Hot-dip galvanized (HDG) steel is the standard material for industrial fixed ladders — offering the best combination of strength, corrosion protection, and cost-effectiveness for general industrial, commercial, and outdoor non-coastal applications.
Dengtai manufactures HDG ladders in Q235B (standard) and Q345B (heavy-duty) grades with minimum 80μm coating thickness. Standard models from $23/m (fixed) and $30/m (caged). 500+ projects in 50+ countries.
Why Galvanized Steel?
| Advantage | Detail |
|---|---|
| Cost-effective | Lowest cost per meter of any durable industrial ladder material: $23/m fixed, $30/m caged |
| Proven protection | Zinc coating provides both barrier and cathodic protection |
| 15-25 year life | In non-coastal outdoor environments, the ≥80μm HDG coating provides decades of service |
| Complete coverage | Hot-dip process coats internal surfaces, welds, and hard-to-reach areas |
| 100% recyclable | End-of-life steel is 100% recycled — zero waste to landfill |
| Weldable | Standard MIG/MAG welding — no specialized processes required |
Galvanized Ladder Products
| Product | Model | Material | Coating | Price (USD/m) |
|---|---|---|---|---|
| Fixed Steel Ladder | FL-HDG-STD | Q235B | ≥80μm HDG | $23.00 |
| Fixed Extended | FL-HDG-EXT | Q235B | ≥80μm HDG | $23.00 |
| Heavy-Duty Fixed | FL-HDG-HD | Q345B | ≥100μm HDG | Custom quote |
| Caged Ladder (Single) | CL-HDG-STD | Q235B | ≥80μm HDG | $30.00 |
| Caged Ladder (Multi) | CL-HDG-MULTI | Q235B | ≥80μm HDG | $30.00 |
| Heavy-Duty Caged | CL-HDG-HD | Q345B | ≥100μm HDG | Custom quote |
| Cat Ladder (BS 4211) | CT-HDG-STD | Q235B | ≥80μm HDG | Custom quote |
The HDG Process
- Surface preparation — Degreasing, acid pickling to remove mill scale, fluxing
- Hot-dip immersion — Immersion in molten zinc at ~450°C; zinc metallurgically bonds to steel
- Cooling and inspection — Air cooling; coating thickness verified with digital gauge
- Post-treatment — Zinc-rich cold galvanizing compound for any post-fabrication welds
When Galvanized Is NOT the Right Choice
- Coastal environments (<5km from saltwater) — upgrade to SS316
- Food processing (wet washdown areas) — upgrade to SS304 or SS316
- Chemical exposure — consult engineering for material recommendation
- Visible architectural applications — SS304 for appearance
Compare Galvanized vs Stainless Steel →
HDG Coating Specifications
Coating Thickness Standards (ISO 1461)
| Steel Thickness | Minimum Local Thickness | Minimum Average Thickness |
|---|---|---|
| ≥6 mm | 70 μm | 85 μm |
| 3 mm to <6 mm | 55 μm | 70 μm |
| <3 mm | 45 μm | 55 μm |
Dengtai standard: ≥80 μm minimum average (exceeds ISO 1461 requirements for steel ≥6 mm). Heavy-duty models (Q345B): ≥100 μm for extended service life in aggressive environments.
How HDG Protects Steel
HDG provides three layers of protection:
- Barrier protection — The zinc coating physically separates steel from the environment
- Cathodic protection — Zinc is more electrochemically active than steel. If the coating is scratched, the surrounding zinc sacrifices itself to protect the exposed steel
- Zinc patina — Over time, the zinc surface develops a dense, adherent layer of zinc carbonate that further slows corrosion
Service Life by Environment (ISO 9223)
| Environment | Corrosivity Category | HDG 80μm Life | HDG 100μm Life |
|---|---|---|---|
| Indoor, dry | C1 | 100+ years | 100+ years |
| Rural | C2 | 60-80 years | 80-100 years |
| Urban | C3 | 30-50 years | 45-65 years |
| Industrial | C4 | 20-30 years | 30-45 years |
| Coastal marine | C5-M | 5-15 years | 10-20 years |
Note: Coastal (C5-M) environments are where stainless steel becomes the more economical choice over the installation lifecycle.
FAQ
Q: What is the difference between hot-dip galvanizing and electro-galvanizing?
Hot-dip galvanizing (HDG) immerses the steel in molten zinc at ~450C, producing a metallurgically bonded coating typically 50-150 microm thick. Electro-galvanizing (zinc electroplating) deposits a thin zinc layer (5-25 microm) through an electrochemical process. HDG provides 5-10× thicker coating and far superior corrosion protection. For industrial ladders, only hot-dip galvanizing is suitable. Electro-galvanized products are not acceptable for structural outdoor applications.
Q: Can HDG ladders be painted?
Yes. This is called a duplex system (HDG + paint) and can extend service life 1.5-2.5× beyond HDG alone. The key requirement is proper surface preparation: the HDG surface must be sweep-blasted or chemically etched before painting to ensure adhesion. Dengtai offers duplex coating (HDG + epoxy or polyurethane topcoat) as a custom option. RAL color matching is available.
Q: How do I inspect HDG coating quality?
Use a digital coating thickness gauge (magnetic induction principle, calibrated per ISO 2808). Take multiple readings across the surface. Verify: (1) minimum thickness at any point meets the specification, (2) coating is continuous (no bare spots, no blisters), (3) no sharp drips or spikes that could injure climbers. Dengtai provides coating thickness reports with every HDG ladder order.
Q: Does welding after galvanizing damage the coating?
Yes. Welding burns off the zinc coating at and near the weld. Post-fabrication welds must be repaired with zinc-rich cold galvanizing compound (minimum 2 coats, >93% zinc in dry film). Dengtai’s manufacturing process minimizes post-galvanizing welding — all fabrication welding is completed before the HDG bath. Any touch-up at bracket attachment points is done with certified zinc-rich compound and documented in the QC report.
View Galvanized Ladder Products
HDG from $23/m. 15-20 day lead time. MOQ 1 unit.
Email: sales@dtsteelladder.com
WhatsApp: +86 155 1187 9488
View HDG Ladders → | View Caged Ladders → | Stainless Steel Ladders → | Compare Materials →
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