Line 03
Continuous Hot-Dip Galvanizing Line
GI, 55% Al-Zn and Al-Zn-Mg coatings on one line, from entry welding through the zinc pot to skin-pass and chemical treatment.
- GI / GL / ZAM
- 50,000 - 300,000 t/yr
- Width 600 - 1,550 mm
- Thickness 0.12 - 4.0 mm
What the line delivers
The line takes cold-rolled or pickled hot-rolled coil through cleaning, annealing, immersion in the coating bath, cooling, skin-pass, tension levelling and chemical treatment, and delivers coated coil with a controlled surface.
Coating type, weight and surface finish are agreed from the end use. General construction, appliance panels, automotive parts and coastal structures each ask for a different combination, so the line is configured around that mix rather than around a single product.
Three coating systems
GI, 55% Al-Zn and Al-Zn-Mg produced on the same equipment.
Coating weight control
Air knife position and pressure set against coating weight and strip speed.
Annealing in protective atmosphere
Preheat, heating, soaking and cooling sections under H2 atmosphere.
Turnkey or modular
Full line supply, or core equipment with auxiliaries procured locally.
Where the coated coil goes
| Industry | Applications |
|---|---|
| Construction | Roofing sheets, wall cladding, light-gauge framing, gutters, sandwich panels |
| Appliances | Refrigerator back panels, washing machine shells, microwave cavities, water heater tanks |
| Automotive | Underbody panels, interior structural parts, fuel tank shields, seat rails |
| General industry | Cable trays, ventilation ducts, storage racks, electrical enclosures |
Coating types and product mix
The same line can run more than one coating system. Changing between GI, 55% Al-Zn and Al-Zn-Mg typically means a pot change, air knife adjustment and cooling tuning, planned as a two-day changeover.
| Coating | Composition | Typical applications | Market position |
|---|---|---|---|
| Pure zinc (GI) | Zn > 99% | General construction, appliance interior parts | Commodity |
| 55% Al-Zn (GL) | Al 55%, Zn 43.4%, Si 1.6% | Premium roofing, wall panels, appliance exteriors | Mid to high tier |
| Al-Zn-Mg (ZAM) | Al, Zn and Mg in varying ratios | Coastal construction, automotive parts, solar structures | Premium |
Corrosion performance depends on coating weight, substrate and environment. The coating system is selected against the application, with the weight range agreed at specification stage.
Technical specifications
The range below is the standard offer. Widths, speeds and coating weights outside it are engineered against the product mix.
| Parameter | Range | Notes |
|---|---|---|
| Annual capacity | 50,000 / 100,000 / 150,000 / 200,000 / 300,000 t | Standard tiers; custom available |
| Strip width | 600 - 1,250 mm, up to 1,550 mm | Wider strip needs a larger pot and air knife |
| Strip thickness | 0.12 - 4.0 mm | Set by the entry section and furnace configuration |
| Maximum line speed | 120 / 150 / 180 / 200 m/min | Higher speeds need more cooling capacity |
| Coating weight | 60 - 350 g/m2, double-sided | Adjusted to the product requirement |
| Furnace type | Vertical, horizontal or L type | Selected against available floor space |
| Heating medium | Gas or electric radiant tubes | Selected against local energy cost |
Standard scope of supply
Scope is offered as a full turnkey line or as core equipment with auxiliaries procured locally, so the split can follow your budget and local sourcing.
| Module | Included equipment | Package |
|---|---|---|
| Entry and welding | Coil car, dual uncoiler, pinch leveler, crop shear, resistance seam welder, entry looper | Full line only |
| Cleaning section | Alkaline spray, brushing, electrolytic cleaning, rinsing, squeegees, hot-air drying | Available separately |
| Annealing furnace | Preheating, heating, soaking and cooling sections with H2 protective atmosphere | Full line, core module |
| Zinc pot area | Ceramic-lined pot, sink roll, stabilizer roll, air knife system, pot heating | Core, supervised supply |
| Post-cooling | Air cooler, water quench, hot-air dryer | Available separately |
| Skin-pass and tension levelling | 4-high or 6-high skin-pass mill, tension levelling unit | Available separately |
| Chemical treatment | Passivation coater (roll or spray), oiler | Available separately |
| Exit and coiling | Exit looper, flying shear, recoiler, belt wrapper, coil car | Available separately |
| Electrical and automation | PLC, HMI workstations, AC drives, field instruments | Full line, core module |
| Hydraulics and lubrication | Hydraulic power station, valve stand, centralised grease system | Available separately |
| Fume and environmental | Alkali steam scrubber and exhaust, furnace exhaust | Available separately, to local regulations |
Project execution
Delivery follows one sequence from process design to site acceptance, with the acceptance criteria agreed before manufacturing starts.
