Section 193.2321 - Nondestructive tests(a) The butt welds in metal shells of storage tanks with internal design pressure above 15 psig must be nondestructively examined in accordance with the ASME Boiler and Pressure Vessel Code (BPVC) (Section VIII, Division 1)(incorporated by reference, see§ 193.2013 ), except that 100 percent of welds that are both longitudinal (or meridional) and circumferential (or latitudinal) of hydraulic load bearing shells with curved surfaces that are subject to cryogenic temperatures must be nondestructively examined in accordance with the ASME BPVC (Section VIII, Division 1).(b) For storage tanks with internal design pressures at 15 psig or less, ultrasonic examinations of welds on metal containers must comply with the following: (1) Section 7.3.1.2 of NFPA Std-59A-2006, (incorporated by reference, see§ 193. 2013);(2) Appendices C and Q of API Std 620, (incorporated by reference, see§ 193.2013 );(c) Ultrasonic examination records must be retained for the life of the facility. If electronic records are kept, they must be retained in a manner so that they cannot be altered by any means; and(d) The ultrasonic equipment used in the examination of welds must be calibrated at a frequency no longer than eight hours. Such calibrations must verify the examination of welds against a calibration standard. If the ultrasonic equipment is found to be out of calibration, all previous weld inspections that are suspect must be reexamined.Amdt. 193-22, 75 FR 48605, Aug. 11, 2010, as amended by Amdt. 193-25, 80 FR 183, Jan. 5, 2015; 80 FR 46848, Aug. 6, 2015