49 CFR 173.163
Hydrogen fluoride.
Hydrogen fluoride (hydrofluoric acid, anhydrous) must be packaged in a specification 3, 3A, 3AA, 3B, 3BN, 3E, or 4A cylinder; or a specification 4B, 4BA, or 4BW cylinder if the cylinder is not brazed. Filling density may not exceed 85 percent of the cylinder's water weight capacity. In place of the periodic volumetric expansion test, cylinders used in exclusive service may be given a complete external visual inspection in conformance with part 180, subpart C, of this subchapter, at the time such periodic requalification becomes due. Cylinders removed from hydrogen fluoride service must be condemned in accordance with § 180.205 of this subchapter and, at the direction of the owner, the cylinder may be rendered incapable of holding pressure.
[68 FR 24660, May 8, 2003]