Despite being very important, no one takes a keen look at manhole covers.
Manhole covers are found almost everywhere these days.
You will find them in your garden, patio, highway or high-speed or highly trafficked areas.
To avoid being left in the dark, below is an ultimate FAQ Guide on this device:
- What is a Manhole Cover?
- Which is the Best Manhole Cover Materials?
- What are the Uses of Manhole Cover?
- What are available Shapes of Manhole Cover?
- What are the Quality Standards of Manhole Covers?
- What are Manhole Cover Load Class Codes?
- How do you Measure Manhole Cover?
- What is the Weight of Manhole Covers?
- What are Manhole Cover Tonne Ratings?
- Who are the Top Manhole Cover Manufacturers in China?
- How do you Test Manhole Cover?
- What are the Components of Manhole Cover?
- How much Does Manhole Cover Cost?
- Do Manhole Covers have Size Limitations?
- Are there Restrictions when Importing Manhole Covers from China?
- Why are Round Manhole Covers Popular?
- How does Manhole Cover compare to Access Cover?
- Which Types of Manhole Covers are available?
- How do you Choose the Right Manhole Cover?
- What are the available Types of Manhole Sealing?
- What are the Safety and Security Features of Manhole Cover?
- How does Manhole Cover compare to Sewer Cover Plate?
- Is Recessed Drain Cover the same as Manhole Cover?
- How long can Manhole Cover Last before Replacement?
- What are the Features of Heavy Traffic Manhole Cover?
What is a Manhole Cover?
It is often made using ductile or cast iron among other materials.
It is a removable plate acting as the lid over the manhole opening.
This cover ensures that nothing or anyone can fall in the manhole/drainage system.
Which is the Best Manhole Cover Materials?
Some of the most common materials for manhole include:
i. Ductile/Cast Iron
The best manhole cover material is cast/ductile iron.
It is the most resilient and strongest covers able to hold maximum weight loads of up to around 90 tonnes.
Ductile iron is the most superior choice over cast iron. It does not corrode as fast as cast iron or is less brittle.
They equally have a greater strength to weight ratio.
Even so, both ductile/cast iron are suitable for highly trafficked and high-speed areas.
They are not suitable for pedestrian or lightly trafficked areas.
ii. Stainless Steel and Galvanized Manhole Cover
They are often lightweight, yet good alternative to iron covers.
This material has a high degree of strength.
Stainless steel and galvanized manhole cover can withstand approximately 17 tonnes of weight, easy to install making them suitable for domestic driveways.
They are not suitable for heavily trafficked areas such as motorways and main roads or high-speed areas.
Steel manhole covers are also rated with a FACTA loading class.
iii. PolypropyleneManhole Covers
This material is usually used in light duty load bearing places such as domestic places, pedestrian only walkways or gardens.
What are the Uses of Manhole Cover?
Manhole covers help cover manholes/drainage systems in:
iv. Pedestrian areas
v. Domestic gardens
vi. Inside homes
Also, they keep unauthorized people/anything from manholes for security reasons.
Further, preventing anyone/anything from falling into the manhole for safety reasons.
As such, they safely and securely conceal the entrance of chambers or drains.
What are available Shapes of Manhole Cover?
Some of the available shapes of manhole covers are:
Circular manhole cover
Rectangular manhole cover
Square manhole cover
Note: the most common shape however is a round manhole cover.
What are the Quality Standards of Manhole Covers?
The following are the quality standards of Manhole Covers:
i. EN 124 of 1994
It is applied to manhole covers often subjected to vehicular/pedestrian traffic.
The opening must be specified to be more than 1 m.
It also specifies different weight classes and this depends on the specific application.
For instance, a manhole cover of cast iron (lightest class A15) can hold a maximum weight of 1.5 tonnes.
It is, therefore, applicable in light duty applications in patios, gardens, pedestrian areas, driveways and others.
Similarly, a heavy F900 class manhole cover can be applicable in airports, docks, and several other extreme heavy-duty applications.
It also shows that the manhole cover can be used outside of the EU.
ii. FACTA specification
All steel products have to be manufactured under the strictest guidelines of Fabricated Access Cover Trade Association.
