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.