Replacement of metallic tube fitted to vacuum housing

摘要

The housing (1) has a cylindrical tubular part (1a) near the vacuum pumping connection (2') into which a circular disc (1b) is soldered or welded with a seam (3). The connection is fitted into an opening which is rendered vacuum-tight by soldering or welding with another seam (4). To replace the connection, a tubular section is bonded to the remaining stump preferably by orbital welding with an electrode revolving about the joint. After reheating and evacuation of the tube, a pinch is formed between dies (6a,6b) with spherical ends (7a,7b) at a sufficient distance (d) from the weld to prevent damage by plastic deformation.