CSST

CSST is a thin-walled, helically corrugated stainless steel tube that carries natural gas, propane, or potable water. The corrugations allow flexibility without kinking, making it ideal for navigating tight spaces, wall cavities, and complex routing where copper or iron would require multiple fittings and soldering or threading.

In gas applications, CSST is installed under code with dielectric fittings at entry and exit points to prevent galvanic corrosion where it meets dissimilar metals. The tubing is typically color-coded yellow for gas and is faster to install than traditional piping. Fittings are push-to-connect or compression type, eliminating joint labor. CSST must be properly secured per code—typically every 3 feet and within 12 inches of a fitting—to prevent vibration damage.

The main trade-off is cost and lightning strike vulnerability. CSST is more expensive than copper or PEX per foot, and there's documented risk of arcing damage from direct or nearby lightning strikes, which can pinhole the thin walls. Some jurisdictions require bonding to address this. It's faster than traditional gas piping on straightforward runs but overkill for simple, accessible layouts where copper or iron makes more sense.