Patent GB-1435004-A (GB)
Title: Pipe clamp means
IPC: B23K37/053
Filed: 1973-05-24
Abstract: 1435004 Welding by fusion; tube expanding COLUMBIA GAS SYSTEM SERVICE CORP 24 May 1973 25026/73 Headings B3R and B3J Apparatus for axially aligning, trueing and clamping together end-to-end "in place" and "set in" pipe sections 12, 14 and for backing the weld groove between said sections comprises radially movable clamping and trueing means 20, 21 respectively supported by relatively axially movable housing sections 26, 28, means for axially separating the housing sections when the clamping means 20, 21 are respectively engaged with abutting pipe sections 12, 14 so as to space the ends of the latter by a predetermined distance, a backing ring assembly 24 supported by the housing section 26 and radially movable to bridge the welding groove, and pipe engaging drive means to propel the apparatus through the pipe sections. The clamping means 20, 21 comprises sets of spring-returned heads (166, 166<SP>1</SP>) radially slidable in the housing sections and acted on by radially acting cams (160, 160<SP>1</SP>) which are rotated, via torque tubes (152, 154) by sets of rams 188, 210 to expand the heads into engagement with the pipe sections and by rams 200, 211 enabling return of the heads. The housing section separating means comprises rams (222) acting between the housing section 28 and, via a tie tube (34), the housing section 26, the housing section separation being limited by a stop (232, Fig. 2b, not shown) which is screw adjusted to determine weld groove width. The backing ring assembly 24 comprises two, three, or four arcuate shoes 246 (Fig. 6) interconnected by yokes 252 which are radially outwardly and inwardly moved by a radially acting cam 240 rotated via a torque tube (150) by rams 268 for shoe expansion and a ram 269 for shoe retraction. Inter-shoe wedges 288 (Fig. 8) carried by the yokes 252 are moved axially of the housing sections by rams 286. The shoes and wedges are of steel with copper cooling inserts. The apparatus propulsion is by fluid actuated motors (66) acting through gear and chain transmissions on bottom wheels 90, carried rigidly or on rocking frames 88, and an upper, outwardly spring-urged, wheel 117. The rams and fluid actuated motors may be hydraulic or, as shown, pneumatic. Actuating fluid is supplied through a reach rod 52 or from a housing mounted reservoir used when fluid is disconnected from the rod. Control is by valves actuated by rotation of a spring-detented manually-actuated reach rod handle 301, indirectly-actuated sequence controlling valves, a valve preventing driving motor actuation when the clamping means 20, 21 are expanded, manual valves mounted on the housing section 28 for fine alignment forward and reverse apparatus propulsion and for clamp means 20 actuation, a valve actuated by spring-actuated outward movement of a wheel 130 to stop apparatus propulsion following its sensing absence of a surrounding pipe, and a valve actuated by axial movement of the reach rod handle to stop apparatus propulsion should said sensing valve fail. In operation, (i) the apparatus is forwardly propelled until the wheel 130 passes the free end of the "in place" pipe section 12 and shuts off the propulsion motors whereupon the apparatus coasts to a stop with the backing ring assembly substantially in alignment with the weld preparation, (ii) the backing ring is fully aligned by forward/reverse actuation of the propulsion motors, (iii) the clamp means 20 is expanded, (iv) the "set in" pipe section 14 is placed in substantial abutment with the "in place" pipe section 12, (v) the clamp means 21 is expanded at low pressure to lightly engage the pipe section 14 to allow accurate final pipe section abutment, (vi) the clamp means 21 is expanded at high pressure, (vii) the housing sections 26, 28 are separated to space apart the pipe sections said predetermined distance, (viii) the backing ring shoes and, then, wedges are moved into place; and on completion of welding (ix) the backing ring wedges and their shoes are retracted, (x) the clamp means 21 is retracted, (xi) the housing sections 26, 28 are drawn together again, and (xii) the clamp means 20 is retracted. In the event of the welding being found unsatisfactory after stage (xi) the clamping means 21 and backing ring assembly may be placed in working position again for weld repetition or repair before stage (xii) is proceeded with. After retraction of the clamp means 20, the apparatus is moved to the next joint position.