Method for welding heat exchanger tube plate and welding joint of heat exchange tube

Abstract

The invention relates to a method for welding a heat exchanger tube plate and a welding joint of a heat exchange tube. During assembling of the heat exchange tube and the tube plate, a structure which is sunken into the surface of the tube plate 0.5 to 1 millimeter is adopted; during welding, a welding sequence from bottom to top is adopted, and a 3-shaped or S-shaped welding running line is adopted; during welding, each heat exchange tube is welded with a half of a cycle, and after 8 to 10 heat exchange tubes are welded disposably without arc quenching, the tube plate is subjected to the arc quenching; and according to the same method, the other half of the cycle is welded from bottom to top. Therefore, the frequency of arc stopping and arc starting can be reduced, the welding efficiency is improved, and the number of arc starting and stopping points and the probability of generating welding defects can be reduced. During welding, a tungsten electrode can be stretched into the root part of an included angle between the heat exchange tube and the tube plate easily; during autogenous welding, an electric arc can get to a sharp corner position, and the root part can be penetrated totally without any hollow cavity, so retention of shell side corrosion media is prevented, interval corrosion is avoided and the service life of a welding line is prolonged.

Description

technical field [0001] The invention belongs to the field of welding, and relates to a welding joint applied to a tube plate and a heat exchange tube of a tube-and-tube heat exchanger, in particular to a welding method for a tube plate and a heat exchange tube welding joint of a heat exchanger. Background technique [0002] In chemical equipment, the tube-and-tube heat exchanger is an important piece of equipment, and the welded joint between the tube sheet and the heat exchange tube is the most important and most likely to fail in the equipment, and its quality directly affects the quality of the equipment. Service life and stability of the device. At present, the connection joints between heat exchange tubes and tube sheets of heat exchangers are divided into two types according to different working conditions: fusion head type and fillet weld type. In the usual fusion head joint, the heat exchange tube hole on the tube plate is grooved at 2×45°. When assembling, the heat...

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Problems solved by technology

The above-mentioned conventional welded joints and welding methods have the following problems: 1. When the first layer is self-melting, incomplete penetration is formed at the root of the joint, leaving a large cavity, and the shell-side medium is easily formed in crevice corrosion, which affects Joint life; 2. The positions of the arc striking and arc striking of the first pass and the second pass overlap, the defects of the arc striking and arc striking of the two passes overlap, the density of the weld seam decreases, and the probability of leakage increases; 3. Comparison of welding efficiency Low

[0003] Through searching, no technical documents identical to this patent application have been found

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