Abstract: Methods and apparatus for cutting a groove in a structure are disclosed. Large structures such as steam turbines have pumping grooves or similar features which may be machined using the simplified methods and apparatus disclosed. In a preferred embodiment, a milling head affixed to a magnet which may be selectively activated is provided. Additional clamping means are also provided which are affixed to the magnet and engage the structure to further affix and align the apparatus in place. The milling head is positioned at the location of the groove and held fast by the magnet; the additional clamping means ensure the apparatus stays in place while the groove is being cut. The apparatus disclosed may be operated by a single operator using conventional power sources and without the need for extensive set up, fixturing and the like normally associated with milling operations of this nature.

Abstract: The method of the present invention uses a combination of gap measurement methods to map the gap in a joint in a high pressure vessel such as a steam turbine or steam valve. An exposed and supported surface is hydraulically balanced allowing any twisting of the surface to be removed. The map is then created using a blue contact method, feeler gages, deformable gap measuring medium and laser profiling for both surfaces of the joint. A restoration plan is produced using the map which minimizes the restoration work and produces matching joint surfaces. The joint surfaces are welded and/or machined and finally finished in accordance with the plan. A laser can be used to guide or reference the machine tool. Matching joint surfaces, especially if relatively flat, provide a better high pressure seal than relatively flat surfaces that do not match while relatively flat surfaces that do match produce an even better seal.