Section 147.66 - [Effective until 10/18/2024] Inert gas fire extinguishing systems(a) Inert gas cylinders forming part of a clean agent fixed fire extinguishing system must be retested every five years, except that cylinders with a water capacity of 125 pounds or less may be retested every 10 years in accordance with 49 CFR 180.209(b) .(b) An inert gas cylinder must be removed from service if it:(2) Is dented, bulging, severely corroded, or otherwise weakened;(3) Has lost more than 5 percent of its tare weight; or(4) Has been involved in a fire.(c) Flexible connections between cylinders and discharge piping for fixed inert gas fire extinguishing systems must be renewed or retested in accordance with section 7.3 of NFPA 2001 (incorporated by reference, see § 147.7 ).USCG-2006-24797, 77 FR 33886, June 7, 2012