As an indispensable component of modern urban infrastructure, the performance of ductile iron manhole covers is directly related to road safety and municipal maintenance efficiency. Compared to traditional gray cast iron covers, ductile iron covers obtain a spheroidal graphite structure through spheroidization and inoculation treatment, making their comprehensive performance approach that of steel and successfully achieving the industrial goal of "replacing steel with iron." This material possesses high strength, high toughness, and excellent wear resistance, with tensile strength reaching over 500 MPa, elongation exceeding 7%, and corrosion resistance five times that of ordinary steel pipes. Luzhongbao Ductile Iron Ordinary Circular Manhole Covers are precisely based on these material advantages, combined with precision manufacturing processes and user-friendly design, making them the preferred choice in fields such as municipal engineering, power and communication, water supply, and sewage.
In terms of engineering design, Luzhongbao circular covers fully consider safety and environmental adaptability. The circular structure effectively prevents falling through through uniform stress design – every diameter has the same length, ensuring the cover is wider than the opening in any direction when lifted by vehicles, fundamentally eliminating the risk of the cover falling into the manhole. Furthermore, the cover system consists of the cover body, load-bearing frame, and an aging-resistant rubber sealing pad, combined with a U-groove embedded T-shaped rubber strip to achieve shock absorption and noise prevention functions; the raised 3mm pattern on the surface significantly enhances the anti-slip effect, while the fixed shaft and pin design provides reliable anti-theft protection. These characteristics give Luzhongbao covers outstanding performance in load-bearing capacity (Heavy-duty 360 kN, Light-duty 210 kN), service life (can exceed 50 years), and maintenance costs.
Core Material Advantages: The Foundation for Performance Beyond Tradition
The exceptional performance of Luzhongbao Ductile Iron Cracks is primarily attributed to its material science innovation. Ductile iron, treated by adding spheroidizing agents like rare earth and magnesium, transforms the graphite from flake to spheroidal. This microstructural change significantly enhances the material's mechanical properties:
Combination of Strength and Toughness: Spheroidal graphite has a much lesser cutting effect on the metal matrix compared to flake graphite, enabling the cast iron strength to reach 70–90% of the matrix strength, with an impact value more than 10 times that of gray iron materials.
Lightweight Design: Benefiting from the material's high strength and toughness, the product weight is approximately 30% lighter than similar gray cast iron covers, reducing transportation and installation burdens.
Strong Corrosion Resistance: In spray corrosion tests, the corrosion amount over 90 days is only 1/40 that of steel pipes, and the service life is five times that of ordinary steel pipes, making it suitable for corrosive environments like rainwater and sewage.
Structural and Functional Design: Perfect Integration of Safety and Practicality
The structural design of Luzhongbao circular covers focuses on solving common pain points in municipal facilities, achieving multi-functional integration:
Shock and Noise Prevention System: A U-groove at the frame register embeds a T-shaped synthetic rubber strip, which absorbs the impact force of vehicle traffic through elastic buffering, overcoming hardness with softness to eliminate noise.
Anti-theft Security: Uses a fixed shaft and pin connection design. The cover requires special tools to open and is fixed using pre-set anchoring bolt holes (evenly distributed at 90 degrees) in the frame, effectively preventing illegal theft and construction displacement.
Anti-slip and Drainage Optimization: The raised surface pattern ensures the friction coefficient in rainy or snowy weather, while the circular structure itself facilitates drainage, avoiding safety hazards caused by water accumulation.
Load-Bearing Performance and Durability: Assurance for Harsh Working Conditions
The load-bearing capacity of Luzhongbao covers strictly complies with industry standards like CJ/T3012-93, and its design fully considers the needs of different scenarios:
High Load Rating: Heavy-duty covers withstand pressure up to 360 kN (approx. 36 tons), light-duty up to 210 kN (approx. 21 tons), meeting vehicle traffic requirements for urban roads, expressways, and other areas.
Anti-breakage Characteristics: Even if the load exceeds the limit, the cover will not shatter suddenly like ordinary cast iron but will undergo moderate deformation, providing a buffer guarantee for pedestrians and vehicles.
Long Service Life: The material's corrosion resistance and anti-aging treatment give the product a service life of over 50 years, and its maintenance-free characteristic significantly reduces the whole-life-cycle cost.
Economy and Social Benefits: A Sustainable Urban Investment
Choosing Luzhongbao Ductile Iron Covers is not only about technical performance but also reflects a balance between economic benefits and social value:
High Material Utilization: The circular design saves material compared to the longer diagonal parts of other shapes, reducing production costs, while also facilitating handling (can be transported by rolling).
Low Maintenance Cost: The corrosion-resistant, maintenance-free characteristics reduce the expense of frequent replacement and repair. Estimates suggest comprehensive costs are reduced by over 30% compared to traditional products.
Significant Safety Benefits: Functions like anti-fall, anti-slip, and anti-theft effectively prevent "urban black hole" incidents, ensure public travel safety, and enhance the municipal image.
Application Scenarios and Adaptability: A Solution for Multi-domain Coverage
Luzhongbao Ductile Iron Circular Covers have a wide range of applications, fully demonstrating their flexibility:
Municipal Roads: Circular covers prevent falling through uniform stress design, suitable for inspection wells like water supply, sewage, heating, and gas.
Public Facilities: Can be used for power pipeline wells, communication cable wells, fire hydrant wells, etc. Square variants are also suitable for preventing rainwater in cable wells.
Environmental Adaptability: Surface treatment with anti-rust asphalt paint or hot-dip galvanizing ensures stability in environments from -50°C to 300°C, adapting to extreme northern and southern climates.
Summary
Luzhongbao Ductile Iron Ordinary Circular Manhole Covers, with their material science innovation (high strength, lightweight, corrosion resistance), optimized structural design (shock absorption, anti-theft, anti-slip), exceptional load-bearing performance (up to 360 kN), and long-term economy (service life over 50 years), have become the ideal choice for urban infrastructure construction. They not only solve the pain points of traditional covers, such as being prone to breakage, theft, and high noise, but also provide reliable support for urban safety and sustainable development through standardized production and user-friendly design. Choosing Luzhongbao means investing in quality and responsibility that stands the test of time.
