· by Michael Blair, Nashville's Plumbing Repair
Most people search for a gas line plumber at one of two moments: they smell something near the range or the water heater, or they are adding a gas appliance and learn the existing pipe cannot feed it. Either way the work sits in a different category from a dripping faucet. A water leak ruins drywall; a gas leak is a fire and a health hazard, which is why Metro Codes treats gas piping as its own permit and inspection, and why the test at the end matters more than the pipe itself. This is how our crews handle a gas line in and around Nashville, and what you should expect from anyone you let work on yours.
If you smell gas right now
Stop reading and leave the house. Piedmont Natural Gas’s safety guidance is specific about what not to do on the way out: do not flip a light switch either direction, do not light a match, and do not use anything electrical that can spark, which includes your cell phone. Once you are outside and away from the odor, call 911 and Piedmont at 800.752.7504.
The rotten-egg smell is added to natural gas on purpose so a leak announces itself. Piedmont also lists signs outdoors: bubbling in standing water, dirt blowing up from the ground, a patch of dead plants over the line, a small sinkhole, or a hissing sound near a pipe or the meter. The piping inside the house, to the furnace, range, dryer, water heater and fireplace, is the part we repair, and only after the utility has made the situation safe. If it happens after hours, our emergency plumbing page has the number to call after Piedmont has been out.
Who is allowed to work on gas piping here
In Davidson County, gas piping is permitted and inspected work. Metro’s adopted codes list shows it adopted, with local amendments, the 2024 International Fuel Gas Code alongside the 2024 residential, mechanical and plumbing codes under ordinance BL2025-898, and Metro’s announcement of the 2024 codes puts them in effect for applications submitted after July 16, 2025. Metro books gas inspections with the gas/mechanical trades rather than with plumbing, and Metro’s own test forms are signed by the gas/mechanical contractor, so ask whether the person pulling the permit is set up with Metro for gas work and not only for plumbing.
State licensing adds a layer that confuses people. The Tennessee Board for Licensing Contractors’ page on the Limited Licensed Plumber covers plumbing projects under $25,000 in materials and labor, says that license is accepted only in some local jurisdictions, and notes that even a state-licensed contractor still needs the local license, permits and inspections. That page does not say whether gas piping falls under the limited plumbing license, so do not take a plumbing card as proof someone may run gas. Ask before the job starts whose permit it will be and under which license, and confirm both with the state lookup and the local codes office. Our permits post covers the rest of what needs a permit in Nashville.
What a gas line replacement actually involves
The first job is sizing, and it is where most homemade gas work goes wrong. A gas line is sized from the total demand of every appliance it feeds and the length of the run from the meter, not from the size of the pipe it is replacing. Adding a tankless water heater or a range with a big burner to a line that was sized decades ago for a furnace and a dryer can starve all of them, which shows up as lazy yellow flames, pilot outages and a tankless unit that throws error codes. We add up the load before choosing the pipe, and sometimes the honest answer is a new trunk line from the meter rather than a branch off the old one.
Then the route and the material. Older Nashville houses usually have black iron threaded pipe through the crawl space; newer ones often have flexible corrugated stainless steel tubing, CSST, the yellow-jacketed pipe that snakes through attics and walls. Each appliance gets its own accessible shutoff valve where it connects, so a range can be serviced without shutting off the house, and every connector and union is a joint we check rather than assume.
Yellow CSST carries one requirement people miss. The ICC’s CodeNotes on bonding CSST explains that non-arc-resistant CSST needs its own bond under IFGC 310.2 and IRC G2411.2: a copper conductor no smaller than 6 AWG, attached with a listed clamp to a rigid pipe or fitting, never to the corrugated tubing. The bond exists because a nearby lightning strike can arc through thin tubing and burn a hole in it. In a region with as many spring and summer thunderstorms as Middle Tennessee, an unbonded run is something we flag on any house we work in.
- Load calculation from every appliance on the line, present and planned
- A shutoff valve at each appliance, reachable without moving it far
- Bonding on any yellow CSST, clamped to rigid pipe
- A pressure test before anything is covered or lit
The permit, the pressure test and the inspection
New or replaced gas piping is pressure tested before the gas is turned on and before walls or insulation hide it. The pipe is capped, filled with air, and watched on a gauge for a set time; any drop means a joint is leaking and the test starts over after the fix. Metro’s amended residential code under the 2018 edition, as hosted on up.codes, section G2417.4.1, called for at least ten pounds per square inch held for at least twenty minutes with no perceptible drop, using air only, verified in writing by the gas/mechanical contractor on Codes forms. We have not confirmed that the 2024 edition now in force keeps the same numbers, so the inspector’s requirement on the permit is the one we test to.
Inspections in Metro are scheduled by phone, not online, unless the contractor is registered: Metro’s inspection request page lists 615-862-6570 for plumbing and gas/mechanical inspections, weekdays from 7:30 a.m. to 4:00 p.m., with the Metro permit number ready. If a contractor tells you a gas job does not need a permit or an inspection, that tells you what you need to know about the contractor.
For gas lines, appliance hookups and fixtures, see our fixtures and gas lines page. For a house inside Davidson County, plumbing in Nashville covers the local permit office, and when you are ready to have the line looked at, ask for a free estimate.
Sources
- Piedmont Natural Gas, Natural Gas Safety — Leak signs, what not to do, and who to call
- Metro Nashville Codes, Adopted Codes List — Metro adopted the 2024 IFGC, IRC, mechanical and plumbing codes with amendments (BL2025-898)
- Metro Nashville Codes, Metro Adopts 2024 International Building Codes — Effective date of the 2024 codes
- Tennessee Board for Licensing Contractors, Limited Licensed Plumber — Scope and limits of the state limited plumbing license
- ICC CodeNotes, Bonding of CSST Gas Piping — IFGC 310.2 and IRC G2411.2 bonding requirements
- Nashville and Davidson County Residential Code 2018, G2417.4.1 (up.codes) — Metro’s amended gas piping pressure test, 2018 edition
- Metro Nashville Codes, Requesting an Inspection — How gas/mechanical inspections are scheduled