| 摘要 |
<p>A welding arc shrouded in an inert gas is made to scan the internal surface of a tube which is to be extracted from a bore in a tube plate, after it has been cooled. The tube plate is of considerable thickness and has a large number of identical bores passing through, forming a uniform network, into which identical tubes are inserted by their ends. The zone of the tube which is heated reaches a high temp., which, however, is below its melting point. The inert gas is fed into the tube at the opposite end from that by which it is to be extracted, and a cooling liq. is circulated in the adjacent tubes to the one to be extracted during the whole operation of relieving the constraints caused by its insertion. Pref. the heat is applied until the internal surface of the tube reaches a point 100 degrees C below the point of fusion of the metal. It is possible to extract tubes which have been expanded in position by "Dudgeoning" into the tube plate of the heat exchanger, without melting or other damage to them so that they can be examined and tested for their performance.</p> |
