GB791464A - Manufacture of finned tubing - Google Patents

Abstract

791,464. Coating with metals. GRISCOMRUSSELL CO. Feb. 29, 1956 [Sept. 27, 1955], No. 6268/56. Class 82(2) [Also in Groups XIII and XXII] In making a finned tube, the tube is heated, sintered brazing alloy is deposited thereon and the tube is heated to melt the brazing alloy to protect the outer edge or edges of the fin or fins and/or to braze the fin or fins to the tube. A tube 16 of ferrous metal e.g. stainless steel, nickel, or " Inconel " (Registered Trade Mark) having a fin 17 of ferrous metal, nickel, " Inconel," or copper clad with stainless steel spirally wound in a groove 18 thereon or on the outer surface thereof, is mounted in a lathe provided with an oxyacetylene torch 15, Fig. 2, in place of the normal tool. The tube is rotated and heated by the torch moving along it for part of its length. The torch is returned to its start point and powdered brazing alloy e.g. of nickel, chromium, iron, silicon and boron, is fed through the flame as the torch is moved along the tube to deposit sintered powder on the outer edge of the fin as at 20, Fig. 3, and on the tube surface as at 19, Fig. 3, at the base of the fin, which edge and surface may be shot- or grit-blasted or knurled. Each portion of the tube is so heated and then sprayed with powder. The tube is then heated in a furnace to melt the brazing alloy which brazes the fin to the tube and if the fin is of steel-clad copper seals the edge of the fin as in Fig. 6. The tube may have longitudinal fins instead of a spiral fin.