Importance

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Abstract

In order to join a tube to a tubesheet of a heat exchanger, the end of the tube is inserted into a socket at the end of a hole that passes through the tubesheet. The socket is large enough to receive the tube, but the hole is not, so the tube bottoms out in the socket and is thus located both radially and axially by the socket. A ring mold is fitted around the tube and moved against the tubesheet, so that its end fits into an annular groove that surrounds the socket in the back face of the tubesheet. The ring mold has a chamfered confining surface that surrounds the tube where the tube emerges from the socket. Once the ring mold is in place the portion of tube that is within the socket is welded autogenously to the tubesheet by rotating an electrode within the hole. The molten weld metal flows outwardly to the confining surface, but is prevented by that surface from flowing circumfentially, even when the welding is performed with the tube in a horizontal position. The molten metal resulting from the welding solidifies against, but does not bond to, the ring mold. The mold is thereafter removed.

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First Claim