Mechanical shoe seal
Mechanical shoe seal or metallic shoe seal means a rim seal consisting of a band of metal (or other suitable material) as the sliding contact with the wall of the storage vessel, and a fabric seal to close the annular space between the band and the rim of the floating roof deck. The band is typically formed as a series of sheets that are overlapped or joined together to form a ring. The lower end of the band extends into the stored liquid.
40 CFR § 63.1061
All terms used in this subpart shall have the meaning given them in the Act and in this section.