A DOT specification or UN cylinder may be filled only if it has been requalified within the period prescribed in the 180.209 table (for example five years for most high-pressure cylinders, ten or twelve years for certain cylinders meeting the extended interval conditions, and the periodic visual inspection regimes for low-pressure cylinders), by a requalifier holding a current PHMSA requalifier identification number (RIN) and following the 180.205 procedures: visual inspection, pressure test to the specified test pressure with permanent and elastic expansion limits, or ultrasonic examination where authorised, with cylinders failing the criteria condemned and marked or rendered unusable (180.205(i)). The requalifier marks each requalified cylinder with its RIN and the test date and keeps records of each requalification for the life of the cylinder's current interval plus the retention period in 180.215; owners and fillers must verify the requalification marking before filling.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.