CRC · California Residential Code
Gas Piping & Sizing
This hub orients readers to the CRC fuel‑gas sizing rules and points them to the Plumbing and Mechanical Code sections (e.g., §1208.3, §1215.0, §1215.3, §1308.3, §1315.1) that contain tables, equations, materials and engineering requirements.
Last reviewed: July 6, 2026
Overview
This hub covers the CRC-level rules and referenced Plumbing/Mechanical provisions that govern sizing, materials, pressure limits, testing, and installation practices for fuel‑gas piping serving residences. It explains how to determine maximum gas demand, pick the correct pipe size from tables or equations, and when to use engineering methods so appliances receive the minimum inlet pressure required by their rating; see §1208.3 for the design basis and system demand rules.
Sizing methods and the actual sizing references (tables and sizing equations) live in the fuel‑gas chapters: the Plumbing Code’s required‑size rules and tables at §1215.0–§1215.6 and associated equations in §1215.3, and the Mechanical Code’s parallel provisions at §1308.3 and §1315.1. These sections cover longest‑run and branch‑length methods, allowable pressure drop, materials/jointing, outlet sizing, and when to escalate to engineering calculations.
In this section
Code references
Grounded in the retrieved California Residential Code — click a citation to read the verbatim passage:
CRC § 0.249 High relevance — show source text
water column = 0.249 kPa
TABLE 1215.3
Cr AND Y FOR NATURAL GAS AND UNDILUTED
PROPANE AT STANDARD CONDITIONS
[NFPA 54: TABLE 6.4.2]
GAS FORMULA FACTORS Col3
GASCr Y
Natural Gas0.6094 0.9992 Undiluted Propane 1.2462 0.9910 1215.4 Sizing of Piping Sections. To determine the size of each section of pipe in a system within the range of Table 1215.2(1) through Table 1215.2(36), proceed as follows:
234 2025 CALIFORNIA PLUMBING CODE
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FUEL GAS PIPING
(1) Measure the length of the pipe from the gas meter location to the most remote outlet on the system.
(2) Select the length in feet column and row showing the distance, or the next longer distance where the table does not give the exact length.
(3) Starting at the most remote outlet, find in the row just selected the gas demand for that outlet. Where the exact figure of demand is not shown, choose the next larger figure in the row.
(4) At the top of this column will be found the correct size of pipe.
(5) Using this same row, proceed in a similar manner to each section of pipe serving this outlet. For each section of pipe, determine the total gas demand supplied by that section. Where gas piping sections serve both heating and cooling appliances and the installation prevents both units from operating simultaneously, the larger of the two demand loads needs to be used in sizing these sections.
(6) Size each section of branch piping not previously sized by measuring the distance from the gas meter location to the most remote outlet in that branch and follow the procedures of steps 2, 3, 4, and 5 above. Size branch piping in the order of their distance from the meter location, beginning with the most distant outlet not previously sized.
1215.5 Engineering Methods. For conditions other than those covered by Section 1215.1, such as longer runs or greater gas demands, the size of each gas piping system shall be determined by standard engineering methods acceptable to the Authority Having Jurisdiction, and each such system shall be so designed that the total pressure drop between the meter or another point of supply and an outlet where full demand is being supplied to all outlets, shall be in accordance with the requirements of Section 1208.4. 1215.6 Variable Gas Pressure. Where the supply gas pressure exceeds 5 psi (34.6 kPa) for natural gas and 10 psi (69 kPa) for undiluted propane or is less than 6 inches (1.5 kPa) of water column, or where diversity demand factors are used, the design, pipe, sizing, materials, location, and use of such systems first shall be approved by the Authority Having Jurisdiction. Piping systems designed for pressures exceeding the serving gas supplier’s standard delivery pressure shall have prior verification from the gas supplier of the availability of the design pressure.
CRC § 5.3.2.3 Medium 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.
