Case Study: 20 m Telescopic Spray Booth for a Bridge Girder Fabricator, India
Summary
| Object | Plate girders and cross frames up to 20 m for a Steel bridge girder fabricator in India |
|---|---|
| Equipment | 20 x 10 x 4 m dry-filter telescopic booth |
| Operating conditions | crane-handled batch painting, dry filter wall: labyrinth paper filters plus glass-fibre bags, cross-draft 0.3 m/s or more |
| Result | Girders painted on stands under the gantry without a building |
| Source | project specification and commissioning scope; client name withheld at the client's request |
Project Background
An Indian fabricator of plate girders for road and rail bridges painted girders to a multi-coat system specified by the client's consultant. Girders of 20 m were laid out in the yard under a gantry crane; painting in the open was stopped by the state pollution rules, and no building was available for a fixed booth.
Pain Points Before the Project
- No indoor bay long enough for 20 m girders
- Open-air painting no longer permitted
- Dust from the yard settling on wet paint
- Painting stopped in rain and wind
Why This Configuration Was Chosen
- A 20 x 10 x 4 m telescopic booth installed outdoors on rails under the gantry crane, with the fixed end, fan and stack on a concrete pad
- UV-stabilised flame-retardant fabric and a 75 kW fan give an enclosed, ventilated space independent of the weather
- Dry filtration plus carbon and UV treatment met the state limit at the yard's painting schedule
Scope of Supply
| Telescopic enclosure | 20 x 10 x 4 m internal (retracted about 3 x 10.7 m); Q235 frames 50 x 70 x 2 mm, flame-retardant PVC fabric |
|---|---|
| Drive and safety | 2 x 1.5 kW explosion-proof geared motors, 8-10 m/min; interlocked drives, double limit switches, rail sweeper, jog control |
| Lighting | 60 explosion-proof LED units, 18 W each, 300 lux or more |
| Paint mist capture | Dry filter wall: labyrinth paper filters plus glass-fibre bags, 98% or more mist capture |
| Exhaust treatment | Activated carbon boxes plus UV photo-oxidation unit, 50,000 m3/h class |
| Fan, duct and stack | 75 kW centrifugal fan, 54,000-79,400 m3/h, 15 m stack |
| Control | Two-station control cabinet, VFD on exhaust fan, emergency stop, audible-visual travel alarm |
| Installed power | about 109 kW installed |
Component brands. Key components are sourced from international first-tier brands at the client's choice; the table lists the options offered on this project.
| Component | Brand options |
|---|---|
| Exhaust fan | Nicotra Gebhardt, Kruger, Systemair |
| Geared drive motors | SEW-Eurodrive, NORD, Bonfiglioli |
| Explosion-proof lighting | Eaton Crouse-Hinds, R. STAHL, ABB |
| Low-voltage switchgear | Schneider Electric, Siemens, ABB |
| Variable frequency drive | ABB, Danfoss, Siemens |
| PLC (RCO control) | Siemens, Mitsubishi Electric, Omron |
| Filter media | Andreae Filters, Freudenberg Viledon, Camfil |
| Activated carbon | Calgon Carbon, Jacobi Carbons, Cabot Norit |
| Oxidation catalyst | BASF, Johnson Matthey, Clariant |
| Flame-retardant fabric | Serge Ferrari, Sioen, Mehler Texnologies |
| Flexible cables | LAPP, Nexans, Prysmian |
| Airless spray units (client side) | Graco, WIWA, WAGNER |
Not included: rail levelling and civil foundations, site lifting, third-party emission testing, workpiece stands unless ordered, and the drying room where forced cure is required.
Programme
Typical programme for this booth class; the dates for each project are fixed in the contract.
| Stage | Typical duration |
|---|---|
| Site survey and data collection | 3-7 days |
| Layout and detail design | 10-15 days |
| Manufacture and factory trial | 30-45 days |
| Sea freight and customs | 15-40 days |
| Rail levelling by site, installation | 7-14 days |
| Commissioning, emission test, training | 3-5 days |
Before and After
Design values from the project specification; the "before" column describes the open-floor condition found at survey, for which no measurements existed.
| Item | Before | After |
|---|---|---|
| Enclosure of the painting area | open bay or shed, no enclosure | telescopic booth, 20 x 10 x 4 m |
| Floor available when not painting | painting area blocked or shared | booth retracted, about 85% of footprint freed |
| Cross-draft over the work | not controlled | 0.3 m/s or more (design) |
| Paint mist capture | none | 98% or more (design) |
| VOC treatment efficiency | none | 85-90% (carbon) with UV pre-oxidation (design) |
| Lighting at the work surface | workshop lighting | 300 lux or more, explosion-proof (design) |
| Noise inside the booth | not controlled | 80 dB(A) or less (design) |
Results
- Girders painted on stands under the gantry without a building
- Painting continued in weather that had stopped open-air work
- Emission test carried out at the stack after commissioning
Applicability
This configuration suits workshops where the crane moves the workpiece, painting is done in batches and the floor must return to assembly use between batches: structural steel, vessels and tanks, machinery frames, crane girders, trailer chassis and hull blocks. It is not the right choice for conveyorised lines painting every shift, for coatings that need forced cure inside the same enclosure, or where a water-curtain booth and water treatment already exist.
The results above apply to the configuration and conditions described. A different part mix, paint system, climate or emission limit changes the numbers, which is why every booth is sized from its own data.
After-Sales
Warranty options of 12, 36 or 60 months, remote diagnosis within 2 hours and on-site attendance within 72 hours where a local partner is available, plus filter media, carbon and catalyst supply for the life of the booth. Details are on our after-sales service page.
FAQ
Can the same booth paint different products?
Yes. Nothing in the enclosure is shaped to the part; the booth on this project handled the full range of plate girders and cross frames.
Why was dry capture chosen here?
Intermittent painting and frequent colour changes favour dry labyrinth-paper filtration: no water or oil circuit, and the filter wall is the only overspray-contact surface.
What did the client have to prepare?
Levelled rails to our drawing, a concrete pad for the fan and treatment unit, three-phase power to the cabinet and a crane for installation.
How was performance checked?
Travel and limit switches in both directions, drive interlock, cross-draft velocity, lighting level, noise, and stack sampling against the local limit.
Can this booth be extended later?
Frames are added in 1 m modules and the rails extended; the fan and filter wall are sized for the final length at the outset.
Get a Similar Solution
Send us the following and we return a booth layout with fan, filter and treatment sizing within a few working days:
- Largest workpiece length, width, height and weight, and how it is handled
- Daily paint and thinner consumption and the paint system
- Indoor or outdoor installation, crane hook height and available floor
- Local emission limit and workplace exposure rule
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Related
- Telescopic mobile spray booth (product page)
- What is a telescopic spray booth and how does it work?
- How to size a telescopic spray booth
- VOC treatment: carbon, UV or RCO
- Paint mixing room
Provided by Lin Cong, Technical Director, MUSI Technology
Published 2026-10-01 · Updated 2026-10-01 · Last technical review: 2026-10-01