A rotary valve is provided for use in highly corrosive and abrasive applications. The valve includes a valve body and an adapter coupled to one end of the valve body, thereby defining an inlet, an outlet, and a valve interior in fluid communication with the inlet and the outlet. The valve also includes a floating ball element pivotably mounted in the valve interior via a valve stem to control fluid flow through the valve, a first valve seat movably disposed in the valve interior, and a second valve seat removably disposed in the valve interior. The first valve seat is biased toward the ball element to sealingly engage a first portion of the ball element. The second valve seat is configured to sealingly engage a second portion of the ball element and is clamped between a surface of the valve body and a surface of the adapter.