ANSI A119.2/NFPA 1192
5.4.6 Gas Tubing Joints. Gas tubing joints shall be permitted to
be made with a single or double flare of 45 degrees conforming
to SAE J533, Flares for Tubing, as recommended by the tubing
manufacturer, or by means of listed vibration-resistant fittings, or
the joints shall be brazed with a material having a melting point
exceeding 1000°F (538°C). Brazing alloys shall not contain phosphorus.
Sealants shall not be used on tubing joints. Ball sleeve or
one-piece internal compression-type tubing fittings shall not be
used. (See 5.5.5.)
As you can tell the NFPA book is dated 2005, the ANSI reference therein is 2002.
5.4.2 Gas Piping System Materials. Materials used for the installation,
extension, alteration, or repair of any gas piping system
shall be new and free from defects or internal obstructions. Inferior
or defective materials in gas piping or fittings shall be replaced
and shall not be repaired. Inferior or defective materials
shall be removed and replaced with acceptable material. The system
shall be made of materials having a melting point of not less
°F (788°C), except as provided in 5.4.5, 5.4.6, and
5.4.12, or of materials (used in piping or fittings) listed for the
specific use intended. Gas piping system materials shall be permitted
to consist of one or more of the following materials:
(1) Gas pipe shall be steel or wrought-iron pipe complying
with ASTM A 53, Specifications for Pipe, Steel, Black and Hot-
Dipped, Zinc-Coated Welded and Seamless. Threaded copper or
brass pipe in iron pipe sizes shall be permitted to be used.
(2) Fittings for gas piping shall be wrought iron, malleable
iron, steel, or brass (containing not more than 75 percent
copper). Brass flare nuts shall be stress relieved or of the
(3) Copper tubing shall be annealed Type K or L, conforming
to ASTM B 88, Standard Specifications for Seamless Copper
Water Tube, or shall comply with ASTM B 280, Specifications
for Seamless Copper Tube for Air Conditioning
Field Service. Where used on systems designed for natural
gas, copper tubing shall be internally tinned.
This applies up to the current 2015 code.