Fuel Gas Piping and Appliance Connections
Fuel Gas Piping and Appliance Connections
This domain tests gas piping sizing, materials, testing, and appliance connections. Expect questions on sediment traps, shutoff valves, connectors, and bonding.
Core rules
- Size gas piping by the total connected load, the longest length, the gas specific gravity, and the pressure drop allowed; use the applicable gas code tables.
- Install a sediment trap at the appliance connection, a shutoff valve ahead of the appliance, and a union or connector for service.
- Appliance connectors must be listed, not concealed, and limited in length; they must not pass through walls, floors, or ceilings.
- Test the system at the required pressure for the required time; isolate the meter and appliances as the code requires.
- Bond metallic gas piping to the electrical grounding system; do not use the gas pipe as a grounding electrode.
Worked example
A range rated 40,000 Btu/h and a water heater rated 50,000 Btu/h are connected to one 1/2 in schedule 40 steel line with a longest length of 30 ft. The total load is 90,000 Btu/h. Check the gas table for 1/2 in at 30 ft and the available pressure drop. If the table capacity is below 90,000 Btu/h, increase the pipe size or shorten the run.
Traps that cost marks
Omitting the sediment trap, installing the shutoff valve downstream of the connector, concealing a flexible connector, and testing with the appliance connected when the code requires isolation.