Case Study: Metal Tube Automatic Coating Line
Summary
A rotating-tube powder coating line for a steel and stainless tube manufacturer in Pakistan producing 100,000 tonnes a year, coating handrail and fitness-equipment tubing of 16–150 mm diameter and 4–6 m length. Tubes spin on V-rollers past eight circumferential powder guns, the pneumatic roller frame adjusts to a new diameter in 30 seconds, and the line runs at 5–15 m/min for 150–300 m of tube per hour with film uniformity of ±10%. Measured capacity is 250 m/h with a 99%+ visual pass rate, as reported after commissioning in 2023.
Project Background
The client is a major steel and stainless steel tube manufacturer in Pakistan, with annual production 100,000 tons. They needed a coating line for premium tubing (outdoor handrails, fitness equipment tubing).
The Challenge
Tubes are long (4-6 m) — traditional spray methods struggle with uniformity. Tube diameters span 16-150 mm — line must handle full range.
MUSI's Solution
MUSI designed a tube-specific rotating conveyor + circumferential spray solution: tubes rotate on V-rollers while passing through 8 circumferentially-mounted powder spray guns — uniform coating around tube circumference. Auto-adjusts to different tube diameters.
Equipment Configuration
| Line type | Tube rotating continuous coating |
|---|---|
| Tube diameter | 16-150 mm auto-adapting |
| Tube length | 4-6 m |
| Conveyance | V-roller rotating conveyor |
| Spray gun layout | Circumferential, 8 guns |
| Conveyor speed | 5-15 m/min |
| Capacity | 150-300 m/hour |
| Film uniformity | ±10% |
Equipment used on this line
- Automatic spray coating lines — overhead chain, floor belt and robotic flexible lines
- Powder coating systems — electrostatic booths, vertical lines, quick colour change and powder recovery
Implementation
65-day delivery. Auto-adapting to different tube diameters was the challenge — MUSI designed a pneumatic V-roller frame that auto-adjusts in 30 seconds.
Results
Line capacity 250 m/hour — 25% above client expectations. Tube surface visual pass rate 99%+.
Client Feedback
"Tube coating is a niche market — finding the right supplier is hard. MUSI's specialized solution made our line investment worthwhile."
— Project Manager, Client Side
Selection logic: why this configuration
A rotating V-roller conveyor was chosen over hanging tubes on an overhead chain because a spinning tube presents its full circumference to fixed guns and leaves no hook mark, and because 4–6 m tubes would need a very tall booth if hung. Eight guns around the tube, rather than reciprocators, were specified so film stays within ±10% around the circumference at 15 m/min. A pneumatic self-adjusting roller frame was designed because the client changes diameter many times a shift.
Scope of supply and key components
| Item | Specification | Notes |
|---|---|---|
| Tube conveyor | V-roller rotating conveyor, 5–15 m/min | Pneumatic diameter adjustment in 30 s |
| Powder booth | 8 circumferential guns | Tubes 16–150 mm, 4–6 m |
| Recovery | Cyclone with after-filter | |
| Pretreatment and oven | Spray pretreatment, gas curing oven | |
| Controls | PLC line control |
Key components
Key components are available from international brands, configurable per customer specification, so that spare parts can be sourced locally over the life of the line. Brand names below are the usual options for this type of equipment; the brands actually fitted are fixed in the contract specification.
| Component | Brands available on request |
|---|---|
| Automatic powder guns and powder feed | International tier-one powder spray gun brands |
| Oven and dryer gas burners | Riello RS series, Weishaupt monarch WM-G, Baltur TBG, Honeywell Maxon OVENPAK, Eclipse |
| PLC and HMI | Siemens SIMATIC S7-1500, Mitsubishi Electric MELSEC iQ-R, Schneider Electric Modicon, OMRON NX, Rockwell Automation Allen-Bradley |
| Variable-frequency drives | ABB ACS580, Siemens SINAMICS G120, Danfoss VLT, Schneider Electric Altivar, Yaskawa, Mitsubishi Electric |
| Conveyor gear motors | SEW-EURODRIVE, NORD DRIVESYSTEMS, Bonfiglioli, Siemens, Sumitomo Drive Technologies |
| Conveyor bearings | SKF, NSK, Schaeffler FAG, Timken, NTN |
| Dust collector filter cartridges | Donaldson Ultra-Web, Parker BHA, Camfil, MANN+HUMMEL |
| Pneumatics | Festo, SMC, Parker Hannifin, Norgren |
Not included in the scope of supply
- Civil works, foundations and pits
- Building services up to the battery limit: power supply, gas, compressed air, water and drainage
- Local permits, emission approvals and third-party inspections
- Paint or powder supply, unless stated in the contract
Services included with every line: engineering design, manufacturing, shipping documentation, installation supervision, commissioning, operator training, warranty and spare parts.
