The invention relates to a valve seat and cage assembly (18) comprising a valve cage (20) and a valve seat (22), the valve seat (22) being adapted to be screwed into the valve cage (20), which valve cage (20), in a connection portion (34) thereof, has a valve cage connection inner diameter (DK) in which the connection portion (32) of a valve seat (22) engages with its valve seat connection outer diameter (DV) and thus provides radial centering, a screw connection portion (37) and a shoulder (38), with the shoulder (38) serving as an axial stop between the valve cage and the valve seat, and with the valve seat (22) and the valve cage (20) being pressed against one another with an axial contact pressure component. The invention is characterized in that the screw-connection portion is located between the connection portion (32) and a shoulder (38), with the valve cage connection inner diameter (DK) and the valve seat connection outer diameter (DV) forming a fit with one another that will act to center the valve seat and the valve cage.