Patent GB-1312954-A (GB)
Title: Method of welding together vertically extending pipe sections
IPC: B23K9/028
Filed: 1970-04-15
Abstract: 1312954 Welding by fusion GURTLER HEBERT & CO Inc 15 April 1970 [24 March 1970] 18009/70 Heading B3R When welding together two vertically extending pipe sections weld metal is deposited in the gap between two juxtapositioned pipe sections beginning at the inner surface and for each individual welding pass both the separation and attitude between the weld metal depositing means and the base metal or previously deposited weld metal and also the deposition rate are maintained constant, irrespective of environmentally-induced movements of the pipe sections and dimensional inaccuracies in the pipe sections or weld space. In one embodiment of the apparatus (Fig. 6) a positioning device comprises a base 32 which can be welded or spiked to a deck of an offshore drilling rig. An arm 26 pivotal about shaft 34 includes portions pivotable about shafts 40, 50 and 62 to allow an end shaft 70 to be varied in position both horizontally and vertically relative to the base 32. A ratchet-turnbuckle 24, or a pneumatic or hydraulic mechanism, is provided for adjusting the relative dispositions of arm parts 46, 48 while a chain, sprocket and gear drive allows variation of the relative dispositions of arm part 48 and shaft 70. In use, shaft 70 is engaged with a split ring welding unit support (90) (Fig. 8, not shown) to position the latter relative to the joint 134 to be welded. The ring is clamped, after positioning, to one section (20) of a conductor pipe inserted in the ocean floor. The welding unit is mounted on a carriage (88) movable about the support by frictional engagement between a drive roller and a flange on the support. The attitude and spacing of the consumable electrode is variable (mechanical means or electro-mechanical means being provided) and the speed of the carriage can be controlled to alter the characteristics of the bead. An interval backing member, fused to form a back bead, can be positioned at the joint. In another embodiment (Fig. 12) of the apparatus, the positioning device has a base mounting a flux tank and other consumable-metering equipment. The multiple pivot joint arm 227 includes a sleeve 233 vertically adjustable by fluid pressure on a post 234. The sleeve supports a reel 237 of consumable electrode wire. A pneumatic actuator 260 acts between arm parts 264 and 255. In use, an end link 265 is connected to the welding unit support. The latter includes a peripheral rack for driving engagement with the welding unit. The latter has support and guide rollers which engage the support, and nozzles for dispensing flux and consumable electrode. The latter are adjustable in attitude. Upper and lower guide rollers are mounted on pivoted plates (306, 307) (Fig. 14, not shown) which allow adaptation of the unit to different diameters of support. To increase welding speed, two welding units may be provided. A flux dam 400 (Figs. 15 and 16) can be clamped about the lower pipe section. This has pipe-engaging pins 405 and an asbestos seal 406 to prevent leakage of melted flux from the trough 401. A support ring locating and mouting surface 411 is provided. In welding a butt joint between the pipe sections, a Vee preparation is used. Various configurations and entrance angles are described (Figs. 2-5, not shown). Welding is by an electric arc technique which, in addition to those mentioned above, can be non-shielded, or gas-shielded arc.