CMC · California Mechanical Code
Fuel Gas Piping
Chapter 13 of the California Mechanical Code sets the rules for safe design, materials, installation, testing, purging, and inspection of fuel-gas piping systems in and around buildings.
Last reviewed: July 6, 2026
Overview
This area of the California Mechanical Code (CMC) governs the installation, materials, testing, inspection, and safe operation of fuel-gas piping from the point of delivery to appliance connections. The chapter scope (see §1301.1) limits building piping to low-pressure systems (generally up to 5 psi for natural gas and 10 psi for undiluted propane) and defines the system coverage and exclusions at the property line and service equipment as the baseline for design and enforcement .
Key technical requirements you’ll consult here include pipe-sizing and allowable pressure drop (§1308.3, §1314.0), acceptable materials and joining methods (§1308.4), appliance and connector rules (§1312.1–1312.6), and purging and leak-detection procedures (Chapter 13, §1313.6 and Table 1313.6.1). The CMC also sets inspection and testing rules (Chapter 13, §1303.0) so installations are verified before service is supplied .
Because fuel-gas piping overlaps plumbing and equipment provisions, the California Plumbing Code and CMC appendices provide related tables, connector guidance (including CSST and flexible connector rules), and manufactured-home provisions; see the Plumbing Code cross-references for sizing tables and connector requirements .
In this section
Code references
Grounded in the retrieved California Mechanical Code — click a citation to read the verbatim passage:
CMC § 1208.0 High relevance — show source text
1208.0 Gas Piping System Design, Materials, and Components. 1208.1 Installation of Piping System. Where required by the Authority Having Jurisdiction, a piping sketch or plan shall be prepared before proceeding with the installation. The plan shall show the proposed location of piping, the size of different branches, the various load demands, and the location of the point of delivery. [NFPA 54:5.1.1] 1208.1.1 Addition to Existing System. When additional appliances are being connected to a gas piping system, the existing piping shall be checked to determine whether it has adequate capacity. If the capacity of the system is determined to be inadequate for the additional appliances, the existing system shall be enlarged as required, or separate gas piping of adequate capacity shall be provided. [NFPA 54:5.1.2] 1208.2 Interconnections Supplying Separate Users. Where two or more meters, or two or more service regulators where meters are not provided, are located on the same premises and supply separate users, the gas piping systems shall not be interconnected on the outlet side of the meters or service regulators. [NFPA 54:5.2.1] 1208.2.1 Interconnections for Standby Fuels. Where a supplementary gas for standby use is connected downstream from a meter or a service regulator where a meter is not provided, equipment to prevent backflow shall be installed. A three-way valve installed to admit the standby supply and at the same time shut off the regular supply shall be permitted to be used for this purpose.
[NFPA 54:5.2.2.1 – 5.2.2.2] 1208.3 Sizing of Gas Piping Systems. Gas piping systems shall be of such size and so installed as to provide a supply of gas sufficient to meet the maximum demand and supply gas to each appliance inlet at not less than the minimum supply pressure required by the appliance. [NFPA 54:5.3.1]
1208.3.1 Maximum Gas Demand. The volumetric flow rate of gas to be provided shall be the sum of the maximum input of the appliances served. The volumetric flow rate of gas to be provided shall be adjusted for altitude where the installation is above 2000 feet (610 m). [NFPA 54:5.3.2.1 – 5.3.2.2] Where the input rating is not indicated, the gas supplier, appliance manufacturer, or a qualified agency shall be contacted, or the rating from Table 1208.3.1 shall be used for estimating the volumetric flow rate of gas to be supplied.
The total connected hourly load shall be used as the basis for piping sizing, assuming all appliances are operating at full capacity simultaneously.
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the inlet connection of all appliances served shall be such that the supply pressure at each appliance inlet is greater than or equal to the minimum pressure required by the appliance. [NFPA 54:5.3.4]
1208.4 Maximum Operating Pressure in Buildings. The maximum operating pressure for any piping systems located inside buildings shall not exceed 5 psi (34 kPa) unless one or more of the following conditions are met:
(1) The piping joints are welded or brazed.
