Design temperature below −55 °C (−67 °F) and down to −165 °C (−265 °F).

Plates, forgings and forged or rolled fittings, and rolled, forged or extruded bars and shapes for cargo tanks, secondary barriers, and process pressure vessels for a design temperature below −55 °C (−67 °F) and down to −165 °C (−265 °F) must: (a) Meet § 54.25-10(b)(2), § 54.25-15, or § 54.25-20 of this chapter; or (b) Be of an aluminum alloy that is specially approved by the Commandant (CG-ENG). [CGD 74-289, 44 FR 26009, May 3, 1979, as amended by CGD 82-063b, 48 FR 4782, Feb. 3, 1983]