Secondary seal for floating roof storage tank

A floating roof storage tank comprising an upstanding cylindrical tank shell for containing a quantity of liquid to be stored, a floating roof within said tank shell and adapted to float on the surface of the liquid within said tank shell, a circular metal shoe encircling said floating roof and slidably engaging the inner surface of said tank shell, pusher structure mounting said metal shoe upon said floating roof and urging said metal shoe into sealing contact with the inner surface of said tank shell, a sealing member extending between said floating roof and said metal shoe and closing the space therebetween to provide a primary seal therebetween, a plurality of seal support members shiftably mounted upon said metal shoe adjacent to the upper end thereof and shiftable toward and away from the associated tank shell, limit means acting between said metal shoe and said seal support members to limit the shifting of said seal support members toward and away from said metal shoe and said tank shell to prevent contact of said seal support members therewith, and flexible means extending between said floating roof and said seal support members and secured thereto and extending beyond said seal support members and lying in sealing engagement with the inner surface of said tank shell to form a secondary seal between said floating roof and said tank shell, said seal support members being shiftable toward and away from said tank shell to accommodate variations in position of said floating roof with respect to said tank shell and being shiftable away from said tank shell to disengage said limit means and to move said flexible means out of contact with said tank shell a distance to permit inspection of the primary seal.

A floating roof storage tank comprising an upstanding cylindrical tank shell for containing a quantity of liquid to be stored, a floating roof within said tank shell and adapted to float on the surface of the liquid within said tank shell, a circular metal shoe encircling said floating roof and slidably engaging the inner surface of said tank shell, pusher structure mounting said metal shoe upon said floating roof and urging said metal shoe into sealing contact with the inner surface of said tank shell, a sealing member extending between said floating roof and said metal shoe and closing the space therebetween to provide a primary seal therebetween, a plurality of seal support members shiftably mounted upon said metal shoe adjacent to the upper end thereof and shiftable toward and away from the associated tank shell, flexible means extending between said floating roof and said seal support members and secured thereto and extending beyond said seal support members and lying in sealing engagement with the inner surface of said tank shell to form a secondary seal between said floating roof and said tank shell, and a wiper member mounted on said seal support member and extending outwardly therefrom and engaging the inner surface of said tank shell to form another secondary seal therewith, said seal support members being shiftable toward and away from said tank shell to accommodate variations in position of said floating roof with respect to said tank shell and being shiftable away from said tank shell to move said flexible means and said wiper member out of contact with said tank shell a distance to permit inspection of the primary seal.