CMC § 1313.6.1. High relevance — show source text
(2) The piping being purged contains one or more sections of pipe or tubing meeting the size and length criteria of Table 1313.6.1. [NFPA 54:8.3.1]
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TABLE 1313.6.1
SIZE AND LENGTH OF PIPING
[NFPA 54: TABLE 8.3.1]*
NOMINAL PIPING SIZE (inches) LENGTH OF PIPING (feet)
≥ 21⁄2 < 3> 50
≥ 3 < 4> 30
≥ 4 < 6> 15
≥ 6 < 8> 10
≥ 8Any length For SI units: 1 inch = 25 mm; 1 foot = 304.8 mm
***** CSST EHD size of 62 is equivalent to 2 inch (50 mm) nominal size pipe or tubing.
1313.6.1.1 Removal from Service. Where existing gas piping is opened, the section that is opened shall be isolated from the gas supply and the line pressure vented in accordance with Section 1313.6.1.3. Where gas piping meeting the criteria of Table 1313.6.1 is removed from service, the residual fuel gas in the piping shall be displaced with an inert gas.
[NFPA 54:8.3.1.1] 1313.6.1.2 Placing in Operation. Where gas piping containing air and meeting the criteria of Table 1313.6.1 is placed in operation, the air in the piping shall first be displaced with an inert gas. The inert gas shall then be displaced with fuel gas in accordance with Section 1313.6.1.3. [NFPA 54:8.3.1.2] 1313.6.1.3 Outdoor Discharge of Purged Gases. The open end of a piping system being pressure vented or purged shall discharge directly to an outdoor location. Purging operations shall comply with all of the following requirements: (1) The point of discharge shall be controlled with a shutoff valve.
(2) The point of discharge shall be located at least 10 feet (3048 mm) from sources of ignition, at least 10 feet (3048 mm) from building openings and at least 25 feet (7620 mm) from mechanical air intake openings. (3) During discharge, the open point of discharge shall be continuously attended and monitored with a combustible gas indicator that complies with Section 1313.6.1.4.
(4) Purging operations introducing fuel gas shall be stopped when 90 percent fuel gas by volume is detected within the pipe. (5) Persons not involved in the purging operations shall be evacuated from all areas within 10 feet (3048 mm) of the point of discharge. [NFPA 54:8.3.1.3]
CMC § 1.11.0. High relevance — show source text
This state agency does not adopt sections identified with the following symbol: † The Office of the State Fire Marshal’s adoption of this chapter or individual sections is applicable to structures regulated by other state agencies pursuant to Section 1.11.0.
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CHAPTER 13
FUEL GAS PIPING
1301.0 Scope of Gas Piping.
1301.1 Applicability. The regulations of this chapter shall govern the installation of fuel gas piping in or in connection with a building, structure or within the property lines of premises up to 5 pounds-force per square inch (psi) (34 kPa) for natural gas and 10 psi (69 kPa) for undiluted propane, other than service pipe.
1302.0 Coverage of Piping System.
1302.1 General. Coverage of piping systems shall extend from the point of delivery to the appliance connections. For other than undiluted liquefied petroleum gas (LP-Gas) systems, the point of delivery shall be the outlet of the service meter assembly or the outlet of the service regulator or service shutoff valve where no meter is provided. For undiluted LP-Gas systems, the point of delivery shall be considered to be the outlet of the final pressure regulator, exclusive of line gas regulators where no meter is installed. Where a meter is installed, the point of delivery shall be the outlet of the meter.
[NFPA 54:1.1.1.1(A)]
1302.2 Piping System Requirements. Requirements for piping systems shall include design, materials, components, fabrication, assembly, installation, testing, inspection, operation, and maintenance. [NFPA 54:1.1.1.1(E)]
1302.3 Applications. This chapter shall not apply to the following items:
(1) Portable LP-Gas appliances and equipment of all types that are not connected to a fixed fuel piping system.
(2) Installation of appliances such as brooders, dehydrators, dryers, and irrigation equipment used for agricultural
purposes.
(3) Raw material (feedstock) applications except for piping to special atmosphere generators.
(4) Oxygen-fuel gas cutting and welding systems.
(5) Industrial gas applications using such gases as acetylene and acetylenic compounds, hydrogen, ammonia, carbon monoxide, oxygen, and nitrogen.
(6) Petroleum refineries, pipeline compressor or pumping stations, loading terminals, compounding plants, refinery tank farms, and natural gas processing plants.
(7) Large integrated chemical plants or portions of such plants where flammable or combustible liquids or gases are produced by chemical reactions or used in chemical reactions.
(8) LP-Gas installations at utility gas plants.
(9) Liquefied natural gas (LNG) installations.
(10)Fuel gas piping in electric utility power plants.
