In the National Fire Protection Association Standard for Chimneys, Fireplaces, Vents, & Solid Fuel Burning Appliances (NFPA 211).

In Chapter 10, maintenance section 10-9 it states: "Damaged or Deteriorated Liners. If the flue liner in a chimney has softened, cracked, or otherwise deteriorated so that it no longer has the continued ability to contain the products of combustion (i.e., heat, moisture, creosote, and flue gas), it shall be either removed and replaced, repaired, or relined with a listed liner system of other approved material that will resist corrosion, softening, or cracking from flue gases at temperatures appropriate to the class of chimney service."