Vapor seal for floating roof tank

Abstract

In a storage tank for liquids, such as petroleum liquids and the like of the type having a generally upstanding cylindrical tank wall and disposed within the wall a generally circular roof therefor adapted to float upon the contents of the tank in vertically movable relation according to a variation in the volume of such contents so as to define a clearance space being defined between the inner wall surface and the outer peripheral rim of said floating roof, an improved vapor seal for said clearance space comprising an elongated resilient pad extending circularly around the inner face of the tank wall with its long axis in generally upstanding relation to the tank top and its outer face at least partially in contact with the wall, such pad having an exterior surface constituted of durable material resistant to attack by the liquid being stored and being supported by a plurality of supports arranged at spaced points around said roof rim, each such support having a base section affixed to the roof rim, a substantially rigid arm hingedly connected at its lower end to the base section and extending generally upwardly therefrom, an extension at the upper end of the arm in engagement with the inner face of the pad, and means for biasing the arm outwardly from said base to urge the outer face of the pad against the tank inner wall; and a circular skirt of flexible impervious material substantially sealed along its top and bottom edges respectively to the lower end of the pad and the tank rim and spanning therebetween.