Catalina Cylinders recommends all CO2 cylinders be given a quick external visual inspection prior to each fill and the items noted in Catalina Cylinders technical support document, Inspection of CO2 Cylinders Prior to Each Fill, be included in this inspection.
All DOT-3AL marked CO2 cylinders are to be inspected and hydrostatically re-tested every five years as required in CFR  Title 49 Part 180.205(c). Cylinders still with charge at the time the 5 year re-test is due, do not have to be re-tested  until the charge is used, but prior to the re-filling of the cylinders.
Visual inspection, at the time of hydrostatic re-testing,  must be performed by a DOT licensed re-test agency. Visual inspection  must be performed in accordance with CGA pamphlet C-6.1; Standards for Visual Inspection  of High Pressure Aluminum Compressed Gas Cylinders. Internal and external visual  inspection of a cylinder should be performed prior to hydrostatic re-testing.
Hydrostatic re-testing must be performed by  a DOT licensed re-test agency. Hydrostatic re-testing must be performed in accordance with  CGA Pamphlet C-1; Methods for Hydrostatic Testing of Compressed Gas Cylinders.  Once a cylinder has successfully passed all visual inspection and hydrostatic  re-test requirements, it is to be permanently marked with the re-test date, month and year,  and licensed re-test agency’s number in the proximity of the previous hydrostatic test date.  No cylinder is to be marked with the licensed re-test agency’s number until  the cylinder has passed all visual inspection and hydrostatic re-test requirements. No  cylinder is to be marked with a licensed re-test agency number by any other person or  agency other than the personnel of the licensed re-test agency.
DOT-3AL marked cylinders used in countries  other than the United States must be inspected and hydrostatically re-tested  in accordance with the rules, regulations, specifications and methods of that country.  If, in other countries, no such rules, regulation, specifications and methods  exist, Catalina Cylinders recommends that the DOT-3AL marked cylinders be visually inspected  in accordance with all applicable DOT specifications and CGA pamphlets.
The CGA pamphlets noted above, as well as all other CGA pamphlets,  can be attained from the CGA for a nominal fee. You can reach the CGA at:
Tel: 703 412-0900Fax: 703 412-0128Website: www.cganet.com