Incidents of manhole cover theft occur across the country, and substandard covers often break under excessive pressure, resulting in economic losses and serious safety hazards. The new generation of ductile iron "Five-Protection" manhole covers eliminates these issues. Here is an introduction to their features:
1. Anti-theft: These covers feature a hinged design; one side connects to the frame via a fixed hinge pin, while the other is secured with a locking clip. The cover can be removed when opened to a vertical position, facilitating maintenance. The concealed lock utilizes a rust-proof nylon bushing and requires a special tool to open, ensuring security.
2. Anti-fall: The inner rim of the cover is equipped with eight attachment points for an optional safety net, providing dual protection to ensure safety.
3. Anti-vibration: A U-shaped groove in the inner rim holds a synthetic rubber strip. This strip acts as a cushion during contact between the cover and the frame as vehicles or pedestrians pass over, reducing vibration.
4. Anti-noise: The rubber strip between the cover and the frame prevents direct metal-on-metal contact, thereby reducing noise when pedestrians or vehicles pass over.
5. Anti-displacement: Four bolt holes are provided on the exterior of the frame, paired with anchor bolts. This prevents the cover from shifting due to traffic loads during daily use and offers an additional layer of theft protection.
6. Anti-breakage: This is a key characteristic of ductile iron "Five-Protection" covers. Heavy-duty versions can withstand loads of up to 60 tons, while light-duty versions handle up to 21 tons. Even if the load exceeds the limit, the physical ductility of the material prevents the catastrophic shattering common with standard cast iron covers; instead, the cover merely deforms slightly, offering greater safety for vehicles and pedestrians.
