Abstract: Two half-discs of a flapper type check valve are mounted on an internally supported shaft in a two piece valve body to swing from a coplanar closed position to a back-to-back relationship when the valve is fully open. Stops integrally formed within a bell-shaped downstream part of the valve body engage mating parts of the half-discs when the valve is in fully open condition with the half-discs so positioned behind a transverse rib that there is no interference with flow. The two pieces of the valve body each have external circumferential grooves for easy attachment to other piping elements.