(11)Proprietary items of equipment, apparatus, or instruments such as gas-generating sets, compressors, and calorime ters.
(12)LP-Gas equipment for vaporization, gas mixing, and gas manufacturing.
CMC § 1312.0 High relevance — show source text
1312.0 Appliance and Equipment Connections to Building Piping.
1312.1 Connecting Appliances and Equipment. Appliances and equipment shall be connected to the building piping in compliance with Section 1312.6 through Section 1312.8 by one of the following:
(1) Rigid metallic pipe and fittings.
(2) Semirigid metallic tubing and metallic fittings. Aluminum alloy tubing shall not be used in exterior locations.
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1312.3 Use of Nonmetallic Gas Hose Connectors.
Listed gas hose connectors shall be used in accordance with the manufacturer’s installation instructions and in accor dance with Section 1312.3.1 or Section 1312.3.2. [NFPA 54:9.6.2]
1312.3.1 Indoor. Indoor gas hose connectors shall be used only to connect laboratory, shop, and ironing appliances requiring mobility during operation and installed in accordance with the following:
(1) An appliance shutoff valve shall be installed where the connector is attached to the building piping.
(2) The connector shall be of minimum length and shall not exceed 6 feet (1829 mm).
(3) The connector shall not be concealed and shall not extend from one room to another or pass through wall partitions, ceilings, or floors. [NFPA 54:9.6.2(1)]
1312.3.2 Outdoor. Where outdoor gas hose connectors are used to connect portable outdoor appliances, the connector shall be listed in accordance with CSA/ANSI
Z21.54/CSA 8.4 and installed in accordance with the fol lowing:
(1) An appliance shutoff valve, a listed quick-disconnect device, or a listed gas convenience outlet shall be installed where the connector is attached to the
supply piping and in such a manner so as to prevent the accumulation of water or foreign matter.
(2) This connection shall be made only in the outdoor area where the appliance is to be used. [NFPA 54:9.6.2(2)]
(3) The connector length shall not exceed 15 feet (4572 mm).
1312.4 Injection (Bunsen) Burners. Injection (Bunsen) burners used in laboratories and educational facilities shall
be permitted to be connected to the gas supply by an unlisted hose. [NFPA 54:9.6.3]
1312.5 Connection of Portable and Mobile Industrial Appliances. Where portable industrial appliances or appliances requiring mobility or subject to vibration are connected to the building gas piping system by the use of a flexible hose, the hose shall be suitable and safe for the conditions under
which it can be used. [NFPA 54:9.6.4.1]
1312.5.1 Swivel Joints or Couplings. Where industrial appliances requiring mobility are connected to the rigid piping by the use of swivel joints or couplings, the swivel joints or couplings shall be suitable for the service required and only the minimum number required shall be installed. [NFPA 54:9.6.4.2]
CMC § 5.3.2.3 High relevance — show source text
The total connected hourly load shall be used as the basis for piping sizing, assuming all appliances are operating at full capacity simultaneously. Exception: Sizing shall be permitted to be based upon established load diversity factors. [NFPA 54:5.3.2.3] 1308.3.2 Sizing Methods. Gas piping shall be sized in accordance with one of the following: (1) Pipe sizing tables or sizing equations in this chapter.
(2) Sizing tables included in a listed piping system manufacturer’s installation instructions.
(3) Engineering methods. [NFPA 54:5.3.3] 1308.3.3 Allowable Pressure Drop. The design pressure loss in a piping system from the point of delivery to the inlet connection of all appliances served shall be such that the supply pressure at each appliance inlet is greater than or equal to the minimum pressure required by the appliance. [NFPA 54:5.3.4] 1308.4 Acceptable Piping Materials and Joining 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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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.