CRC § 0.293 Medium 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
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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}
CRC § 5.5.2.4 Medium relevance — show source text
Threaded copper, copper alloy, or aluminum alloy pipe shall not be used with gases corrosive to such material. [NFPA 54:5.5.2.4]
1308.4.2.4 Aluminum Alloy Pipe. Aluminum alloy pipe shall comply with ASTM B241 (except that the use of alloy 5456 is prohibited), and shall be marked at each end of each length indicating compliance. Aluminum alloy pipe 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, detergents, or sewage. [NFPA 54:5.5.2.5]
Aluminum alloy pipe shall not be used in exterior locations or underground. [NFPA 54:5.5.2.6]
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ular supply shall be permitted to be used for this purpose.
[NFPA 54:5.2.2.1 – 5.2.2.2] 1308.3 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]
1308.3.1 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 2 000 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 1308.3.1 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. 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.
CRC § 1302.0 Medium relevance — show source text
1302.0 Coverage of Piping System . . . . . 275
1302.1 General. . . . . . . . . . . . . . . . . . . . . 275
1302.2 Piping System Requirements . . . . 275
1302.3 Applications . . . . . . . . . . . . . . . . . 275
1303.0 Inspection . . . . . . . . . . . . . . . . . . . 275
1303.1 Inspection Notification . . . . . . . . . 275
1303.2 Excavation . . . . . . . . . . . . . . . . . . 275
1303.3 Type of Inspections . . . . . . . . . . . 275
1303.4 Inspection Waived . . . . . . . . . . . . 276
1304.0 Certificate of Inspection . . . . . . . . 276
1304.1 Issuance . . . . . . . . . . . . . . . . . . . . 276
1304.2 Gas Supplier. . . . . . . . . . . . . . . . . 276
1304.3 Unlawful . . . . . . . . . . . . . . . . . . . . 276
1305.0 Authority to Render Gas Service . . 276
1305.1 Authorized Personnel . . . . . . . . . . 276
1305.2 Outlets . . . . . . . . . . . . . . . . . . . . . 276
1306.0 Authority to Disconnect. . . . . . . . . 276
1306.1 Disconnection . . . . . . . . . . . . . . . . 276
1306.2 Notice . . . . . . . . . . . . . . . . . . . . . . 276
1306.3 Capped Outlets. . . . . . . . . . . . . . . 276
1307.0 Temporary Use of Gas . . . . . . . . . 276
1307.1 General. . . . . . . . . . . . . . . . . . . . . 276
1308.0 Gas Piping System Design, Materials, and Components . . . . . 276
1308.1 Installation of Piping System . . . . 276
1308.2 Interconnections Supplying Separate Users. . . . . . . . . . . . . . . 276
1308.3 Sizing of Gas Piping Systems . . . 277
1308.4 Acceptable Piping Materials and Joining Methods . . . . . . . . . . 277
Table 1308.3.1 Approximate Gas Input for Typical Appliances . . . . . . . . . . . . 277
Table 1308.4.6.2 Specifications for Threading Metallic Pipe . . . . . . . . . . . . . . . . . 278
1308.5 Gas Meters . . . . . . . . . . . . . . . . . . 280
1308.6 Gas Pressure Regulators . . . . . . . 280
1308.7 Overpressure Protection. . . . . . . . 281
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CRC § 1215.1.2 Medium relevance — show source text
1215.1.2 Branch Length Method. Pipe shall be sized as follows:
(1) Pipe size of each section of the longest pipe run from the point of delivery to the most remote outlet shall be determined using the longest run of piping and the load of the section.
(2) The pipe size of each section of branch piping not previously sized shall be determined using the length of piping from the point of delivery to the most remote outlet in each branch and the load of the section. [NFPA 54:6.1.2]
1215.1.3 Hybrid Pressure. The pipe size for each section of higher pressure gas piping shall be determined using the longest length of piping from the point of delivery to the most remote line pressure regulator. The pipe size from the line pressure regulator to each outlet shall be determined using the length of piping from the regulator to the most remote outlet served by the regulator.
