WELDING METHOD FOR SHELL AND TUBE

A method for welding tubes to tube insertion holes formed through tube sheets of a shell and tube heat exchanger, including forming ring-shaped tube sheet grooves, spaced from the tube insertion holes by a designated distance in the outer circumferential direction, on one surface of the tube sheet at the shell side, inserting tube joint members, having a cylindrical shape with the same diameter as that of the tubes, into the tube insertion holes of the tube sheet, manufacturing ring wires by cutting a welding wire having a long length into pieces having a designated length and bending the pieces into a ring shape so as to be inserted into the outer circumferences of the tubes, inserting the ring wire into the outer circumference of one end of the tube, inserting the one end of the tube into the tube sheet in one direction such that the one end of the tube contacts one end of the tube joint member facing the one end of the tube and is located within the recessed distance range of the tube sheet groove, performing tube side welding by welding the other end of the tube joint member to the other surface of the tube sheet at the tube side, and performing shell side welding by inserting a welding torch into the tube joint member and thus welding the one end of the tube joint member, the one end of the tube and the joint part to the one surface of the tube sheet at the shell side using the ring wire as a filler metal.