GB1093662A - Sectional double-walled metal flue pipes - Google Patents

Abstract

1,093,662. Pipe joints; flue pipes. WALLACE MURRAY CORPORATION. June 15, 1966, No. 26726/66. Headings F2G and F2P. [Also in Division F4] A metal flue comprises a plurality of double walled pipe sections 10, 10a, adjacent sections being interconnected by mating female and male elements on the adjacent ends of said sections wherein the female element is formed by radially inwardly and outwardly extending interconnected annular grooved portions 20 and 21 in the outer and inner walls 12 and 11 respectively, and downwardly extending skirt portions 26 and 28, and the male element is formed by a return bend 19 at the end of the outer wall which is lapped by the flaired end 32 of the inner wall. The male element fits into the female element, the return bend 19 of the male element making a line contact with the outer wall groove portion 20. The joint is then secured by screws 37 passing through slots 38 in the female element into those holes of a plurality of holes 36 in the male element which register with said slots, Fig. 5 (not shown). The seamed or seamless tube forming the outer wall 12 of each section is preferably of galvanized iron and may be tapered slightly from the male element end to the female element end by forming it from a suitably shaped blank. The tube forming the inner wall is preferably of aluminium. Since the only positive connection between the inner and outer walls occurs at the female element end, the inner wall is free to expand due to thermal changes at the male element end. Furthermore, the inner walls of the stacked pipe sections are not interconnected and hence do not act as weight or load-transmitting walls. In a modification, Figs. 6-8 (not shown), the annular grooved portions 20 and 21 on either or both the inner and outer walls of each pipe section may be replaced by spaced peripheral recesses (25). As illustrated in Figs. 9-15 (not shown), the stacked flue pipe sections are secured in a building structure at spaced intervals by pairs of rectangular plates (72) having semicircular cut-outs (74) which embrace the peripheral grooves 20 in the pipe sections, said plates having overlapping extension pieces 76. The plates are also provided with downwardly dependent lugs (78) which are bolted together to secure each pair of plates around the appropriate pipe section. The peripheral edges of the plates are then nailed, screwed or otherwise secured to transverse structural members of the building. The coaxial spaced wall flue construction eliminates the inherent fire hazard of hot flue pipes.