Metallic shoe seal
Metallic shoe seal or mechanical shoe seal means metal sheets that are held vertically against the wall of the storage vessel by springs, weighted levers, or other mechanisms and connected to the floating roof by braces or other means. A flexible coated fabric spans the annular space between the metal sheet and the floating roof.
40 CFR § 63.111
All terms used in this subpart shall have the meaning given them in the Act, in subpart F of this part, and in this section, as follows.