CCITech-
Simple enough… See VIII-1 UG-116:
(e) When a vessel has been radiographed in accordance with UW-11, marking shall be applied under the Code Symbol as follows:
(1) “RT 1” when all pressure-retaining butt welds, other than Category B and C butt welds associated with nozzles and communicating chambers that neither exceed NPS 10 (DN 250) nor 11?8 in. (29 mm) wall thickness [except as required by UHT-57(a)], have been radiographically examined for their full length in the manner prescribed in UW-51; full radiography of the above exempted Category B and C butt welds, if performed, may be recorded on the Manufacturer’s Data Report; or
(2) “RT 2” when the complete vessel satisfies the requirements of UW-11(a)(5) and when the spot radiography requirements of UW-11(a)(5)(b) have been applied; or
(3) “RT 3” when the complete vessel satisfies the spot radiography requirements of UW-11(b); or
(4) “RT 4” when only part of the complete vessel has satisfied the radiographic requirements of UW-11(a) or where none of the markings “RT 1,” “RT 2,” or “RT 3” are applicable.
The extent of radiography and the applicable joint efficiencies shall be noted on the Manufacturer’s Data Report.
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