Ductile Iron Manhole Cover Heavy-Duty EN124 D400 GGG50 Round Square for Municipal Road Sewer Anti-Theft Watertight

Our ductile iron manhole covers are precision-engineered and manufactured from high-grade nodular ductile cast iron (GGG50 / QT500-7), strictly manufactured in accordance with European Standard EN124-1:2015. As a professional manufacturer with over 15 years of experience in casting and municipal infrastructure products, we supply heavy-duty manhole covers and frames to contractors, municipalities, and distributors across Europe, the Middle East, Southeast Asia, Africa, and South America.
Ductile iron, also known as spheroidal graphite iron, offers significantly higher tensile strength, elongation, and impact resistance compared to traditional gray cast iron. This makes our manhole covers capable of withstanding extreme traffic loads, heavy impact, and harsh weather conditions without cracking or deforming, ensuring a service life of 30 years or more under normal usage.
Detailed Product Features
1. Superior Material & Mechanical Properties
Base material: Ductile cast iron GGG50 / QT500-7
Tensile strength: ≥ 500 MPa
Proof stress (yield strength): ≥ 320 MPa
Elongation: ≥ 7%
Hardness: 170–230 HB
Graphite nodularity: ≥ 85%, ensuring uniform microstructure and consistent mechanical performance throughout the casting
2. Full Range of EN124 Load Classes
We offer the complete range of load classes as defined by EN124, each designed for specific application scenarios:

3. Anti-Theft & Safety Design
• Non-slip surface: Diamond or grid embossed pattern on the cover top provides excellent slip resistance for pedestrians and vehicles, even in wet or icy conditions.
• Locking mechanism: Optional bolted locking system, hinge connection, or spring-loaded anti-theft lock prevents unauthorized removal and reduces the risk of theft for scrap metal.
• Hinged design: Optional hinge allows the cover to open to 180° and stay attached to the frame, preventing the cover from falling into the manhole during maintenance.
• Lifting holes: Standard 2 lifting holes or integrated lifting lugs for easy removal with standard manhole hooks.
• Safety label: Custom engravings such as "WATER", "SEWER", "GAS", "ELECTRICITY", "TELECOM", or company logo can be cast onto the cover surface for easy identification.
4. Watertight & Odor-Proof Sealing
• A continuous EPDM or NBR rubber sealing gasket is fitted into a groove around the frame perimeter, creating a tight seal between the cover and frame.
• Effectively prevents foul odor, sewer gas, and water leakage from escaping into the surrounding environment.
• Reduces noise and rattling caused by vehicle traffic passing over the cover.
• Rubber gasket material options: EPDM (excellent weather & ozone resistance), NBR (oil & fuel resistance), silicone (high temperature resistance).
5. Corrosion & Weather Resistance
• Standard surface treatment: Black bituminous paint (bitumen varnish) applied to both internal and external surfaces, providing a protective barrier against corrosion.
• Optional upgraded surface treatment: Epoxy powder coating (≥ 80μm), zinc-rich primer + epoxy topcoat, or hot-dip galvanizing for highly corrosive environments such as coastal areas or chemical plants.
• All castings are shot-blasted to SA2.5 grade before coating, ensuring excellent coating adhesion.
6. Dimensional Accuracy & Perfect Fit
• All covers and frames are machined on the contact surfaces to ensure a perfect, flush fit.
• The cover sits flush with the frame top, eliminating trip hazards and providing a smooth riding surface for vehicles.
• Tolerances comply with EN124 requirements; each cover is test-fitted with its frame before packing.
Manufacturing Process
1. Raw material inspection: Each batch of pig iron, scrap steel, and alloying elements is tested for chemical composition before melting.
2. Melting & alloying: Medium-frequency induction furnace melts the charge; nodularizing and inoculation treatments are performed to achieve the desired graphite structure.
3. Chemical analysis: Spectrometer analysis verifies C, Si, Mn, P, S, Mg, and other elements meet GGG50 specification.
4. Molding: Automatic resin sand molding line or clay sand molding produces high-precision molds with consistent dimensional accuracy.
5. Casting: Controlled pouring temperature and speed ensure sound castings free from porosity, shrinkage, and inclusions.
