GB813244A - Improvements in the bonding of fins to tubes, plates and the like - Google Patents

Abstract

813,244. Making finned heat-exchanger tubes; brazing. FOSTER WHEELER Ltd. Dec. 12, 1955 [Dec. 17, 1954], No. 36610/54. Classes 83 (2) and 83 (4). In attaching fins to a basic element, a metal tube, plate or the like, the fins are disposed on the basic element in the position they are finally to occupy with spaced elements between them, brazing metal is disposed in confined spaces, each of which is bounded by a spacer element and the basic element or by at least one spacer element, the basic element and a single fin, and in communication with clearance spaces between the fins, the spacer elements and the basic element, and the assembly is heated to melt the brazing metal. In an embodiment radial copper fins 12, Fig. 1, spaced by copper rings 16 are arranged on a steel tube 10 and brazed by brazing metal wire in annular grooves 14 formed by recesses in one side face of the rings 16. In modifications a groove may be formed on each side face of the rings or one groove may be formed on the inner face of each ring (Fig. 3). Fins 12, Fig. 4, may be fitted on the tube to form with spacer rings 16 spaces 14 to house the brazing metal. The basic element may be of mild or stainless steel, the spacers of brass, copper or mild steel and the brazing metal may be silver solder. In making a heat-exchanger having a number of tubes joined together by a number of copper plates forming fins, the plates, drilled to fit the tubes with small clearance, e.g. 0.005 inch, are fitted on the tubes with mild steel or brass distance pieces also having clearance of 0.005 inch recessed as in Fig. 1 or on both side faces to hold silver solder wire. After coating the fins and distance-pieces with flux the assembly is clamped up and brazed. Specification 813,243, [Group XIIII, is referred to.