46 CFR §52.15-5

1. (a)Tubes, pipe, and nipples must be attached to sheets, heads, headers, and fittings as indicated in PWT-11 of Section I of the ASME BPVC (incorporated by reference; see § 52.01-1) except as noted otherwise in this section.
2. (b)(Replaces PWT-9.2 and PWT-11.3.) Threaded boiler tubes are not permitted as described by PWT-9.2 and PWT-11.3 of Section I of the ASME BPVC.
3. (c)In welded wall construction employing stub and welded wall panels that are field welded, 10 percent of the field welds must be checked using any acceptable nondestructive test method.
4. (d)Nondestructive testing of the butt-welded joints must meet the requirements of § 56.95-10 of this subchapter.