CMC § 1308.4.2.4 High relevance — show source text
Underground
installations . . . . . . . . 1308.4.2.4, 1308.4.3.4, 1310.0,
D 101.2, D 109.3, D 110.3
Venting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1308.6.4
FUEL GAS TUBING
Cathodic protection . . . . . . . . . . . . . . . . . . . . . . D 105.0 Change in direction . . . . . . . . . . . . . . . . . . . . . 1310.8.3
Concealed location . . . . . . . . . . . . . . . . . . . . . . . 1310.4
Detection of leaks . . . . . . . . . . . . . . . . . . . . . . . . 1313.4
Electrical bonding and grounding. . . . . . . . . . . . . 1311.0 Inspection and testing . . . . . . . . . . . . . . 1303.0, 1313.0
Installation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1310.0
Interconnections . . . . . . . . . . . . . . . . . . . . . . . . . 1308.2
Joints and fittings . . . . . . . . . . . . . . 1308.4.4–1308.4.8,
1313.2.1, 1313.2.2
Materials. . . . . . . . . . . . . . . . . . . . . . . . 1308.4, D 109.0
Obstruction of flow. . . . . . . . . . . . . . . . . . . . . . . 1310.12
Purging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1313.6 Sizing . . . . . . . . . . . . . 1308.3, 1314.1, 1315.0, D 108.0,
Table 1315.2(1)–Table 1315.2(36)
Supports. . . . . . . . . . . . . . . . 1310.3.5, Table 1310.3.5.1
Underground installations . . . . . . . . . . . . . . 1308.4.2.4,
1308.4.3.4, 1310.1,
D 101.2, D 109.3, D 110.3
Venting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1308.6.4
FURNACES
Approximate gas input . . . . . . . . . . . . . . Table 1308.3.1
Automatic control required . . . . . . . . . . . . . . . . . . 608.6
CMC § 404.3 High relevance — show source text
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APPENDIX E
E 404.3 Mechanical Protection. All gas outlet risers, regulators, meters, valves, and other exposed equipment shall be protected against accidental damage. [NFPA 501A:4.4.3]
E 404.4 Special Rules on Atmospherically Con- trolled Regulators. Atmospherically controlled regulators shall be installed in such a manner that moisture cannot enter the regulator vent and accumulate above the diaphragm. Where the regulator vent is obstructed due to snow and icing conditions, shields, hoods, or other suitable devices shall be provided to guard against closing of the vent opening. [NFPA 501A:4.4.4.1 – 4.4.4.2]
E 404.5 Fuel Gas Piping Test. The manufactured home fuel gas piping system shall be tested only with air before it is connected to the gas supply. The manufactured home gas piping system shall be subjected to a pressure test with all appliance shutoff valves in their closed positions. [NFPA 501A:4.4.5]
E 404.5.1 Procedures. The fuel gas piping test shall consist of air pressure at not less than 10 inches water column or more than 14 inches water column (2.5 kPa to 3.5 kPa). The fuel gas piping system shall be isolated from the air pressure source and shall maintain this pressure for not less than 10 minutes without perceptible leakage. Upon satisfactory completion of the fuel gas piping test, the appliance valves shall be opened, and the gas appliance connectors shall be tested with soapy water or bubble solution while under the pressure remaining in the piping system. Solutions used for testing for leakage shall not contain corrosive chemicals. Pressure shall be measured with a manometer, slope gauge, or gauge that is calibrated in either water inch (mm) or psi (kPa) with increments of either [1] ⁄ 10 inch (2.5 mm) or [1] ⁄ 10 psi (0.7 kPa) gauge, as applicable. Upon satisfactory completion of the fuel gas piping test, the manufactured home gas supply connector shall be installed, and the connections shall be tested with soapy water or bubble solution. [NFPA 501A:4.4.5.1.1 – 4.4.5.1.6]
E 404.5.2 Warning. The following warning shall be supplied to the installer:
WARNING: Do not overpressurize the fuel gas piping system. Damage to valves, regulators, and appliances can occur due to pressurization beyond the maximums specified. [NFPA 501A:4.4.5.2]
E 404.5.3 Vents. Gas appliance vents shall be visually inspected to ensure that they have not been dislodged in transit and are connected securely to the appliance.
[NFPA 501A:4.4.5.3]
E 404.6 Oil Tanks. Oil tank capacities shall comply with the following:
(1) No more than one 660 gallon (2498 L) tank or two tanks with an aggregate capacity of 660 gallons (2498 L) or less shall be connected to one oil-burning appliance.
CMC § 8.3.1.1 High relevance — show source text
[NFPA 54:8.3.1.1] 1313.6.1.2 Placing in Operation. Where gas piping containing air and meeting the criteria of Table 1313.6.1 is placed in operation, the air in the piping shall first be displaced with an inert gas. The inert gas shall then be displaced with fuel gas in accordance with Section 1313.6.1.3. [NFPA 54:8.3.1.2] 1313.6.1.3 Outdoor Discharge of Purged Gases. The open end of a piping system being pressure vented or purged shall discharge directly to an outdoor location. Purging operations shall comply with all of the following requirements: (1) The point of discharge shall be controlled with a shutoff valve.
