Device for selectively tensioning and clamping studs mounted on a pressure vessel to permit nuts to be tightened or loosened

摘要

Apparatus for tightening and releasing nuts on screw-threaded studs to fit or release a cover on a pressure vessel employs several devices for subjecting each of the studs to tension to clamp the stud whilst the nut is rotated thereon. Each device has a passage for receiving one of the studs and a threaded sleeve engaged thereon. An hydraulic piston and cylinder unit subjects the sleeve to tensile force and likewise the stud coupled thereto. Also in the passage there is a sensor which has spring biased relatively movable components for engaging on a head of the stud and on a system of rods providing a reference. The sensor is suspended in the passage and provides an indication of the strain imposed on the stud by the hydraulic unit.