Cast Iron Manholes: Cast iron manholes are available in various sizes for different pipeline maintenance, with specifications and dimensions varying. In the north, due to weather conditions, heavier ones are made: 600D400, 450*750B125, and generally 600mm in size.

(D700 refers to the diameter of the manhole cover. In the north, it's usually 75-95. Additional information: Ductile iron manhole covers are generally divided into circular and square sizes. The specifications mainly include: 450*750D400, how much? In fact, in the north, due to weather conditions, they tend to be heavier.

750B1C250700*800B125, etc. However, there are also some around 550MM, which are also widely used. In fact, there are various sizes for manhole covers.