Patent Number: 061047724
Section: description

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now in detail to the single FIGURE of the drawing, there is seen a pipeline 140 in a primary loop of a nuclear power plant with a pressurized water reactor, which leads from a stub 142 in a dome of a steam generator 144 to a non-illustrated pump. The stub 142 forms an opening which can be reached only through a relatively narrow manhole 146 of the steam generator 144. A self-propelled in-pipe manipulator 2 must be driven in through this opening. To that end, the in-pipe manipulator 2 is introduced into a tubular hollow-cylindrical hollow body 150 that is open on both ends. The in-pipe manipulator 2 is positioned together with the hollow body 150 above the stub 142 with the aid of a boom or crosspiece 152 which is part of a positioning device and protrudes through the manhole 146 into the steam generator 144. To that end, the hollow body 150 is provided with a shell-like support frame 154, which is pivotably supported about a pivot axis extending perpendicular to the boom 152, in a pivot bearing 156 on the boom 152. This pivoting motion is executed with a hydraulic cylinder 158, which is supported between the hollow body 150 and the boom 152. The boom 152 is mounted on a support stand 160, which is positionable outside the steam generator 144, and the boom is oriented in such a way that a pivot axis of its pivot bearing 156 is oriented perpendicular to a plane defined by center axes of the stub 142 and the manhole 146. Through the use of a linear displacement of the boom 152, as represented by an arrow 162 in the drawing, the pivot bearing 156 is positioned virtually at an angle bisector between these center axes, so that a simple pivoting motion, indicated by an arrow 164, enables an adequately exact positioning of the hollow body 150 oriented coaxially to the center axis of the stub 142. A deflection roller 166 which is also disposed on the support frame 154 is provided both for a cable required for supplying the in-pipe manipulator 2 and for a recovery rope, with which the in-pipe manipulator 2 can be retrieved from the pipeline 140 if it fails. The in-pipe manipulator 2 which is shown as an example in the drawing includes a pivot arm 200 disposed on its end surface, with two pivotable intermediate members 282 and 284 and a pivotable terminal member 320 that can be retracted nearly all the way into the interior of the chassis. The in-pipe manipulator 2 is also provided with a plurality, for example six or eight, rollers 206 which are supported extensibly on the base body of the in-pipe manipulator 2. With such an in-pipe manipulator 2, poorly accessible pipelines 140 can be reached even under spatially tight conditions, since the in-pipe manipulator has relatively small dimensions in an initial state. Moreover, since the rollers 206 can be extended relatively far, the demands for precision in positioning the hollow body 150 above the opening are less stringent, because the in-pipe manipulator can be driven into the pipeline 140 even if its center axis and the center axis of the opening are not exactly aligned with one another. In the drawing, the in-pipe manipulator 2 is shown in various working positions. It can be seen that the hollow body 150 performs not only the function of positioning the in-pipe manipulator 2 at a location suitable for introduction into the pipeline 140, but moreover also makes it possible to inspect weld seams positioned directly at the beginning of the pipeline, in this example weld seams 168, 169 on the stub 142 of the steam generator 144, with the aid of the in-pipe manipulator 2, without requiring that the in-pipe manipulator 2 be driven back into the pipeline 140 again in reverse orientation, after inspecting the weld seams located farther into the pipeline 140. Once the pivot arm 200 has been extended, the in-pipe manipulator 2 can already begin its inspection when the chassis is still completely inside the hollow body 150 or is still partly inside the hollow body 150, as explicitly shown in the drawing. This enables inspection of all of the weld seams of the pipeline 140 without requiring the in-pipe manipulator 2 to be turned around. In principle, however, other in-pipe manipulators, for instance of the kind known from the references cited at the outset, may also be introduced into a pipe with the aid of the apparatus of the invention. Depending on the structural layout of the in-pipe manipulator, it may be necessary in an individual case to use a hollow body which is adapted in its dimensions to the dimensions of the opening of the pipeline and which must be positioned at the opening in relatively exact alignment with the pipeline.