Abstract: With a method and apparatus for the percussive cleaning of objects disposed in a chamber that is under process pressure, whereby an elongated percussive element is held below and in contact with the object that is to be cleaned and percussive energy is applied to the percussive element via an accelerated elongated striker, it is provided for a more simple pressure balancing that at least during the acceleration of the striker, the two ends of the striker be maintained at the same pressure, which essentially corresponds to the pressure in the process chamber.

Abstract: A method and apparatus for rolling tubes into tube plates, especially heat exchangers, with a tube roller. Prior to the rolling process, the desired holding expansion value is set, and during the rolling process the holding expansion is measured. When the preset expansion value is reached, the expansion is discontinued. The magnitude of the holding expansion is determined by ultrasonically measuring the changing thickness of the wall of the tube during the expansion. The apparatus includes a tube roller that is operated by a drive mechanism. Also provided is a roll controller that can be set to the desired holding expansion value. An ultrasonic measuring head is provided in the tube roller, and is connected with the roll controller.