TVR T System relief cones, rings and (foundation) slabs made from plastics are elements used to construct surface finials of manholes and non-manholes installed in areas of vehicle traffic, as well as outside of it, marked with T3 and T04 symbols, and in class A15, B125, and D400. Elements relieving shafts of ascending pipes of plastic wells and concrete rings simultaneously allow to adjust the height of a well and constitute as a protective element and element allowing to support/install well finial. They also constitute as a support for telescopes of plastic wells and foundation for installing compensation rings and adapters. The structure of relief rings and cones is compatible with the upper elements of appropriate sewer and rain water manhole made a c c . t o P N – E N 1 9 1 7 : 2 0 0 4 a n d PN-EN 13598-2:2009. As the construction surface elements of plastic wells, they meet the suitability for use conditions determined, among others, in PN-EN 14802:2005.
- moving traffic loads influencing the manhole and nonmanhole finials, and street drains outside of the shaft of a well to the construction layers of ground or road surface,
- securing a sewer manhole shaft against damages resulting from vehicle traffic both in horizontal and vertical plane,
- adjusting the height of a sewer manhole to the roadsurface ordinate,
- reducing the free clearance and internal diameter of shaftpipe (chimney) of a manhole, inspection chamber, or street drain,
- creating a construction support (base and foundation) for compensation rings, adapters, as well as directly for manhole and street drain finials and for recreated or installed anew road surface around the finial of a street drain or manhole.