Abstract: In a vertical type heat exchanger including a water chamber delimited by a drum end plate and a header plate on which a large number of heat transfer tubes are arrayed, a novel manipulator for working in the heat exchanger is provided such that a support frame is disposed within the water chamber, a base end portion of a freely extensible and contractible main arm which is rotatable about its base end portion and vertically swingable about a fulcrum at its base end portion, is mounted on the support frame, a base end portion of a sub-arm which is rotatable about its base end portion and vertically swingable about a fulcrum at its base end portion and also which can be positioned in parallel to the header plate, is mounted at the tip end portion of the main arm, a vertically movable clamp shaft which can be inserted into the heat transfer tube is provided coaxially with the rotational axis of the sub-arm, and a position detector for detecting the position of the clamp shaft so as to assist in positioning the c

Abstract: An electron beam working apparatus for cylindrical workpieces having a circular working line is improved so that a volume of a vacuum chamber to be maintained can be minimized and the vacuum chamber may not contain a contamination source such as a driving motor. In order to achieve the improvements, two disk-shaped partition plates having inflatable annular seal members disposed along their respective outer peripheral surfaces are placed inside the cylindrical workpieces respectively above and below the working line with said seal members pressed against the inner peripheral surfaces of said cylindrical workpieces to form a first vacuum chamber surrounded by said two partition plates and the inner peripheral surfaces of said cylindrical workpieces.