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Things to Consider When Choosing a Manhole Cover

Updated on March 28, 2014
650mm Round manhole cover C250
650mm Round manhole cover C250 | Source

Manhole covers are considered quite important for any property, whether it’s residential or any public property. It’s because these covers are used in sealing off underground sewerage systems and tunnels. There are many fatal accidents which have occurred around the world when sewer systems and tunnels are left uncovered. Additionally, these covers play a significant safety role by ensuring that no one falls in these sewerage systems. It is important to note that a random drop in a sewerage system can be quite fatal, since it can result in a broken spinal cord or even death.

There are a number of factors, which require you to buy manhole covers. There are cases, when the cover in a place is old and decayed so it requires a replacement. In addition, you may need to buy a cover for a new sewage system that has just been built. Whatever the need is for buying these covers, it is important to make sure that you go for the best quality covers - covers that come with a guarantee for durability for a long period of time. Some of the things, which you may need to consider while buying these covers are listed as follows.

Source

Size

The classification of manhole covers in respect to size is done on the basis of clear opening size. It is the size which is needed for the cover to completely cover the hole. The edges of the cover should fit perfectly on the linings of the hole. If you are buying a replacement cover, you should measure the frame of cover accurately as time and decay can possibly bring a change in size of the hole. In case the frame is bigger than the cover bought, you can chip off some of the surrounding concrete until you get the perfect size.

Holding Capacity

When using a manhole cover, it is important that you determine whether the cover will come in contact with any heavy machinery or vehicle. If yes, then you should get a cover that has the ability to sustain the weight of the machine/vehicle without any damage. In most cases, such incidents happen in commercial properties like companies or industries. A concrete cover that is reinforced with steel or other hard metals may be ideal for use as manhole covers which come in contact with heavier weights. There are different types of covers that come with varying holding capacities in the form of tons.

600mm Round manhole cover D400
600mm Round manhole cover D400 | Source

Cover Materials

There are many types of manhole covers manufactured by companies using various type of materials and designing techniques. Some of these materials include the following:

1. BMC Covers

Bulk Molding Compound (BMC) is a composite material that is used in the manufacture of BMC covers. Elements used in the making of BMC covers include steel bars, polyester resins, calcium carbonate, glass fiber and trasys. The best thing about covers of this type is that they come with smooth surfaces and have great uniformity in their designs. However, their loading capacity is a bit limited because they are very vulnerable to friction and cannot sustain heavier weights.

2. SMC Covers

Sheet Molding Compound is yet another composite material used in the manufacture of manhole covers. Elements used in the manufacture of these covers are unsaturated polyester resins, calcium carbonate, glass fiber and additives. The manufacturing process of these covers is much complex as compared to Bulk Molding Compound covers and equally more expensive. These covers come with incredibly smooth surfaces but they are still quite susceptible to friction. So, they are not fit for use in areas with heavy loading capacities.

3. Fiber Reinforced Plastic Covers

Fiber Reinforced Plastic materials are considered best for manufacturing manhole covers. Covers manufactured using FRP materials contain polyester resin, quartz, two unique additives and glass fiber. Although their manufacturing is complex, however they come with quite smooth surfaces and are resistant to wear and tear. Their load ability is extremely very high and they have a long lifespan which makes them durable in the long-term.

400X600 Square sewer cover B125
400X600 Square sewer cover B125

4. Concrete Covers

These are the most common types of manhole covers found in residential properties and other properties where load capacity is low. They are quite easy to manufacture and only require concrete which is then reinforced with steel for strengthening purposes. The lifespan of these covers is low as compared to FRP covers. It is primarily because concrete is susceptible to friction and wear. Additionally, extreme weather conditions such as extreme heat and heavy rain also affects the durability of these covers especially if they are not constructed properly.

There is a new trend as far as manufacturing and use of manholes is concerned. This is where precast concrete covers are slowly replacing the other types of manhole covers currently available in the market. The precast manhole covers have been constructed exclusively using the latest technological advancements and modern techniques. It has made it easier for covers to come in superior quality and in great definition in terms of designs and shapes. The best thing is that they are resistant to extreme weather conditions, which makes them durable for many years to come.

When shopping for the best manhole covers, you should mainly focus on durability, flexibility in terms of use and cost effectiveness in the long-term. The more a cover is durable, the easier it becomes for it to sustain friction and wear out in the long run.

As far as Installation is concerned, it must be done in a professional manner. It ensures that quality of the cover is not affected by any means possible! The edges of the cover should be also aligned perfectly on the frame to ensure that it fits properly.

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    • pctechgo profile image

      pctechgo 3 years ago from US

      I had to do a double-take at the title of this hub as I was hopping through. It is certainly an innovative topic. In my area, manhole covers come in one size and shape, round - at least that is what I believed to be the case.

      Until coming across this hub, I thought it was one size fits all . Now, because of this hub, I will certainly have to take a closer look at covers to see if I catch any differences amongst them - at least when I'm in a large city again where covers are plentiful. It will be a quick look only however as I will have to remain mindful of oncoming traffic.

    • briscover profile image
      Author

      Rock Yuan 3 years ago from Changsha,China

      I think the most important thing for manhole cover is its load ablity.

    • pctechgo profile image

      pctechgo 3 years ago from US

      I always though they were all round. Round covers are supposed to be stronger covers just because of their roundness.

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