JPH06300480A - Repair method for heat exchanger - Google Patents

Abstract

(57) [Summary] [Purpose] To facilitate the radiation transmission test on the welded part of the plug fixed to the tube sheet. When a heat transfer tube 7 communicating with a through hole 6 provided in a high temperature side tube sheet 4 in a heat exchanger body is damaged, a small diameter portion 23 having an outer diameter that can be inserted into the through hole 6 and a through hole A plug 25 having a large diameter portion 24 having an outer diameter larger than that of the hole 6 and having a hollow portion 21 extending from the large diameter portion 24 toward the small diameter portion 23.
The small diameter portion 23 of the plug 25 is inserted into the through hole 6 to be closed, the large diameter portion 24 of the plug 25 is welded to the tube sheet 6, and then the film 16 is wound around the outer periphery of the plug welding portion 26 formed by the above welding. The radiation source 14 is inserted into the hollow portion 21 of 25 to take a transmission photograph of the plug welding portion 26, the film 16 is developed, and the transmission photograph is observed to determine whether there is a defect in the plug welding portion 26.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat exchanger repair method.

[0002]

2. Description of the Related Art FIG. 4 shows an example of a heat exchanger for exchanging heat between two kinds of fluids via a heat transfer tube, 1 is a substantially cylindrical heat exchanger body, and 2 is a heat exchanger. The primary fluid inlet 3 provided at the portion near the front end of the outer portion of the body 1 is a primary fluid outlet 3 provided at the portion near the rear end of the outer portion of the heat exchanger body 1, and the heat exchange is performed as described above. A high temperature side tube sheet 4 is provided in the vicinity of the front end portion in the body portion 1, and a low temperature side tube sheet 5 is provided in the vicinity of the rear end portion.

A required number of through holes 6 are bored in the high temperature side tube sheet 4 and the low temperature side tube sheet 5 at positions facing each other, and the high temperature side tube branch 4 and the low temperature side tube sheet 5 are bored. Through hole 6 facing each other
Are communicated with each other via the heat transfer tube 7.

Further, 2 are provided at the front end of the heat exchanger body 1.
A dome-shaped front end plate 9 having a next fluid inlet 8 at the top,
A secondary fluid outlet 1 is provided at the rear end of the heat exchanger body 1.
Dome-shaped rear end plates 11 having 0 at the top are connected to each other.

Reference numeral 12 is a baffle plate provided in the heat exchanger body 1 for restricting the flow of the primary fluid.

The primary fluid (arrow A) flows into the inside of the heat exchanger body 1 from the primary fluid inlet 2 provided in the heat exchanger body 1, is guided to the baffle plate 12 and is transmitted while bending. It flows between the heat pipes 7 and flows out of the heat exchanger body 1 from the primary fluid outlet 3 provided in the heat exchanger body 1.

The secondary fluid (arrow B) is the front end plate 9
From the secondary fluid inlet 8 to the front end plate 9 and the high temperature side tube plate 4
Flows into the space formed by and flows from the space 35 into the plurality of through holes 6 provided in the high temperature side tube sheet 4, passes through the inside of the heat transfer tube 7 communicating with each of the through holes 6, and Heat transfer tube 7
To the space 36 formed by the rear end plate 11 and the low temperature side pipe branch 5, and the secondary fluid outlet provided in the rear end plate 11 from the space 36. It flows out from 10.

At this time, heat is exchanged between the primary fluid (arrow A) and the secondary fluid (arrow B) via each heat transfer tube 7.

In the heat transfer tube 7, for example, when damage such as corrosion on the wall of the heat transfer tube 7 at the portion C is broken, the fluid having a higher pressure flows out from the break hole, and two kinds of fluids are discharged. Intermingle inside the heat exchanger body 1 or inside the damaged heat transfer tube 7, resulting in a decrease in heat exchange efficiency, and when heat exchange is attempted by the above heat exchanger, for example, 2
It is very dangerous when the kind of fluid is one that causes a strong reaction when they are mixed with each other, such as water and sodium metal.

