Gas Line Installation: Safety and Tools You Will See

What the work looks like

Gas fitters run supply lines for natural gas and propane to furnaces, water heaters, dryers, stoves, and commercial equipment. The work happens alongside plumbing apprenticeships in most states; some states issue a separate gas-fitter license. Entry-level helpers carry pipe, hold the cutter while the journeyman threads it, and help pressure-test the completed line.

Safety and tools

Materials:

• Black iron pipe (steel): threaded, the traditional supply line material.
• CSST (corrugated stainless steel tubing): yellow- or black-jacketed flexible tubing that uses specialized fittings (TracPipe, Gastite, HOME-FLEX). Requires special bonding per NFPA 54 to mitigate lightning-induced failures.
• Copper (allowed in some jurisdictions for natural gas with approved fittings).

Sizing (from the gas code, NFPA 54 in the US): you size by total BTU load, developed pipe length, and allowable pressure drop. An 80-foot run feeding a 120,000 BTU furnace plus a 40,000 BTU water heater has a different pipe-size answer than the same run feeding only the furnace. Reference the manufacturer's sizing table.

Shutoffs and sediment traps: every gas appliance gets an individual shutoff valve within 6 feet of the appliance (local rules vary), plus a sediment trap (drip leg) between the shutoff and the appliance to catch debris and condensate before it reaches the gas valve.

Leak testing: the line is pressurized with air or inert gas (never with fuel) and held for a set period. Soap solution (or an electronic sniffer) is applied to every joint. Any bubbles mean a leak. Some jurisdictions require a manometer test held at 1.5 times the working pressure for a specified duration.

PPE: safety glasses, work gloves (leather for threading, cut-resistant for CSST), and hearing protection around threading machines. Never use an open flame near a suspected gas leak.

Tools: pipe wrenches (14 and 18 inch), pipe threader (manual or power), reamer, pipe cutter, vise (chain or yoke), Teflon tape or gas-rated pipe dope (yellow Monster, RectorSeal No. 5, or similar), manometer, and an electronic gas leak detector (Bacharach Informant or Sensit).

Your first exercise

Find the gas meter and main shutoff for a building you know. Follow the supply line visually from the meter to each appliance. Note the size of each section and where the shutoff valves are. This is the same walk-through a gas inspector does before signing off a new install.

Where to go next

Build with Gas Line Installation Basics (Introduction to Gas Line Installation) plus Plumbing Fundamentals (Introduction to Plumbing), Plumbing Code Basics (Introduction to Plumbing Code), Pipe Fitting (PEX/Copper/PVC), and Water Heater Installation. Safety: Workplace Safety, Fire Safety & Prevention, Hazardous Materials Handling, Confined Space Entry (meter pits and mechanical rooms).