A flange structure (10′) for a fuel supply unit of a vehicle includes at least one electrically conductive fuel port (16′) having first and second ends (22, 24) and features (25, 26) defining a channel (28) about a periphery thereof. An elastomer seal (30) is disposed in the channel. A plastic flange (20′) is overmolded on at least a portion of the fuel port between the first and second ends and on at least a portion of the elastomer seal, with the elastomer seal defining a barrier preventing fuel or fuel vapor from passing between the periphery of the fuel port and the overmolded flange.