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2022-08-12

Most manhole covers consist of cover itself and a frame. The manhole cover and frame are placed on a precast concrete or composite manhole. The frame to a specified height set to suit the surrounding paving or ground level and the cover inside the frame. and the cover and frame are enclosed surrounded by a steel frame base and backfill concretes or asphalt. 

The precast concrete /composite manhole is to redistribute the transmitted load to protect the manhole cover from breakage. The supporting manhole base and frames reduce the load on the cover 10 (ten) times. The scheme below shows the mounting sequence for the assembled manhole

NOTE!

 

The ring with the cover is placed on the reinforced concrete base/cone and not on the shaft covering plate.

Do not place the ring (frame) directly on the shaft plate or on the base of brickwork. Due to constant loading and under aggressive environmental conditions the bricks (masonry) under the pressure from the ring on the cover are destroyed and the cover along with the ring drops below the road surface level. Due to its incorrect position / incorrect supporting surface, the ring flange breaks leading to the destruction of the shaft plate and an overhaul of the sewerage system. The resulting repair works create problems for the road users, cost a lot of money, and can lead to traffic accidents.

The cover of the manhole shaft should be installed on the same level as the carriageway. No element of the manhole shaft should protrude above the road surface to avoid shock loading and vevehicle damage.

Manhole cover tilting during mounting is not allowed. This will result in its dropping and formation of bumps, provoking the destruction of the cover and damage to the vehicles.

When installing manhole covers, use only certified manhole units, factory-made from precast concrete. When a manhole cover is broken, debris and garbage might clog the sewer system. And hazardous to people and vehicles.

  

How to install a new manhole cover?

  1. It is necessary to measure the height and level of the manhole, determine the reserved depth, and ensure that the manhole cover is flush with the road surface when the installation is completed. Level ruler and lazer ruler can measure out accurate values.
  2. Clean the dirt on the frame seat.
  3. Lay sealing concrete in the valve seat area with a thickness of less than 40mm. If the base layer is made of bricks, it should be moistened with water in advance.
  4. Put the frame on the concrete.
  5. Hit with a mallet to make the frame level. Adjust the frame to the same height as the ground. When adjusting, use a wooden hammer to press down on the frame to ensure that the sealing concrete is evenly and firmly applied to the sealing area of the frame. Depending on the degree of inclination of the road, use wedges, hooks, or other systems that can maintain stability in the next stage to level it.
  6. Clean up the spilled concrete from the edge of the opening in the frame fixing place.
  7. Install the cover on the frame.
  8. Pour concrete into the gap between the frames and dig a hole until the concrete is poured into the same level.
  9. After the concrete is finally set, clean the installation site and maintain it for no less than 7 days before use.

 

During installation, the base must be kept flat and the manhole cover frame should be on the ground as a whole and should be stable and sturdy.

When adjusting, use a wooden hammer to press down on the frame to ensure that the sealing concrete is evenly and firmly applied to the sealing area of the frame.

If there are screw holes, use expansion bolts to fix the inspection manhole cover frame.

After covering the manhole cover, pay attention when sealing the surrounding with concrete or asphalt. Concrete or asphalt cannot stick in the gap of the manhole cover, nor can it directly cover a part of the manhole cover. Therefore, the manhole cover cannot be lifted later.

Replace a broken manhole cover

The same procedure applies if you are replacing a broken manhole cover, but the debris and cut construction waste from the road should be handled properly. The backfill must use new mortar and bitumen because old materials lack of strength to hold the manhole cover and frame, as well as to support it when vehicles pass.

Select manhole cover and frame 

The composite manhole cover, from the frame can be lifted and possibly removed when access to the manhole is required. The outer frame of the manhole screws to the plastic riser to hold it in place. The lid then sits back into the frame and has securing screws to ensure the lid lock the frame. 

The Right Manhole Cover and Frame Installation

 Manhole Cover and Frame Installation

Cast iron manhole covers. These covers need to be heavy so that when vehicles drive over them, they do not become dislodged. The cover and frame are designed with a locking system for cleaning and safety considerations. The cast iron covers are plated or coated to prevent corrosion.

 

 

 

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