- Every line is run at our works before shipment; open issues are closed before packing
- Field engineers stay through the first qualified coil, not only through installation
- Warranty covers replacement parts and air freight for design or manufacturing defects
- After warranty, spare parts and technical support continue
Standard turnkey timeline
| Phase | Duration | Key activities |
|---|---|---|
| Engineering and design | 30 - 45 days after signing | Process calculations, general layout, foundation loads, utility requirements |
| Equipment manufacturing | 60 - 210 days, capacity-dependent | Inspector on site, hold-point inspections, quality reports |
| Factory acceptance test | 7 - 10 days before shipment | No-load run with water circulation; test certificate issued |
| Shipping and logistics | 21 - 30 days by sea | Customs support, export documentation, HS codes, certificate of origin |
| Installation supervision | 105 - 135 days after arrival | Field engineers on site with full installation guidance |
| Commissioning and trial run | 20 - 60 days after installation | Cold run, hot run, continuous trial and performance check |
| Operator training | During commissioning | Bilingual classroom training, shift training and SOP manuals |
| Site acceptance | On performance validation | Acceptance certificate signed; warranty 12 - 18 months |
Spare parts and retrofit
Wear parts for the pot, air knife and furnace are kept to a defined specification. Existing lines can be modernised whether or not we supplied them, and an on-site inspection with a diagnostic report is available before any retrofit commitment.
Typical spare parts
| Part | Application | Detail |
|---|---|---|
| Air knife blades | Air knife system | Factory-ground matched pairs, drop-in replacement |
| Sink roll | Zinc pot area | Specialty alloy resistant to molten zinc, with bearing housing |
| Stabilizer roll | Zinc pot area | Same alloy specification as the sink roll |
| Squeeze rolls | Cleaning and cooling sections | Acid-resistant or heat-resistant grades |
| Thermocouples | Furnace and zinc pot | K-type or S-type, 310S or Inconel sheath |
| Edge position sensors | Looper sections | Optical or capacitive, replacement for major brands |
| Hydraulic filter elements | Hydraulic station | Various micron ratings |
Retrofit options
| Retrofit | Scope | Typical driver |
|---|---|---|
| Air knife automation | Manual or semi-automatic to servo closed-loop control | Zinc consumption and coating uniformity |
| ZAM conversion | Melt composition control, cooling modification, pot replacement | Moving a GI line into premium coated products |
| Waste heat recovery | Recuperators on the furnace flue | High gas cost |
| Remote monitoring | Data gateway, cloud dashboard and mobile alerts | Remote sites with limited engineering staff |
| Capacity debottlenecking | Drive, motor and furnace capacity upgrades | Demand growth on a space-constrained site |
Configuration inputs
What we need to specify this line
- 01Coating systems and coating weight range
- 02Strip width, thickness and coil weight
- 03Target output and line speed
- 04Energy source, site utilities and emission limits
Questions
Questions we hear on this line
Can one line run GI, GL and ZAM?
Yes, with planning. The bath, air knife and cooling section are set for each system, and a changeover is typically planned as two days of production time.
What controls coating weight?
Air knife position and pressure, strip speed and bath temperature work as one loop, with the measuring point agreed during configuration.
Can an existing galvanizing line be converted to ZAM?
In many cases yes. Melt composition control, cooling capacity and pot condition are reviewed first, and the conversion is planned as a retrofit rather than a new line.
Related terms
What engineers search for on this line
- galvanizing line
- hot-dip galvanizing
- GI line
- GL line
- ZAM line
- Al-Zn-Mg coating
- steel coating line
- turnkey galvanizing plant
- continuous galvanizing line
Other lines
Sections planned in the same scope
Pickling Lines (PPL & CPL)
Turnkey push-pull and continuous pickling lines for hot-rolled strip, covering scale breaking, acid pickling, rinsing, fume treatment and acid regeneration.
Reversing Cold Rolling Mills (CRM & TCRM)
Turnkey single-stand and tandem reversing cold rolling mills for carbon, silicon, stainless and HSLA strip, with hydraulic gauge and automatic flatness control.
Continuous Color Coating Line (CCL)
Turnkey colour coating lines for prepainted steel: 2C2B and 3C3B configurations, PE to PVDF coating systems and RTO fume treatment in one scope.
Planning a new line or an upgrade?
Send the product mix and target capacity, and we will review the configuration.