Covers and grates for external sewers

Covers are a closing and protection element for the manholes in the sewage or water supply network. Grates represent protection elements and they capture rain wastewater especially in case of drains.

Given their location at soil level, these are exposed to numerous types of demands, especially mechanical due to the charge exercised by the passengers or vehicles that travel above them.

In this regard the covers and the grates are classified into several classes according to the EN124 standard.

TeraPlast offers a wide range of covers and grates of different sizes and resistance made from the traditional material, cast iron, as well as from new generation material such as composite materials.

See TeraPlast Catalog

You can find the complete range of products in the TeraPlast 2020 catalog.

Features and advantages of the Covers and grates for external sewers

Group 1 - A15 – 1.5 tones/axle (15kN) – for areas with pedestrian traffic, alleys, courtyards or bicycle lines.

Group 2 - B125 – 12.5 tones/axle (125kN) – reduced traffic (parking with weight restrictions, markets, private roads, parking).

Group 3 - C250 – 25 tones/axle (250kN) – roads, roads for easy commercial vehicles, parking for vehicles up to 25 tones, drainage.

Group 4 - D400 – 40 tones/axle (400kN) – roads for heavy vehicles, highways, parking areas for all types of vehicles.

The classification includes also:

Class E600 – 60 tones/axle (600kN) – areas with heavy and very heavy traffic (ports, airports).

Class F900 – 90 tones/axle (900kN) – exceptional vehicles, ports, airports, etc.


The covers and grates offered by Teraplast are black and are made from ductile cast iron by casting. They are delivered as an assembly made from frame + cover. In certain situations the two components are joint through a hinge.

Ductile cast iron offers a higher elasticity and tear resistance to the product, thus, lately it became more popular the traditional grey cast iron. Ductile cast iron has a higher safety rate compared to the grey cast iron, due to the fact that it allows higher stress when it is submitted to certain charges and it returns to the initial state once these have disappeared.

The corrosion resistance degree is also higher and the degree of cracks spreading is much lower due to the presence of graphite in nodular shape not in lamellar shape as it is in the grey cast iron.


In order to respond to the market demands, Teraplast completed its range of covers with a new range of covers and grates made out of composite materials. The covers and grates offered by Teraplast are made out of a patented, modern and innovative composite material (KinextTM).

This innovative composite material allows the production of manhole covers with a higher resistance to charges. Hereinafter, will state several advantages due to the use of these types of covers.

Reduced weight – the composite covers made out of KinextTM are 70% lighter than the similar covers in cast iron, thus these reduce the handling costs and especially the transport cost.

With high resistance to stress and breaking – the composite covers have a higher resistance to stress and breaking under the charge, these being easily classified in the resistance classes in accordance with EN124 standard.

Reduce the noise level – the composite covers reduce significantly sound pollution. KinextTM has a lower density than cast iron and it reduces the noise and inconveniences caused by the vehicles that cross over the installed manholes covers.

Electrical insulation – the covers can be installed for pedestrian traffic areas. . KinextTM is nonconductive, thus these covers protect the pedestrians especially against voltage dispersions, especially in humid environments.

Corrosion resistance – KinextTM resists to chemicals and it does not rust or chordates due to constant exposure to atmosphere agents. For this reason, the covers don’t need to be repainted and the products are ideal for areas with flammable liquids such as gas stations, storage installations, as they reduce significantly the risk of fire as result of a sparkle as it is the case for ferrous materials.

Anti-theft – the scrap value continues to increase and the number of thefts has a high impact on the costs incurred by the local authorities and the services companies. Besides the economic impact caused by the product theft there is also the risk of sever accidents caused by the holes in the road. Composite covers have no value (or an extremely low value) for the companies that recycle different types of materials

Resistance to temperature changes – the covers were tested at -30°C și +150°C and have maintained the same features, that is why they are suitable for extremely hot or cold areas

Permeability to electromagnetic waves – due to RFID (identified through radio frequency) the “Smart cover” is the manhole cover that allows you to:

  • To receive and send without battery when it is questioned by a reader.
  • To be located in case it is covered with asphalt.
  • You have all the information related to what it is inside the manhole.
  • Registers the maintenance actions.
  • Has a unique product registration (each cover has its own number on the microchip).

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