GB1405359A - Resistance butt-welding apparatus - Google Patents

Abstract

1405359 Welding by pressure INSTITUT ELEKTROSVARKI IMENI E O PATONA AKADEMII NAUK UKRAINSKOI SSR 31 May 1973 26098/73 Heading B3R [Also in Division B8] Apparatus for welding together borehole casing pipes and lowering the welded string of pipes into the borehole comprises a resistance butt welding machine 1, Fig. 1, having annular housings with clamping means for embracing and clamping both the pipe to be welded and the already-welded easing string, lifting means 5 and pipe gripping means 2 for lifting and lowering the pipe 3 to be welded into the welding machine and for supporting the weight of the welded string after each welding operation as the string is lowered into the borehole, the pipe gripping means 2 having a maximum cross-sectional dimension not exceeding the outer diameter of the pipe so as to permit passage of the gripping means through the clamps of the welding machine. The welding machine is fixedly mounted on the table 6 of a drilling rig 7. The pipe gripping means (see Division B8) has wedge-shaped jaws (Fig. 4, not shown) which grip the pipe (or welded casing string) under the weight of the pipe (or pipes). The welding machine itself comprises upper and lower annular housings 9, 8, Fig. 2, adapted to be forced together for welding and upsetting by hydraulic cylinder units 21, and each housing 8, 9 encloses an annular member 10, Fig. 3, adapted to be turned by the action of hydraulic cylinders 11 in order to force a series of clamping and current-carrying shoes 14 on to the pipe surfaces to clamp the pipes during welding and upsetting. Reverse action of the cylinders 11 frees the shoes 14 from the pipe surface by means of cranked levers 18 which engage abutment shoulders 20 on the holders 10. The pipe gripping means has a central through bore to allow passage of a tool for removing weld flash.