The cover cover of the ductile iron well is a detachable plate, which forms a cover at the opening of the ductile iron shaft cover to prevent anyone or anything from falling into it。 It can also prevent unauthorized persons or materials。
The bearing surface of the ductile iron manhole cover frame and covers the machinery to ensure flatness and to prevent shedding traffic.
Spheroidal graphite cast iron well cover
The cast iron manhole covers and frames should be in accordance with 1726:1991, as follows:
Grades and types:
The cast iron covers and frames covered by this standard should include the following four grades and types:
Please refer to the recommended location in section 1726.1991, Section 3.2, for placing manholes and frames of different grades and types / shapes.
Material: 210: 1978.
The appropriate grade of grey cast iron is not less than grade FG 150.
Cover cover and frame part of ductile iron well
Cover and frame
The cover and frame should be clean and cast。
The cover should be provided with proper non skid resistance before the operation of the lattice design。 The rise of the lattice should not be less than 4 millimeters。
Keyhole and key
Table 1: manhole covers and frame requirements for basic performance (per 1726:1991)
Table 2: tolerance of cover and frame dimensions (per 1726:1991)
Table 3: the size of the cast iron well cover (per 1726:1991)
The cover and frame of nodular cast iron well should be coated with black asphalt composition. The coating should be smooth and tough. When exposed to a temperature of 63 C, it should not flow and should not be so fragile that it falls off at a temperature of 0 C.
Sampling defects and allowable numbers
Table 4 sampling defects and allowable quantities (per 1726:1991)
Load test samples: the number of samples per batch of 50 or part of each batch should be one, the type, shape and size.
The cover of ductile iron covers should not be broken, and the load specified in the given table will be at least 30 seconds in the load test.