GB1482741A - Device for performing operations on a tube - Google Patents

Abstract

1482741 Welding by fusion; cutting off FOSTER WHEELER POWER PRODUCTS Ltd 29 July 1974 [30 May 1973] 25844/73 Headings B3R and B3T An apparatus for internal welding, cutting or grinding of a tube comprises a tool-carrying workhead which carries a tool rotatable by way of a flexible elongate member and which is positionable within the tube bore by members which are spaced around the workhead and hydraulically, pneumatically or mechanically radially expandable to engage the tube bore surface. The workhead may carry a plurality of tools or, as shown, one tool for a specific purpose. In Figs. 1, 2 a workhead of end-to-end tube welding apparatus comprises an arc welding torch rotatable within a positioning sleeve assembly securable in a tube bore. The torch comprises an electrode 14 screw-clamped in an electrically conducting body 12, 20 having a ceramic casing 30. The positioning sleeve assembly comprises tube bore surface engaging segments 46 supported and axially acted upon by conically-ended axially fixed and movable sleeves 48, 42, the latter being relatively axially moved, to radially outwardly cam the segments, on pneumatic pressurizing of an annular chamber 45 formed therebetween. The segments are radially inwardly urged by garter springs 51 and are circumferentially connected by springs (70, Fig. 3, not shown). The body 12, 20 is connected to a flexible, corrugated, electrically conductive tube 26 the remote end of which is connected to a tube 86. The latter is connected to a hollow shaft 88 to which rotation is imparted via a worm drive 99/100 and electric current is supplied by a brush 95. A rubber sleeve 28 surrounding the tube 26 is connected to the hollow shaft 88 and, by way of a synthetic fabric bearing 68 and a ceramic sleeve 64, the body 12, 20. Pressurizing of the chamber 45 is effected via a polythene tube 82 and coiled pipe 60. Shielding gas is supplied via a polythene tube 85, a coiled pipe 58 and a passage 63 in the body 12, 20. Cooling water is fed to the torch through a pipe 102, the tubes 86, 26 and a body bore 22, and returned through body bores 24, an annular space between the rubber sleeve 28 and the flexible tube 26, and a pipe 104. In an alternative embodiment, the shielding gas or pressurizing fluid may be directed through said annular space. In Fig. 4, a workhead for severing a tube from therewithin comprises a circular cutting tool 182 mounted on a spindle 180 eccentrically journalled in a cylindrical member 178 in turn eccentrically journalled in a cylindrical member 176. Workhead positioning, tube-bore-surfaceengaging segments 170 are supported by and axially acted upon by conically-ended axially fixed and movable sleeves 152, 158, the latter being relatively axially moved, to radially outwardly cam the segments against the bias of a garter spring 174, on hydraulic pressurizing of an annular chamber 168 formed therebetween. The member 176 is journalled in the axially fixed sleeve 152. In operation of this workhead, when inserted into a tube with the peripheral edge of the tool 182 initially not projecting radially of the segments 170, the spindle 180 and cutting tool are rotated via a flexible cable 184, the member 178 is then rotated via a flexible cable 188 to radially outwardly move the cutting tool to cut into the tube wall. After 180 degrees rotation of the member 178, a spring-pressed pawl (192) therein engages a recess (194) in the member 176, and after cable-effected removal of a pin (200) preventing rotation of the member 176, further rotation of the member 178 effects co-rotation of members 178, 176 and the cutting tool translates circumferentially to sever the tube. Cutting fluid is fed via a polythene tube 204 and a tube 202. Hydraulic pressure in the chamber 168 may be adjusted via an airactuated intensifier. In a further tube severing workhead, the cutting is effected by a point-cutter, the radial extension of which is effected by a cam tooth device actuated by an axially moved rod. In cutting out a defective portion of tube and welding in a replacement portion in a tube bank (e.g. in a nuclear power generator), the defective tube portion is cut into, e.g. sawn, at a remote position, the severing workhead is inserted through the defective portion and the severing is effected, the end of the tube remaining in the bank is prepared for welding, as by grinding, and the welding workhead inserted through the replacement tube, e.g. before the latter is placed in the bank, and the welding effected. Correct position of the replacement portion may be achieved by use of an intrascope or fibre optic tube.