A hatch is a chamber that provides repair workers with access to serviced drains, sewers and other underground utilities. Manhole covers hide the entrance to the chamber.
Most manhole covers are made from very durable ductile iron. Due to its strength, ductile iron allows vehicles to move on manhole covers without breaking or bending them, and people can walk across them safely. Manhole covers can also be made from stamped steel and plastic.
Access covers and access plates
Inspection covers and access plates are other names for manhole covers. They come in different sizes and are part of various underground systems such as plumbing, sewerage, electricity and television.
Control plate
A viewing plate or viewing cover leads into the viewing chamber, typically no more than 450 mm (17.5 inches) wide and no more than 600 mm (24 inches) deep. They are round or rectangular and open with a hatch key.
Access cameras
Access chambers are large enough for a person to drill drainage or perform other maintenance.
Hatches
Hatches are the largest chambers. A person can access the underground system through the entrance. Manholes can be of any depth, but the hole size is usually 600 x 900 mm (62 x 35 inches). Their lids are usually made of heavy cast iron and have keyways and prize slots (gaps where a crowbar can be inserted to loosen the lid before lifting).
Manhole covers
Some manhole covers are made of polypropylene, which is a lightweight and durable plastic; they are usually found in driveways or pedestrian areas. They open and close with screws or the lightweight plastic key included with the hatch cover. Some people choose this type of manhole cover because the initial cost is minimal. As a result, they have no scrap value, so they are less likely to be stolen.