[NFPA 54:6.1.3] 1215.2 Sizing of Gas Piping Systems. Sizing of piping systems shall be in accordance with Section 1215.2.1 for natural gas piping systems and Section 1215.2.2 for propane piping systems. 1215.2.1 Natural Gas Piping Systems. Table 1215.2(1) through Table 1215.2(23) shall be used in conjunction with one of the methods described in Section 1215.1.1 through Section 1215.1.3 for piping materials other than non-corrugated stainless steel tubing. Section 1215.3 shall be used in conjunction with one of the methods described in Section 1215.1.1 through Section 1215.1.3 for non-corrugated stainless steel tubing.
[NFPA 54:6.2.1, 6.2.2] 1215.2.2 Propane Piping Systems. Table 1215.2(24) through Table 1215.2(36) shall be used in conjunction with one of the methods described in Section 1215.1.1 through Section 1215.1.3 for piping materials other than non-corrugated stainless steel tubing. Section 1215.3 shall be used in conjunction with one of the methods described in Section 1215.1.1 through Section 1215.1.3 for non-corrugated stainless steel tubing.
[NFPA 54:6.3.1, 6.3.2] 1215.3 Sizing Equations. The inside diameter of smooth wall pipe or tubing shall be determined by Equation 1215.3(1), Equation 1215.3(2) and Table 1215.3 using the equivalent pipe length determined by the methods in Section 1215.1.1 through Section 1215.1.3. [NFPA 54:6.4]
LOW-PRESSURE GAS FORMULA (LESS THAN 1.5 psi)
[NFPA 54:6.4.1]
[Equation 1215.3(1)]
Q [0.381] D =
0.206
19.17 [(]
Δ H
)Cr x L
Where:
D = inside diameter of pipe, inches
Q = input rate appliance(s), cubic feet per hour at 60 ˚ F and 30 inch mercury column
L = equivalent length of pipe, feet
CRC § 1315.3 Medium relevance — show source text
TABLE 1315.3
Cr AND Y FOR NATURAL GAS AND UNDILUTED
PROPANE AT STANDARD CONDITIONS
[NFPA 54: TABLE 6.4.2]
GAS FORMULA FACTORS Col3
GASCr Y
Natural Gas0.6094 0.9992 Undiluted Propane 1.2462 0.9910 1315.4 Sizing of Piping Sections. To determine the size of each section of pipe in a system within the range of Table 1315.2(1) through Table 1315.2(36), proceed as follows:
(1) Measure the length of the pipe from the gas meter location to the most remote outlet on the system.
(2) Select the length in feet column and row showing the distance, or the next longer distance where the table does not give the exact length.
(3) Starting at the most remote outlet, find in the just selected the gas demand for that outlet. Where the exact figure of demand is not shown, choose the next larger figure in the
row.
(4) At the top of the column in the table will be found the correct size of pipe.
(5) Using this same row, proceed in a similar manner for each section of pipe serving this outlet. For each section of pipe, determine the total gas demand supplied by that section. Where gas piping sections serve both heating and cooling appliances and the installation prevents both units from operating simultaneously, the larger of the two demand loads needs to be used in sizing these sections.
(6) Size each section of branch piping not previously sized by measuring the distance from the gas meter location to the most remote outlet in that branch and follow the procedures of steps 2, 3, 4, and 5 above. Size branch piping in the order of their distance from the meter location, beginning with the most distant outlet not previously sized.
1315.5 Engineering Methods. For conditions other than those covered by Section 1315.1, such as longer runs or greater gas demands, the size of each gas piping system shall be determined by standard engineering methods acceptable to the Authority Having Jurisdiction, and each such system shall be so designed that the total pressure drop between the meter or other point of supply and an outlet where full demand is being supplied to outlets, shall be in accordance with the requirements of Section 1308.3.
