Quick Guide to Manhole Covers | Types & Specifications

A manhole cover is a removable lid over a manhole that keeps unauthorized people out and prevents falls. They serve the function of restricting entry to sewer or surface water drainage systems and other underground chambers used for maintenance purposes by the workers.

Manhole covers can be made of cast iron, ductile iron, concrete, or a combination of these and are manufactured based on the standard code BS EN 124:2015 (Gully Tops and Manhole Tops for Vehicular and Pedestrian Areas).

The type of manhole covers based on material and design, along with their standard codes and classes are explained in this article.

Types of Manhole Covers Based on Material

Manhole covers can be classified into various types based on the material used as cast iron, steel, R.C.C, composite materials, and polypropylene manhole covers. 

The code requirements for each type are explained in the table below.

Table 1: Code Standards for Different Manhole Types

TYPE OF MANHOLE COVER CODE	CODE REQUIREMENTS
Cast Iron	BS EN 124-2:2015
Steel/Aluminium Alloys	BS EN 124-3:2015
Steel Reinforced Concrete	BS EN 124-4:2015
Composite Materials	BS EN 124-5:2015
Polypropylene (PP), Polyethylene (PE), or Unplasticized Poly (PVC-U)	BS EN 124-6:2015

1. Cast Iron Manhole Covers

Cast iron manholes can be gray cast iron and ductile cast iron. Ductile iron is stronger because they are commonly used at airplane terminals and places with heavy vehicular traffic.

These are manhole covers made of ductile iron or nodular iron. Ductile iron is known for its solidness, strength, heavy-duty, and resilient features. The loading classes for ductile manhole covers are mentioned in BS EN 124:2015 and they are used over D400 Class (covers and gratings capable of withstanding a 400kN test load).

2. Carbon Steel Manhole Covers

Steel Manhole Covers
Image Credits: Huber Technology Middle East

Carbon steel is not tough as cast iron manhole covers, but it can be used where a strong manhole cover that is light in weight and can be easily removed and closed.

3. Concrete Manhole Covers

Reinforced concrete manhole covers are manufactured with concrete and steel reinforcement. Mild steel rims are provided to protect the edges from damage. 

Concrete manholes are manufactured with perforation or slots or grating for stormwater drainage applications. M 30 and greater concrete mix is used for the manhole cover is used. The code used is mentioned in the table-1 above.

4. Composite Materials Manhole Covers

Manhole covers can be manufactured with a combination of different types of plastics, fiberglass, and other composite materials. It is the common type of manhole cover used in Europe.

Composite Manhole Cover
Image Credits: Composite World

They are light and strong manhole covers available in different colors. But it is not suitable for immense amounts of friction and is susceptible to breaking.

5. Polypropylene (PP), Polyethylene (PE), or Unplasticized Poly (PVC-U) Manhole Covers

Polypropylene Manhole Cover

These manhole covers have been developed with safety in mind to include slip-resistant surface designs, restricted access where Building Regulations apply, and dual-locking capabilities. These manhole covers are made from 100% recycled polypropylene they are designed to fit all major shallow inspection chambers with 300/450 mm clear openings. These manhole covers are a durable solution for underground environments also.

Manhole Covers Grade and Classes

The BS EN 124:2015 categorizes these types into various classes and grades based on how they work under static load tests and the preferable locations they work best. 

The exposure environment and site conditions are classified from Grade 1 to Grade 6. 

• Group 1 — areas where only pedestrians have access.
• Group 2 — car parks and pedestrian areas where only occasional vehicular access is likely (incl. driveways).
• Group 3 — car parks, forecourts, industrial sites, and, areas with slow-moving traffic. Also, in highway locations up to 500mm from the curb and up to 200mm into the verge, excluding motorways.
• Group 4 — areas where cars and lorries have access, including carriageways, hard shoulders, and pedestrian areas.
• Group 5 — areas where high wheel loads are imposed, such as loading areas, docks, or aircraft pavements.
• Group 6 — areas where particularly high wheel loads are imposed such as aircraft pavements.,

Based on the static load test, they are categorized as 

• Class A15 — covers and gratings capable of withstanding a 15kN test load.
• Class B125 — covers and gratings capable of withstanding a 125kN test load.
• Class C250 — covers and gratings capable of withstanding a 250kN test load.
• Class D400 — covers and gratings capable of withstanding a 400kN test load.
• Class E600 — covers and gratings capable of withstanding a 600kN test load.
• Class F900 — covers and gratings capable of withstanding a 900kN test load.

The table below shows different classes recommended for different group types.

Loading Group	Installation Area	BS EN 124 Class	BS EN 124 Test Load
Group 1	For use in pedestrian areas where vehicles have no access	A15	15kN (1.5 tonnes)
Group 2	For use in car parks & pedestrian areas where infrequent vehicle access is likely (incl. driveways)	B125	125kN (12.5 tonnes)
Group 3	For access covers & gully gratings in areas of slow-moving, heavy traffic; also, for gully gratings in certain carriageway areas (see full definition above)	C250	250kN (25 tonnes)
Group 4	For use in carriageways of roads, hard shoulders, and parking areas	D400	400kN (40 tonnes)
Group 5	For use in areas where high wheel loads are present	E600	600kN (60 tonnes)
Group 6	For use in areas where extremely high wheel loads are present	F900	900kN (90 tonnes)

Types of Manhole Covers Based on Design

Based on the design, manhole covers can be divided into:

1. Solid Manhole Covers
2. Recessed Manhole Covers

1. Solid Manhole Covers

These are light manhole covers, and often fit the flush at the ground level. It also possesses grab handles. It is commonly installed for light use.

Solid manhole covers are mainly made from galvanized steel.

2. Recessed Manhole Covers

Recessed manhole covers are covers that are designed to stay hidden by paving a block, tile, or, a layer of screed to match the surrounding. 

Recessed Manhole Covers

These covers provide a decorative finish to the driveways. 

The recessed manhole covers are designed based on FACTA regulations.

• FACTA A – Pedestrian use and up to 5kN wheel loads
• FACTA AA – Small vehicles up to 15kN wheel loads
• FACTA AAA – Cars up to 25kN wheel loads
• FACTA B – Cars and vans up to 50kN wheel loads
• FACTA C – Trucks up to 65kN wheel loads
• FACTA D – Articulated lorries up to 108kN wheel loads
• FACTA E – heavy, moving plant up to 158kN wheel loads
• FACTA F – Aircraft and heavy plant up to 237kN wheel loads

(All FACTA wheel loads are for moving pneumatic-tired vehicles. Please check before ordering that you have the correct load class.)

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