The non-sanded version of the DURAN® spherical ground joint only seals over the sealing ring. Basically 2 versions of the sealing rings are available: - FEP-coated silicone rings - VITON sealing rings The nominal size is composed of the nominal diameter of the spherical ground joint and, if applicable, the clear width of the pipe diameter. This variant also enables flexible connections, these are in the angle range of 10-15°.