Abstract: A gravity closed swing check valve is provided in which the downstream surface of the solid clapper is semi-spherical and convex. The body of the valve forms a concave semi-spherical cavity. The radii of the clapper and cavity surfaces is the same. The clapper is positioned so that its downstream surface bears evenly across the surface of the body cavity, when the clapper is in the fully open position. Thus the cavity surface of the body acts as a stop for the clapper and the area of stop surface is relatively large. Impact damage is reduced as a result.