GB1504131A - Apparatus for internal circumferential welding - Google Patents

Abstract

1504131 Welding by fusion REDPATH DORMAN LONG (CONTRACTING) Ltd 12 Feb 1975 [13 Feb 1974] 6601/74 Heading B3R In effecting internal butt arc welds between cylindrical "cans" and further "cans" or "nodes", in fabricating tubular legs of oil production platforms, wherein workpieces are supported on and rotated by pairs of rollers 11, 12, the latter part being driven by an electric motor 14, a submerged arc welding head is carried at the remote end of a boom extension 22 which is provided at or near said remote end with at least one driven boresurface-engaging boom extension support wheel and is connected at its other end to a welding machine arm 16. The boom extension may be up to 50 feet long. It is preferred to use a boom extension support tractor having driven wheels. The rotational speeds of the driven boom extension support wheels and workpiece support rollers may be controlled by an operator inside the workpiece. The boom extension may be provided with intermediate spring- loaded mountings 58. As shown in Fig. 2, the boom extension comprises two tubes (32), 33 which are connectable to a conventional boom 16 by two pairs of clamping members 24, 25 which have twoengaging clamping screws 28, 29 and are welded to an operator access trough 17 fast with the boom 16. At their ends remote from the boom 16, the tubes (32), (33) carry a welding head 47 which is adjustable vertically and horizontally of the workpiece by slot-engaging screws 55, 56. A bracket 48 welded to the tubes (32), 33 at said remote ends carries a control panel 53. A guide light 57 provides a cruciform marker image. Flux is fed through a pipe 54 from a box 53. Consumable electrode wire is fed from an adjustably positioned reel 51. A boom extension support tractor 41 is located adjacent the welding head and comprises wheels 42 driven by a motor 50. The boom extension may alternatively be of "A" frame form, and may comprise a plurality of longitudinal sections so that the length of said boom extension may be increased as workpiece fabrication proceeds. Workpiece weld preparation is by grinding and the preparations are pre-heated before welding is effected.