1308.4 Acceptable Piping Materials and Joining Methods — 2025 California Mechanical Code

Methods. Materials used for piping systems shall comply with the requirements of Section 1308.4.1 through Section 1308.4.4.2.3. {NFPA 54:5.5.1.1} 1308.4.1 Used Materials. Pipe, fittings, valves, or other materials shall not be used again unless they are free of foreign materials and have been ascertained to be adequate for the service intended. [NFPA 54:5.5.1.2] 1308.4.2 Metallic Pipe. Metallic pipe shall be in accordance with Section 1308.4.2.1 through Section 1308.4.2.4.

1308.4.2.1 Cast Iron. Cast-iron pipe shall not be used. [NFPA 54:5.5.2.1] 1308.4.2.2 Steel, Stainless Steel, and Wrought-Iron. Steel, stainless steel, and wroughtiron pipe shall be at least Schedule 40 and shall comply with the dimensional standards of ASME B36.10M and one of the following: (1) ASTM A53 (2) ASTM A106 (3) ASTM A312 {NFPA 54:5.5.2.2}

TABLE 1308.3.1

APPROXIMATE GAS INPUT FOR TYPICAL APPLIANCES

[NFPA 54: TABLE A.5.3.2.1]

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FUEL GAS PIPING

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1308.4.3 Metallic Tubing. Tubing shall not be used with gases corrosive to the tubing material. [NFPA 54:5.5.3.1] 1308.4.3.1 Steel Tubing. Steel tubing shall comply with ASTM A254. [NFPA 54:5.5.3.2] 1308.4.3.2 Stainless Steel Tubing. Stainless steel tubing shall comply with one of the following: (1) ASTM A268 (2) ASTM A269 [NFPA 54:5.5.3.3] 1308.4.3.3 Copper and Copper Alloy Tubing. Copper and copper alloy tubing shall not be used if the gas contains more than an average of 0.3 grains of hydrogen sulfide per 100 scf of gas (0.7 mg/100 L). Copper tubing shall comply with standard Type K or Type L of ASTM B88 or ASTM B280. [NFPA 54:5.5.3.4] 1308.4.3.4 Aluminum Alloy Tubing. Aluminum alloy tubing shall comply with ASTM B210 or ASTM B241. Aluminum alloy tubing shall be coated to protect against external corrosion where it is in contact with masonry, plaster, or insulation or is subject to repeated wettings by such liquids as water, detergent, or sewage. Aluminum alloy tubing shall not be used in exterior locations or underground. [NFPA 54:5.5.3.5] 1308.4.3.5 Corrugated Stainless Steel Tubing. Corrugated stainless steel tubing shall be listed in accordance with CSA/ANSI LC 1/CSA 6.26. [NFPA 54:5.5.3.6] 1308.4.4 Plastic Pipe, Tubing, and Fittings. Polyethylene plastic pipe, tubing, and fittings used to supply fuel gas shall conform to ASTM D2513. Pipe to be used shall be marked “gas” and “ASTM D2513.” [NFPA 54:5.5.4.1.1] Polyamide pipe, tubing, and fittings shall be identified in and conform to ASTM F2945. Pipe to be used shall be marked “gas” and “ASTM F2945.” [NFPA 54:5.5.4.1.2] Polyvinyl chloride (PVC) and chlorinated polyvinyl chloride (CPVC) plastic pipe, tubing, and fittings shall not be used to supply fuel gas. [NFPA 54:5.5.4.1.3] 1308.4.4.1 Regulator Vent Piping. Plastic pipe and fittings used to connect regulator vents to remote vent terminations shall be PVC (Schedule 40 and 80). PVC vent piping shall not be installed indoors. {NFPA 54:5.5.4.2}

1308.4.4.2 Anodeless Risers. Anodeless risers shall comply with Section 1308.4.4.2.1 through Section 1308.4.4.2.3.

1308.4.4.2.1 Factory-Assembled Anode- less Risers. Factory-assembled anodeless risers shall be recommended by the manufacturer for the gas used and shall be leak-tested by the manufacturer in accordance with written procedures. [NFPA 54:5.5.4.3(1)] 1308.4.4.2.2 Service Head Adapters and Field-Assembled Anodeless Risers. Service head adapters and field assembled anodeless risers incorporating service head adapters shall be recommended by the manufacturer for the gas used and shall be design-certified to meet the

requirements of Category I of ASTM D2513 and 49 CFR 192.281(e). The manufacturer shall provide the user qualified installation instructions as prescribed by 49 CFR 192.283(b). [NFPA 54:5.5.4.3(2)]

1308.4.4.2.3 Undiluted Liquefied Petro- leum Gas Piping. The use of plastic pipe, tubing, and fittings in undiluted LP-Gas piping systems shall be in accordance with NFPA 58.

