Double Hot-Dip Galvanized Double HDG Cable Tray Fittings

1. Product Overview

Double Hot-Dip Galvanized Cable Tray (2-time HDG Cable Tray) is high anti-corrosion steel cable support made of Q235 cold rolled steel. After the finished tray completes the first full hot-dip galvanization, it is polished, repaired and fully immersed into molten zinc for the second time to form double superimposed thick zinc coating. It covers all series including solid trough, perforated tray, ladder, corrugated energy-saving and long-span types. Ordinary single hot-dip galvanized trays have thin zinc at welding, cutting and punched holes, prone to rusting. Double HDG tray provides triple-layer zinc protection, specially designed for coastal, heavy humidity, light chemical, offshore PV and other high salt-spray corrosive environments.

2. Core Double HDG Production Process

1. Form complete cable tray via bending, punching and welding;
2. First full hot-dip galvanization to form basic zinc-iron alloy layer;
3. Polish & repair thin-zinc areas at welds, holes and edges to remove oxidation defects;
4. Re-pickling & activation, full second immersion in molten zinc at 460℃;
5. Cooling & passivation to obtain uniform double zinc coating without missing plating.

3. Coating Technical Data vs Single HDG Tray

- Single hot-dip galvanized: Zinc thickness 65–100μm, only 30–50μm at welds & holes, easy to corrode;
- Double hot-dip galvanized: Average zinc thickness 120–180μm, doubled thickness at weak zones; salt spray resistance ≥1500h, more than twice of single HDG tray.
Coating structure: Inner zinc-iron alloy layer + middle pure zinc layer + outer secondary zinc protective layer, metallurgically bonded with ultra-high adhesion, no peeling under impact.

4. Full Range Structural Types

1. Double HDG Solid Trough Cable Tray: Fully enclosed with matching cover, dust & corrosive gas proof for outdoor weak current & instrument cables.
2. Double HDG Perforated Cable Tray: Heat dissipation holes on base, general use for factory power cables.
3. Double HDG Ladder Cable Tray: Hollow rung design for superior ventilation, for large-section high-voltage cables & high-temperature workshops.
4. Double HDG Corrugated Energy-Saving Tray: Reinforced ripple lightweight structure for PV rooftops & long-distance utility tunnels.
5. Double HDG Long Span Cable Tray: Thickened steel, supports 3–6m unsupported overhead installation.

5. Core Product Advantages

1. Outstanding resistance to salt spray & chloride ion corrosion
Double thick zinc coating covers weak welding & cutting positions, resisting rust penetration for coastal docks, offshore wind power and sewage plants. Its service life is twice as long as single HDG tray, close to 304 stainless steel with lower cost.
2. Zero weak anti-corrosion points all over the tray
Welds, screw holes and inner bent edges are all fully coated during second galvanization, eliminating local rust breakthrough points that damage the whole wiring system.
3. Dual sacrificial anode anti-rust protection
Double zinc layers provide dual cathodic protection. Even if surface coating is scratched during construction, inner zinc layer continuously isolates moisture to prevent substrate rusting, with higher tolerance for collision damage.
4. High wear & weather resistance for outdoor exposure
Ultra-thick hard zinc layer resists denting during lifting and cross construction; no chalking or peeling under long-term sunlight, rain and temperature difference cycles.
5. Stable conductive earthing, compliant with fire codes
Integral metal connection with excellent zinc conductivity, continuous earthing circuit for lightning & static protection, meeting standards of outdoor power and fire distribution projects.
6. Full set matching double HDG accessories
Splice plates, elbows, tees and support arms all go through the same double hot-dip galvanizing process, consistent anti-corrosion performance without rust-prone fittings.

6. Standard Specifications

Size (Width × Height mm): 100×50, 200×100, 300×100, 400×150, 600×200, 800×200
Standard wall thickness: 1.0–2.5mm; standard length 4m per piece, custom width, height, divider and long-span sizes available.

7. Application Range

Coastal ports, offshore wind farms, photovoltaic rooftop power stations, seawater desalination plants, sewage treatment stations, light chemical workshops, municipal underground utility tunnels, open-air substations, outdoor rail transit sections, coastal logistics parks, island municipal power distribution projects.

8. Matching Accessories

Double HDG splice plate, cable tray cover, 90° horizontal elbow, 45° elbow, vertical up/down elbow, tee, cross, reducer, end cap, HDG support bracket, U-type hanger, grounding jumper, anti-corrosion M8/M10 bolts