(2) The point of discharge shall be located at least 10 feet (3048 mm) from sources of ignition, at least 10 feet (3048 mm) from building openings and at least 25 feet (7620 mm) from mechanical air intake openings. (3) During discharge, the open point of discharge shall be continuously attended and monitored with a combustible gas indicator that complies with Section 1313.6.1.4.
(4) Purging operations introducing fuel gas shall be stopped when 90 percent fuel gas by volume is detected within the pipe. (5) Persons not involved in the purging operations shall be evacuated from all areas within 10 feet (3048 mm) of the point of discharge. [NFPA 54:8.3.1.3]
1313.6.1.4 Combustible Gas Indicator. Combustible gas indicators shall be listed and calibrated in accordance with the manufacturer’s instructions. Combustible gas indicators shall numerically display a volume scale from 0 percent to 100 percent in 1 percent or smaller increments. [NFPA 54:8.3.1.4]
1313.6.2 Piping Systems Allowed to be Purged Indoors or Outdoors. The purging of piping systems shall be in accordance with the provisions of Section 1313.6.2.1 where the piping system meets both of the following: (1) The design operating pressure is 2 psig (14 kPag) or less.
(2) The piping being purged is constructed entirely from pipe or tubing not meeting the size and length criteria of Table 1313.6.1. [NFPA 54:8.3.2] 1313.6.2.1 Purging Procedure. The piping system shall be purged in accordance with one or more of the following: (1) The piping shall be purged with fuel gas and shall discharge to the outdoors. (2) The piping shall be purged with fuel gas and shall discharge to the indoors or outdoors through an appliance burner not located in a combustion chamber. Such burner shall be provided with a continuous source of ignition. (3) The piping shall be purged with fuel gas and shall discharge to the indoors or outdoors through a burner that has a continuous source of ignition and that is designed for such purpose. (4) The piping shall be purged with fuel gas that is discharged to the indoors or outdoors, and the point of discharge shall be monitored with a listed combustible gas detector in accordance with Section 1313.6.2.2. Purging shall be stopped when fuel gas is detected.
CMC § 113.3 High relevance — show source text
D 113.3 Mechanical Protection. All gas outlet risers, regulators, meters, valves, and other exposed equipment shall be protected against accidental damage. [NFPA 501A:4.4.3]
D 113.4 Special Rules on Atmospherically Con- trolled Regulators. Atmospherically controlled regulators shall be installed in such a manner that moisture cannot enter the regulator vent and accumulate above the diaphragm. Where the regulator vent is obstructed due to snow and icing conditions, shields, hoods, or other suitable devices shall be provided to guard against closing of the vent opening. [NFPA 501A:4.4.4.1 – 4.4.4.2]
D 113.5 Fuel Gas Piping Test. The manufactured home fuel gas piping system shall be tested only with air before it is connected to the gas supply. The manufactured home gas piping system shall be subjected to a pressure test with all appliance shutoff valves in their closed positions. [NFPA 501A:4.4.5]
D 113.5.1 Procedures. The fuel gas piping test shall consist of air pressure at not less than 10 inches water column or more than 14 inches water column (2.5 kPa to 3.5 kPa). The fuel gas piping system shall be isolated from the air pressure source and shall maintain this pressure for not less than 10 minutes without perceptible leakage. Upon satisfactory completion of the fuel gas piping test, the appliance valves shall be opened and the gas appliance connectors shall be tested with soapy water or bubble solution while under the pressure remaining in the piping system. Solutions used for testing for leakage shall not contain corrosive chemicals. Pressure shall be measured with a manometer, slope gauge, or gauge that is calibrated in either water inch (mm) or psi (kPa) with increments of either [1] ⁄ 10 of an inch (2.5 mm) or [1] ⁄ 10 psi (0.7 kPa) gauge, as applicable. Upon satisfactory completion of the fuel gas piping test, the manufactured home gas supply connector shall be installed and the connections shall be tested with soapy water or bubble solution.
[NFPA 501A:4.4.5.1.1 – 4.4.5.1.6]
D 113.5.2 Warning. The following warning shall be supplied to the installer:
WARNING: Do not overpressurize the fuel gas piping system. Damage to valves, regulators, and appliances can occur due to pressurization beyond the maximums specified. [NFPA 501A:4.4.5.2]
D 113.5.3 Vents. Gas appliance vents shall be visually inspected to ensure that they have not been dislodged in transit and are connected securely to the appliance.
