Watertube boilers and parts thereof shall be as indicated in PWT-1 through PWT-15 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 subpart. [CGD 81-79, 50 FR 9434, Mar. 8, 1985; USCG-2003-16630, 73 FR 65161, Oct. 31, 2008]