Method of welding the ends of thin-walled heat exchanger tubes free of residual crevices

摘要

The process enables gap-free welding of the ends of thin-wall heat exchanger tubes to the wall separating the heat exchange media. This wall has bores (13) corresponding to the ID of the tubes (2) and surrounding seat faces (17) for the tube ends (18). A rotating welding head is inserted in the bores (13) without filler metal addition and with the use of weld pool protectors on the outside of the tubes. The media separating wall (12) is a section of a cylindrical header (3a,3b), the outer curved surface of which is provided with tube end seat faces (17). The header (3a,3b) is assembled from two half shells (8,9) and has an ID of at least 400 mm. A shielded gas welding process, esp. tungsten inert gas (TIG), is used. The seat faces (17) and tube ends (18) are flat and the ratio of tube centre pitch to tube diameter is not greater than 1.5.