Abstract: A dual wall duct constructed of heat resistant polymer with a reinforcing cord interposed between the inner and outer tube to form an annulus for entrapment for thermally insulated gas such as air.

Abstract: A flexible fire resistant duct constructed of a flexible fire resistant membrane forming a tube and reinforced with a metallic multi-strand cable.

Abstract: A tubular and compressible seal attached to one tube and formed with a cowling projecting over a peripheral bead in a second tube and formed with a rearwardly inwardly projecting sealing ring engaging such second tube. A constraining sleeve compressing the cowling and sealing ring against the second tube.

Abstract: A dual wall duct constructed of heat resistant polymer, a reinforcing cord interposed between the inner and outer tube and the outer tube heat shrunk on the inner to form an annulus for entrapment for thermally insulated gas such as air.

Abstract: An environmental control system muffler including a thin wall polyetherether ketone (PEEK) cover tube, an open cell polymer attenuator tube slip fit there into and polymer end fitting securing the two tubes together and cooperating to form a pneumatic seal with the cover tube. The method of making the muffler apparatus includes the selection of tubing constructed of such PEEK corrugated construction and the open cell polymer noise attenuation construction, telescoping the tubes together and securing the end fittings thereto.