[NFPA 501A:4.4.5.3]
D 113.6 Oil Tanks. Oil tank capacities shall comply with the following:
(1) No more than one 660 gallon (2498 L) tank or two tanks with an aggregate capacity of 660 gallons (2498 L) or less shall be connected to one oil-burning appliance.
(2) Two supply tanks, where used, shall be cross-connected and provided with a single fill and single vent, as described in NFPA 31 and shall be on a common slab and rigidly secured, one to the other.
CMC § 1312.1 High relevance — show source text
Materials addressed in Section 1312.1(2), Section 1312.1(3), Section 1312.1(4), Section 1312.1(5), and Section 1312.1(6) shall not be installed through an opening in an appliance housing, cabinet, or casing, unless the tubing or connector is protected against damage.
[NFPA 54:9.6.1.2]
1312.1.2 Food Service Appliance Connectors. Connectors used with food service appliances that are moved for cleaning and sanitation purposes shall be installed in accordance with the connector manufacturer’s installation
instructions. Such connectors shall be listed in accordance
with ANSI Z21.69/CSA 6.16. [NFPA 54:9.6.1.3]
1312.1.3 Restraining Device. Movement of appliances with casters shall be limited by a restraining device installed in accordance with the connector and appliance manufacturer’s installation instructions. [NFPA 54:9.6.1.4]
1312.2 Suspended Low-Intensity Infrared Tube Heaters. Suspended low-intensity infrared tube heaters shall be connected to the building piping system with a connector listed for the application in accordance with ANSI Z21.24/CSA 6.10 as follows:
(1) The connector shall be installed in accordance with the tube heater installation instructions, and shall be in the same room as the appliance.
(2) Only one connector shall be used per appliance. [NFPA 54:9.6.1.5]
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length and shall not extend from one room to another or pass through any walls, partitions, ceilings, or floors. Flexible connections shall not be used in any concealed location. They shall be protected against physical or thermal damage and shall be provided with gas shutoff valves in readily accessible locations in rigid piping upstream from the flexible connections. [NFPA 54:9.6.4.4]
1312.6 Appliance Shutoff Valves and Connections. Each appliance connected to a piping system shall have an accessible, approved manual shutoff valve with a nondisplaceable valve member, or a listed gas convenience outlet. Appliance shutoff valves and convenience outlets shall serve a single appliance only. [NFPA 54:9.6.5] The shutoff valve shall be located within 6 feet (1829 mm) of the appliance it serves. [NFPA 54:9.6.5.1] Where a connector is used, the valve shall be installed upstream of the connector. A union or flanged connection shall be provided downstream from the valve to permit removal of appliance controls. [NFPA 54:9.6.5.1(A)]
Exceptions:
(1) Shutoff valves serving decorative appliances in a fireplace shall not be located within the fireplace firebox except where the valve is listed for such use. [NFPA 54: 9.6.5.1(B)]
(2) Shutoff valves shall be permitted to be accessibly located inside wall heaters and wall furnaces listed for recessed
installation where necessary maintenance is performed without removal of the shutoff valve.
CMC § 0.293 High relevance — show source text
automatic storage
30 to 40 gallon tank
Water heater, automatic storage
50 gallon tank
Water heater, automatic instantaneous
Capacity at 2 gallons per minute
Capacity at 4 gallons per minute
Capacity at 6 gallons per minute
Water heater, domestic, circulating or
side-arm|
35 000
50 000
142 800
285 000
428 400
35 000| |
Cooking Appliances
Range, freestanding, domestic
Built-in oven or broiler unit, domestic
Built-in top unit, domestic|
65 000
25 000
40 000| |
Other Appliances
Refrigerator
Clothes dryer, Type 1 (domestic)
Gas fireplace direct-vent
Gas log
Barbecue
Gaslight|
3000
35 000
40 000
80 000
40 000
2500|For SI units: 1000 British thermal units per hour = 0.293 kW
1208.3.2 Sizing Methods. Gas piping shall be sized in accordance with one of the following:
(1) Pipe sizing tables or sizing equations in this chap ter.
(2) Sizing tables included in a listed piping system manufacturer’s installation instructions.
