Fuzhou cast iron manhole covers are generally divided into circles and squares. In urban areas, rounds are generally used because circular manhole covers are not easy to tilt and can better protect the safety of pedestrians and vehicles. The use of circular is mainly considered that the length of each diameter of the circular manhole cover through its center is the same, so if the manhole cover is rolled up by the passing vehicle, because the diameter will be slightly larger than the wellhead below, Wide, the manhole cover will not fall into the wellhead.
If a square is used, because the diagonal of the square is obviously longer than the length of each side, when such a manhole cover is rolled up, it is easy to fall into the well along the diagonal direction of the wellhead, causing hidden safety hazards. If the wellhead is made round or significantly smaller than the well cover, the square well cover will not fall into the well. This involves the issue of large-scale utilization and conservation of materials. The use of the manhole cover depends on the size of the wellhead. If a square manhole cover with an area much larger than the wellhead has to be installed on it, the use and practical value of the material is naturally more effective than using a round manhole cover directly. Guaranteed the safety of the wellhead.
There are in-depth studies on the quality, technology and materials of cast iron manhole covers. The quality of cast iron manhole covers generally depends on the following directions.
First of all, the quality of cast iron manhole cover depends on its application: the south is lighter, the north is heavy due to weather, the south is generally 60KG-90KG, and the common heavy manhole cover 70KG is 75-95KG in the north.
The cast iron manhole cover is not the heavier the better the quality, its two main parameters are hardness and toughness. Generally speaking, the higher the hardness, the better the quality, but the higher the hardness and the better the toughness, this is the good manhole cover. When designing, in addition to determining the geometry and size of the cast iron manhole cover according to the working conditions and metal material properties, the rationality of the design must be considered from the perspective of casting alloy and casting process characteristics, that is, obvious size effects and solidification. Shrinkage, stress and other problems to avoid or reduce the occurrence of defects such as segregation, deformation and cracking of cast iron manhole covers.
The second is to have a reasonable casting process. Years of accumulation know the casting process well and use good raw materials, so that the quality of our factory manhole covers is good.
The design and production of Fuzhou cast iron manhole cover are in accordance with some specific requirements, so as to ensure the quality of the product and also have the characteristics of the manhole cover. The specific technology and performance are introduced in detail below for everyone
General cast iron manhole cover requirements can be made of gray cast iron, nodular cast iron, steel, and non-metallic materials. It should meet the requirements of various cast iron manhole cover sizes in the "Quality Inspection Specifications for Municipal Engineering". Flat processing. Defects such as cracks and cold insulation and shrinkage that affect the use are not allowed; the manhole covers and well rings formed by casting shall be clean and flat. Manhole covers made of metal materials shall comply with relevant quality inspection and assessment specifications; the carrying capacity of cast iron manhole covers shall comply with the unified provisions of municipal and national standards.