Section 147.65 - Carbon dioxide and Halon fire extinguishing systems(a) Carbon dioxide cylinders forming part of a fixed fire extinguishing system must be maintained as follows:(1) Cylinders must be retested at least every 12 years. If a cylinder is discharged and more than 5 years have elapsed since the last test, it must be retested before recharging.(2) Carbon dioxide cylinders must be rejected for further service when they: (ii) Are dented, bulging, severely corroded, or otherwise in a weakened condition;(iii) Have lost more than 5 percent of their tare weight; or(iv) Have been involved in a fire.(3) Cylinders which have contained gas agents for fixed fire extinguishing systems and have not been tested within 5 years must not be used to contain another compressed gas onboard a vessel, unless the cylinders are retested and re-marked in accordance with § 147.60(a)(3) and (4) .(4) Flexible connections between cylinders and distribution piping of semi-portable or fixed carbon dioxide fire extinguishing systems and discharge hoses in semi-portable carbon dioxide fire extinguishing systems must be replaced or tested at a pressure of 6.9 MPa (1,000 psig). At test pressure, the pressure must not drop at a rate greater than 1.03 MPa (150 psi) per minute for a 2-minute period. The test must be performed when the cylinders are retested.(b) Halon cylinders forming part of a fixed fire extinguishing system must be maintained as follows: (1) The agent weight must be ascertained annually by one of the methods identified in paragraphs (b)(2) through (b)(4) of this section. Measured weights or liquid levels must be recorded and compared with the recommended fill levels and previous readings. If cylinder weight or liquid level, adjusted for temperature, shows a 5 percent loss of pressure, the cylinder must be refilled. If cylinder pressure, adjusted for temperature, shows a 10 percent loss of pressure, the cylinders must be refilled.(2) The cylinders may be removed from the mounting racks and weighed.(3) The contents of cylinders fitted with integral floating dipstick liquid level indicators may be measured with the dipstick indicator.(4) With approval of the cognizant Officer in Charge, Marine Inspection (OCMI), liquid level indication measures such as ultrasonic/audio gauging or radioisotope gauging may be used, provided that all of the following conditions are met: (i) Measurement equipment is calibrated for the cylinder wall thickness and Halon liquid.(ii) Calibration is verified by weighing the cylinders that indicate the lowest levels of Halon in each release group, but in no case less than 10 percent of the inspected cylinders in each release group.(iii) The acceptable liquid level is identified by the original system installer or coincides with all other cylinder liquid levels of the same release group.(iv) Measurements are made by personnel skilled in ultrasonic/audio gauging or radioisotope gauging techniques.(5) Effective 12 years after commissioning of the system or 5 years after the last hydrostatic test, whichever is later, the following inspections must be completed every 5 years:(i) Cylinders continuously in service without discharging must be removed from mounting racks and given a complete external visual inspection. The inspection must be conducted in accordance with the CGA Pamphlet C-6 (incorporated by reference, see § 147.7 ).(ii) The volume of agent must be ascertained either by removing and weighing the cylinder or by floating liquid level indicators, integral with the cylinder construction, taking into account adjustments necessary for cylinder temperature and pressure.(6) Flexible connections between cylinders and distribution piping of fixed Halon fire extinguishing systems must be:(i) Visually inspected for damage, corrosion, or deterioration every year and replaced if found unserviceable; and(ii) Inspected and tested in accordance with NFPA 12A, paragraph 6.3.1 (incorporated by reference, see § 147.7 ) except that hydrostatic testing must be performed every 12 years instead of every 5 years.(7) During any inspection, cylinders must be removed from service if they: (ii) Are dented, bulging, severely corroded, or otherwise in a weakened condition; or(iii) Have been involved in a fire.(c) Cylinders that have contained carbon dioxide or Halon and have not been tested within 5 years must not be used to contain another compressed gas onboard a vessel, unless the cylinder is retested and re-marked in accordance with § 147.60(a)(3) and (4) .USCG-2012-0196, 81 FR 48272, July 22, 2016