TUBE MILL COATING PLANT
FOR INLINE WELD SEAM SPRAY.
Metaflux Spray Solutions manufactures inline tube mill coating plants in Pimpri-Chinchwad, Pune, India, that spray zinc or Zn-Al onto the weld seam of ERW steel tube at full mill speed to restore the corrosion protection lost during welding.
Automated Weld-Seam Spray Station
When galvanised strip is welded into tube, the zinc burns off along the seam and the heat-affected zone becomes the first place the tube corrodes. The plant sits directly after the weld box and sprays a zinc or Zn-Al band back over that strip, synchronised to mill speed so thickness stays constant from the first metre to the last.
TYPICAL
SPECIFICATIONS.
Typical configuration data for an inline tube mill coating plant retrofitted to an existing ERW mill. Exact specifications vary by configuration — request a datasheet for the model you are evaluating.
| Parameter | Typical Range |
|---|---|
| Spray Process | Wire flame spray or twin wire arc spray |
| Tube Outside Diameter | 12 – 200 mm |
| Mill Line Speed | Up to 60 m/min, PLC synchronised |
| Coating Materials | Zinc, Zn-Al 85/15, Aluminium |
| Wire Diameter | 2.0 / 2.5 mm |
| Coated Band Width | 10 – 50 mm across the weld seam |
| Coating Thickness | 40 – 120 microns |
| Number of Spray Guns | 1 – 4, depending on line speed and thickness |
| Fume Extraction | Integrated hood, 2,000 – 6,000 m³/hr |
| Control System | PLC with HMI, line-speed feedback and flame monitoring |
| Compressed Air | 5 – 6 bar, oil and moisture free |
| Power Supply | 415 V, 3 phase, 50 Hz |
FREQUENTLY ASKED
QUESTIONS.
The questions tube mill owners and plant engineers ask most often about inline weld seam coating.
What is a tube mill coating plant?
A tube mill coating plant is an inline thermal spray station installed on an ERW tube mill that sprays zinc or Zn-Al onto the weld seam immediately after welding. It sits between the weld box and the sizing section and is synchronised to line speed by a PLC, so the coating band stays the same thickness from the first metre of tube to the last.
Why does the weld seam of galvanised tube need recoating?
When pre-galvanised strip is welded into tube, the zinc burns off along the seam and the heat-affected zone is left as bare steel. That strip is the first place the tube corrodes, and it defeats the purpose of using galvanised strip in the first place. Spraying zinc or Zn-Al back over the seam inline restores continuous cathodic protection along the whole tube.
Can a tube mill coating plant be retrofitted to an existing mill?
Yes. A Metaflux tube mill coating plant is designed to mount on an existing ERW mill between the weld box and the sizing section. It covers tube outside diameters of 12 to 200 mm at line speeds up to 60 m/min, with 1 to 4 spray guns depending on the speed and thickness required.
How thick is the inline weld seam coating?
The plant typically applies 40 to 120 microns of zinc, Zn-Al 85/15 or aluminium over a band 10 to 50 mm wide across the weld seam, using 2.0 or 2.5 mm wire. A narrow, well-aimed band keeps wire consumption and fume load down, which is why band width control and manipulator accuracy matter more than raw spray rate.
What utilities and extraction does the plant need?
An inline tube mill coating plant runs on a 415 V, 3 phase, 50 Hz supply with 5 to 6 bar of oil-free and moisture-free compressed air, and includes an integrated fume extraction hood rated at roughly 2,000 to 6,000 m³/hr. Control is by PLC with an HMI, line-speed feedback, flame monitoring and wire break detection.
Does Metaflux install and commission the plant?
Yes. Metaflux Spray Solutions engineers, installs and commissions tube mill coating plants from Pimpri-Chinchwad, Pune, and supplies the wire, nozzles and spare parts that the line consumes afterwards. Send the mill's tube diameter range and line speed through the enquiry form on this page to get a line layout and a written quotation.
Tube Mill Coating Applications
and Line Integration.
Galvanised Tube
Restores zinc over the burnt-off weld seam on GI and pre-galvanised tube.
Retrofit Ready
Mounts on existing ERW mills between the weld box and the sizing section.
Low Overspray
Narrow banded spray pattern keeps wire consumption and fume load down.