What Is a Protective Cover?
Protective Covers are used to protect the covers of vertical pipes such as manholes and hoardings. The upper end of a vertical water or sewage pipe has a hole for maintenance and cleaning, and if a load is applied to the covering, it may be damaged.
Protective coverings are classified according to their load capacity, and those that can withstand higher loads should be selected for installation in areas where large vehicles pass. The surface of the protective lid is installed so that it is at the same height as the road surface so that there are no steps on the road surface.
Uses of Protective Covers
Before wastewater from homes and businesses is discharged into the public sewer system, it is passed through a vertical pipe called a hoarding or pit. Once passed through the vertical pipe, large debris is allowed to settle out, preventing clogging of the sewer system.
Public sewers also have manholes for administrative purposes, and vertical pipes lead to waterways.
The tops of these vertical pipes have holes for internal maintenance and cleaning and are usually sealed with protective covers.
Principle of Protective Cover
The protective cover consists of a metal lid and a plastic base.
The load capacity of protective covers varies from product to product.
- T25: Withstands up to 25 tons. Used on roadways where vehicles of 14t or more pass through.
- T14: Withstands up to 14 tons. Used on roadways with few large vehicles.
- T8: Withstands up to 8 tons. Used on sidewalks and grounds where large vehicles will not pass over.
When installing the protective cover, the following points should be considered:
- To prevent the protective cover from coming into contact with the vertical pipe lid when it settles under load, a space of about 15 cm should be created between the lid of the vertical pipe and the protective cover.
- Install the protective cover so that its surface is at the same level as the road surface.
In order to meet the above requirements, the top opening of the vertical pipe is installed at a location that is excavated at least 15cm below the ground surface. A protective lid is placed on top of it, and the height of the pedestal is adjusted with granulated soil so that the surface of the protective lid is at the same height as the road surface.
Construction
When a new water pipe is installed or the protective cover needs to be replaced, a contractor is hired to install it.
The specific construction work for Protective Covers is carried out in the following steps:
- Foundation: Dig down around the top of the pipe to make room for the Protective Cover. To prevent the foundation from settling, granulated crushed stone is placed and carefully compacted. Grain-size-adjusted crushed stone is a rock that has been crushed and sieved to a uniform grain size. Because of its strength, it is used for the foundations of roads and railroad tracks.
- Installation: A pedestal and protective cover are placed on top of the foundation. Protective Covers should be installed level with the ground. If the ground itself is inclined, the inclination should be adjusted within the allowable inclination angle for each product.
- Backfill: Backfill around the piping and protective cover using granulated crushed stone or asphalt.
Locking and Baghole Types
Protective Covers are divided into Locking and Baghole types, depending on how they open and close. When opening the protective cover for inspection or cleaning, it is helpful to keep in mind the differences between the two types to avoid confusion.
- The locking type has a mechanism to secure the lid. The locking mechanism varies from product to product. Some have a key operated by a flat-blade screwdriver, while others have a hook-type bridle that is opened and closed with a crowbar. When opening, check the locking mechanism and use the appropriate method to unlock. When closing, if the lid is misaligned, it may not lock. Close the lid and lock it so that it does not move, and check that it is fixed.
- The baghole type is not equipped with a mechanism to secure the lid. There is a hole called a blind hole in the part where the lid and the pedestal meet. The operation is simpler than the locking type, but since there is no lock operation when closing, even if the lid is misaligned, it may be overlooked. Please be aware that if the lid is left in place, it may cause rainwater to flow in through the gaps or bad odors to leak out.