Hot-Dip Galvanized Trench Cover Grating – Corrosion‑Resistant Safety Protection for Industrial Drains & Cable Trenches

Hot-dip galvanized trench cover grating is made of steel grating panels that have been hot-dip galvanized. It is widely used to cover industrial plant drainage trenches, cable trenches, catch basins, and wastewater treatment channels. Compared to traditional cast iron covers, hot-dip galvanized trench covers offer light weight (approx. 1/3 of cast iron), high open area (40%-70%), no water pooling, easy opening, and excellent corrosion resistance (20-30 year service life).

Hot-dip galvanized trench cover grating is available in models such as G203/30/100, G255/40/100, and G325/30/100, with bar heights of 20-32mm and bar pitches of 30-40mm, suitable for loads ranging from sidewalks to light vehicle traffic areas. Depending on the application, they can be fitted with welded frames (angle or flat bar), hinges, anti-theft bolts, U-channels, rubber gaskets, and more.

As a professional manufacturer of hot-dip galvanized trench cover grating, we provide one‑stop service from load selection, grating welding, hot-dip galvanizing to accessory installation. Below is a complete technical introduction.

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1. Specifications of Hot-Dip Galvanized Trench Cover Grating

1.1 Common Bar Sizes & Recommended Spans

Note: Pedestrian = personnel only (≤2 kN/m²). Light vehicle = cars, SUVs, small trucks (≤5 t/m²). For heavy vehicle traffic, choose taller bars or closer supports.

1.2 Common Dimensions

Cover dimensions are customized based on trench width. Common standard sizes:

Custom sizes available. Contact sales for minimum order quantity.

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2. Load Classes & Selection 

GuideBased on installation location and expected load, we define three load classes for hot-dip galvanized trench cover grating:

Important: For frequent forklift or heavy truck traffic (>8 kN/m²), choose taller bars (e.g., 50×5) and closer supports.

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3. Product Line of Hot-Dip Galvanized Trench Cover Grating

3.1 Unframed Hot-Dip Galvanized Trench Cover

Basic type – grating panel placed directly over the trench without a frame. Suitable for low-load areas such as indoor cable trenches and small drains.

Common models: G203/30/100, G255/40/100

Features: Simple structure, lowest cost, lightweight, easy to handle and clean.

3.2 Framed Hot-Dip Galvanized Trench Cover

Angle or flat bar is welded around the perimeter of the grating panel, increasing rigidity, preventing edge curling, and ensuring a tight fit with the trench frame. Bolt holes or hinge holes can be added.

Common models: G255/40/100 with frame, G325/30/100 with frame

Features: High rigidity, impact resistant, secure installation – standard for municipal and industrial applications.

3.3 Hinged Hot-Dip Galvanized Trench Cover

One side of the cover is connected to the trench frame with hinges, allowing it to be lifted open for cleaning. Ideal for drains requiring regular maintenance, such as kitchen drains, car washes, and wastewater treatment plants.

Common models: G255/40/100 with hinges, G325/30/100 with hinges

Features: Easy to open without removing the cover completely; can be fitted with gas springs or limit chains.

 3.4 Anti‑Theft Hot-Dip Galvanized Trench Cover

The cover is secured to the trench frame with anti‑theft bolts or special locks, preventing removal with ordinary tools. Suitable for public areas and unattended locations.

Common models: G255/40/100 anti‑theft, G325/30/100 anti‑theft

Features: Bolt heads are pentagonal or other special shapes requiring a专用 wrench; anti‑theft hinges also available.

3.5 U‑Channel Embedded Trench Cover

The cover sits into a U‑channel pre‑embedded in the trench wall, with the top surface flush with the ground. Ideal for plazas, pedestrian streets, airports, and other high‑aesthetic areas.

Common models: G203/30/100, G255/40/100 with stainless steel or galvanized U‑channels

Features: Hidden installation – cover does not protrude above ground, smooth for vehicle traffic.

3.6 Closed (15mm Pitch) Hot-Dip Galvanized Trench Cover

Grid openings approx. 15×100mm, preventing small items (keys, phones, high heels) from falling through. Suitable for drainage or cable trenches in shopping malls, schools, hospitals, and other high‑traffic areas.

Common models: G203/15/100, G255/15/100

Features: High safety while maintaining good drainage capacity.

3.7 Custom‑Shape Hot-Dip Galvanized Trench Cover

Non‑rectangular covers such as circles, sectors, trapezoids – CNC cut, bent, welded. Suitable for curved drains, corner areas, and around equipment.

