GB497355A - Improvements in or relating to lined metallic tubes - Google Patents

Abstract

497,355. Making lined tubes. BABCOCK & WILCOX, Ltd. June 17, 1937, No. 16929. Convention date, July 25, 1936. [Classes 83 (ii) and 83 (iv)] Uniting by fusion.-An apparatus for applying metal, such as a non-corrosive alloy, by fusion to the inner surface of a tube, particularly a long tube of small diameter, comprises a tube support, a weld rod holder supported by but capable of movement in any direction with respect to but insulated from the tube so as to guide a weld rod fed to the arc towards the wall of the tube, and means for rotating the tube and simultaneously effecting relative movement longitudinally between the tube and the holder. The tube 1, with a welded extension 6 removed after operation, is arranged on roller supports 7 and secured to a hollow chuck 15 driven by gear 17, 18, and change speed gear 19 from an electric motor 21 mounted on a carriage 10. The carriage is traversed on a bed 9 through change gear 19, worm gear 23, 25, pinion 26 and stationary rack 28. A bare or coated electrode 2, preferably a steel alloy containing 18 per cent of nickel and 8 per cent of chromium, which is fed to the work in such a manner as to maintain the length of the arc constant, preferably automatically in co-ordination with the movement of the tube, passes through an electrode holder 3, the inner barrel 31 of which has a curved end 33 to direct the electrode towards the tube. The outer shell 29 is separated by insulation from and secured in a clamp 4 on a support 5 and is separated from the tube by an insulating plug 35 at one end and an insulating block 34 at the other end. The forward end of the shell 29 is thickened and provided with a guide having an inclined bottom surface 41 engaging the corresponding inclined surface 43 of the barrel 31. Adjustment of the electrode in the direction of the tube wall may thus be effected by axial movement of the barrel, the parts being then secured in position by a bolt 45 passing through a longitudinal slot 46 in the shell. The space between the two parts is closed by a sealing ring 36. The electrode or holder is connected at 37 to one terminal of the circuit, the other terminal of which is connected at 38 to one or more of the rollers 7. A helical layer is first applied to the tube and then overlapping convolutions. A quick-return motion for the carriage may be provided. Reducing or inert gas such as hydrogen, propane, &c. or a mist or vapour of liquid flux may be supplied at 47 so that it passes through the tube and is discharged through openings 49 in the extension 6 into a rotatably sealed gas housing 50 provided with an outlet 51. The Specification as open to inspection under Sect. 91 states that the rotary and longitudinal movements of the tube may be effected in succession. This subject-matter does not appear in the Specification as accepted.