Therefore, the heat transfer tube 7, which has been conventionally damaged by corrosion or the like, is closed at both ends to prevent the secondary fluid from flowing into the heat transfer tube 7.

FIGS. 5 and 6 show an example of a conventional heat exchanger repair method, and the procedure thereof will be described below.

A short tube 13 having substantially the same diameter as the heat transfer tube 7 is connected to the surface of the high temperature side tube plate 4 facing the front end plate 9 (see FIG. 4), and the heat transfer tube 7 damaged by corrosion or the like is connected. After welding so as to communicate with the through hole 6 of the high temperature side tube sheet 4, the film 16 is wound around the outer periphery of the short tube welded portion 15 by the welding, and the radiation source 14 is inserted inside the short tube 13. The transmission photograph of the short pipe weld 15 is taken, and the film 16 is developed and observed to determine whether there is a defect in the short pipe weld 15.

If there is no defect in the short pipe welded portion 15, a cap-shaped plug 17 is welded to the tip portion of the short pipe 13 as shown in FIG. The radiation source 14 is moved along the outer periphery of the plug 17 in the vicinity of, and the film 16 is placed at a position facing the radiation source 14 with the plug 17 sandwiched therebetween, thereby taking a transmission photograph of the plug welded portion 18 to obtain the film 16 described above. Is developed and observed to determine whether or not there is a defect in the plug welded portion 18.

Further, with respect to the through hole 6 of the low temperature side tube sheet 5 to which the heat transfer tube 7 to be closed is connected, the short tube 13 and the plug 17 are formed by the same procedure as the high temperature side tube sheet 4. Are welded and radiographic photographs are taken to determine the presence or absence of defects in the weld.

Further, as other conventional heat exchanger repair methods, there are respective examples as shown in FIGS. 7 to 9.

In the conventional example shown in FIG. 7, a small-diameter portion 23 that can be inserted into the through-hole 6 and a large-diameter portion 2 having an outer diameter larger than that of the through-hole 6.
4 is used, the small diameter portion 23 of the plug 19 is inserted into the through hole 6 communicating with the damaged heat transfer tube 7,
The outer portion of the large diameter portion 24 is V-shaped groove welded to the outer surfaces of the tube sheets 4 and 5. In the conventional example shown in FIG. 8, a cap-shaped plug 20 having an opening 22 at one end surface is used. 20 so as to face the through hole 6 to be closed.
The outer surface of No. 5 is I-shaped groove welded.

Furthermore, in the conventional example shown in FIG. 9, a plug 19 having the same shape as that shown in FIG. 7 is used, and the small diameter portion 23 of the plug 19 is inserted into the through hole 6 communicating with the damaged heat transfer tube 7. The outer portion of the large diameter portion 24 is fillet welded to the outer surfaces of the tube sheets 4 and 5.

When the above heat exchanger repairing method is carried out, the V-shaped groove welded portion 37 in FIG. 7, the I-shaped groove welded portion 38 in FIG. 8 and the fillet welded portion 3 in FIG.
9 is subjected to a penetrant flaw detection test (PT) to form a V-shaped groove welded portion 37, an I-shaped groove welded portion 38, and a fillet welded portion 3.
The presence or absence of defect 9 is determined.

[0019]

However, in the heat exchanger repairing method shown in FIGS. 5 and 6, the short pipe welded portion 15 and the plug welded portion 18 are welded to each other in order to perform the radiation transmission test. However, there is a demand for reducing the number of welded portions in order to improve the reliability of welding, especially for the through holes 6 of the high temperature side tube sheet 4 under severe thermal conditions.

On the other hand, in the penetrant inspection (PT) conducted by each heat exchanger repairing method shown in FIGS. 7 to 9, the V-shaped groove welded portion 37, the I-shaped groove welded portion 38, and the fillet welded portion 39 were detected. Since it is inevitable to check the presence or absence of defects at the work site, it may not be possible to find minute defects that have occurred in the weld.