Applications: Round catch basins, sector corner covers, equipment foundation drainage

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4. Key Design Elements for Hot-Dip Galvanized Trench Cover Grating

4.1 Drainage Efficiency (Open Area)

The open area of the trench cover directly affects drainage speed. Reference open areas for common specifications:

• General drains: recommend open area ≥50%

• Heavy rain areas: choose 40mm pitch for higher open area

• High fall prevention: choose 30mm or 15mm pitch

4.2 Anti‑Slip Performance

• Standard surface: Plain flat bars, friction coefficient approx. 0.5 – suitable for general environments

• Wet environments: Serrated bars (suffix F), friction coefficient ≥0.6

• Sloped covers (e.g., ramps): Serrated bars mandatory

4.3 Frame & Fixing Methods

4.4 Vibration Damping & Noise Reduction

• Add rubber gaskets between the cover and trench frame to reduce noise and impact from vehicle traffic

• Rubber thickness: 3-5mm – effective cushioning

4.5 Anti‑Theft Design

• Anti‑theft bolts: Pentagonal head, hexagon with center pin, etc.

• Anti‑theft hinges: Hinge pins cannot be removed

• Locks: Special lock cylinders available

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5. Production Process of Hot-Dip Galvanized Trench Cover Grating

Our plant strictly follows the process below to ensure every product meets export standards:

1. Raw material inspection – MTC for bars and cross bars (Q235B/A36/S235JR)

2. Grating welding – Fully automatic resistance welding line, strong welds, flat surface

3. Cutting & hole punching – Plasma/laser cutting to required dimensions

4. Frame welding – Weld angle or flat bar frame (if required) – full penetration welds

5. Accessory welding – Weld hinge tabs, lift handles, lock brackets, etc.

6. Hot-dip galvanizing:

• Pretreatment: Degreasing → Pickling → Fluxing

• Galvanizing: Zinc bath 445–465°C, immersion 2–4 minutes

• Post-treatment: Centrifuging/air knife → Passivation & cooling

• Coating thickness: ≥65μm (typical 65–85μm, can be custom thickened to >100μm)

7. Final inspection – Coating thickness test, full visual inspection, dimensional check, hinge flexibility test

Quality commitment: Each batch includes material test certificate and coating thickness test report. Third‑party inspection (SGS/BV/TÜV) available.

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6. Installation & Fixing of Hot-Dip Galvanized Trench Cover Grating

6.1 Trench Preparation

• The trench frame (angle or channel steel) should be pre‑embedded or welded securely, with the top surface flush with the ground

• The inner dimension of the frame should be 5-10mm larger than the cover (for installation clearance)

6.2 Direct Placement Installation

• Place the cover directly into the trench frame, with even gaps on all sides

• Suitable for sidewalks, plazas, and other non‑vehicle areas

6.3 Bolted Installation

• Drill matching holes in the cover frame and trench frame

• Fasten with hot-dip galvanized or stainless steel bolts

• For anti‑theft type, use a专用 wrench

6.4 Hinged Installation

• Weld or bolt the hinge base to the trench frame

• Connect the cover to the base via hinge pins

• Install limit chains or gas springs to control opening angle

6.5 Installation Notes

• The bearing bar direction must be perpendicular to the direction of vehicle travel (if applicable)

• Install rubber gaskets between the cover and frame for vehicle traffic areas

• Check that the cover sits flat without warping after installation

• Test hinged covers for smooth opening and closing

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7. Typical Application Industries for Hot-Dip Galvanized Trench Cover Grating

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8. Customization & Procurement Guide

As a direct manufacturer of hot-dip galvanized trench cover grating, we offer comprehensive custom services:

• ✅ Material: Q235B, ASTM A36, S235JR, S355JR

• ✅ Bar sizes: Height 20–50mm, thickness 3–6mm

• ✅ Grid spacing: Bar pitch 15/30/40mm, cross bar pitch 50/100mm

• ✅ Cover dimensions: Custom from CAD drawings – typical from 300×500mm to 800×1000mm

• ✅ Frame: Angle steel (30×3, 40×4, 50×5) or flat bar

• ✅ Surface treatment: Standard HDG (65–85μm), thick HDG (85–120μm)

• ✅ Accessories: Hinges (standard/anti‑theft), anti‑theft bolts (pentagon, etc.), U-channels, rubber gaskets, lift handles

• ✅ Custom shapes: Sector, circle, trapezoid, etc.

Packaging: Steel banding + wooden pallet, with edge protectors on frames

Lead time: ≤500 pieces → 7–10 days; >1000 pieces → 15–20 days

Incoterms: FOB Tianjin/Shanghai/Ningbo, CIF major ports, or EXW factory