(3) Engineering methods. [NFPA 54:5.3.3]
1208.3.3 Allowable Pressure Drop. The design pressure loss in a piping system from the point of delivery to
TABLE 1208.3.1
APPROXIMATE GAS INPUT FOR
TYPICAL APPLIANCES
[NFPA 54: TABLE A.5.3.2.1]
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For SI units: 1000 British thermal units per hour = 0.293 kW
2025 CALIFORNIA PLUMBING CODE 217
), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.
FUEL GAS PIPING
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1208.5.4 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.” 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.” Polyvinyl chloride (PVC) and chlorinated polyvinyl chloride (CPVC) plastic pipe, tubing, and fittings shall not be used to supply fuel gas. [NFPA 54:5.5.4.1.1 – 5.5.4.1.3]
1208.5.5 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}
CMC § 1.1.1.2 High relevance — show source text
(14)Installation of LP-Gas systems for railroad switch heating.
(15)Installation of LP-Gas and compressed natural gas (CNG) systems on vehicles.
(16)Gas piping, meters, gas pressure regulators, and other appurtenances used by the serving gas supplier in distribution of gas, other than undiluted LP-Gas.
(17)Building design and construction, except as specified herein.
(18)Fuel gas systems on recreational vehicles manufactured in accordance with NFPA 1192.
(19)Fuel gas systems using hydrogen as a fuel.
(20)Construction of appliances. {NFPA 54:1.1.1.2}
1303.0 Inspection. 1303.1 Inspection Notification. Upon completion of the installation, alteration, or repair of gas piping, and prior to the use thereof, the Authority Having Jurisdiction shall be notified that such gas piping is ready for inspection. 1303.2 Excavation. Excavations required for the installation of underground piping shall be kept open until such time as the piping has been inspected and approved. Where such piping is covered or concealed before such approval, it shall be exposed upon the direction of the Authority Having Jurisdiction.
1303.3 Type of Inspections. The Authority Having Jurisdiction shall make the following inspections and either shall approve that portion of the work as completed or shall notify the permit holder wherein the same fails to be in accordance with this code.
1303.3.1 Rough Piping Inspection. This inspection shall be made after gas piping authorized by the permit has been installed before such piping has been covered or concealed, or before fixture or appliance has been attached thereto. This inspection shall include a determination that the gas piping size, material, and installation meet the requirements of this code. 1303.3.2 Final Piping Inspection. This inspection shall be made after piping authorized by the permit has been installed and after portions thereof that are to be covered or concealed are so concealed and before fixture, appliance, or shutoff valve has been attached thereto. This inspection shall comply with Section 1313.1. Test gauges used in conducting tests shall be in accordance with Section 1303.3.3 through Section 1303.3.3.4.
2025 CALIFORNIA MECHANICAL CODE 275
), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.
FUEL GAS PIPING
1303.3.3 Test Gauges. Tests required by this code, which are performed utilizing dial gauges, shall be limited to gauges having the following pressure graduations or increments.
1303.3.3.1 Pressure Tests (10 psi or less). Required pressure tests of 10 psi (69 kPa) or less shall be performed with gauges of 0.10 psi (0.69 kPa) increments or less.
1303.3.3.2 Pressure Tests (greater than 10 psi to 100 psi). Required pressure tests exceeding 10 psi (69 kPa) but less than or equal to 100 psi (689 kPa) shall be performed with gauges of 1 psi (7 kPa) increments or less.
1303.3.3.3 Pressure Tests (exceeding 100 psi). Required pressure tests exceeding 100 psi (689 kPa) shall be performed with gauges of 2 percent increments or less of the required test pressure.
Frequently asked questions
What pressure limits apply to fuel gas piping inside buildings?
The CMC limits building piping service pressures—typically 5 psi for natural gas and 10 psi for undiluted propane—unless higher pressures are specifically covered by weld/braze joints or other listed methods; see §1301.1 and related material/joint rules in Chapter 13 .
What are the basic purging and leak‑test requirements?
Purging and venting of piping are controlled by §1313.6 and Table 1313.6.1: large/long runs require outdoor discharge during purging, monitoring with a listed combustible-gas indicator, and strict distancing from ignition and air‑intakes; appliances and piping must be tested and inspected per §1303.0 before use .
Can flexible connectors or CSST be used?
Yes—when listed and installed per the connector and appliance manufacturer’s instructions and the CMC (see §1312.1–§1312.6). Flexible connectors must be protected, limited in length, and provided with accessible shutoff valves; CSST is permitted per manufacturer instructions and local adoption rules noted in the code cross-references .
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