GB1303641A - - Google Patents

Abstract

1303641 Welding by fusion FOSTER WHEELER JOHN BROWN BOILERS Ltd 23 Feb 1970 [21 Feb 1969] 9592/69 Heading B3R In making a seal weld between a tube 10 and a tube plate or header 14 in a heat exchanger, wherein the tube extends partly or, preferably, completely, through a plate bore, a filler insert 20 is fitted into an annular groove preparation 16 in the plate surrounding the tube and is retained in place during non-consumable electrode arc welding by which the tube, plate and insert are fused together. The insert may be a piece of filler wire e.g. of circular cross-section, bent to shape, or in sections providing the gaps therebetween are less than 3/32 inch. The insert composition is such as to avoid hot cracking or embrittlement. The insert may be retained by a shoe or roller fitted on the welding head; or, preferably, so as to centre the tube, by punching over, at 24, the edge of the preparation 16. In addition, the lower edge 26 of the preparation may be burred to assist tube centring. In the event of tube or weld failure in use, the weld may be removed by cutting, the tube removed if necessary, the plate re-prepared, a new tube inserted if necessary, and a new seal weld made. To prevent entry of contaminants into the weld, a soft metal ring (34, Fig. 4, not shown) may be tightly fitted between the tube and plate adjacent the filler insert.