Abstract: A seal is described herein for covering the rim space of a cylindrical tank container having a floating roof laterally spaced from the interior wall of the tank. The seal includes a flexible shield, preferably of metal, having one end rigidly connected to an upper portion of the floating roof and a second end extending outwardly from the roof and toward the interior wall of the tank. A flexible wiper blade is connected to the extending end of the shield for engaging the inner surface of the tank wall. The combined shield and wiper blade extend from the upper portion of the roof toward the interior tank wall at an acute angle A with respect to the horizontal, with the length of the shield being greater than the average rim space dimension divided by the cosine of the angle A. Covering the shield is a flexible, light-reflective, gas impermeable fabric which extends continuously around the perimeter of the roof.