6. Heat treatment: As-cast castings are annealed to optimize microstructure and mechanical properties.
7. Shot blasting: All castings are shot-blasted to remove sand and oxide scale, revealing a clean metal surface.
8. Machining: CNC machining of the cover-frame contact surfaces, lifting holes, and gasket grooves.
9. Surface coating: Bitumen paint or epoxy powder coating applied in a controlled coating line.
10. Final inspection & testing: Load test, dimensional check, coating thickness test, visual inspection, and assembly fit test.
Quality Control & Certifications
• ISO 9001:2015 certified quality management system.
• In-house hydraulic testing machine capable of testing up to 1000 kN, verifying load capacity for each production batch.
• Spectrometer for chemical composition verification.
• Universal testing machine for tensile strength and elongation testing.
• Coating thickness gauge for paint/coating thickness verification.
• Dimensional inspection with calibrated measuring tools for every batch.
• Third-party inspection (SGS, BV, TUV) available upon customer request.
Available Sizes & Specifications
We offer a comprehensive range of standard sizes, and custom sizes can be produced based on customer drawings or samples:
Round Covers:
• Clear opening: Φ300, Φ350, Φ400, Φ450, Φ500, Φ550, Φ600, Φ650, Φ700, Φ750, Φ800, Φ900, Φ1000, Φ1200 mm
Square Covers:
• Clear opening: 300×300, 400×400, 450×450, 500×500, 550×550, 600×600, 650×650, 700×700, 750×750, 800×800, 900×900, 1000×1000 mm
Rectangular Covers:
• Custom sizes available, e.g., 400×600, 500×700, 600×800, 700×900 mm
Note: Overall dimensions (cover + frame) are larger than the clear opening and vary by load class. Please contact us for detailed dimensional drawings.
Applications
• Municipal roads, highways, urban streets, and residential areas
• Sewer and drainage systems, stormwater management
• Water supply networks and potable water access chambers
• Telecommunication and fiber-optic cable manholes
• Electricity power cable chambers and underground substations
• Gas pipeline access points
• Industrial plants, factories, and warehouses
• Airports, seaports, railway stations, and bus terminals
• Parking lots, commercial complexes, and public facilities
• Parks, gardens, and pedestrian zones
Packaging & Shipping
• Standard packaging: Heavy-duty wooden pallets or steel pallets, covers and frames stacked and secured with steel bands, wrapped with stretch film for moisture protection.
• Bulk packaging: For large container orders, covers can be packed in bulk directly into containers to maximize loading capacity and reduce packaging cost.
• Labeling: Each pallet labeled with product name, size, load class, quantity, gross weight, and customer PO number.
• Loading port: Tianjin, Qingdao, Shanghai, or any Chinese port as required.
• Container loading: 20GP / 40GP / 40HQ containers; we optimize loading to maximize quantity and reduce unit shipping cost.
Order & Trade Information
• MOQ: 100 pcs for standard sizes; sample orders of smaller quantities are negotiable.
• Lead time: 15–30 days after receipt of deposit, depending on order quantity and specification complexity.
• Trade terms: FOB, CIF, CFR, EXW, DDP all accepted.
• Payment terms: T/T (30% deposit in advance, 70% balance before shipment); irrevocable L/C at sight; other payment terms negotiable.
• OEM / ODM: We warmly welcome custom orders based on customer drawings, samples, or specific requirements. Custom logos, engravings, labels, and packaging are all available.
• Sample policy: Samples can be provided for quality evaluation; sample cost and shipping fee to be borne by the buyer, and sample cost can be deducted from future bulk orders.
Why Choose Us
1. Direct factory: We are a manufacturer with our own foundry and machining workshop, ensuring competitive factory-direct prices and full control over quality and lead time.
2. Rich experience: Over 15 years of specialization in ductile iron castings and municipal infrastructure products, with exports to 50+ countries.
3. Strict quality control: From raw material to finished product, every step is monitored by our QC team; defective rate is controlled below 0.5%.
4. Fast delivery: Large production capacity (10,000+ tons per year) ensures on-time delivery even for large orders.
5. Professional service: Our experienced sales team provides quick response within 24 hours, technical support, and after-sales service.
6. One-stop solution: We supply not only manhole covers but also gully gratings, drain covers, tree grates, bollards, and other municipal cast iron products, allowing you to consolidate purchases.
We are committed to providing high-quality products, competitive prices, and reliable service. Please feel free to contact us with your inquiries, drawings, or project requirements. Our team will respond within 24 hours with a detailed quotation and professional technical support.