What is Stainless 316 Alloy? | TSE Glossary

Texas Service Experts — DFW chimney & fireplace specialists. Free inspection, written quote, no surprise fees.

Stainless 316 is an austenitic stainless steel containing approximately 16 percent chromium, 10 percent nickel, and 2 to 3 percent molybdenum. The molybdenum addition gives 316 superior resistance to chloride and acid corrosion compared to 304, making it the preferred alloy for gas-burning chimney liners. UL 1777 lists 316 grades, including 316L and 316Ti, for both gas and solid-fuel service.

When natural gas burns, the combustion products include water vapor, carbon dioxide, and trace sulfur and nitrogen oxides. As the flue cools, especially during shoulder-season cycling on gas inserts, those gases condense into mildly acidic water that pools in the liner. Chromium alone is not sufficient to resist this acid; molybdenum is what shields the alloy from pitting and stress corrosion at the condensate dew point.

For chimney liner applications, 316 is supplied as either a flexible double-wall corrugated tube or as rigid sectional pipe. The flexible variant is favored for retrofits into existing masonry chimneys with minor offsets, while rigid 316 is used in new Class A chimney runs serving high-efficiency gas appliances. Sweeps verify alloy markings on the liner during installation to confirm 316 specification when condensate exposure is expected.

DFW’s high concentration of gas-log retrofits and direct-vent gas insert installations makes 316 stainless the dominant relining alloy for the region. The local climate’s humidity also worsens condensate accumulation in shoulder seasons. TSE specifies 316 stainless for every gas appliance reline, and the installation includes a properly insulated wrap and a sealed top plate to keep moisture out of the chase or masonry surround.

• [Stainless 304 alloy](/glossary/stainless-304-alloy/)
• [UL 1777 listed liner](/glossary/ul-1777-listed-liner/)
• [Direct vent](/glossary/direct-vent/)
• [B-vent](/glossary/b-vent/)

• ASTM A240 stainless steel standard
• UL 1777 Standard for Chimney Liners
• NFPA 211 (2024), Section 10.6

Reach Out To Our Pros

Free inspection · written quote · no surprise fees

We restore and protect what matters most. Same-week scheduling.

Join the Hearth Club — $19.99/mo

Annual chimney sweep included · Priority same-week scheduling · 10% off all repairs · Free emergency calls. Never worry about your chimney again.

Our Sister Companies — Specialists in Related Services

Texas Service Experts is part of a network of CSIA-certified chimney specialists. Depending on your specific need:

• Texas Chimney Experts — chimney repair/masonry
• Prime Chimney Experts — multi-state national service

Related Services & Areas

• Brand Partners — Heatilator, Majestic, Valor, Vermont Castings & More
• Chase Cover Replacement in Rockwall, TX
• Chimney Sweep in Lavon, TX
• Designer Partnerships

Learn More From Our Knowledge Base

Find Service Near You

• CLICK TO CALL NOW

Drop your name + phone and we'll text you within 1 business hour.