[NFPA 54:5.5.4.3(3)]

1308.4.5 Workmanship and Defects. Gas pipe, tubing, and fittings shall be clear and free from cutting burrs and defects in structure or threading and shall be thoroughly brushed and chip and scale blown. Defects in pipe, tubing, and fittings shall not be repaired. Defective pipe, tubing, and fittings shall be replaced. [NFPA 54:5.5.5]

1308.4.6 Metallic Pipe Threads. Metallic pipe and fitting threads shall be taper pipe threads and shall comply with ASME B1.20.1. [NFPA 54:5.5.6.1]

1308.4.6.1 Damaged Threads. Pipe with threads that are stripped, chipped, corroded, or otherwise damaged shall not be used. Where a weld opens during the operation of cutting or threading, that portion of the pipe shall not be used. [NFPA 54:5.5.6.2]

1308.4.6.2 Number of Threads. Field threading of metallic pipe shall be in accordance with Table 1308.4.6.2. [NFPA 54:5.5.6.3]

TABLE 1308.4.6.2

SPECIFICATIONS FOR THREADING METALLIC PIPE

[NFPA 54: TABLE 5.5.6.3]

For SI units: 1 inch = 25.4 mm

1308.4.6.3 Thread Joint Sealing. Threaded joints shall be made using a thread joint sealing material. [NFPA 54:5.5.6.4.1] Thread joint sealing materials shall be compatible with the pipe and fitting material on which the compounds are used.

[NFPA 54:5.5.6.4.2] Thread joint sealing materials shall be resistant to the chemical constituents of the gases to be conducted through the piping. {NFPA 54:5.5.6.4.3} 1308.4.7 Metallic Piping Joints and Fittings. The type of piping joint used shall be suitable for the pressure

TABLE 1308.4.6.2

SPECIFICATIONS FOR THREADING METALLIC PIPE

[NFPA 54: TABLE 5.5.6.3]

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For SI units: 1 inch = 25.4 mm

278 2025 CALIFORNIA MECHANICAL CODE

FUEL GAS PIPING

approved by the Authority Having Jurisdiction.

(e) Fittings in sizes 6 inches (150 mm) and larger shall not be used unless approved by the Authority Having Jurisdiction.

(6) Aluminum alloy fitting threads shall not form the joint seal.

(7) Zinc-aluminum alloy fittings shall not be used in systems containing flammable gas-air mixtures.

(8) Special fittings such as couplings, proprietarytype joints, saddle tees, gland-type compression fittings, and flared, flareless, or compressiontype tubing fittings shall be as follows: (a) Used within the fitting manufacturer’s pressure-temperature recommendations. (b) Used within the service conditions anticipated with respect to vibration, fatigue, thermal expansion, or contraction. (c) Acceptable to the Authority Having Jurisdiction.

(9) When pipe fittings are drilled and tapped in the field, the operation shall be in accordance with the following: (a) The operation shall be performed on systems having operating pressures of 5 psi (34 kPa) or less. (b) The operation shall be performed by the gas supplier or their designated representative.

(c) The drilling and tapping operation shall be performed in accordance with written procedures prepared by the gas supplier. (d) The fittings shall be located outdoors. (e) The tapped fitting assembly shall be inspected and proven to be free of leaks.

[NFPA 54:5.5.7.5] 1308.4.8 Plastic Piping Joints and Fittings. Plastic pipe, tubing, and fittings shall be joined in accordance with the manufacturers’ instructions. Section 1308.4.8.1 through Section 1308.4.8.4 shall be observed when making such joints. [NFPA 54:5.5.8] 1308.4.8.1 Joint Design. The joint shall be designed and installed so that the longitudinal pullout resistance of the joint will be at least equal to the tensile strength of the plastic piping material. [NFPA 54:5.5.8(1)] 1308.4.8.2 Heat Fusion Joint. Heat fusion joints shall be made in accordance with qualified procedures that have been established and proven by test to produce gastight joints at least as strong as the pipe or tubing being joined. Joints shall be made with the joining method recommended by the pipe manufacturer. Polyethylene heat fusion fittings shall be marked “ASTM D2513.” Polyamide heat fusion fittings shall be marked "ASTM F2945." [NFPA 54:5.5.8(2)]

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and temperature conditions and shall be selected giving consideration to joint tightness and mechanical strength under the service conditions. The joint shall be able to sustain the maximum end force due to the internal pressure and any additional forces due to temperature expansion or contraction, vibration, fatigue, or the weight of the pipe and its contents. [NFPA 54:5.5.7] 1308.4.7.1 Pipe Joints. Schedule 40 and heavier pipe joints shall be threaded, flanged, brazed, welded, or assembled with press-connect fittings listed to CSA/ANSI LC 4/CSA 6.32.

(1) Where nonferrous pipe is brazed, the brazing materials shall have a melting point in excess of 1000°F (538°C).

