Vapor seal for floating roof tank

Claim 1

In a storage tank for liquids such as petroleum liquids and the like, comprising a generally upstanding cylindrical tank wall and disposed within said wall a generally circular roof therefor adapted to float horizontally upon the contents of the tank in vertically movable relation according to a variation in the volume of such contents, a clearance space being defined between the inner wall surface of said tank and the outer peripheral rim of said floating roof, in combination, an improved vapor seal for said clearance space comprising a resilient pad extending annularly around the inner wall surface of the tank in vertically spaced relation above the roof rim, said pad being elongated in vertical cross section with a height substantially greater than its thickness and having two oppositely facing tall faces extending between upper and lower ends, said pad being arranged with its height direction extending generally vertically so that one of said tall faces faces generally radially outwardly and the opposite tall face faces generally radially inwardly; a casing constituted of durable material resistant to attack by the liquid being stored tightly enveloping said pad in generally tubular fashion and having sections thereof generally coextensive with the tall pad faces, at least one of which sections is adhered to the corresponding pad face; a plurality of supports for the annular pad arranged around said roof rim in peripherally spaced apart relation, each of said supports comprising a base affixed to the roof rim, a substantially rigid arm hingedly connected at its lower end to said base and extending generally upwardly therefrom, a separate extension at the upper end of said arm, a hinged connection between the upper end of said rigid arm and the lower end of said extension, and means for biasing said extension generally radially outwardly of said arm about said hinged connection; means anchoring said extension to the casing section corresponding to the inwardly facing tall pad face over more than half the tall dimension thereof; means for biasing said arm outwardly from said base to urge the outer face of the pad toward said tank inner wall; and a skirt of flexible impervious material extending from the casing to the tank rim to close the space therebetween.