1315.6 Variable Gas Pressures. Where the supply gas pressure exceeds 5 psi (34 kPa) for natural gas and 10 psi (69 kPa) for undiluted propane or is less than 6 inches (1.5 kPa) of water column, or where diversity demand factors are used, the design, pipe, sizing, materials, location, and use of such systems first shall be approved by the Authority Having Jurisdiction. Piping systems designed for pressures exceeding the serving gas supplier’s standard delivery pressure shall have prior verification from the gas supplier of the availability of the design pressure.
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CRC § 304.8 Medium relevance — show source text
31
30
30
29|66
64
62
60
59|116
112
108
105
102|164
159
154
149
145|350
339
329
319
310|630
610
592
575
559|994
962
933
906
881|2070
2000
1940
1890
1830|For SI units: 1 inch = 25 mm, 1 foot = 304.8 mm, 1 cubic foot per hour = 0.0283 m [3] /h, 1 pound-force per square inch = 6.8947 kPa
Notes : 1 Table capacities are based on Type K copper tubing inside diameter (shown), which has the smallest inside diameter of the copper tubing products. 2 Table entries are rounded to 3 significant digits.
2025 CALIFORNIA MECHANICAL CODE 307
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TABLE 1315.2(12) SEMI-RIGID COPPER TUBING [NFPA 54: TABLE 6.2.1(m)]3 Col2 Col3 Col4 Col5 Col6 Col7 Col8 Col9 Col10 Col11 GAS: GAS: NATURAL NATURAL INLET PRESSURE: INLET PRESSURE: 2.0 psi 2.0 psi PRESSURE DROP: PRESSURE DROP: 1.5 psi 1.5 psi SPECIFIC GRAVITY: SPECIFIC GRAVITY: 0.60 0.60 INTENDED USE: PIPE SIZING BETWEEN POINT OF DELIVERY AND THE HOUSE LINE REGULATOR. TOTAL LOAD SUPPLIED BY A
SINGLE HOUSE LINE REGULATOR NOT EXCEEDING 150 CUBIC FEET PER HOUR2.INTENDED USE: PIPE SIZING BETWEEN POINT OF DELIVERY AND THE HOUSE LINE REGULATOR. TOTAL LOAD SUPPLIED BY A
SINGLE HOUSE LINE REGULATOR NOT EXCEEDING 150 CUBIC FEET PER HOUR2.INTENDED USE: PIPE SIZING BETWEEN POINT OF DELIVERY AND THE HOUSE LINE REGULATOR. TOTAL LOAD SUPPLIED BY A
SINGLE HOUSE LINE REGULATOR NOT EXCEEDING 150 CUBIC FEET PER HOUR2.**INTENDED USE: PIPE SIZING BETWEEN POINT OF DELIVERY AND THE HOUSE LINE REGULATOR. CRC § 1213.0 Medium relevance — show source text
1213.0 Pressure Testing, Inspection, and Purging . . . . . . . . . . . . . . . . .231
1213.1 Piping Installations . . . . . . . . . . . .231
1213.2 Test Preparation . . . . . . . . . . . . . .231
1213.3 Test Pressure . . . . . . . . . . . . . . . .232
1213.4 Detection of Leaks and Defects . .232
1213.5 Piping System Leak Test . . . . . . .232
1213.6 Purging Requirements . . . . . . . . .232
Table 1213.6.1 Size and Length of Piping . . . . . .232
1214.0 Required Gas Supply . . . . . . . . . .233
1214.1 General . . . . . . . . . . . . . . . . . . . . .233
1214.2 Volume . . . . . . . . . . . . . . . . . . . . .233
1214.3 Gas Appliances . . . . . . . . . . . . . .233
1214.4 Size of Piping Outlets . . . . . . . . . .233
1215.0 Required Gas Piping Size . . . . . .234
1215.1 Pipe Sizing Methods . . . . . . . . . . .234
1215.2 Sizing of Gas Piping Systems . . .234
1215.3 Sizing Equations . . . . . . . . . . . . . .234
Table 1215.3 Cr and Y for Natural Gas
