Types Of Manhole Covers
Manhole covers (
دریچه منهول ( are mainly divided based on the type of materials used in it. In this article, we will discuss the most important types of manhole covers:
NANOCOMPOSITE Composite
Improving the properties of existing covers as well as building new covers that have fewer disadvantages and more advantages than previous models, has always been the goal of researchers and manufacturers in this field. Nanocomposite covers, the newest generation of manhole covers on the market, have gradually found their place in the oil and gas, telecommunications, water and sewage, electricity and industrial plants. The reason for the growing popularity of these covers is that while they are cheaper than other covers on the market, they have all the desirable features for a manhole cover such as anti-theft, long life, low weight and high mechanical and hydraulic resistance.
Among the advantages of nanocomposite covers can be mentioned the following:
Very economical and reasonable price compared to other covers in the country
High durability and useful life (more than 50 years)
Resistant to shock and high pressures
Resistant to corrosion and rot
High resistance to the sun's UV rays
Resistant to water penetration into the middle and stable layers against freezing-thawing
Anti-theft due to its resemblance to concrete and high malleability
Flame resistant
Resistant to slipping and abrasion
Possibility of installation and operation in the temperature range of -60 to +250 degrees Celsius
Less weight than cast iron and concrete covers
Ability to connect to any type of concrete, clay, metal, cast iron, steel and PVC manhole
Variety of colors and designs of the cap according to the principles of beautifying the city
Ability to register the trademark or name of the end user institution on the product
No sound when passing the vehicle
Can be found by metal detectors if buried
Production capability in all 6 resistance categories (from A15 to F900)
One of the disadvantages of most manhole covers (such as polyethylene and composite covers) is that they cannot be found with a metal detector if buried under the road. Nanocomposite covers, on the other hand, are easily found by metal detectors due to the presence of steel fibers in their composition.
CAST IRON MANHOLE COVER
Due to its reasonable price and high strength, the primary base of all manhole covers has long been made of cast iron and has been used for a variety of electrical, telecommunications, water and sewage, gas and urban applications. For this reason, even today, many do not believe in what kind of manhole is used for what purpose, and if a material has favorable conditions, it will be used in all applications.
Manhole cast iron covers are divided into two categories: gray and ductile iron. Ductile iron manhole covers have a higher impact resistance than gray cast iron and therefore less weight, and therefore, they are easier to move and install than gray covers. But the higher cost of ductile covers is a factor that sometimes makes gray cast iron covers more widely used, despite being heavier and more fragile.
Disadvantages of cast iron covers include the following:
Rust and rot in humid environments
High weight and high handling and installation costs
More price than other types of manhole covers
Generate sound when passing a vehicle
Inability to produce in different colors