JPH01285833A - Inspecting method of leak in slender pipe of condenser - Google Patents

Abstract

PURPOSE:To enable the detection of a leaking pipe by a pinhole, by a method wherein at least one of sealing plugs at book ends is formed by a foam plug body for the leaking pipe. CONSTITUTION:When a pressure inside a condenser is reduced, a pinhole 6 is formed and a foam plug body 12 in a leaking pip communicating with the condenser moves toward the inside of the pipe with the reduction of a pressure inside the pipe.The plug body 12 of a foam layer 11 acts as a moving plug body, and the leaking pipe 7 can be detected by observing the movement of the plug body. By pressing the plug body 12 against pipe plate surfaces 1a and 1b, a part of it is made to intrude into the pipe and formed therein. Since the surface of the foam layer 11 being continuous in a part of a port edge is leveled according to this constitution, a change due to the movement of the plug body 12 can be judged and perceived at a time in the whole area of the pipe plate surfaces 1a and 1b. At the same time, the surface of the foam layer 11 on the pipe plate surface 1a and 1b is depressed, or a bubble is generated, in a leaking part, and therefore the leaking part can be detected.

Description

[Detailed Description of the Invention] [Industry - Field of Application] The present invention is a means for inspecting thin tubes and tube plate surfaces without passing through seawater for cooling condensers in thermal power and nuclear power plant equipment. This invention relates to a method for detecting leakage tubes and tube plate surface leaks from a group of multiple thin tubes.

[Conventional technology]

Condenser tubes in power plant equipment often leak cooling seawater due to local erosion caused by clogging with foreign objects (such as shellfish in seawater).

However, although this problem has been alleviated by removing foreign substances through measures such as installing filters in the seawater flowing into the condenser, there is currently a leakage of less than one pipe per 10,000 pipes per year. It has occurred.

Another cause of seawater leakage in such condensers is leakage from the rim of the narrow tubes attached to the tube sheet.

Therefore, at such facilities, the conductivity of condensate is constantly measured while the power generating equipment is in operation, and leaked seawater is mixed into the condensate.
When the electrical conductivity (which is logarithmically proportional to the condensate concentration of seawater chlorine) exceeds 10 S/cm, reduce the operating output,
Leakage inspections are conducted for each independent condenser unit.

Conventional means for this purpose include the foam film method shown in the third figure or the film method shown in the fourth figure.

That is, in the bubble film method, the mouth of the capillary tube 9 on one tube plate surface 1a (mainly on the downstream side) of the condenser from which seawater has been removed is sealed with a rubber stopper 2 or the like, and the capillary tube on the other tube plate surface 1b is sealed. A foam film 3 made of soapy water or the like is formed at the mouth, several of the thin tube ports arranged in a row are surrounded by a transparent case 4 made of an acrylic resin plate, etc., and the thin tube ports are closed under suction inside the case by a pump 5. Changes (111 appearance or breakage) in the bubble film 3 at the edge of the case 4
I was observing through it.

In the film method, a thin film 8 is attached to the other tube plate surface 1b while the thin tube opening on one tube plate surface 1a of the condenser under drainage is sealed with a rubber plug 2, or , both tube plate surfaces 1b and 1a are covered with the thin film 8, and the inside of the condenser is depressurized to cause a change in the film on the end surface of the pipe ( (dents or damage) were observed.

[Problem to be solved by the invention]

On the other hand, there are difficulties in forming and holding the membrane 3. In particular, the air bubbles in the bubble membrane 3 at the mouth edge of the capillary tube tend to expand due to the reduced pressure inside the case 3, and this causes the bubbles to be destroyed. If membrane formation is not sufficient, bubble membrane changes may occur even at the rim of a normal tube, so it is necessary to compare and judge the early bubble membrane change that occurs at the leak site with that at other locations. In addition to requiring a certain level of skill for detection, the inspection work using the case 4 must be performed repeatedly on a large number of thin tube openings on the wide tube plate surface 1b, resulting in a problem of poor work efficiency. There is.

On the other hand, in the film method, the reaction sensitivity to change is poor due to the sealing performance between the film 8 and the thin VO and the film rigidity, and the detection of leakage due to minute pinholes (about 5 μS/cm at the above conductivity) is poor. Under the current situation, the present invention improves the sensitivity of leak detection in condenser tubes and provides detection with excellent reliability and workability. The purpose is to develop methods.

