Who may touch the gas in Texas
Gas piping is plumbing under Texas law (Occupations Code §1301.002(7)). Gas line work is done only by Texas-licensed plumbers (or, for propane, Railroad Commission-licensed LP-gas companies); inside San Antonio a Plumbing, Gas and Sewer permit applies. That covers any new stub, valve or line to a fireplace, and a plumber working under a responsible master plumber pulls the permit. Ask who will touch the gas. Burner, pilot and log-set service on the appliance itself is a different question: ask whether the company holds a TDLR ACR (TACL) license for that work, and have it explain which parts of the job fall to a plumber, which to its hearth technician and, on propane, which to an RRC-licensed installer.
Texas has no "gas fireplace technician" license, so the credentials to ask for are the same as elsewhere on this site plus the trade licenses above: NFI certification (verify on nficertified.org) or CSIA certification (csia.org), proof of insurance, and a written scope with photos. A carbon monoxide check with a meter at the end of the service is a reasonable thing to ask for on any vented or vent-free gas appliance. If you are selling, note that the TREC Seller's Disclosure Notice (Form 55-1, 2026) asks about "Natural Gas Lines," "Gas Fixtures" and "Fuel Gas Piping" by material, so keep the service invoice. This is general information, not legal advice; our guide to who can work on a gas fireplace in Texas has the detail.