A rotary valve includes a valve body with an inlet, an outlet, a flow passage extending between the inlet and the outlet, and a rotating control element disposed within the valve body for selectively opening and closing the flow passage. The valve also includes a retainer ring mountable to the valve body which holds in place a seal carrier ring having an annular mounting flange mounted between the valve body and the retainer ring. The seal carrier ring also includes a seal carrier cartridge and a flexible portion coupling the seal carrier cartridge to the mounting flange to provide an improved seal and greater ease of assembly.