Fluid-sealed sheet metal joint

Claim 1

A fluid-sealed sheet metal joint having an axis and comprising: a first sheet having an edge, and along said edge a first turned-under flange; a second sheet having an edge, and along said edge a second turned-under flange; a clip having a base with two parallel edges, and along a first of said edges a first turned-over flange, and along the second of said edges, a second turned-over flange; and a core having a cap with two parallel edges, and along a first of said edges a first U-shaped flange, and along the second of said edges a second U-shaped flange, said U-shaped flanges having respective first and second bights, and first and second upper and lower arms, said first and second turned-under flanges being disposed between the respective first and second turned-over flanges and the first and second lower arms; said first and second turned-over flanges being disposed between the respective first and second sheets and the first and second turned-under flanges; said first and second lower arms being disposed between said first and second turned-under flanges and said base; said first and second upper arms respectively bearing against said first and second sheets, said joint being pressed flat at least adjacent to the edges of the cap, the cap and upper arms being flat against each other, and the upper and lower arms, the sheets, the turned-under and turned-over flanges and the clip base adjacent its edges all being substantially parallel, whereby the parts recited as disposed relative to one another are in contact with one another along at least respective lines of contact parallel to the said edges.