Secondary seal for tank having floating roof

Abstract

An arrangement for sealing the space between the outer rim of a floating roof and the inner wall of a tank includes a primary seal coupled to and extending between the inner wall of the tank and the rim and a secondary seal mounted on the rim of the roof and extending upwardly and outwardly and into contact with the inner wall of the tank above the primary seal. The primary seal comprises a flexible vapor barrier element. The secondary seal is made highly flexible and readily able to conform to the inner wall of the tank by use of a support structure in the form of a plurality of support plates mounted on the rim of the roof in side-by-side relation with overlapping but unjoined edges. The support plates support and force a pair of wipers mounted on top of the plates into contact with the inner wall of the tank. The support structure is made vapor-impermeable by a flexible vapor barrier mounted at one end between the rim of the roof and the lower ends of the support plates and extending along the support plates and between the tops of the plates and the wipers so as to wrap at least partly around the wipers. The vapor barrier seals the region between the rim of the roof and the wipers and at the same time is protected from weather and sunlight by the support plates. Relatively free flexing of the wipers so as to conform to the relatively continuous inner wall of a welded tank is provided by breaks in each wiper which are spaced apart along the length thereof and yet staggered relative to the breaks in the other wiper to seal the area between the top of the support structure and the inner wall of the tank.

Dependencies are inferred from the claim text.