Abstract: The duct assembly of the present disclosure includes one or more air impingement ducts and a plenum plate for receiving the impingement duct. Each impingement duct includes a housing, a columnating plate with one or more columnating orifices, and a cover plate with one or more cover orifices. The housing, columnating plate, and cover plate are arranged in stacked arrangement, and collectively define an interior space in the duct. Heated air is passed through the interior space and out through the orifices. At least one of the plenum plate, housing, columnating plate, and cover plate includes a mechanical feature that mates with a corresponding feature on another of the duct components, to ensure that only specific duct components can be assembled together. In one embodiment, the columnating plate includes a pin protruding with an end that mates with a corresponding notch on the cover plate.