403.1.1 Pipe size and pressure limitations.
FGC § 403.1.1
1.All requirements for installation of gas distribution piping shall be in accordance with Chapter 4. Gas distribution piping with operating pressures of 15 psig (103.4 kPa gauge) or more shall be in accordance with Appendix G.
2.Gas distribution piping operating at a pressure of over 1/2 psig (3.5 kPa gauge) shall be welded. Exception: Manufactured and listed gas trains provided with the appliance may be threaded.
3.All welding of gas distribution piping shall be subject to radiography or special inspection as set forth in Section 406.
4.Threaded piping may be used up to 4 inches (101.6 mm) in diameter at pressure no greater than 1/2 psig (3.5 kPa gauge). All piping greater than 4 inches in diameter shall be welded, regardless of operating pressure.
5.All welded piping 2 1/2 inches (63.5 mm) or greater in diameter shall be butt-welded, and welded piping less than 2 1/2 inches (63.5 mm) in diameter may be socket-welded or butt-welded.