and Undiluted Propane at Standard Conditions . . . . . . . . . . .234
1215.4 Sizing of Piping Sections . . . . . . .234
1215.5 Engineering Methods . . . . . . . . . .235
1215.6 Variable Gas Pressure . . . . . . . . .235
Table 1215.2(1) Schedule 40 Metallic Pipe . . . . . .237
Table 1215.2(2) Schedule 40 Metallic Pipe . . . . . .238
Table 1215.2(3) Schedule 40 Metallic Pipe . . . . . .239
Table 1215.2(4) Schedule 40 Metallic Pipe . . . . . .240
Table 1215.2(5) Schedule 40 Metallic Pipe . . . . . .241
Table 1215.2(6) Schedule 40 Metallic Pipe . . . . . .242
Table 1215.2(7) Semi-Rigid Copper Tubing . . . . . .243
Table 1215.2(8) Semi-Rigid Copper Tubing . . . . . .244
Table 1215.2(9) Semi-Rigid Copper Tubing . . . . . .245
Table 1215.2(10) Semi-Rigid Copper Tubing . . . . . .246
Table 1215.2(11) Semi-Rigid Copper Tubing . . . . . .247
Table 1215.2(12) Semi-Rigid Copper Tubing . . . . . .248
Table 1215.2(13) Semi-Rigid Copper Tubing . . . . . .249
Table 1215.2(14) Corrugated Stainless Steel Tubing (CSST) . . . . . . . . . . . . . . .250
CRC § 1314.2 Medium relevance — show source text
Where gas of a different specific gravity is to be delivered, the serving gas supplier shall be permitted to be contacted for specific gravity conversion factors to use in sizing piping systems from the pipe sizing tables in this chapter. 1314.2 Volume. The hourly volume of gas required at each piping outlet shall be taken as not less than the maximum hourly rating as specified by the manufacturer of the appliance or appliances to be connected to each such outlet.
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1314.3 Gas Appliances. Where the gas appliances to be installed have not been definitely specified, Table 1308.3.1 shall be permitted to be used as a reference to estimate requirements of typical appliances. To obtain the cubic feet per hour (m [3] /h) of gas required, divide the input of the appliances by the average Btu (kW•h) heating value per cubic foot (m [3] ) of the gas. The average Btu (kW•h) per cubic foot (m [3] ) of the gas in the area of the installation shall be permitted to be obtained from the serving gas supplier. 1314.4 Size of Piping Outlets. The size of the supply piping outlet for a gas appliance shall be not less than [1] ⁄ 2 of an inch (15 mm). The size of a piping outlet for a mobile home shall be not less than [3] ⁄ 4 of an inch (20 mm).
1315.0 Required Gas Piping Size. 1315.1 Pipe Sizing Methods. Where the pipe size is to be determined using any of the methods in Section 1315.1.1 through Section 1315.1.3, the diameter of each pipe segment shall be obtained from the pipe sizing tables in Section 1315.2 or from the sizing equations in Section 1315.3. [NFPA 54:6.1] 1315.1.1 Longest Length Method. The pipe size of each section of gas piping shall be determined using the longest length of piping from the point of delivery to the most remote outlet and the load of the section. [NFPA 54:6.1.1] 1315.1.2 Branch Length Method. Pipe shall be sized as follows:
(1) Pipe size of each section of the longest pipe run from the point of delivery to the most remote outlet shall be determined using the longest run of piping and the load of the section.
