METHOD AND DEVICE FOR MOUNTING ADDITIONAL SCREW

摘要

PURPOSE: To provide a proper means for repairing an internal thread for sealingly bolting down a vessel cover by means of a bolt passing through a small hole internally threaded in the flange of a pressurized-water nuclear reactor vessel. CONSTITUTION: To repair the internal thread 2b of an internally threaded small hole 2 in a large diameter an added thread is screwed into the small hole 2 with the internal thread. The added thread is screwed into the small hole 2 in a form wound on a threaded part of the surface of a drum screwed into an internally threaded centering ring engaged in the entry part 2a of the small hole 2. A thread is arranged opposing to the internal thread 2b and is engaged in the wall of the internally threaded small hole 2 and is fixed by installing a pin penetrating the thread.