Typical programme
The durations below are typical for equipment of this class and are given for planning; they are not the recorded schedule of this project. A complete line usually runs 90–180 days from contract to acceptance, a single unit 30–60 days.
| Stage | Typical duration | What happens |
|---|---|---|
| Site survey and workpiece review | 5–10 days | Remote review of drawings and photos, or an engineer visit |
| Layout and detail design | 15–30 days | Layout drawing, utilities list and specification sign-off |
| Manufacturing | 45–90 days | Booths, ovens, conveyor, pretreatment and controls built and pre-assembled at the works |
| Shipping | 20–45 days | Sea freight; equipment shipped in sections for on-site assembly |
| Installation | 15–40 days | MUSI supervision with the client's installation crew or MUSI crew |
| Commissioning, training and acceptance | 7–15 days | Trial runs on the client's parts, operator training, acceptance record |
Results: before and after
Figures are those published on this page; measurement party, sample size, test date and method are not on record here and are left blank rather than estimated.
| Metric | Before | After | Change | Measured by | Single / average | Samples | Test date | Method / instrument |
|---|---|---|---|---|---|---|---|---|
| Line capacity | 200 m/h expected | 250 m/h | +25% | |||||
| Visual pass rate | — | 99%+ | — | |||||
| Diameter changeover | — | 30 s | — |
Applicability and limits
The ±10% film uniformity and 250 m/h capacity apply to straight round tubes within 16–150 mm. Bent tubes, square sections or tubes with welded brackets cannot spin on V-rollers and are coated on a hanging line instead, and the throughput figure depends on the diameter mix run in a shift.
Results shown in this case study reflect the stated operating conditions and should not be interpreted as guaranteed performance under different feed, production, environmental, or site conditions.
After-sales and spare parts
Warranty on a MUSI coating line runs from acceptance: 12 months on the complete line excluding consumables, 36 months on critical components such as motors, drives and the PLC, and 60 months on structural parts such as steel structure, ducting and oven bodies. Failures within warranty, excluding misuse, are repaired free of charge.
Support starts remotely: the service line is staffed around the clock, a preliminary diagnosis with recommendations is given within 2 hours, and where a site visit is needed an engineer reaches any major city within 72 hours. A spare-parts inventory is held at the Changzhou headquarters with same-day shipping, and customers can keep a dedicated parts stock at MUSI for emergencies. Details are on the after-sales service page.
FAQ
How are long tubes coated evenly? By spinning them on V-rollers past eight guns arranged around the tube, so the whole circumference passes the guns at the same speed; film uniformity is ±10%.
How fast does the line change tube diameter? Thirty seconds, with a pneumatic roller frame that resets to the new diameter without tools.
What capacity does a tube line reach? Two hundred and fifty metres per hour measured on this line, within a design range of 150–300 m/h depending on diameter.
Can square or bent tubes run on it? No. Rotating conveyors need straight round tube; other sections go on a hanging line with reciprocators.
How long was delivery? Sixty-five days, with the self-adjusting roller frame as the main engineering item.
Next step: a configuration proposal for a similar line
If your parts, volumes or plant conditions are close to this project, MUSI can return a line configuration and layout proposal. To prepare it we need four things:
- Photos and dimensions of the workpieces, with weight and material
- Required output (pieces per hour or per day, and shifts)
- Number of colours and how often colour changes are needed
- Available floor space and ceiling height, with the utilities on site
Message us on WhatsApp with these details, or use the quotation form.
Provided by Lin Cong, Technical Director, MUSI Technology · Published 2026-05-02 · Updated 2026-09-30 · Last technical review: 2026-09-30
QQuestions buyers ask before ordering
quotation · price · lead time · installation · warranty
What information do you need to prepare a quotation?
Send part drawings or photos, the largest part size and weight, the material, the required output per shift, the paint or powder type and number of colours, and the available floor space, ceiling height and power or gas supply. MUSI engineers reply within 24 hours; a recommended configuration and quotation follow once your part data is complete.
How much does this equipment cost?
Budget depends on part size, throughput and the level of automation. Indicative ex-works ranges are published in our complete coating line cost guide; a configured quotation is prepared from your part data. Published indicative ex-works ranges: a complete powder coating line is roughly USD 75,000–230,000 semi-automatic, USD 200,000–600,000 for a standard automatic line and USD 600,000–2,000,000 for a high-throughput automated plant.
What is the lead time?
Standard configurations ship in 30–60 days from contract signing and down payment; custom configurations take longer. The delivery date is fixed in the contract.
Do you install and train operators overseas?
Yes. MUSI engineers carry out on-site installation and commissioning and give 3–5 days of operator and maintenance training. MUSI has delivered 800+ coating lines to customers in 36 countries.
What warranty and after-sales support are included?
12 months full-machine warranty, 36 months on critical components and up to 60 months on structural parts. International customers get 24-hour phone response and 72-hour on-site arrival; spare parts ship from the Changzhou headquarters.
Can the environmental equipment be supplied with the line?
Yes. VOC treatment (RTO, RCO, activated carbon, zeolite rotor), dust collection and paint wastewater treatment are supplied with the coating line under one contract; MUSI has equipped 50+ coating facilities whose projects all passed local environmental compliance reviews.
Get a Similar Solution
If your industry and requirements match this case, contact MUSI to schedule a free consultation. We'll design an optimal solution based on your specific workpieces, capacity, and facility.