402.6 Gas Distribution Pressures

No gas distribution piping containing gas at a pressure in excess of ¹/₂ psig (3.5 kPa gauge) shall be run within a building, except that pressure not exceeding 3 psig (20 kPa gauge) is permitted for the following uses: (a) commercial (b) industrial (c) other large volume use in which fuel requirements for boiler room equipment exceed 4,000 cubic feet per hour (113.2 m³/h) and such large volume use is supplied through separate gas distribution piping to the boiler room. Gas pressure not exceeding 15 psig (100 kPa gauge) is permitted for boiler room equipment in excess of 100,000 cubic feet per hour (2830 m³/h) provided the gas distribution piping is installed as provided for in Section 404. The use of pressure in excess of 15 psig (100 kPa gauge) shall be permitted for distribution piping provided all of the requirements of Section 406 are met.