AUTOMATIC DEVICE AND PROCESS FOR TIGHTENING AND UNTIGHTENING A NUT ON A TENSION BOLT

摘要

Stud bolts are threaded into the body of a nuclear reactor vessel and tensioned by exerting forces on tensioning nuts located on the upper end of the studs. While the studs are under tension, a cover is attached to the vessel by tightening nuts on the studs against the cover. The tensioning nuts are applied to the studs by immobilizing the studs axially and rotationally, and rotating the tensioning nuts with a pair of driven, diametrically opposed striking rollers. External threads on the striking rollers, external threads on the nut and internal threads on the nut all have the same pitch so that the threads on the striking roller remain engaged with the external threads on the nut as the nut moves axially while being threaded onto the immobilized stud.