GB1393736A - Joining tubes to plates involving friction welding - Google Patents

Abstract

1393736 Welding by pressure and fusion CLARKE CHAPMAN Ltd 17 Aug 1973 [19 Oct 1972] 48156/72 Heading B3R In joining a metal tube to a metal plate one end of a metal stub which may be hollow or solid is friction welded to an annular region of the plate surrounding a pilot hole through the plate, metal is then removed from the plate and the stub and subsequently the tube is welded to the free end of the stub, said removal of metal including removal of metal from the exterior of the stub so as to remove friction welding flash and to form a curved surface adjacent the junction of the stub and plate and removal of metal from the wall of the pilot hole and from the stub to remove internal welding flash and to produce a uniform passage through the plate and stub. In an embodiment a tubular stub 10, Fig. 1A, is rotationally friction welded to a plate 12 provided with a pilot hole 14 used to position a mandrel for maintaining the position of the stub during rotation. An unwanted length of the stub is removed and weld flash 16, Fig. 1B, is removed externally by machining the outside of the stub to reduce the stub thickness, remove external flash and form a curved surface 18, Fig. 1C. Metal is also removed from the pilot hole 14 and from the bore of the stub to produce a finished bore 19 of uniform diameter in both stub and plate. The tube is butted to the stub 10 and welded internally using a TIG arc torch inserted through the plate. A layer of material, e.g. mild carbon steel or Inconel or Inco (Registered Trade Marks) capable of controlling the weld pool composition may be orbitally friction welded, plasma sprayed or plated on the stub end prior to the arc welding. After the tube welding the arc welded joint is heat treated. In a modification the stub 30, Fig. 3A, may have a frusto-conical end 31 friction welded to a corresponding surface 33 on the plate 32. Solid bodies, otherwise similar to those shown in Fig. 1A and 3A may be used, being bored after friction welding, and that corresponding to stub 10 may carry a temporarily attached spigot journalled in the pilot hole in the plate. The outer machining may extend below the plate surface to produce a trough having a curved surface. The plate may be of low alloy or stabilized chromium steel of austenitic steel, of Incolloy or Inconel (Registered Trade Marks) or of titanium alloy and the stub and tube may be of Incolloy, Inconel, low carbon or chromium niobium stabilized steel.