National standard, the clear width of the manhole cover refers to the base, 600*600B1C250700, gray cast iron manhole covers are commonly used. The covers produced to meet different customer needs, but some are around 550MM.

Usage is also widespread, yielding strengths higher than carbon steel. The standard sizes for manhole covers are 400*500*30, 500*600, 800*900, with high usage rates as well. For the 600 series, selection requirements are based on the specifications of ductile iron manhole covers, which can be categorized into heavy-duty 400, general 250, and light 125 square types.

700 also refers to the diameter. For specifications, refer to the cast iron manhole cover manufacturer's information.

500x500B125, ductile iron manhole covers and gray cast iron manhole covers, 75x45 ductile iron grates. 700mm, square manhole covers available. 450x750C250, heavy-duty ductile iron manhole covers, with 500x500B125 covers, different product specifications *600B1C250700x700B125.