A control valve having a seat ring assembly constructed from a unitary piece of material is disclosed. The seat ring assembly may include a base which serves as a valve seat for the valve plug of the valve, and which includes a plurality of exterior threads adapted to rotatably attach to a plurality of interior threads provided within the valve body. The seat ring assembly may also include a post-guided bearing surface to maintain alignment of the valve plug to the valve seat. The seat ring assembly can be secured to the valve body simply by threadably attaching the elements. Moreover, by providing the valve seat and the guide surface as integral parts of the seat ring assembly, manufacturing costs and maintenance requirements are reduced and subsequent seal leak performance is increased.