The present invention has been made in view of the above-mentioned circumstances, and it is possible to easily carry out a radiation transmission test and to use only one welding point for the plug that closes the through hole of the tube sheet. It is intended to provide a method of repairing an exchange.

[0022]

In order to achieve the above object, in the heat exchanger repair method of the present invention, when the heat transfer tube communicating with the through hole provided in the tube plate in the heat exchanger body is damaged,
In a heat exchanger repair method for welding a plug to a tube plate to close a through hole communicating with a damaged heat transfer tube, the outer diameter is larger than the small diameter portion having the outer diameter insertable into the through hole and the through hole. The small diameter portion of the plug having a large diameter portion and a hollow portion extending from the large diameter portion toward the small diameter portion is inserted into the through hole to be closed, and the large diameter portion of the plug is welded to the tube sheet. rear,
A radiation source is inserted into the hollow portion of the plug, and a radiation transmission test is performed on the welded portion between the tube sheet and the plug by the radiation source.

Similarly, in the heat exchanger repair method of the present invention, when the heat transfer tube communicating with the through hole provided in the tube sheet in the heat exchanger body is damaged, the plug is welded to the tube sheet. In a heat exchanger repairing method for closing a through hole communicating with a damaged heat transfer tube, a small diameter portion having an outer diameter insertable into the through hole and a large diameter portion having an outer diameter larger than the through hole are provided. A hollow portion extending from the small diameter portion to the large diameter portion is provided, and the small diameter portion of the plug having the radiation source fixed therein is inserted into the through hole to be closed, and the large diameter portion of the plug is welded to the tube sheet. After that, a radiation transmission test is performed on the welded portion between the tube sheet and the plug using the above-mentioned radiation source.

[0024]

In the heat exchanger repair method of the present invention, the small diameter portion of the plug is inserted into the through hole, the large diameter portion of the plug is fixed to the tube plate by welding, and then the radiation source is inserted into the hollow portion of the plug. Since the radiation transmission test of the welded portion between the tube sheet and the plug is performed, the radiation transmission test can be easily performed, and the number of welded portions of the plug to the tube sheet can be one.

Further, in the heat exchanger repairing method of the present invention, the small diameter portion of the plug having the radiation source in the hollow portion is inserted into the through hole, and the large diameter portion of the plug is fixed to the tube sheet by welding. Since the radiation transmission test of the welded portion between the tube sheet and the plug is performed by the radiation source of (1), the radiation transmission test can be easily repeated, and the number of welding points of the plug to the tube sheet can be one.

[0026]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of the heat exchanger repairing method according to claim 1 of the present invention. In the figure, the parts designated by the same reference numerals as those in FIGS. 5 and 6 represent the same parts.

Reference numeral 25 denotes a plug used to close the through holes 6 provided in the high temperature side tube sheet 4 and the low temperature side tube sheet 5 in this embodiment. The plug 25 has a diameter substantially equal to the inner diameter of the through hole 6. It has a small diameter portion 23 having an equal outer diameter, a large diameter portion 24 having an outer diameter larger than that of the through hole 6, and a hollow portion 21 extending from the large diameter portion 24 toward the small diameter portion 23.

The procedure for repairing the heat exchanger will be described below.

When the through hole 6 communicating with the damaged heat transfer tube 7 is closed, the small diameter portion 23 of the plug 25 is inserted into the through hole 6 to be closed, and the large diameter portion 24 of the plug 25 is inserted into the high temperature side tube sheet. 4 (low temperature side tube sheet 5).

Then, the plug welded portion 2 by the above-mentioned welding
The film 16 is wound around the outer periphery of the plug 6, and the radiation source 14 is inserted into the hollow portion 21 of the plug 25 to take a transmission photograph of the plug welding portion 26. After the film 16 is developed, the transmission photograph is observed and the plug is observed. The presence or absence of defects in the welded portion 26 is determined.

