Abstract: An improved laser beam welding apparatus for an inner circumferential surface of a tube is disclosed herein, which apparatus comprises an elongated flexible tube containing an optical fiber extended along the length thereof so as to transmit a laser beam, position detecting means disposed in the vicinity of the top end of the flexible tube to determine relative positioning thereof with respect to a work tube in which the flexible tube is inserted, holding means provided with an expander and disposed adjacent to the position detecting means for holding the tip end of the flexible tube in the work tube, rotary drive means disposed closer to the tip end of the flexible tube than the holding means, a rotary cylinder connected to the rotary drive means to be rotated with respect to the flexible tube, guide means mounted on the rotary cylinder in a relatively rotatable manner with respect to the rotary cylinder and held in contact with the inner surface of the work tube for supporting the rotary cylinder in a conce

Abstract: An extendable and retractable cleaning apparatus includes a multi-stage extendable and retractable arm assembly formed of a plurality of cylindrical members assembled in a telescopic manner, an ejection nozzle provided at a tip end of the innermost cylindrical member of the arm assembly, a mount housing surrounding a substantially central portion of the arm assembly to rotatably support the arm assembly and a casing integrally formed at a base end of the outermost cylindrical member of the arm assembly to form a pressure chamber in cooperation with the assembly. A rotational driving device is provided within the housing for rotationally driving the arm assembly. A washing liquid feed hose is connected to the ejection nozzle. A compressed air feed pipe has one end mounted to the casing to communicate with the pressure chamber.