All joints are butt flanged stainless steel utilizing a gasket and secured by bolting together exterior overlying carbon steel companion rings. As such, these ducts shall be listed in the FMRC Approval Guide and shall bear an FMRC Approval Identification Marking whenever they are fabricated. 1.6 Fire tests and quality control tests are conducted in accordance with FMRC Approval Standard 4922 and used in conjunction with an in-plant audit inspection as the basis of Approval. This FMRC Approval Examination Report, 3W1A2.AM, has been reissued and supersedes the initial version dated January 26, 1994. All ducts shall be fabricated from type 316L stainless steel.
Security is achieved by bolting together exterior overlying carbon steel companion rings.
The minimum number of holes in the companion ring for the flange connections is one hole for each 6 in. The prime coat is spray applied electrostatically to each section of fabricated circular stainless steel duct and then baked to cure. Immediately after the first cure period, the top coat is spray applied electrostatically and as the prime coat, baked to cure. Smoke Exhaust Ducts dated December 20, 1993. Fire performance is considered satisfactory if flaming does not spread from the fire exposed end to the 23 ft.