It applies to recessed covers and top covers often designed for non-structural and structural infill as well as surface draining products.
iii. BS EN ISO 1461
This standard is to ensure that the manhole covers have a good finish via galvanization.
What are Manhole Cover Load Class Codes?
The load classes are classified into Steel manhole classifications and Iron manhole classifications.
Steel manhole classifications:
D400 – a manhole cover in this category is suitable for places with has moving heavy traffic such as carriageways.
C250 –good for areas with slow moving heavy traffic
B125 – good for areas accessible by vehicles and driveways
A15 – suitable for areas only accessible to pedal cyclists and pedestrians
Iron Manhole Classification:
Class A – good for pedestrian usage
Class AA – good for vehicular traffic of up to 5 tonnes
Class AAA – good for vehicular traffic up to 10 tonnes
How do you Measure Manhole Cover?
The size of the manhole is the clear opening size.
A manhole cover has to sit securely hence you have to ensure that you have a clear opening size.
It is often measured in millimeters for accuracy.
MM is also the standard unit for the manufacturers of manhole covers.
It can be rectangular, square or circular.
For instance, it can be (450 X 600 mm), (450 X 450 mm), or (a diameter of 450 mm) respectively.
For you to measure a manhole cover, you must take the measurements from one side to the other and inside the walls of the manhole.
If you choose a rectangular or square manhole cover, you must take up height and width measurements.
What is the Weight of Manhole Covers?
You must determine the right load rating needed for your application.
Manhole covers carry different weights under the BS EN 124 class ratings.
They range from A15 – Very light duty to F900 – Extremely heavy duty.
The average weight of a manhole cover is between 113-136 kg.
A ductile/cast iron manhole cover can weigh up to 90 tonnes.
Note: It is important for sewer manhole covers to be as heavy as sewers often produce methane gas which could push out lightweight covers letting poisonous gases into the street.
What are Manhole Cover Tonne Ratings?
Cast iron manhole covers have the following tonne ratings:
1.5 tonnes–Very light duty mainly for patios, pedestrian areas like gardens and driveways
2.5 tonne – pedestrian use only
5 tonne – this manhole cover can support a slow-moving wheel load of around 1.25 tonnes
12.5 tonnes–suitable for domestic driveway thresholds for vans, family cars and 4 X 4s.
25 tonnes–lightly trafficked small private care parts and roads
40 tonnes–suitable for highways, main roads, high traffic areas like public car parks
60 tonnes–suitable for loading bays, industrial estates and cargo handling yards
90 tonnes–suitable for extreme heavy-duty applications, airports and docks
Steel manhole covers have the following tonne ratings:
2.5 tonnes – suitable for very light duty for pedestrian areas such as patios, gardens and driveways
5 tonnes – suitable for domestic driveway threshold for 4 X 4s, vans, and family cars
10 tonnes–suitable for small private car parks and lightly trafficked roads.
17 tonnes–suitable for highways, main roads, and high traffic areas such as public car parks
25 tonnes – suitable for loading bays, industrial estates, and cargo handling yards
38 tonnes–suitable for airports, docks and extreme heavy duty applications
Who are the Top Manhole Cover Manufacturers in China?
Some of the top Manhole Cover manufacturers in China are:
i. SYI Industrial Company Ltd.
ii. Shijiazhuang Transun Metal Products Co., Ltd
iii. Beijing FanyaDiantong Industry & Trade Co., Ltd
iv. Handan Qunshan Foundry Co., Ltd.
How do you Test Manhole Cover?
Some of the tests done on a manhole cover include:
This test involves radiographic examination and ultrasonic testing.
They measure the internal thickness as well as the internal integrity of the casting.
Radiographic testing determines the casting’s internal integrity.
This test is done to determine the physical properties of a manhole cover.
It will show whether the device is strong or brittle or long.
This test helps determine if the measurements of the manhole cover are accurate.
A manhole cover leak test is done to determine if the device is leaking or not before it is released into the market.
It involves pouring water into the gap between the casting and the manhole cover.
If the water disappears into the manhole then it is leaking.
If it stays in the gaps, it is not leaking.
Casting Bar Test
This test assesses the ductility and strength of the cast irons used to make manhole covers.
One uses casting bar test specimens from the specific metal used to cast the manhole covers.
You place the bars into a tensiometer which then pulls on the ends up to the point when they break/elongate over their elastic limit.
