Seal for floating roof tank

Claim 1

In a floating roof tank having a vertical wall of circular shape adapted to contain a stored volatile liquid, a buoyant roof floating on said stored liquid and extending to the interior side of said wall and a dependent sealing element extending downwardly from the periphery of said roof to engagement with said wall, an auxiliary seal mounted on the periphery of the upper surface of said roof and spaced above said dependent sealing element thus defining a vapor space between said dependent sealing element and said auxiliary seal, said auxiliary seal being constituted by a plurality of substantially horizontal layers each constituted by a plurality of segments of which the adjacent ends are overlapped, said layers being vertically spaced one from the other and having the edges thereof remote from said roof in engagement with said wall, and closure means connecting the inner edges of said layers to said roof adapted to inhibit leakage from spaces defined by said layers; the improvement wherein the said horizontal layers are radially slit from the edges thereof adjacent said wall to a region intermediate said edges and said closure means to form a plurality of radial fingers engaging said wall.