A duct has: a first non-metallic member extending between a first end and a second end, at least at the first end having an outwardly-projecting flange portion; a metallic flange member having a sleeve extending between a first end and a second end and a flange extending outward from the sleeve and having a first face and a second face; and a second non-metallic member extending between a first end and a second end having an outwardly-projecting flange portion, the first non-metallic member flange portion mounted to the flange first face and the second non-metallic member flange portion mounted to the flange second face.