(a) The rules for openings and compensation shall be as indicated in PG-32 through PG-55 of section I of the ASME Boiler and Pressure Vessel Code (incorporated by reference; see 46 CFR 52.01-1) except as noted otherwise in this section.
(b) (Modifies PG-39.) Pipe and nozzle necks shall be attached to vessel walls as indicated in PG-39 of section I of the ASME Boiler and Pressure Vessel Code except that threaded connections shall not be used under any of the following conditions:
(1) Pressures greater than 4,137 kPa (600 psig);
(2) Nominal diameters greater than 51 mm (2 in.); or
(3) Nominal diameters greater than 19 mm (0.75 in.) and pressures above 1,034 kPa (150 psig).
(c) (Modifies PG-42.) Butt welding flanges and fittings must be used when full radiography is required by Sec. 56.95-10. [CGD 81-79, 50 FR 9432, Mar. 8, 1985, as amended by USCG-2003-16630, 73 FR 65161, Oct. 31, 2008]