This standard has been prepared for the visual inspection of aluminum alloy compressed gas cylinders with service pressures of 1800 psi (12 410 kPa) or greater.2 This standard does not address all cylinder manufacture defects. Cylinders authorized by regulation may require testing by ultrasonic examination (UE) or pressure testing. This standard does not include testing that may be required bv regulation. UE of aluminum alloy cylinders shall meet the requirements of CGA C-20. Methods for Ultrasonic Examination of Metallic. DOT and TC 3-Series Gas Cylinders and Tubes [6]. Pressure testing shall meet regulatory requirements.