Ductile cast iron withstands between 2% – 10% elongation before it eventually breaks.
What are the Components of Manhole Cover?
A manhole consists of:
i. A removable plate
ii. Pick hole
How much Does Manhole Cover Cost?
Manhole covers are sold at competitive prices.
The costs depend on the material of construction, sizes, weight and additional features.
For instance, a recessed SlimTRAY Manhole Cover and Frame 600 X 450 mm equaling 10 tonnes costs 50.95 Euros.
Similarly, a Double Sealed Manhole Cover and Frame of 450 X 450 mm costs 62.40 Euros.
Do Manhole Covers have Size Limitations?
Dimensions of manhole cover
Manhole covers come in different sizes depending on the context of use as well as size of the manhole and location.
A manhole cover can be 650 X 550 mm and built to cover a hole size of 600 X 450 mm.
Manhole covers can be as high as 60 in 1.5 m in diameter and a minimum of 22 in 56 cm.
All you have to do is source the right size for your manhole cover.
A square manhole cover can be from (300 X 300 mm) to (1200 X 1200 mm).
Are there Restrictions when Importing Manhole Covers from China?
There is an anti-dumping tax rate for importing ductile iron manhole covers from China.
The tax rate is usually between 25.4% – 38%.
Some countries, especially in Europe do not allow the manufacture or import of manhole covers made using plastic materials due to the associated environmental problems.
However, Europe imports manhole covers from China and pay the anti-dumping tax rate charges.
There are some nations that do not allow weighty manhole covers.
Europe has shifted towards lighter weight composite manhole cover materials.
Why are Round Manhole Covers Popular?
Manhole covers are round because it can resist the earth’s compression around it.
Besides, manhole covers are easier to manufacture as compared to rectangular or square shapes.
A manhole cover that is round cannot fall via a circular opening.
Usually, there is a lip around the manhole’s rim holding the cover meaning that the underlying manhole is smaller than the actual cover.
No matter how you position the round manhole cover, the cover would always be wider than the hole.
On the contrary, an oval, rectangular or square manhole cover can fall in the manhole if it is inserted diagonally.
Unobservant drivers and pedestrians may fall in the holes if they fail to see the non-round manhole covers.
Since manhole covers are heavy and have to be moved around with ease, a round one is better.
They even easily slip into place when used on manholes.
With just a quarter turn, you can easily lock a round manhole cover.
And, this makes them difficult to open without a unique/special tool.
You do not have to rotate round manhole covers to align with the manhole
You can machine the bearing surfaces of manhole covers to ensure flatness and therefore prevent them from being destroyed by traffic.
You can easily machine round castings using a lathe.
The surface area of a round manhole cover of a specific diameter is smaller than that of a square of the same width.
As such, you need less material to cast manhole cover.
All these results in lower costs.
How does Manhole Cover compare to Access Cover?
The majority of the people often question the difference between these two devices, yet they look the same.
Below are some of the ways in which manhole covers and access covers compare:
Manhole cover and access covers are each access covers as they restrict access to a drainage system and manhole respectively.
While manhole covers are made using ductile/cast iron, access covers are made using aluminum, steel or composite material.
While all manhole covers can be access covers, not all access covers are manhole covers.
They are both diversified as they come in different shapes, weight and design to fit their intended purposes and place of use.
Access covers are far more attractive than manhole covers. They are designed and built to be aesthetically pleasing. They may look like the floor hence one may fail to notice them.
While access covers are often rectangular and square in shape, manhole covers are usually round, but are also rectangular and square.
While manhole covers are designed with pick holes for lifting when needed, access covers are specially designed for lifting with unique lifting keys.
Manhole covers are heavy duty ductile/cast covers, while access covers are recessed/solid composite/steel/aluminum covers.
Which Types of Manhole Covers are available?
There are several types of manhole covers available in the market, all with different load-bearing recommendations and materials.
As such, it may be confusing to identify which manhole cover is the best for your program/project.
However, the common manhole covers include:
i. Recessed Covers
This cover has an insert tray which is utilized where tiling, block paving, or other type of infill is needed.
As such, only a few mm of the cover frame is visible.
This cover can blend in with its surroundings which is suitable for pedestrian areas where aesthetics is key.