[Means to solve the problem]

According to the invention, this purpose is achieved by plugging at least one end of the condenser tubes with a layer of foam that reaches its mouth, thereby sealing each tube, A leakage inspection method in a condenser tube in which a leakage pipe is detected by a change in the suction of a plugged foam layer.Furthermore, a foam layer is formed on the tube plate surface of the condenser, and then the foam layer is removed from the tube plate surface by treatment with a trowel or the like. A part of the core layer penetrates into each capillary and the layer surface is leveled. Under reduced pressure in the condenser, the suction change of the foam layer prevents leakage at the capillary edge of the tube plate and inside the capillary. This can be achieved by a leak testing method in condenser tubes that detects leaks.

[Effect]

That is, one end of the condenser capillary tube is sealed at the other end, or the foam layer that also serves as the other end seal and plugs both ends of the condenser tube has excellent airtightness as a plug body, and also has excellent airtightness between the tube and the inner wall of the condenser tube. The sliding resistance is extremely small.

Therefore, when the pressure inside the condenser is reduced, a pinhole or the like is generated and the foam stopper in the leak pipe communicating with the inside of the condenser moves toward the inside of the pipe as the pressure inside the pipe is reduced.

On the other hand, the foam plug in the normal pipe is not affected by this reduced pressure inside the condenser at all.

That is, in a foam plugging means that plugs a thin tube with a foam layer that reaches the tube opening, the plug of the foam layer acts as a moving plug, and a leaking pipe can be detected by observing its movement. .

The foam plug body is formed by pressing the foam layer from the outside toward the tube plate surface so as to spread the foam layer formed over the entire area of the tube plate surface, so that a portion of the foam plug penetrates into each tube.

As a result, not only do the foam plugs reach the rim of the capillary opening, but also the surface of the continuous foam layer at the rim of these plugs is smoothed, so that changes due to movement as described in 2. At the same time, the surface of the foam layer on the F plate surface is depressed in the leak area at the edge of the tube IJ, and 1 hole is formed, so the leak area is can be detected.

〔Example〕

Next 1.4. Embodiments of the invention will be explained based on the accompanying drawings.

In FIG. 1, the leakage pipe 7 with the pinhole 6 has the following:
As with all other capillary tubes, a foam layer +1 is formed on both tube plate surfaces 1a and 1b, and a foam plug 12 is formed by pushing a portion of the layer into the tube to close all capillary openings. It is plugged.

In this case, the foam layer 11 is formed by foaming a water-soluble solution of detergent or shaving agent in advance by stirring, etc., by any means such as a 4-li, J-ke, blower, etc.
It is formed over the entire area of the tube plate surfaces 1a and 1b by spraying a foaming solution containing a foaming agent or an aerosol solution on the tube plate surface. It is effective to add a thickener to the foaming solution as a foam stabilizer to preserve the life of the foam formed.Additionally, as a foaming means, in addition to the above-mentioned stirring, air supply means, shoulder It goes without saying that various conventionally known means suitable for the type of foaming solution, such as boiling means, may be selectively employed.

When the foam layer 11 formed on the entire surface of the tube plate surfaces 1a and 1b is leveled by applying it with a trowel, a part of the core layer 11 invades the tube opening as shown by the solid line in FIG. The foam stopper 12 is thus formed.

In this way, the foam plug 12 formed in the tubule [J]
Usually, the outer side of each tube plate surface 1a and I b-, 1-
: is continuous with each foam layer 11, and the rim of the capillary tube is sealed, and this continuity allows the foam stopper 12 to follow this slope even if the capillary is somewhat inclined. There is no natural movement, and the plugged state shown in the figure is maintained at the eye of the tube.

In this state, reduce the pressure inside the condenser (-200 to -800mm)
(approximately Ig), the inside of the leakage pipe 7 where the pinhole 6 has occurred is depressurized through the pinhole 6, so the foam stopper 12 is pushed by the outside pressure and moves toward the inside of the pipe, and as shown in the same figure. 1 - The state shown by the chain line is reached.

As a result, in the case of an initial stage where the movement is small or a very small pinhole occurs, the surface of the foam layer 11 in that part becomes depressed and sinks after 5 hours have passed.

