5. Weld Bead Removal (Optional)
Internal and external weld beads are scarfed off to ensure a smooth surface.
6. Cooling
The welded tube is cooled, usually with water spray or air.
7. Sizing and Shaping
The cooled tube enters a sizing section, where rolls:
Adjust outer diameter (OD)
Round or square the tube
Ensure proper straightness and dimensional tolerance
8. Cutting
A flying cutoff machine cuts the moving tube to the desired length.
Methods include cold saw, friction saw, or rotary cutter.
9. End Finishing and Inspection
Tubes can undergo:
Deburring
Hydrostatic testing
Ultrasonic or eddy current testing
Chamfering or threading
Core Components of a Tube Mill Line
| Section | Equipment Used |
|---|---|
| Coil Handling | Decoiler, coil car |
| Preparation | Leveler, shear & end welder |
| Forming | Forming roll stands |
| Welding | ERW welder or TIG/Laser welder |
| Bead Removal | Bead scarfing tools |
| Sizing | Sizing roll stands |
| Cutting | Cold saw, flying saw, friction saw |
| Finishing | Deburring tools, hydrotester, chamfering |
Types of Tubes Produced
Round Tubes
Square & Rectangular Tubes
Oval or Custom Profiles
Materials used:
Carbon Steel
Stainless Steel
Aluminum
Copper Alloys
Titanium (with TIG welding)
Benefits of the Tube Mill Process
| Advantage | Description |
|---|---|
| High Efficiency | Continuous production line |
| Cost-Effective | No filler material in ERW |
| Accurate and Uniform | Tight tolerances, smooth surface finish |
| Flexible Shapes | Round, square, rectangle, etc. |
| Scalable Production | From small tubes to large pipes |
Summary Table
| Process Stage | Purpose |
|---|---|
| Uncoiling | Feed flat strip from coil |
| Forming | Gradually shape strip into a tube |
| Welding | Join edges to make solid pipe |
| Sizing | Ensure final dimension and shape |
| Cutting | Create pipe of required length |
| Finishing | Inspect and prepare for shipment |