It is suitable for use in hospitals, domestic gardens and workshops.
ii. Solid Top (flush)
A solid top cover is often visible. The device fit flushes with the ground.
Solid top flush is built in such a way that it is prominent in the floor.
It is installed where visibility of a manhole cover is key to regular maintenance and safety.
Solid top flush has a visible anti-slip surface with a visible silver manhole cover.
They can be raised but this depends on the place they are installed. Even so, they are easy to identify.
iii. Cast & Ductile Iron
This cover is similar to solid top flush fit. It, however, has a sub-category for gully gratings.
It is heavy duty covering used over a D400 class, resilient and strong.
It has great strength. This material also has a long-life span for installation in docks, airports, and other heavy duty industrial places.
How do you Choose the Right Manhole Cover?
Steel or Cast Iron?
No seal or seal?
External dimensions or clear opening size? Whichever manhole cover you choose to use for your project, you have to consider a number of factors.
If you choose an unsuitable cover for your application, you are likely to have significant security and safety implications.
Choosing the right manhole cover should not be daunting work for you.
Below are the factors to consider:
- Weight loading
- Seal type
- Cover type
Note: if you are looking for a manhole cover for a highway, you can always use ductile/cast iron BS EN 124 manhole covers rather than steel covers.
What are the available Types of Manhole Sealing?
To ensure the safety and security of materials/people while using manhole covers, it is imperative to use the right sealing.
Some of the manhole sealing types are:
i. Single Seal Covers
The majority of manhole covers today are single sealed.
It includes a tongue and groove joint that is airtight when sealed.
The manhole cover surround is typically filled with grease which aids in the formation of the seal.
ii. No Seal/Unsealed Covers
With this, the manhole cover is placed on top of its frame.
It can be a slide out cover, cast iron or heavy duty that is not sealed.
iii. Double Seal Covers
Double seal covers are responsible for comprehensive seals.
It is mainly a groove joint and a double tongue.
It prevents air from leaving as long as the manhole is not under pressure.
When you position foul drainage manholes in buildings, a double seal is a better choice.
What are the Safety and Security Features of Manhole Cover?
Pick holes help in easily opening a manhole without posing safety issues.
Manhole covers made using composite material have a lightweight and ergonomic, yet high strength solution.
It cannot cause serious physical injuries to whoever comes into contact with it.
The seals/rims help keep the manhole covers tightly closed at all times thus preventing any entry into the manholes.
They have thick casting/sides hence manhole covers cannot be displaced/negatively impact traffic.
How does Manhole Cover compare to Sewer Cover Plate?
While a Sewer cover plate and Manhole cover are lids/covers used to cover a sewerage system and manholes respectively, they share some differences/similarities.
A sewer cover plate can be round just as a manhole cover.
A sewer cover plate can be found within and close to buildings/home.
Manhole covers are often found most on roads, pedestrian areas, gardens and patios.
Is Recessed Drain Cover the same as Manhole Cover?
Of course not.
A recessed drain cover is mainly a cover with a grating or holes in it utilized in the coverage of water drain.
While it allows drainage of water, it also prevents larger particles from passing into the water drain.
A manhole cover does not have any holes or grating, there is a lid that prevents the entry of unauthorized, anyone or materials into the manhole.
How long can Manhole Cover Last before Replacement?
Square manhole cover
Manhole cover can last around 50 years. Following this period, you can replace the manhole cover with a new one.
Manhole covers can be damaged by extreme weather conditions leading to wear and tear.
What are the Features of Heavy Traffic Manhole Cover?
A heavy traffic manhole cover is one for heavy volume traffic.
Some of the features of a Heavy Traffic Manhole Cover are:
i. Resistant due to excellent mechanical properties of ductile cast iron
ii. Durable; they have a long-life span as they are made using steel and ductile/cast iron that offer these properties.
iii. Silent in response to heavy traffics; they do not move upon contact with the traffic as they are stable enough.
iv. Stable; they can cover the manholes on the roads without causing any problems as they are very stable.
v. Strong; the lid/cover can withstand very high pressure from the traffic
In China, you can find many manholes cover manufacturers.
The best part, BanSar will help you ship all your manholes from China to any global destination.
Contact us now for all your freight forwarding needs.