To ensure the proper use of cast iron manhole covers, attention must be paid to installation quality, ensuring accurate dimensions, secure installation, easy opening, and a clean and aesthetically pleasing appearance. Based on the technical standards for cast iron manhole covers, the following installation details are formulated: According to the specifications, installation requirements can be divided into general requirements, installation of adjustable anti-settlement manhole covers, and installation of direct-bearing manhole covers.
The brickwork for cast iron manhole covers should be constructed according to the dimensions designed by the design institute, determining its inner diameter or length*width, and whether it is square or round (ideally, construction should follow the actual sample). Alternatively, relevant standards can be referenced. When constructing the manhole, ensure that the inner diameter of the manhole opening matches the inner diameter of the manhole cover and grate. The installed manhole cover should be flush with the road surface. After the concrete or asphalt base is poured and laid, the cover should be opened and cleaned promptly to prevent mortar or asphalt from fusing the manhole cover and base together, which could affect future opening.
When installing manhole covers on cement roads, cast a 20cm thick C25 concrete ring beam on the brickwork around the manhole opening and smooth it. Ensure the manhole cover is firmly secured on all four sides, level, and not loose. Cast a 40cm wide concrete protective ring around the manhole cover (or a 20cm wide concrete protective ring for cement roads, reinforced with steel bars). Allow at least 10 days for curing.
To maintain the aesthetic appearance and clarity of the surface patterns and lettering, when constructing asphalt roads, cover the manhole cover with a thin sheet of iron or brush the surface with waste engine oil to prevent asphalt from spraying onto it. When constructing cement roads, cover the manhole cover with plastic film to prevent cement mortar from staining the surface and damaging the patterns and lettering. Alternatively, clean the surface of the manhole cover with water after construction is completed on the same day.
When installing cast iron manhole covers on asphalt roads, avoid direct pressure from construction machinery. When casting the entire road surface, leave a hole slightly larger than the manhole cover in the road surface for installation after the asphalt is laid. (For all-concrete pavements, manhole covers should be installed after the secondary aggregate has been laid and compacted.) Ensure the quality of manhole cover installation to extend its service life.
Maintenance work includes establishing an inspection and maintenance management system, and conducting regular inspections, maintenance, and repairs. Any defects in manhole covers, such as loosening, breakage, loss, settlement, height differences, tilting, or damage, should be addressed immediately. An emergency response mechanism should be established; when a manhole cover is missing or severely damaged, it must be repaired within 6 hours; upon receiving a complaint, warning signs must be set up within 2 hours, and repairs must be completed within 6 hours.
