1.1 This specification covers seamless and welded black and hot-dipped galvanized steel pipe in NPS 1/8 to NPS 26 [DN 6 to DN 650] (Note 1), inclusive, with nominal wall thickness (Note 2) as given in Table X2.2 and X2.3. It shall be permissible to fu This specification covers seamless and welded black and hot-dipped galvanized steel pipe in NPS 1/8 to NPS 26. The steel categorized in this standard must be open-hearth, basic-oxygen or electric-furnace processed and must have the following chemical r