The manhole cover is a removable disc which is consisted of a lid which is placed on the opening of the manhole, to prevent individuals from falling inside. Composite manhole covers are made of the mixture of polymeric resins, silica fibers, calcium carbonate, color pigments, peroxide and other chemicals.

The popularity and tendency of replacing metal covers with composite manhole covers, due to reduction of the costs caused by the theft of cast-iron covers, high mechanical and hydraulic resistance, chemical resistance, decent appearance, resistance against corrosive sewer gases and being erosion-proof, is on the rise. 

 

Composite Covers’ Benefits Against Metal Covers:

  • Having less weight than cast-iron covers 

  • Theftproof

  • Having consistency and long life span

  • Resistant against corrosion and erosion 

  • Resistant against UV rays 

  • Variety in color and design

  • Could be lifted by one person

  • Doesn’t make sound when vehicle passes on the composite cover

  • Lacking the possibility welding between composite manhole cover lid and coil fusion

 

Composite Manhole Cover’s Safety and Quality Tips:

Not electrically conductive

thermal insulator

not moving (slipping) more than 6% according to standard-ASTM C1028 

less than 1/16 inches of dimensional deviation

 

Classes

Group 1: Sustaining 1.5 tons only for courses of pedestrians and cyclists (A15)

Group 2: Sustaining 12.5 tons for pavements, pedestrian zones and such, and parking zones (B125)

Group 3: Sustaining 25 tons for the street curb margins, at most 0.5 meters to the roadway and 0.2 meters to the pavement (C250)

Group 4: Sustaining 40 tons for the roadway of main streets (D400)

Group 5: Sustaining 60 tons for areas of heavy vehicles’ passage such as docks and airports (E600)

Group 6: Sustaining 90 tons for special areas sustaining heavy vehicles such as airports (F900)

Comparing cast-iron manhole covers with composite manhole covers

Cast-iron Manhole Cover

Composite Manhole Cover

Might be stolen due to recyclability and possibility of resale

Theftproof due to impossibility of recycling or resale

Difficult to carry due to heaviness

Can be carried easily due to lightness

May cause damage when dropped due to heaviness

Low probability of causing damage when dropped due to lightness

Low durability due to low resistance against blow and corrosion

High durability (more than 30 years) due to high resistance against blow and corrosion

Low potential of embellishment due to little color variety

High potential of embellishment due to the vast variety of color use and practicable designs on the outer surface

Extra cost for implementing a corrosion protective cover

Not requiring an extra cover in order to be protected against corrosion

High expense of epoxy coloring

Not requiring the use of epoxy pigment colors for embellishment due to existence of pigment in composite’s ingredients

Delamination of the epoxy covering due to sunlight

Resistant to sun due to existence of pigments in resin