Embodiments of a flapper valve assembly are provided. In one embodiment, the flapper valve assembly includes a flowbody, a flapper valve element, and an elongated stiffening rib formed in the flowbody. The flowbody includes a generally flat plate portion, and an arcuate portion adjacent the generally flat plate portion. The flapper valve element is hingedly coupled to the flowbody proximate the generally flat plate portion. The elongated stiffening rib extends from the generally flat plate portion to the arcuate portion to distribute mechanical stress and to reduce deflection of the flowbody during pressure loading.