Fuel-Gas-Pipe-SizingCity of Cypress
Community Development: Building Division
5275 Orange Avenue
Cypress, CA 90630
(714) 229-6730
FUEL GAS PIPE SIZING &
INSTALLATION with
Excerpts from the 2019 CPC
Revised January 26, 2019
Code and Installation Information
The information provided in this brochure answers a number of commonly asked questions. For additional
information please refer to the California Plumbing Code or speak with one of the City’s Building Inspectors.
Material
All pipe used for the installation, extension, alteration, or repair of any gas piping shall be standard weight
Schedule 40 wrought iron or steel (galvanized or black) or corrugated stainless steel tubing. Approved
PE pipe may be used in exterior buried piping systems when installed by certified technicians.
Used Piping
Pipe shall be either new, or shall previously have been used for no other purpose than conveying gas.
Isolation of Underground Pipe
Underground ferrous gas piping shall be electrically isolated from the rest of the gas system with listed
or approved isolation fittings installed a minimum of six inches above grade.
Unions
Where unions are necessary, right and left nipples and couplings shall be used. Ground joint unions may
only be used at exposed fixtures, appliance, or equipment connections and in exposed exterior locations
immediately on the discharge side of a building shutoff valve.
Shutoff Valves
An accessible shutoff valve shall be installed in the fuel supply piping outside of each appliance and
ahead of the union connection thereto, in addition to any valve on the appliance. Shutoff valves shall be
in the same room as the appliance and no further than 3 feet from the appliance.
Burial Depth
Steel pipe installed outside and underground shall have no less than 12 inches of cover. Plastic pipe shall
have no less than 18 inches of cover.
Permits
A plumbing permit must be obtained prior to the installation, alteration or repair of a gas piping system.
Inspections of Underground Exterior Gas Pipe
Underground exterior gas piping requires one inspection which will occur after the pipe has been installed
in a trench and pressurized but before it is covered.
Inspections of Above Ground Interior Gas Pipe: All gas piping systems within buildings shall be inspected
twice.
CPC Table 1208.4.1
Appliance Input (btu/happrox.)CF/H
Space Heating Units
Warm air furnace
Single-family 100,000 91
Multi-family, per unit 60,000 55
Hydronic boiler
Single-family 100,000 91
Multi-family, per unit 60,000 55
Space and Water Heating Units
Single-family 120,000 109
Multi-family, per unit 75,000 68
Water Heating Appliance
Water heater, automatic storage
30-40 gallon tank 35,000 32
50 gallon tank 50,000 45
Water heater, automatic instantaneous
Capacity at 2 gallons per minute 142,800 130
Capacity at 4 gallons per minute 285,000 259
Capacity at 6 gallons per minute 428,800 389
Water heater, domestic, circulating or side-arm 35,000 32
Cooking Appliances
Rages, freestanding, domestic 65,000 59
Built-in oven or broiler unit, domestic 25,000 23
Built-in top unit, domestic 40,000 36
Other appliances
Refrigerator 3,000 3
Clotehs dryer, Type 1 domestic 35,000 32
Gas fireplace direct vent 40,000 36
Gas Log 80,000 73
Barbeque 40,000 36
Gas light 2,500 2
First Inspection: (referred to as a rough inspection) occurs after the piping system has been installed but
prior to it being covered or concealed, or any fixture or appliance has been attached thereto. This inspection
will check for proper pipe size, material, and installation. Although not required, it is recommended that the
piping system be pressurized.
Second Inspection: (referred to as a final inspection) consists of a pressure test and occurs after the
building is completely enclosed but prior to connecting any equipment or appliances. For projects in which
the gas piping will remain exposed, both inspections would be combined into a single inspection.
Pressure Tests
All gas piping systems will be pressure tested at least once during the inspection process. It is the
responsibility of the permit holder to provide and install a temporary pressure gauge and to pressurize the
piping system. All gas piping systems shall be pressurized using air, CO2, or nitrogen. For most residential
installations the gas piping system shall be pressurized to no less than ten (10) psi and shall hold that
pressure for no less than 15 minutes. The gauge used for the pressure test shall have a pressure range
not greater than twice the test pressure applied and shall have 1/10 psi incrementation.
Sizing Gas Pipe
Gas pipe needs to be sized correctly. You can size the
gas pipe by following the example in this handout or
you may request assistance from a Building Inspector.
For the Building Inspector to help, you must provide a
piping layout (similar to Figure “C”) with the lengths of
all piping and the input demand load of all appliances
shown on the drawing. Sizing the pipe will depend on
the type of pipe being used.
Figure B
For pressure testing gas lines use a
15 lb. gauge with 1/10 lb. increments
Note 1 The demand ratings of the appliances listed in this
table are minimums. Demand ratings of the actual installed
appliances may be higher. Refer to name plate rating on
appliance–use the input Btu/h number. The tables used to
size gas piping are based on Cubic Feet per Hour (CFH).
To determine the CFH divide the input of the appliances
by the average Btu per cubic foot. Contact your local gas
supplier to obtain the Btu per cubic foot in your area.
Example for Determining Pipe Sizes
Problem:
The local utility can deliver 1,100 Btu per cubic feet. Determine the required pipe size of each section
and outlet of the piping system shown in Figure “C”. To figure the CFH (cubic feet per hour) of natural
gas, divide the Btu/h (British thermal units per hour) input rating of an appliance by 1,100. The type of
pipe used will be Schedule 40 Metallic (Table 1215.2(1)).
Solution:
1. Determine the maximum input gas demand for each appliance by using Table 1208.4.1 or from the
actual name plate of the appliance whichever is higher.
2. Determine the length of pipe from the gas meter to each outlet. If the length falls between those
lengths shown on appropriate gas size piping table then go to the next higher column.
3. Figure the lateral pipe sizes feeding the individual appliances
Outlet A – Use 60' column – with a demand load of 32 CFH the minimum pipe size is ½"
Outlet B – Use 60' column – with a demand load of 73 CFH the minimum pipe size is ¾"
Outlet C – Use 60' column – with a demand load of 59 CFH the minimum pipe size is ½"
Outlet D – Use 40' column – with a demand load of 91 CFH the minimum pipe size is ¾"
4. Figure the size of the main pipe which is feeding more than one appliance. Select the most remote
outlet in the system which is Outlet A. It is 60' from the meter so use the 60' column. Then determine
the various pipes sizes based upon the demand loads in each section of pipe.
Section 1 – Serves Outlets A and B with a total demand load of 105 CFH – minimum pipe size
is ¾"
Section 2 – Serves Outlets A, B and C with a total demand load of 164 CFH – minimum pipe
size is 1"
Figure C
Example Piping Layout and Appliance Demand
Outlet DFurnace100,000 BTUH91 CFH40’ from meter
Outlet CGas range65,000 BTUH59 CFH55’ from meter
Outlet BGas log lighter80,000 BTUH73 CFH55’ from meter
Example exercise for sizing gas pipe
Outlet A30 gallon water heater35,000 BTUH 32 CFH60’ from meter
Section 330'Section 210'10'10'5'15'Section 110'
1"
¾"
1"
½"
½"
¾"
¾"
The following tables are excerpts from the 2019 California Plumbing Code. The proposed gas pipe The following tables are excerpts from the 2019 California Plumbing Code. The proposed gas pipe
type and pressures may vary. Contact your local Gas utility company to determine the correct pres-type and pressures may vary. Contact your local Gas utility company to determine the correct pres-
sures. Additional tables are found in the Plumbing Codesures. Additional tables are found in the Plumbing Code