JPS594978A - Welding of long member - Google Patents

Abstract

PURPOSE:To eliminate necessity of shrainkage allowance of a tube at the time of welding and reduce working time remarkably in welding both ends of a long member to a base metal, by rotating a welding machine in the same direction or reverse direction along the weld line of the both ends and performing welding at the same time. CONSTITUTION:For instance, in a shell and tube type heat exchanger having perfectly straight heat transmitting tubes, the heat transmitting tubes and tube plates 5 are kept at a fixed distance. Many straight heat transmitting tubes 1 are positioned between the tube plates 5, 5, and both ends of the heat transmitting tubes 1 are welded to the tube plates 5 respectively. Accordingly, in the method that welds many tubes to the tube plates 5, grooves on both ends of the tubes 1 are conformed and both ends of the tubes 1 are welded simultaneously. In this method, welding is performed rotating the welding machine along the weld line. The welding machine is rotated in the same direction or reverse direction at both ends of the tubes 1. Consequently, it is not necessary to provide shrinkage allowance of the tube due to welding, and defects such as discordance of grooves etc. due to shrinkage of the tube are eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an elongated member in which both ends of the elongated member are simultaneously welded when both ends of a heat transfer tube in a heat exchanger or the like are welded to a tube plate (base material). This relates to a welding method.

At present, liquid metal (IJ) cooled fast breeder reactors (LM)
There are several types of heat exchangers used in FBR, etc., depending on the shape of their heat transfer parts, but the heat transfer parts in shell-and-tube heat exchangers generally have a large number of heat transfer parts. It has a structure with heat tubes, and both ends of these heat transfer tubes are all welded to the tube sheet. For example, as shown in FIG. 1, a shell-and-tube heat exchanger having a long member such as a completely straight heat exchanger tube has a tube bundle consisting of a large number of heat exchanger tubes 1 and A tube plate 5 disposed to form a lower chamber 4 of the chamber 3, a high temperature side fluid population 6 and a high temperature side flow outlet lower provided in the upper chamber 3, and a body section to cool the surroundings of the tube bundle. It consists of a low-temperature side fluid port 8 and a low-temperature side fluid outlet 9 provided in is fixed by.

The welding methods for welding a long member such as the heat exchanger tube l and the tube plate 5 serving as the base material include a seal welding method as shown in FIG.
There is a butt welding method as shown in the figure, but the tube plate 5,
Heat exchanger tube between 5! When a tube bundle section having a shape in which a tube is located is fixed by welding and isostatic pressure, distortion and shrinkage of the tubes due to welding becomes a particular problem. That is, in the seal welding method as shown in FIG. 3, the heat exchanger tube 1 thermally expands during welding.

At this time, since the pipe wall end is fixed to some extent during the welding process, a compressive force is generated in the heat exchanger tube l, and the stress is eventually relaxed. After this, as the tube cools, the welded portion begins to shrink, and due to hysteresis, the heat exchanger tube 1 becomes shorter than before welding. Therefore, measures such as providing sufficient shrinkage allowance in advance for the heat transfer tube 1 are taken, and after welding one end of the tube and shrinking the tube to a certain extent, the excess portion is cut off and the other end of the tube is welded. The welding process is extremely complicated and requires a great deal of labor.

In addition, in the butt welding method as shown in FIG. 4, it is necessary to match the grooves of the welded part, so if the tube shrinks after welding one end, the tube plate 5 and the heat exchanger tube 1 may Butt welding of the other end is not possible due to the gap created in between.

Therefore, in order to weld all one ends of a tube bundle consisting of a large number of heat transfer tubes 1 to one tube sheet 5, and then weld the other end to the other tube sheet 5, it is necessary to match all the grooves at the other ends. This is an extremely difficult task. In other words, completely improving the reliability of the welded portion between the heat exchanger tube 1 and the tube plate 5 will lead to improving the reliability of the equipment, and this requirement is particularly strict for equipment using Atomic Kaglan H7C.

The present invention was proposed based on such actual situation,
A long component designed to simultaneously weld both ends of a heat transfer tube using the proven butt welding method, solving the problem of tube shrinkage caused by welding and reducing the number of welding steps required for the entire tube bundle. The purpose is to provide a welding method, the gist of which is that when welding both ends of a long member to a base metal, the welding machine is moved in the same direction along the welding line of both ends of the long member. Or, it is characterized by welding at the same time while rotating in opposite directions.

Hereinafter, a method for welding a long member according to the present invention will be explained based on the embodiment shown in FIG.

In a shell-and-tube heat exchanger having completely straight heat exchanger tubes, as described above, the heat exchanger tubes 1 and the tube sheets 5 are kept at a constant distance, and a large number of straight tubes are placed between the tube sheets 5, 5. A heat exchanger tube 1 is located therein, and both ends of the heat exchanger tube 1 are welded to a tube plate 5, respectively. Therefore, in the method of welding a large number of heat exchanger tubes 1 to the tube sheet 5 according to the present invention, the grooves at both ends of the heat exchanger tubes 10 are aligned, and then both ends of the heat exchanger tubes 1 are welded simultaneously.

That is, both ends of the heat exchanger tube 1 according to the present invention are simultaneously attached to the tube plate 5.
The welding method is to first weld while rotating the welding machine along the welding line, and the welding machine is rotated in the same direction or in opposite directions at both ends of the heat exchanger tube 1. It will be done.

As explained above, in the method for welding a long member according to the present invention, both ends of the heat exchanger tube are simultaneously welded when welding both ends of the heat exchanger tube to each tube sheet. For example, since there is no need to provide an allowance for shrinkage of the pipe due to welding, drawbacks such as the grooves not matching due to shrinkage of the pipe are eliminated. In addition, since both ends of the pipe are welded at the same time, welding time is significantly reduced, and there is no strain relief work required after welding, making it possible to reduce the cost and improve the reliability of the welded part. There are advantages.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an example of a shell-and-tube heat exchanger, FIG. 2 is an enlarged view showing the tube bundle part of FIG. 1,
Fig. 3 is a sectional view of the main part showing the conventional seal welding method, Fig. 4 is a sectional view of the main part showing the conventional butt welding method,
FIG. 5 is an explanatory diagram showing an embodiment of the welding method according to the present invention. In the figure, iFi heat transfer tube, 2 is the heat exchanger body, 3 is the upper chamber, 4 is the lower chamber, 5 is the tube plate, 6Ifi is the high temperature side fluid inlet, 7 is the high temperature side fluid outlet, 8 is the low temperature side fluid inlet , 9 is a low temperature side fluid outlet. Patent applicant Mitsubishi Heavy Industries, Ltd. Patent attorney Shibe Mitsuishi (and 1 other person) Figure 1 Figure 2

Claims (1)

[Claims] A long member characterized in that when welding both ends of the long member to a base metal, welding is carried out simultaneously while rotating a welding machine in the same direction or in mutually opposite directions along the weld line of both ends of the long member. welding method.