Fuel-Gas Piping and Appliance Connections
This domain tests fuel-gas piping and appliance connections: pipe sizing, materials, CSST bonding, sediment traps, shutoff valves, connectors, leak testing, clearances, and connection to appliances.
Core rules
- Gas piping is sized using total connected load, longest length, allowable pressure drop, and pipe material. Do not size by existing pipe size or by appliance count alone.
- Materials and fittings must be approved for fuel gas. CSST must be installed per listing, including bonding and protection from damage. Concealed piping needs protection and access where required.
- A sediment trap is required at the appliance connection where specified, and a shutoff valve must be accessible and located within the required distance. Connectors must be listed, not reused improperly, and protected from strain.
- Leak testing must use the specified test medium and pressure for the piping system. Appliances are isolated or connected per the test procedure. Leaks must be repaired and retested.
- Appliance connections must maintain clearances, support, and venting requirements. Gas piping cannot obstruct service access or be used to support other loads.
Worked example
A homeowner adds a 50,000 Btu/h range to an existing 100,000 Btu/h furnace. The existing 1/2 in branch worked for the furnace, so the installer reuses it. The correct method is to size the branch for 150,000 Btu/h at the longest length and available pressure, then verify the meter and regulator capacity. Reusing the old size because it worked before is not a sizing method.
Traps
Sizing by existing pipe size; omitting CSST bonding; installing an inaccessible shutoff; skipping the sediment trap; using unlisted connectors; and failing to isolate appliances during leak testing.