Patent GB-916647-A (GB)
Title: Tube butt welding apparatus
IPC: B23K13/06
Filed: 1960-11-15
Abstract: 916,647. Welding by pressure. COMBUSTION ENGINEERING Inc. Nov. 15, 1960 [Dec. 9, 1959], No. 39169/60. Class 83 (4). Apparatus for butt welding tube ends comprises two sets of clamp blocks for the ends and an inductor coil positionable between the sets of blocks for heating the tube ends, one set of blocks being movable relatively to the other set by pressure fluid operated expansible envelopes. The tubes A, B are encircled by a hinged induction coil C, C<SP>1</SP> supplied from a transformer 50 and are held in hinged clamp blocks 12, 12<SP>1</SP> and 14, 141, block 12, 12<SP>1</SP> being fixed and block 14, 14<SP>1</SP> being axially movable within a hinged shell 18, 18<SP>1</SP>. The block 14, 14<SP>1</SP> is spring urged to the right in Fig. 9 and is urged to the left to apply welding pressure by a pair of semicircular hollow rubber envelopes P, P<SP>1</SP> supplied with fluid by pipes 23 and acting on the block through plates 24. Each clamp block comprises six circumferential segments 33 each having a friction shoe attached to a wedge 34 co-operating with an outer wedge 38 through a slide 39, the outer wedges being spring urged against the plates 24. With the tubes initially abutting pressurizing of the envelopes P, P<SP>1</SP> urges the wedges 38 to slide relatively to wedges 34 and tightly lock tubes A and B. The water-cooled inductor coil C, C<SP>1</SP> in two parts hinged at 49 encased in magnetic material embedded in insulation material 60, 601 has a radial clearance from the tube ends which with two closely fitting inserts 54, 54<SP>1</SP> forms a space which is supplied with protective gas by tubes 56. The welding assembly is adjustably supported on a carriage 91, 92, Fig. 14, movable by a handle 103 transverse by of the pipe axes in tracks 89 on a carriage adjustable vertically in a framework 77, 78 by motor-operated jacks. A further carriage 94, 95 pivotally carrying the transformer and unit is movable parallel to the pipe axes by a handle 105. In operation, the end faces of the tubes which may be of ferritic or stainless steel are machined, preferably bevelled, and with the envelope 18, 18<SP>1</SP> carrying the clamp parts 12<SP>1</SP>, 14<SP>1</SP> hinged open and the inductor hinged open the tubes are inserted with their ends in contact or slightly spaced in the lower clamp and inductor parts. The inductor is closed and clamped and the envelope is closed and latched by member 64 and clamped by link members 68. Link members 72 on the lower clamp members are positioned to engage - the upper clamp members and eccentric pins 74 are rotated to clamp the pipes. Protective gas is supplied to the space about the tube ends, water is supplied to the inductor and pressure is supplied to the envelopes P, P<SP>1</SP> to clamp the pipes and force their ends together. Current of 3-10 kc. per second is supplied to the inductor and when an upset as determined by movement forward of an actuator 119 to contact its switch 115 has been obtained the switch cuts off the supply of current, pressure fluid, gas and cooling water. The current may be continued after welding and if long tubes are to be welded adjustable pipe support rollers are provided on each side of the framework 76, 77. Specification 916,646 is referred to.