DOUBLE WALL FIRE PROOF DUCT

摘要

A composite plastic duct structure (10) comprised of an outer layer (12) of fabric material impregnated with a fire-resistant resin material and an inner liner layer (14) of chemically corrosion resistant resin material impregnated with a fabric material. The invention includes a method wherein multiple wrappings (18) of resin impregnated material are wound on a mandrel (16) to form the inner and outer layers.