A sealing system for a liquid storage tank having a roof freely floating on the contents stored within the storage tank. The sealing system is in wiping contact with the tank shell and may utilize a primary and a secondary seal. As a primary seal, the system forms a seal above the liquid level and eliminates capillary action of the liquid between the seal and the tank shell. The sealing system also exerts a continuous pressure against the inner walls of the storage tank preventing the storage tank roof from shifting due to wind loading and effectively preventing vaporization of the liquid due to wind effected negative pressures. As a secondary seal, the system acts as a vapor barrier preventing vapors from escaping and preventing contaminants from entering into contact and deteriorating the primary seal which could result in contamination of the liquid contained within the storage tank.
