Call Rick Martin, Patent Attorney 800-575-8263 TANCO ENGINEERING, INC. An established oil and gas storage tank roof manufacturer uses the Patent Law Offices of Rick Martin, P.C. for patent prosecution and licensing. U.S. Patent No. 5,284,269 The space saving double seal uses a lower shoe, and an upper shoe and a pair of vapor barriers joining them to a conventional outer rim plate on a floating roof. The secondary vapor barrier extends from the outer rim plate to the top of the upper shoe. A pair of pusher springs maintain the shoes against the tank's inner wall. The invention provides for liquid storage to the full height which the floating roof allows. CLOSE THIS WINDOW