JPS62275572A - Welding method for heat exchanger tube - Google Patents

Abstract

PURPOSE:To perform the full penetration butt welding on both and inner tube and an outer tube of a duplex tube from the outside by butting two inner tubes with the same diameter to weld these from the outside and next, covering half-split cylindrical sleeves on two outer tubes with the same diameter from the outside to perform the circumferential joint welding. CONSTITUTION:Projecting parts 7 are provided in advance on both the outer tubes 2 by the working or the build-up welding of raw tubes. Then, after two inner tubes 1 with the same diameter are butted and welded from the outside to form a welded joint part 5, the outer tubes 2 are arranged in the neighborhood of the butt-welded joint part 5 of the inner tubes 1 so as to cover the inner tubes 1 and the half-split cylindrical sleeves 3 and 3a are fitted inside the projecting parts 7 so as to cover both the outer tubes 2. Then, after the butt-weld zones 10 of the cylindrical sleeves 3 and 3a are welded, the circumferential joint weldings 8 of the projecting parts 7 of the outer tubes and the cylindrical sleeves 3 and 3a are performed. In this way, both the inner tubes and the outer tubes of the duplex tubes can be welded from the outside and besides, the outer tubes can be also subjected to the full penetration butt welding to perform the welding excellent in respect of strength and inspection.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention [Field of Industrial Application] The present invention is applied to heat exchangers having welded parts of a double pipe structure in nuclear power plants, thermal power plants, chemical plants, etc. This invention relates to a method of welding heat exchanger tubes.

[Conventional technology]

In conventional double pipe welding, the inner pipe OI is welded from the inside and the outer pipe 02 is welded from the outside, as shown in Figure 4.
In this case, the inner tube 01 can only be welded from the inside, and cannot be applied to welding long tubes together.

Here, 04 indicates the weld bead of the outer tube, 05 indicates the weld bead of the inner tube, and G indicates the gap between the inner tube 01 and the outer tube 02.

[Problem that the invention seeks to solve]

In addition to the problems mentioned above, conventional welding of double pipes has the fifth problem.
Inner tube 01 as shown in the figure. There is a method of using Nulig 03 for the outer tube 07 and welding both from the outside as in 05, but the disadvantage of this method is that the weld bead 06 is fillet welded, so it is inferior in terms of strength and inspection. Also, welding to ensure the length of each leg requires advanced technology.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention provides a structure in which a convex protrusion is previously provided in the outer tube of a double-tube structure either by processing the blank tube or by overlay welding.

A method of butt welding a half-split cylindrical sleeve covering the outer tube, and the outer tube has no convex shape.

In this method, grooves are provided in advance on the outer periphery of both ends of the halved cylindrical sleeve, and the sleeve is welded to the outer tube by penetration. That is,
A heat exchanger tube with a double tube structure having an inner tube and an outer tube, and in a welding method in which the inner tube and outer tube are butted and welded, two inner tubes of the same diameter are butted and welded from the outside. Next, the inner tube is covered with a cylindrical nullip in the vicinity of the butt weld joint of the inner tube, and circumferential joint welding is performed from the outside to two outer tubes of the same diameter. This is what we provide.

[Effect]

The method of welding the heat exchanger tube of the present invention is as described above, so the inner tube is butt welded, the outer tube is welded by protrusion welding, and by slotting.
- Butt welding is a welding method that allows welding from the outside, which improves the strength of the welded part and makes it easy to inspect for leaks.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments shown in the drawings. FIG. 1 is a diagram illustrating the shape of an outer tube in which a convex portion is provided in the outer tube and a halved cylindrical Nureve is fitted therein using the heat transfer tube welding method according to the first embodiment of the present invention. FIG. 2 relates to this example (a
) shows a part of the longitudinal cross-section of FIG. 1, and FIG. Fig. 3 shows a welding method for a heat exchanger tube according to a second embodiment of the present invention (Fig. 81 is a cross-sectional view in which a bevel is provided on the outer periphery of a halved cylindrical sleeve that covers the outer pipe and penetration welding is performed on the outer pipe). FIG. 2B shows an enlarged sectional view of the groove shape provided on the outer periphery of the cylindrical sleeve.

In Fig. 1, a blank tube is processed in advance for both outer tubes 2.

Alternatively, a convex portion 7 is provided by build-up welding, and a half-split cylindrical sleeve a, 3a (see Fig. 2 (bl)) is placed inside the convex portion 7.
Then, butt welding between 3 and 38 is performed at 10 locations. 1. Next, attach the cylindrical sleeves 3, 3a to the convex portion 7 of the outer tube.
This method involves welding circumferential joints at a total of 8 locations. Second
The figure shows this state, and (a) the inner tube 1 is welded from the outside at points 5 as shown in the figure. An outer tube 2 is machined near the butt weld joint of the inner tube 1 so as to cover the inner tube 1, as explained in FIG.
) shown in figure. In Fig. 3, the inner tube 1 is welded from the outside at points 5. An outer tube 2 is arranged near the butt weld joint of the inner tube 1 so as to cover the inner tube 1, and a half-split cylindrical sleeve is provided with a groove 9 in advance so as to cover the outer tube 2. 3 onto the outer tube 2 (see figure (b)). Using the grooves on the outer periphery of the outer tube 2 and the cylindrical sleeve 3, insert the outer tube 2 from the outside.
Welding with full penetration to 4.

This is a method of performing circumferential joint welding 4.

〔Effect of the invention〕

As specifically explained above, in the joint type of the present invention, both the inner pipe and the outer pipe of the double pipe can be welded from the outside, so long pipes can be welded.

Since it is possible to butt weld the outer tube with full penetration without sagging, it is possible to have a joint with extremely excellent strength and testability.

[Brief explanation of the drawing]

FIG. 1 is a shape diagram of an outer tube in which a convex shape is provided on the outer tube and a half-split cylindrical sleeve is fitted in the heat transfer tube welding method according to the first embodiment of the present invention, and FIG. 2 is a diagram of the present embodiment. Figure (a) relating to
A part of the longitudinal section in the figure, (b) is a sectional view taken in the direction of the arrow 1-1 in FIG. A cross-sectional view of a groove formed on the outer circumference of a half-split cylindrical sleeve that covers a pipe and welded to the outer tube by penetration welding. Figure (b) is an enlarged cross-sectional view of the groove shape provided on the outer circumference of the cylindrical sleeve. Fig. 4 is a sectional view of a welded joint part of conventional embodiment 1, and Fig. 5 is a sectional view of a welded joint part of conventional embodiment 2. 1... Inner pipe, 2... Outer pipe, a, aa...Half cylindrical sleeve, 4...Penetration welding, 5...Welded joint part of inner pipe, 7...Convex part of outer pipe, 8...Circumferential joint Welding, 9... Groove of cylindrical sleeve, 10... Butt weld of cylindrical sleeve, 01... Inner tube, 02
．． 07... Outer pipe, 03... Sleeve, 04... Welded joint part, 05... Welded joint part, 06... Corner welded part. Figure 4 Figure 5

Claims (1)

[Claims] A heat exchanger tube with a double tube structure having an inner tube and an outer tube, and in a welding method in which the inner tube and the outer tube are butted and welded, two inner tubes of the same diameter are butted and welded from the outside, Next, the inner tube is covered with a cylindrical sleeve near the butt weld joint of the inner tube, and circumferential joint welding is performed from the outside to two outer tubes of the same diameter. .