Abstract: A valve for controlling the flow of hot fluids in nuclear reactor plants or similar institutions has a tubular body whose internal surface is welded to an annulus of metallic leaf springs each connected to the outer end of a radially inwardly extending metallic spoke. The inner ends of the spokes are adjustably connected with a metallic sealing ring which is movable axially by a bellows into and from sealing engagement with a plate-like sealing member forming part of a plug-shaped or spherical valving element which is turnable or shiftable between open and closed positions. The bellows is caused to disengage the sealing ring from the sealing member prior to movement of the valving element to open or closed position and to engage the ring with the sealing member when the valving element assumes the open or closed position.

Abstract: A ball valve for controlling the flow of hot fluids in nuclear reactor plants has a tubular body for a spherical valving element which is flanked by two axially movable seats and is turnable between open and closed positions. Discrete bellows are provided to move the seats away from the valving element before the latter is set in motion and to urge the seats against the valving element when the latter assumes and dwells in the newly selected position. The body and the valving element define a main cooling chamber which accommodates the seats and receives pressurized coolant. Such coolant flows into the fluid-conveying passage of the body by way of a clearance between cylindrical heat-insulating layers at both sides of the valving element and the periphery of the valving element. Additional cooling chambers which are provided between the bellows and the insulating layers communicate with the clearance via gaps between the seats and the respective insulating layers.