The cover, regardless of standard size, is a type of ductile iron product. Firstly, it particularly enhances plasticity and toughness. Generally, the covers are made of different materials, with a standard size of 600MM and a wall thickness of about 13mm or more.

Cast Iron Manhole Covers: Cast iron manhole covers are available in various sizes for easy maintenance of different pipelines, with specifications and dimensions varying. In the north, due to weather conditions, heavier covers are used such as 600D400, 450*750B125, and generally 600mm in size.