49 CFR § 179.202-7 - Jackets.

The entire thermal protection system must be covered with a metal jacket of a thickness not less than 11 gauge A1011 steel or equivalent; and flashed around all openings so as to be weather tight. A protective coating must be applied to the exterior surface of a carbon steel tank and the inside surface of a carbon steel jacket.

[80 FR 26749, May 8, 2015]