Abstract: A piston check valve for use in a system which conveys abrasive materials includes a gland nut which connects the valve to the piping system, a valve body mounted on the gland nut, a valve seat mounted on the valve body, and a piston mounted within the valve body. The piston can translate within the through bore of the valve seat and has a shaft and a head which contacts the first end of the valve seat when the valve is closed. A coil spring is located within the through bore of the valve seat and biases the valve closed. A first O-ring is mounted on the first end of the valve seat and is sufficiently wide to prevent sufficient quantities of chips from becoming lodged within the surface of the inner O-ring to form a hard bridge across the resilient O-ring, allowing erosion of the valve sealing surfaces. The first end of the valve seat has an O-ring groove which receives the O-ring. A second O-ring can be mounted on the first end of the valve seat at the outer periphery of the valve seat.