StacksVerified U.S. regulatory reference

49 CFR §179.202-4

Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗
The wall thickness after the forming of the tank shell and heads must be, at a minimum, 9/16 of an inch AAR TC-128 Grade B, normalized steel, in accordance with § 179.200-7(b).