GB1179190A - Apparatus for Performing Operations at the Ends of Tubes. - Google Patents

Abstract

1,179,190. Repairing heat exchangers; welding by fusion; drilling machines. GULF GENERAL ATOMIC Inc. 13 Sept., 1967 [19 Sept., 1966], No. 41780/67. Headings B3A, B3C and B3R. Apparatus for performing operations at the ends of tubes 20 in a heat exchanger comprises a rotary turret 11 carrying extensible tools, means for supporting the turret and for displacing the supporting means so that the tools may be aligned successively with any of the tubes. In the embodiments, after the water and steam have been drained from a gas-cooled nuclear reactor, one tool detects a faulty tube by the presence of helium coolant in the tube, another tool or tools, e.g. a counterboring tool, prepares the end of the faulty tube for welding, further tool inserts a metal plug, e.g. from a magazine, and another tool welds the plug to the end of the tube to seal the leak. A second detecting tool, or the original detector, may check the plugged tube. The tools are extended into engagement with the tubes by pneumatic cylinders in the tool housings 40. Welding.-An inclined, arc-welding tip 49, Fig. 3, to which shielding helium is fed through passages 47, is carried on the turret 11 by a head 42 rotatable by a motor to carry the tip around the tube end. The turret is eccentrically mounted in the end 32 of a saddle 13 which is rotatable in bearings 56, 57 in a casing 17. Rollers 22 on the casing facilitate its insertion in the conduit 14 where it is secured by pneumatic pistons 24. A central shaft 36 driven by a motor 41 rotates, through gears 33, 34, a shaft 28 carrying the turret. Rotation of the saddle 13 is by an electric motor 61 driving a gear 58 on the saddle. Electronic positioning transmitters 62 correlate the movements of the turret and saddle to position the tools. The motors 41, 61 are operated to traverse the detecting tool across the tube ends by an electronic control 60 or by an operator through visual observation of an indicator (not shown) operated from the transmitter 62. Upon helium being detected, the motor 61 is stopped and motor 41 operated to index the turret to position the next tool. In another embodiment, Figs. 4 and 5, a housing 63 of the apparatus is located against a lip in the steam conduit 65, and retained by struts 131 on a back housing 66 which is bolted to the conduit and may be filled with shielding 67. The tool turret 71 is mounted on four rods 83 so as to remain parallel to the tube plate and is connected to a floating beam 79 by a universal joint 77. A drive shaft 88 for the turret passes through the beam 79 and drives gears 97, 101 and a gear 102 meshing with a toothed crown 107 on the turret, which is mounted on bearings 75 on the saddle 73. The axial position of the saddle on its support 70 is regulated, to keep the tools close to the tube ends as the saddle moves through an arcuate path, by a piston 138 operated pneumatically against a return spring 139. The saddle is " walked " over the tube ends by the drive of the turretmotor with the turret located at one point by an extensible plunger 110. Further plungers 108, 109 are carried by the saddle for locking the saddle while the turret is turned. It is stated that the saddle may be " walked " by applying a brake to the idler shaft 98. A visual indication of the position of the tools is provided by a secondary turret 113 at the end of the shaft 88. The turret 113 has a contact for each tool and plunger and co-operates with a scanning screen 123 having contacts 124 corresponding to the tubes. Alternatively, a light source and photo-cell arrangement can be used. The tools may be arranged radially for use with a " header " type of heat exchanger in which the tubes are arranged radially of a cylindrical wall.