In this embodiment, the plug 25 having the hollow portion 21 is welded to the high temperature side tube sheet 4 or the low temperature side tube sheet 5, and the radiation source 14 is inserted into the hollow portion 21 of the plug 25 to obtain a radiographic image. Since the image is taken, the high temperature side tube sheet 4 that communicates with the damaged heat transfer tube 7 with only one plug welding portion 26.
Alternatively, the through hole 6 of the low temperature side tube sheet 5 can be closed, and the radiation transmission test of the plug welded portion 26 can be easily performed.

FIG. 2 shows another example of the heat exchanger repairing method according to the first aspect of the present invention. In the figure, the same reference numerals as those in FIG. 1 represent the same parts.

In this embodiment, the outer diameter of the small diameter 23 of the plug 25 used to close the through holes 6 provided in the high temperature side tube sheet 4 and the low temperature side tube sheet 5 is made smaller than the inner diameter of the through hole 6. In the large-diameter portion of the plug 25, a circumferential groove 27 that has an inner diameter substantially the same as the outer diameter of the small-diameter portion 23 and an outer diameter substantially the same as the outer diameter of the through hole 6 and is continuous with the small-diameter portion 23 is provided. ing.

When repairing the heat exchanger, the hot side tube sheet 4
After welding to the (low temperature side tube sheet 5), the radiation source 14 is inserted into the hollow portion 21 of the plug 25 and a radiation transmission test is performed on the plug welding portion 26.

Therefore, also in this embodiment, the same operational effect as the heat exchanger repair method can be obtained.

In this embodiment, since the plug 25 is provided with the circumferential groove 27, the plug 25 and the high temperature side tube sheet 4 are provided.
Since the plug welded portion 26 fixing the (low temperature side tube sheet 5) has a butt weld structure, the plug 25 and the high temperature side tube sheet 4 are formed.
(Low temperature side tube sheet 5) can be more firmly fixed.

FIG. 3 shows an example of the heat exchanger repairing method according to the second aspect of the present invention. In the figure, the same reference numerals as those in FIG. 1 represent the same parts.

Reference numeral 33 designates a plug used to close the through hole 6 provided in the high temperature side plate 4 and the low temperature side tube sheet 5 in the present embodiment, and the plug 33 has an outer diameter substantially equal to the inner diameter of the through hole 6. A small diameter portion 29 having a large diameter portion 31 having an outer diameter larger than that of the through hole 6, and the small diameter portion 29 to the large diameter portion 3
It has a hollow portion 28 extending toward 1 and a radiation source 32 fixed to a bottom portion 30 of the hollow portion 28 so as to be located inside the hollow portion 28.

The procedure for repairing the heat exchanger will be described below.

When closing the through hole 6 communicating with the damaged heat transfer tube 7, the small diameter portion 29 of the plug 33 is inserted into the through hole 6 to be closed, and the large diameter portion 31 of the plug 33 is inserted into the high temperature side tube sheet. 4 (low temperature side tube sheet 5).

Then, the plug welded portion 3 by the above-mentioned welding
The film 16 is wound around the outer circumference of the plug 4, and a transmission photograph of the plug welding portion 34 is taken by the radiation emitted from the radiation source 32 inside the hollow portion 28 of the plug 33.
Of the plug welded portion 3
The presence or absence of the defect of No. 4 is determined.

In this embodiment, the plug 33 provided with the radiation source 32 is welded to the high temperature side tube sheet 4 or the low temperature side tube sheet 5, and a radiation transmission photograph is taken by the radiation source 32. The plug welding portion 34 alone can close the through hole 6 of the high temperature side tube sheet 4 or the low temperature side tube sheet 5 communicating with the damaged heat transfer tube 7, and the radiation transmission test of the plug welding portion 34 can be easily performed. obtain.

In this embodiment, the radiation source 32
Is fixed to the plug 33, the radiation transmission test can be performed again by winding the film 16 around the outer periphery of the plug welded portion 34 at the occasion of the periodic inspection after the above-mentioned repair.

The method of repairing the heat exchanger of the present invention is not limited to the above-described embodiment, but the present invention can be applied to other heat exchangers such as a helical coil type, and other methods of the present invention. Of course, various changes can be made without departing from the scope of the invention.

