Section 173.198 - Nickel carbonyl(a) Nickel carbonyl must be packed in specification steel or nickel cylinders as prescribed for any compressed gas except acetylene. A cylinder used exclusively for nickel carbonyl may be given a complete external visual inspection instead of the pressure test required by § 180.205 of this subchapter. Visual inspection must be in accordance with CGA Pamphlet C-6 (IBR, see § 171.7 of this subchapter).(b) Packagings for nickel carbonyl must conform to § 173.40 .Amdt. 173-224, 55 FR 52643, Dec. 21, 1990, as amended at 67 FR 51643, Aug. 8, 2002; 68 FR 75742, Dec. 31, 2003