Fuel Gas Piping and Gas-Fired Appliances
Fuel Gas Piping and Gas-Fired Appliances tests gas pipe sizing, sediment traps, shutoffs, connectors, and appliance connections. The exam checks whether the piping can deliver the connected load at the available pressure and whether the appliance is protected and accessible.
Core rules
- Gas piping is sized by total connected Btu/hr, longest length, gas pressure, and the adopted gas code table.
- A sediment trap is required downstream of the shutoff valve and before the appliance controls.
- Appliance connectors must be listed, protected from damage, and within the length limit in the code.
- CSST must be bonded and installed per the manufacturer’s instructions and code.
- Gas piping must not be concealed in ducts or plenums and must be tested before being covered.
Worked example
A natural gas appliance has a 120,000 Btu/hr input. At about 1,000 Btu per cubic foot, demand is 120 ft³/hr. If the longest run is 60 feet, you must enter the gas table at 120 ft³/hr and 60 feet to select the pipe size. Reasoning: the table already accounts for allowable pressure drop and gas properties; choosing pipe by nominal size or by the shortest run is not a sizing method. The table, not arithmetic alone, gives the answer.
Traps that cost marks
- Sizing from the appliance connector instead of the longest run.
- Omitting the sediment trap.
- Using an unlisted or overlong connector.
- Concealing a gas joint before pressure testing.