Abstract: The invention relates to a flange joint assembly for connecting together cylindrical duct sections. A tubular slip collar fits within opposing sections which engage an exterior projecting bead encircling the exterior of the slip collar. Opposing flange clamps are mounted on the ducts having leaf elements pressing against the duct surfaces. Opposing band clamps are mounted around the leaf elements securing the leaf elements to the duct surfaces. Opposing V-band ring locking devices encircle the flange clamps. In the alternative, Van-Stone flange rings secure the flange clamps together by means of locking bolts.

Abstract: Fiberglass reinforced plastic fume exhaust systems include duct walls having apertures therein covered with meltable thermoplastic resins mounted thereon which melt and open up the apertures when exposed to high temperatures thereby admitting ambient air therein to reduce the temperature downstream of the systems and reduce the suction pressure at source of the high temperatures.