(2) The pipe size of each section of branch piping not previously sized shall be determined using the length of piping from the point of delivery to the most remote outlet in each branch and the load of the section. [NFPA 54:6.1.2] 1315.1.3 Hybrid Pressure. The pipe size for each section of higher pressure gas piping shall be determined using the longest length of piping from the point of delivery to the most remote line pressure regulator. The pipe size from the line pressure regulator to each outlet shall be determined using the length of piping from the regulator to the most remote outlet served by the regulator. [NFPA 54:6.1.3] **1315.2 Sizing of Gas Piping Systems.
CRC § 1214.1 Medium relevance — show source text
1214.1 General. The following regulations shall comply with this section and Section 1215.0, shall be the standard for the installation of gas piping. Natural gas regulations and tables are based on the use of a gas having a specific gravity of 0.60 and for undiluted liquefied petroleum gas, having a specific gravity of 1.50. Where gas of a different specific gravity is to be delivered, the specific gravity conversion factors provided by the serving gas supplier shall be used in sizing piping systems from the pipe sizing tables in this chapter.
1214.2 Volume. The hourly volume of gas required at each piping outlet shall be taken as not less than the maximum hourly rating as specified by the manufacturer of the appliance or appliances to be connected to each such outlet.
1214.3 Gas Appliances. Where the gas appliances to be installed have not been specified, Table 1208.3.1 shall be permitted to be used as a reference to estimate requirements of typical appliances. To obtain the cubic feet per hour (m [3] /h) of gas required, divide the input of the appliances by the average Btu (kW•h) heating value per cubic foot (m [3] ) of the gas. The average Btu (kW•h) per cubic foot (m [3] ) of the gas in the area of the installation shall be permitted to be obtained from the serving gas supplier.
1214.4 Size of Piping Outlets. The size of the supply piping outlet for a gas appliance shall be not less than [1] ⁄ 2 of an inch in diameter (15 mm).
The size of a piping outlet for a mobile home shall be not less than [3] ⁄ 4 of an inch in diameter (20 mm).
2025 CALIFORNIA PLUMBING CODE 233
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FUEL GAS PIPING
1215.0 Required Gas Piping Size. 1215.1 Pipe Sizing Methods. Where the pipe size is to be determined using any of the methods in Section 1215.1.1 through Section 1215.1.3, the diameter of each pipe segment shall be obtained from the pipe sizing tables in Section 1215.2 or from the sizing equations in Section 1215.3. [NFPA 54:6.1]
1215.1.1 Longest Length Method. The pipe size of each section of gas piping shall be determined using the longest length of piping from the point of delivery to the most remote outlet and the load of the section. [NFPA 54:6.1.1] (see calculation example in Figure 1215.1.1)
1215.1.2 Branch Length Method. Pipe shall be sized as follows:
(1) Pipe size of each section of the longest pipe run from the point of delivery to the most remote outlet shall be determined using the longest run of piping and the load of the section.
(2) The pipe size of each section of branch piping not previously sized shall be determined using the length of piping from the point of delivery to the most remote outlet in each branch and the load of the section. [NFPA 54:6.1.2]
Frequently asked questions
Which code sections do I use for residential gas piping sizing?
Use the Plumbing Code fuel‑gas sizing chapter (see §1215.0 et seq.) for the tables and equations and the Plumbing Code design rules at §1208.3; the Mechanical Code contains parallel fuel‑gas provisions (see §1308.3 and §1315.1) that apply where mechanical scope or AHJ practice points you to them.
When must I use engineering methods instead of the tables?
When conditions fall outside the tables’ limits — longer runs, higher total demands, nonstandard pressures, or variable/greater-than‑standard supply pressures — the code requires sizing by standard engineering methods acceptable to the AHJ (see §1215.5 / §1315.5).
Can I apply load diversity or must I size for simultaneous full load?
The baseline is to size for the total connected hourly load (all appliances at full capacity). An exception permits the use of established load diversity factors where recognized and allowed — check the specific provision in §1208.3.2 and applicable AHJ guidance.
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