Welding method for shell and tube

摘要

A method for welding tubes in a shell and tube heat exchanger, including forming ring-shaped tube sheet grooves on the tube sheet at the shell side, inserting tube joint members into the tube insertion holes of the tube sheet, producing ring wires by cutting a welding wire into pieces and bending the pieces into a ring shape, affixing the ring wire to the outer circumference of one end of the tube, inserting the end of the tube into the tube sheet such that the end of the tube contacts one end of the tube joint member and is located within the recessed distance range of the tube sheet groove, and performing shell side welding by inserting a welding torch into the tube joint member and welding the end of the tube joint member, the end of the tube and the joint part to the tube sheet at the shell side using the ring wire as filler metal.

主权项

1. A method for welding tubes to tube insertion holes formed in tube sheets of a shell and tube heat exchanger, the shell and tube heat exchanger being configured such that different fluids are introduced into and discharged from a tube side and a shell side so as to exchange heat with each other, the method comprising:
forming ring-shaped tube sheet grooves, spaced from the tube insertion holes by a designated distance in the outer circumferential direction, on a first face surface of the tube sheet at the shell side so as to form joint parts between the tube sheet grooves and the tube insertion holes; inserting tube joint members, having a cylindrical shape with a shorter length than the length of the tube insertion holes of the tube sheet and the same diameter as that of the tubes, into the tube insertion holes of the tube sheet; producing 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 having a greater diameter than the diameter of the tubes so as to be affixed to the outer circumferences of the tubes; affixing the ring wire to the outer circumference of a first end of the tube; inserting the first end of the tube into the tube sheet in a manner such that the first end of the tube contacts a first end of the tube joint member facing the first end of the tube and that the contact area of the first end of the tube and the first end of the tube joint member is located within a recessed distance range of the tube sheet groove with the ring wire affixed to the first end of the tube simultaneously contacting to the joint part formed between the tube sheet groove and the tube insertion hole; performing tube side welding by welding a second end of the tube joint member to a second face 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 welding the first end of the tube joint member, the first end of the tube and the corresponding joint part to the first face surface of the tube sheet at the shell side using the ring wire as a filler metal, wherein in inserting the tube joint members, the tube joint member is inserted into the tube insertion hole of the tube sheet such that the second end of the tube joint member is generally aligned with the second face surface of the tube sheet at the tube side and the first end of the tube joint member is located within the recessed distance range of the tube sheet groove, and in shell side welding, when the welding torch is inserted into the tube joint member under the condition that the corresponding ends of the tube joint member and the tube contact each other within the recessed distance range of the tube sheet groove of the tube sheet, welding heat is directly transmitted to a contact region between the corresponding ends of the tube joint member and the tube and to the corresponding joint part of the tube sheet through a contact gap there-between, such that the ring wire contacting the joint part of the tube sheet is melted and thus the ends of the contacting tube joint member and the contacting tube are welded to the joint part of the tube sheet using the ring wire as the filler metal.