Fuel Gas Piping, Safety, and Job-Site Practices
Sizing and materials
The fuel gas code (IFGC family, as amended) governs sizing, materials, installation, and testing. Low-pressure sizing uses the longest-length method with a permitted pressure drop, typically 0.5 inch water column, and a capacity table indexed by pipe size and length. Fittings, future appliances, and the actual routed length all count. Steel, copper where permitted, CSST, and semi-rigid connectors each carry restrictions. CSST must be bonded, and appliance connectors are limited in length (6 feet) and cannot be concealed or run through walls, floors, or ceilings.
Components and testing
Each appliance needs a shutoff valve, a union or flanged connection, and a sediment trap ahead of the controls - gas flows down into the drip leg, then up to the appliance. Regulators vent to a safe location clear of openings and intakes. Testing uses air or inert gas, never the gas supply: 1.5 times working pressure, minimum 3 psi for low-pressure systems, typically held 10 minutes with no drop.
Job-site safety
Leak checks with soap solution, never a flame. Trenches 5 feet or deeper require protective systems. Confined spaces require atmospheric testing and an attendant. Protect combustibles with a heat shield and fire watch before soldering or brazing.
Traps
Installing the sediment trap in line rather than as a drip leg, orienting the shutoff valve incorrectly, venting a regulator too close to a window, and adding an appliance to an existing line without re-running the longest-length calculation.
Worked example
An existing 1/2-inch line serves a water heater; a range is added. Total length and load now exceed the table for 1/2 inch, so re-size rather than adding a tee.