The Primary Delta Seal can be used on external floating roofs or internal floating roofs. This seal design has been used on tanks from 6.0 m. to 91.0 m. in diameter, containing the full range of Crude and Refined products. The design of this joint allows the installation and removal of the latter only from the top of the roof. The effect of the seal between the roof and the tank wall is achieved by the use of trapezoidal sections of special PU foams.