Is CSST Safe for Gas Lines? Yes — If It's Bonded to Ground

CSST stands for corrugated stainless steel tubing: a flexible stainless piping system used to carry natural gas and propane, coated on the outside with a standard yellow plastic jacket. That thin stainless wall is what lets a plumber snake it through framing in a single run. It's also the reason bonding is part of the job and not an afterthought.

You don't need a manometer to spot the one thing that matters most on a CSST system. You need to know whether the yellow tubing is bonded.

If lightning strikes on or near a house, the surge can travel through the structure's gas piping. Where the CSST runs close to another metal system — the electrical ground, a copper water line, ductwork — a large voltage difference between the two can jump the gap as an arc. An arc against that thin tubing wall can burn a pinhole. Gas escapes at the puncture, and a number of fires have been reported from gas leaks at exactly that kind of lightning-caused hole. That failure mode is what the bonding rule exists to stop.

Bonding removes the voltage difference. A single clamp ties the building's gas piping to the home's electrical grounding system, so the gas line and the ground sit at the same potential and there's nothing for the surge to arc across. The code language is specific: the bonding conductor is 6 AWG copper wire, no smaller — that's the normal size for this kind of equipotential bond. The clamp has to be listed to UL 467, and the attachment point has to stay accessible so an inspector can verify it. The connection is made on the building gas piping downstream of the meter, or on a propane system downstream of the second-stage regulator, near where the service enters the house. It never goes on the underground utility line coming in from the street.

None of this is new or optional. Since 2006, every CSST manufacturer's instructions have required direct bonding and grounding of yellow CSST on new installations — whether or not the appliance it feeds is electrically powered, because the surge doesn't care whether your furnace plugs into an outlet. In the fuel gas code the requirement lives in IFGC Section 310.2; the national fuel gas code, NFPA 54, carries it as Section 7.13. Wherever that code is enforced, Oklahoma included, a qualified person has to make the bond.

CSST earns its place in the runs rigid black iron can't do cleanly — threading through an attic or crawlspace where black pipe would need joint after joint, each one another place to leak. Black iron still makes sense for exposed, straight trunk runs. Our gas line repair and upgrades page covers why some plumbers distrust flexible line and where that distrust is misplaced. The short version: installed to its listing and bonded, CSST is safe.

Standard CSST is yellow, and yellow tubing needs the bond described above. There's a second generation built to handle the lightning problem in the jacket itself: arc-resistant CSST, sold under names like TracPipe CounterStrike. It uses a conductive black jacket, introduced in 2004 and reformulated in 2007, designed to resist arcing from an indirect lightning strike without a separate bonding conductor. The code treats it as its own path — the arc-resistant product follows the National Electrical Code (NFPA 70) and its own manufacturer's instructions in place of the standard bond, and that alternative sits in its own subsection of the fuel gas code (Section 310.3).

What's actually true: if the CSST holds pressure and isn't physically damaged, the pipe is fine. An unbonded system isn't a rotted system. It's a sound system missing one connection. The correct fix is to add the bond — a listed clamp on the gas piping, a length of 6 AWG copper run to the grounding system, made by someone qualified, at a point an inspector can reach. A pressure test proves the tubing is sound before and after, so nobody has to guess.

What we do: pressure-test the system to confirm it holds, then check whether a bond already exists and whether it's done right — correct wire, listed clamp, correct location downstream of the meter, accessible. If it's missing or wrong, we add or correct it. We don't tear out pipe that passes a pressure test to sell a repipe. The lightning-and-bonding section of our gas-lines guide walks through the same logic.

Bonding is a one-time installation item, not a part that wears out on a schedule, so there's no service interval to invent. Have the bond confirmed when the situation actually calls for it: you buy a house with yellow CSST and don't know its history; you've had gas work done and want to be sure it was left compliant; or an inspector flags the tubing as unbonded. After a close lightning strike, there's no need to panic — but a pressure test is how you prove the tubing wasn't punctured. That's the definitive check, not a hunch.

If you've got yellow CSST and you're not sure it's bonded, or someone quoted you a full gas repipe over it, get the pipe pressure-tested and the bond checked first. We'll tell you plainly whether you're looking at a clamp or a real problem — and if it's just the bond, that's what we'll fix. Call or text us — 405-519-1868.