A manhole (utility hole, maintenance hole,[1] or sewer hole) is an opening to a confined space such as a shaft, utility vault, or large vessel. Manholes are often used as an access point for an underground public utility, allowing inspection, maintenance, and system upgrades. The majority of underground services have manholes, including water, sewers, telephone, electricity, storm drains, district heating, and gas.
The design and implementation of an 18-inch manhole cover are far more complex than one might assume. Typically made from materials like cast iron or composite materials, these covers are engineered to withstand significant load and pressure. Their circular shape is not merely aesthetic; it is a practical decision. The round design prevents the cover from falling through the opening, regardless of how it is positioned—something that cannot be guaranteed with square or rectangular covers.
What is a Full Circle Repair Clamp?