The Graver Primary Tank Seal (GVR) can be used on either external floating roofs or internal pan decks. This seal design has been used on tanks of long range of diameters, containing the full range of Crude and Refined products, though it is not generally used with Waxy Crudes. This Tank Seal is designed to enable installation and removal to be carried out from the top of the roof. The sealing effect between the roof and the tank shell is achieved by the use of special octagonal foam sections. The foam sections are held in position by an internal hold-down plate.