Ductile Cast Iron Overflow Manhole Cover

Technical Features

1. Material & Process

Ductile Iron Substrate: Spheroidal graphite distribution via magnesium/rare-earth treatment, tensile strength ≥420 MPa, elongation ≥10%, offering superior strength and dynamic load capacity vs. gray cast iron.

Overflow Hole Design:

Directional holes (rectangular/honeycomb patterns) with drainage capacity ≥50 L/s·m², meeting extreme rainfall standards (e.g., 100-year storm events).
Reinforced hole edges prevent debris clogging, reducing maintenance frequency.
Anti-Corrosion Process: Zinc spraying (≥80 μm) + epoxy coal tar coating, salt spray resistance ≥1,000 hours (ASTM B117), pH 4–11 compatibility, lifespan ≥30 years.

2. Structural Design

Anti-Slip Surface: Diamond or wave patterns (friction coefficient ≥0.65), ensuring slip resistance in rain/snow.
Anti-Theft Locking: Three-point spring locks or hinge latches require specialized tools (e.g., T-wrench), deterring theft (≥20-minute dismantling time, 90% theft reduction).
Overflow Optimization: Bottom diversion slope (0.5%–1% gradient) accelerates rainwater flow into pipelines, minimizing surface ponding.

Core Advantages

1. Extreme Weather Resilience

High-capacity drainage: Optimized overflow holes boost efficiency by 40% vs. standard covers, mitigating urban flooding (e.g., post-Zhengzhou’s July 2021 Storm upgrades).
Impact resistance: Compressive strength 400–600 MPa, withstands flood impacts and heavy equipment (D400 grade: 40-ton load).

2. Ultra-Durability & Safety

Fatigue resistance: Passes 2 million dynamic load cycles without deformation, ideal for frequent maintenance access.
Anti-drop design (gaps ≤15 mm) prevents accidental falls, complying with EN124 safety standards.

3. Cost Efficiency & Sustainability

Low lifecycle costs: No frequent replacements (3× lifespan vs. composites), 60% lower maintenance costs.
100% recyclable material with 50% lower carbon emissions vs. cast steel, aligning with LEED certification.

4. Smart Integration Potential

IoT-enabled models monitor water levels, flow rates, and pipeline status for real-time smart drainage management (e.g., Shenzhen’s smart water pilot).

Applications

1. Flood-Prone Urban Zones

Low-lying roads, tunnel entrances (e.g., Wuhan’s South Lake renovation), rapid water discharge.
Riverbank overflow outlets, protecting pipelines from flood surges.

2. Industrial & Transport Hubs

Chemical plant acid-resistant covers (polyurethane coating upgrades, pH 3–12 compatibility).
Airports/railway stations, ensuring traffic flow during heavy rains.

3. Eco-Sensitive Areas

Wetland parks, sponge city zones: Overflow holes + ecological filters for debris removal and rainwater purification.
Coastal tidal gate systems (e.g., Zhuhai’s Hengqin project), resisting chloride corrosion.

Standards & Selection Guidelines

International: EN124 (load rating), ISO1083 (ductile iron).

China:

GB/T23858-2009 (manhole covers).
CJ/T511-2017 (ductile iron covers).
GB50014-2021 (outdoor drainage design code).

Selection Criteria:

Drainage capacity: Match hole size/density to local rainfall intensity formulas.
Load rating: D400 (40 tons) for roads; C250 (25 tons) for greenbelts.
Supplier qualifications: Prioritize ISO9001-certified manufacturers (e.g., Xinxing Ductile Iron Pipes, Saint-Gobain PAM).

Summary

The ductile iron overflow manhole cover redefines urban stormwater management through intelligent regulation, extreme environmental resilience, and eco-friendly design. Key strengths:

1. Precision Flow Control: Dynamic overflow adjustment balances drainage safety and ecological protection.
2. Full-Lifecycle Economy: 30-year maintenance-free operation, 40% lower lifecycle costs vs. concrete structures.
3. Smart Empowerment: Data-driven decision-making accelerates drainage system digitization.
This product is a strategic infrastructure solution for climate-driven extreme rainfall, particularly suited for high-density urban areas, eco-sensitive zones, and industrial drainage systems.

Technical Parameters