Abstract: 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.

Abstract: Apparatus for automatically inserting and removing screw-threaded elements into and from threaded bores of a pressure vessel to fit or detach a cover employs a screw-clamping device with a carrier ring supporting individual mechanisms for each screw-threaded element. Each mechanism employs a pair of parallel hydraulic piston and cylinder units with their cylinders supported for sliding on a flat surface of the carrier ring and their piston rods linked to a pressure bridge which brace on a shoulder of a screw-threaded sleeve fitted onto the associated screw-threaded element. The entire mechanisms is displaceably adjustable relative to the carrier ring predominantly in a radial direction relative to a common pitch circle for all the screw-threaded elements.

Abstract: Apparatus employs a device for automatically threading and unthreading studs into tapped bores of a pressure vessel containing nuclear fuel to detach or fit a cover thereto. The apparatus also employs a device with a carrier ring supporting piston and cylinder units for tensioning the studs while nuts are fitted thereon. The stud threading device is supported on a carriage displaceable along a circular track to access each stud in turn. The stud threading device has a drive member, such as a tube or rod, which is driven by a rotary drive as well as a reciprocating drive. At the lower end the drive member has a coupler which fits onto a coupler at the upper end of each stud. The couplers on the studs take the form of bayonette-type fittings with U-shaped grooves for receiving locking projections on the coupler of the drive member to establish a connection resistant to tension and relative rotation.

Abstract: A remote controlled bolt removing device for bolts securing the head of a reactor pressure vessel is provided which includes a vertically movable rotating device which automatically grips and turns the bolts and at least one hydraulic cylinder for raising and lowering the rotating device. The device is provided with a rotating drive associated with the hydraulic cylinder which imparts a relative rotating movement between the piston and the cylinder during the operating stroke.

Abstract: A high-pressure seal having a dynamic seal ring and a static seal ring supported by a backup ring is improved upon such that support ring is a one-piece construction having sealing chambers respectively defined together with the bore wall of the cylinder with the piston recess for the dynamic and static seal rings. The seal chamber for the static seal ring is formed to induce a stretching of this ring when the high-pressure seal is assembled in place, whereby the seal between the piston and cylinder is improved as the static seal ring is stretched to provide a tight seal between the backup ring and the piston.

Abstract: A fluid-operated device for simultaneously pretensioning a plurality of bolts connecting a first body to a second body in which the bolts are screwed with threaded end portions thereof into corresponding threaded bores in the second body and project with clearance through bores in the first body and with opposite threaded end portions thereof beyond the first body.