گریتینگ فلزی و گریتینگ کامپوزیت انواع قالب بتن تونل لاینینگ دستگاه سی ان سی - ام پیکو / مشبک پردازان

A manhole cover is a removable plate forming the lid over the opening of a manhole, an opening large enough for a person to pass through that is used as an access point for maintenance and other work on an underground utility vault or pipe. It is designed to prevent anyone or anything from falling in, and to keep out unauthorized persons and material.

Manhole covers date back at least to the era of ancient Rome, which had sewergrates made from stone.

A typical manhole cover