The polyethylene ring is a ring which has a soundproofing function.
It's necessary to be ensured, during the handling of covers and notably before the closing, that the polyethylene ring is free from dirtinesses and to clean if it's necessary.
The presence of dirtinesses (for example small stones) between the cover and the ring involves the premature degradation of this one.
In the event of degradation, it's imperative to change the ring quickly.
The change is carried out by unsnapping of degraded ring and reinstallation of a new ring adapted to the manhole cover.