An upstream seat ring and an auxiliary seat ring, which improve valve's capability resistant to erosion by the fluid carrying solid particles or containing liquid drops. One end of the auxiliary seat ring passes through bore of the upstream seat ring and the other end is fixed in the pocket of the valve upstream passageway. There are many bar barriers or analogous mechanism with rectangular, tooth-like or any other geometrical shapes cross-section around the circumferential surface of their bores, which are radially concaved inward or projected outward from the circumferential surface, are longitudinally extended an overall distance from one radial end face of the seats to opposite radial end face or a distance from the radial end face next to the upstream surface of the valve closure member towards the opposite radial end face, and spaced each other radially.