[0046]

As described above, according to the heat exchanger repair method of the present invention, various excellent effects as described below can be obtained.

(1) In the heat exchanger repairing method according to the first aspect of the present invention, the small diameter portion of the plug is inserted into the through hole, the large diameter portion of the plug is fixed to the tube sheet by welding, and then the plug is replaced. Since the radiation source is inserted into the hollow portion to perform the radiation transmission test of the plug welded portion with respect to the tube sheet, the heat exchanger repair method according to claim 2 of the present invention uses a plug having a radiation source in the hollow portion. After inserting the small diameter part into the through hole and fixing the large diameter part of the plug to the tube sheet by welding, the radiation transmission test of the plug welded part to the tube sheet is performed by the above-mentioned radiation source. Can be easily performed, and the number of welding points of the plug to the tube sheet can be set to one.

(2) In the heat exchanger repairing method according to the second aspect of the present invention, since the radiation source is fixed to the plug, the radiation transmission test is repeated on occasions such as periodic inspection of the heat exchanger. It can be carried out.

(3) In both the heat exchanger repairing method according to the first and second aspects of the present invention, since the tube sheet and the plug are fixed to each other by welding at one place, the number of welding steps is reduced. The welding reliability can be improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a heat exchanger repairing method according to claim 1 of the present invention.

FIG. 2 is a cross-sectional view showing another example of the heat exchanger repairing method according to claim 1 of the present invention.

FIG. 3 is a sectional view showing an example of a heat exchanger repairing method according to claim 2 of the present invention.

FIG. 4 is a sectional view showing an outline of a conventional heat exchanger.

FIG. 5 is a cross-sectional view showing a short pipe weld portion in an example of a conventional heat exchanger repair method.

FIG. 6 is a cross-sectional view showing a plug weld portion in an example of a conventional heat exchanger repair method.

FIG. 7 is a cross-sectional view showing another example of a conventional heat exchanger repair method.

FIG. 8 is a sectional view showing still another example of the conventional heat exchanger repair method.

FIG. 9 is a cross-sectional view showing still another example of the conventional heat exchanger repair method.

[Explanation of symbols]

 1 Heat Exchanger Body 4 High Temperature Side Tube Sheet (Tube Sheet) 5 Low Temperature Side Tube Sheet (Tube Sheet) 6 Through Hole 7 Heat Transfer Tube 14,32 Radiation Source 21,28 Hollow Section 23,29 Small Diameter Section 24,31 Large Diameter Part 25,33 Plug 26,34 Plug weld

Claims (2)

[Claims] 1. When a heat transfer tube communicating with a through hole provided in a tube plate in a heat exchanger body is damaged, heat is applied to the tube plate by welding a plug to block the through hole communicating with the damaged heat transfer tube. In the exchanger repair method, a hollow portion having a small diameter portion having an outer diameter that can be inserted into the through hole and a large diameter portion having an outer diameter larger than the through hole, and extending from the large diameter portion toward the small diameter portion is formed. The small diameter portion of the provided plug is inserted into the through hole to be closed, the large diameter portion of the plug is welded to the tube sheet, and then the radiation source is inserted into the hollow portion of the plug, and the tube sheet and the plug are inserted by the radiation source. A method for repairing a heat exchanger, characterized by performing a radiation transmission test of a welded portion with. 2. Heat for closing a through hole communicating with a damaged heat transfer tube by welding a plug to the tube plate when the heat transfer tube communicating with the through hole provided in the tube plate in the body of the heat exchanger is damaged. In the exchanger repair method, a hollow portion extending from the small diameter portion to the large diameter portion having a small diameter portion having an outer diameter insertable into the through hole and a large diameter portion having an outer diameter larger than the through hole is provided. The small diameter portion of the plug provided with the radiation source fixed in the hollow portion is inserted into the through hole to be closed, the large diameter portion of the plug is welded to the tube sheet, and then the tube sheet and the plug are formed by the radiation source. A heat exchanger repair method, characterized by performing a radiation transmission test of the welded part of the.