(2) Brazing alloys shall not contain more than 0.05 percent phosphorus. {NFPA 54:5.5.7.1} 1308.4.7.2 Copper Tubing Joints. Copper tubing joints shall be assembled with approved gas tubing fittings, shall be brazed with a material having a melting point in excess of 1000°F (538°C), or shall be assembled with press-connect fittings listed to CSA/ANSI LC 4/CSA 6.32. Brazing alloys shall not contain more than 0.05 percent phosphorus. [NFPA 54:5.5.7.2] 1308.4.7.3 Stainless Steel Tubing Joints. Stainless steel joints shall be welded, assembled with approved tubing fittings, brazed with a material having a melting point in excess of 1000°F (538°C), or assembled with press-connect fittings listed to CSA/ANSI LC 4/CSA 6.32. Brazing alloys and fluxes shall be recommended by the manufacturer for use on stainless steel alloys. [NFPA 54:5.5.7.3] 1308.4.7.4 Flared Joints. Flared joints shall be used only in systems constructed from nonferrous pipe and tubing where experience or tests have demonstrated that the joint is suitable for the conditions and where provisions are made in the design to prevent separation of the joints. [NFPA 54:5.5.7.4] 1308.4.7.5 Metallic Pipe Fittings. Metallic fittings shall comply with the following:

(1) Threaded fittings in sizes exceeding 4 inches (100 mm) shall not be used. (2) Fittings used with steel, stainless steel, or wrought-iron pipe shall be steel, stainless steel, copper alloy, malleable iron, or castiron. (3) Fittings used with copper or copper alloy pipe shall be copper or copper alloy. (4) Fittings used with aluminum alloy pipe shall be aluminum alloy. (5) Cast-iron fittings shall comply with the following: (a) Flanges shall be permitted.

(b) Bushings shall not be used.

(c) Fittings shall not be used in systems containing flammable gas-air mixtures.

(d) Fittings in sizes 4 inches (100 mm) and larger shall not be used indoors unless

» 1308.4.7.5 Metallic Pipe Fittings. Metallic fit- 1308.4.8 Plastic Piping Joints and Fittings. Plas- «

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1308.4.8.3 Compression-Type Mechanical Joints. Where compression-type mechanical joints are used, the gasket material in the fitting shall be compatible with the plastic piping and with the gas distributed by the system. An internal tubular rigid stiffener shall be used in conjunction with the fitting. The stiffener shall be flush with the end of the pipe or tubing and shall extend at least to the outside end of the compression fitting when installed. The stiffener shall be free of rough or sharp edges and shall not be a force fit in the plastic. Split tubular stiffeners shall not be used. [NFPA 54:5.5.8(3)] 1308.4.8.4 Liquefied Petroleum Gas Piping Systems. Plastic piping joints and fittings for use in LP-Gas piping systems shall be in accordance with NFPA 58. [NFPA 54:5.5.8(4)] 1308.4.9 Flange Specifications. Cast iron flanges shall be in accordance with ASME B16.1. [NFPA 54:5.5.9.1.1] 1308.4.9.1 Steel Flanges. Steel flanges shall be in accordance with the following:

(1) ASME B16.5 or

(2) ASME B16.47. [NFPA 54:5.5.9.1.2]

1308.4.9.2 Non-Ferrous Flanges. Non-ferrous flanges shall be in accordance with ASME B16.24.

[NFPA 54:5.5.9.1.3]

1308.4.9.3 Ductile Iron Flanges. Ductile iron flanges shall be in accordance with ASME B16.42.

[NFPA 54:5.5.9.1.4]

1308.4.9.4 Dissimilar Flange Connections. Raised-face flanges shall not be joined to flat-faced cast iron, ductile iron or nonferrous material flanges.

[NFPA 54:5.5.9.2]

1308.4.9.5 Flange Facings. Standard facings shall be permitted for use under this code. Where 150 psi (1034 kPa) steel flanges are bolted to Class 125 cast-iron flanges, the raised face on the steel flange shall be removed. [NFPA 54:5.5.9.3]

1308.4.9.6 Lapped Flanges. Lapped flanges shall be used only aboveground or in exposed locations accessible for inspection. [NFPA 54:5.5.9.4]

1308.4.10 Flange Gaskets. The material for gaskets shall be capable of withstanding the design temperature and pressure of the piping system and the chemical constituents of the gas being conducted without change to its chemical and physical properties. The effects of fire exposure to the joint shall be considered in choosing the material. [NFPA 54:5.5.10]

1308.4.10.1 Flange Gasket Materials. Acceptable materials shall include the following:

(1) Metal (plain or corrugated)

(2) Composition

(3) Aluminum “O” rings

(4) Spiral-wound metal gaskets

(5) Rubber-faced phenolic

(6) Elastomeric [NFPA 54:5.5.10.1]

1308.4.10.2 Metallic Flange Gaskets. Metallic flange gaskets shall be in accordance with ASME B16.20. [NFPA 54:5.5.10.2.1]

1308.4.10.3 Non-Metallic Flange Gaskets. Nonmetallic flange gaskets shall be in accordance with ASME B16.21. [NFPA 54:5.5.10.2.2]

1308.4.10.4 Full-Face Flange Gasket. Full-face flange gaskets shall be used with all non-steel flanges. [NFPA 54:5.5.10.3]

1308.4.10.5 Separated Flanges. When a flanged joint is separated, the gasket shall be replaced.

[NFPA 54:5.5.10.4]