Ductile Iron Manhole Cover
Ductile iron manhole covers are generally divided into round and square. In the urban area, circular is generally used, because the round manhole cover is not easy to tilt, which can better protect the safety of pedestrians and vehicles. The use of a circle is mainly due to the fact that the circular manhole cover has the same length through each of its centers, so that if the manhole cover is rolled up by the passing vehicle, the diameter will be slightly smaller than the wellhead below.
Wide, the manhole cover will not fall into the wellhead.
If a square is used, since the diagonal of the square is significantly longer than the length of each side of the well, when the manhole cover is rolled up, it is easy to fall into the well along the diagonal direction of the wellhead, posing a safety hazard. If the wellhead is rounded or significantly smaller than the manhole cover, the square manhole cover will not fall into the well. This involves the maximum use and savings of a material.
The use of the manhole cover depends on the size of the wellhead. If a square manhole cover with a much larger area than the wellhead is to be installed on it, the utilization and practical value of the material are naturally not more effective than directly using the round manhole cover, which not only saves the material of the manhole cover, but also The safety of the wellhead is guaranteed. In the countryside and cable wells, squares are generally used, which can better prevent the entry of liquids such as rainwater.
Performance and application of ductile iron:
Ductile iron is a kind of high-strength cast iron material developed in the 1950s. Its comprehensive performance is close to that of steel. It is used to cast some parts with high requirements for strength, strength, toughness and wear resistance. The so-called “iron-based steel” mainly refers to ductile iron. Ductile iron is obtained by spheroidizing and inoculation to obtain spheroidal graphite, which effectively improves the mechanical properties of cast iron, especially the plasticity and toughness, thereby obtaining higher strength than carbon steel.
Ductile iron castings have been used in almost all major industrial sectors, requiring high strength, plasticity, toughness, wear resistance, resistance to severe thermal and mechanical shocks, high or low temperatures, corrosion resistance and dimensional stability. Ductile iron has many grades that provide a wide range of mechanical and physical properties.
Pearlescent spheroidal graphite cast iron with medium and high strength, medium toughness and plasticity, high comprehensive performance, good wear resistance and vibration damping, and good casting process performance. It can be changed by various heat treatments. Mainly used in various power machinery crankshafts, camshafts, connecting shafts, connecting rods, gears, clutch plates, hydraulic cylinders and other components.
Ductile iron is sometimes referred to as “the best of the two worlds”, meaning that ductile iron has the strength of cast steel and cast iron has excellent corrosion resistance.
Ductile iron manhole cover installation conditions:
In order to ensure the normal use of the cast iron manhole cover, attention should be paid to the installation quality, accurate size, firm installation, convenient opening, and clean appearance.
According to the technical standards for inspection of cast iron manhole covers, the following installation rules are formulated:
The masonry masonry of the cast iron manhole cover shall be determined according to the size of the manhole cover designed by the design institute, and the inner diameter or length*width, square circle (if the construction is carried out according to the actual sample), it may also be carried out according to the standard.
When constructing the well, it must be noted that the inner diameter of the wellhead should be consistent with the inner diameter of the well cover well, and the installed manhole cover should be level with the road surface.
After the concrete or asphalt is cast and laid, the cover should be opened and cleaned in time to prevent the mortar or asphalt from inspecting the manhole cover and the seat, so as not to affect the opening in the future.
The cement pavement well seat is installed, the C25 concrete cast 20CM thick ring beam is smoothed on the brickwork of the wellhead.
It is necessary to keep the well seat square, the whole flat, not loose, and cast a concrete protection ring with a width of 40CM in the manhole cover.
(If it is a cement pavement, it can also cast a concrete protection ring with a width of 20CM and strengthen it with steel bars.) The maintenance period should be more than 10 days.
In order to maintain the appearance of the cover, the surface pattern and the writing are clear. When the asphalt pavement is applied, the thin iron cover is used to cover the cover on the manhole cover or the waste engine oil to prevent the asphalt oil from being sprayed on the manhole cover.
When the cement pavement is applied, the application is applied.
The plastic film covers the well cover to prevent the cement mortar from contaminating the surface of the manhole cover, damaging the surface pattern and writing, and the surface of the well cover can be cleaned with water when the construction is completed on the same day.
Installing a cast iron manhole cover on an asphalt road, it is necessary to pay attention to avoid the construction machinery directly crushing the well seat.
Whole road surface is cast, a hole slightly larger than the well seat should be reserved on the road surface and placed after the asphalt is laid.(The full pavement should be installed after the two stones are paved and finished) to ensure the quality of the manhole cover to extend the service life.
All the above items are required to pay attention to the use and construction units.
Why is the price of ductile iron manhole cover more expensive than ordinary manhole cover?
The strength of nodular cast iron is 70% to 90% of the strength of the matrix structure, the tensile strength is almost 120kgf/mm2, and the toughness is also very good. Ductile iron contains chemical components such as iron, carbon (3.6 to 3.8%), silicon (2.0 to 3.0%), manganese, phosphorus, sulfur (1.5%), and a small amount of spheroidizing agents such as magnesium and rare earth. The spheroidal graphite cast iron manhole cover is made of such a hard ductile iron through complicated production process and steps, and the quality is very good and very durable.
Eternal Bliss Alloy Casting & Forging Co, Ltd.
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