In this state, the tube plate surface 1a on which the foam layer 11 is formed is
, 1b occur at the same time, so by observing this, it becomes possible to inspect a wide area of the tube plate surface 1a or 1b, that is, the thin tubes before and after the strength wood at the same time.

At the same time, m at each tube plate surface 1a, lb
If there is a leakage part 13 at the pipe installation "-1" edge, air intake through this part 13 due to the reduced pressure in the condenser will cause the
As shown in 1\, the foam layer 11 on the surface of the part is depressed and the pores are formed L2, which can be seen.It may be L5, but the foam layer 11 and the foam stopper 12 are sealed +1 It is lightweight and has extremely low sliding resistance with the pipe wall, so it responds subtly to internal and external pressure changes and increases the degree of condition change over time. It is easy to detect changes in the foam layer 11 on the body 12 or its -1-face and on the rim, and as a result, a capillary with seawater leakage corresponding to the above-mentioned conductivity of 17i/cm is detected. Can be detected.

In addition, as in the conventional case, one end of these thin tubes is connected to the aforementioned Go 1,
It is also possible to seal with the stopper 2 and plug only the other end with the foam stopper 12, but it takes about 300 minutes for five people to put on the rubber stopper 2, and about 60 minutes for five people to remove it. Condenser - It took a lot of time to work per room, and it was extremely difficult to work in a hot and humid environment, but this foam plug has the advantages of high sensitivity and good change over time. from,
Instead of the rubber stopper 2 at the other end 1, the foam stopper 12 is also formed on the other end face, and the leakage pipe 7 and leakage portion 13 can be detected by observing the tube plate surfaces on both sides. As a result, the working time can be reduced even more by λ.

Moreover, the foam applied here is, for example, commercially available
Since it has foam strength and viscosity comparable to that of kneading cream, it is possible to operate ventilation fans to improve the working environment.

〔Effect of the invention〕

As described above, according to the method of the present invention, for a leaking pipe whose internal pressure is reduced by the condenser internal pressure reducing means, at least one of the J4J plugs that are sealed at both ends is connected to a valve that has a high sealing property and is connected to the inner wall of the pipe. By forming a foam plug with extremely low sliding resistance, we took advantage of the phenomenon in which the foam plug is drawn into the pipe in response to reduced pressure within the pipe.Firstly, the reaction sensitivity of the foam plug in this phenomenon was Therefore, it is possible to detect a leaky tube through an extremely small pinhole, and the reaction can be recognized as a clear change in state, such as the rim of a capillary being exposed, and the change reliably progresses over time. Therefore, this state determination can be carried out accurately without requiring any skill, and the labor of the entire work can be saved. Moreover, by applying such foam plugs to both end ports of each thin tube, the conventional rubber stoppering work is not required, labor-saving and work time can be saved, and the thin tube can be attached on the tube plate surface. Leakage from the rim of the mouth can also be detected at the same time.

Such a foam plug can be formed very easily and simply by the method of the present invention as set forth in claim 2, and can be easily removed by washing with water, etc. The method of the present invention is extremely effective in practice as this type of detection means, as it can further promote accuracy and labor saving.

Note that the method of the present invention is not limited to one double water device, but can also be applied to heat exchangers in a wide sense.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional side view showing an example of an embodiment of the method of the present invention, Fig. 2 is a sectional view of essential parts showing a state of leakage at the rim of a capillary tube by the method of the present invention, and Figs. 3 and 4 are by the conventional method. FIG. 3 is a longitudinal side view showing each embodiment. 6-...Pinhole, 7φ/φ leakage pipe, 1]...Foam layer, 12...Foam stopper, 13...Leak part 2] Bad

Claims (2)

[Claims] (1) At least one end of the condenser capillary tubes is plugged with a foam layer that reaches the tube opening to seal each capillary tube, and leakage tubes are detected by suction changes in the plugged foam layer under reduced pressure inside the condenser. Leakage inspection method in a condenser tube characterized by (2) Form a foam layer on the tube plate surface of the condenser, and then press the foam layer toward the tube plate surface by troweling or the like to infiltrate a portion of the layer into each capillary tube. A method for inspecting leakage in a condenser capillary, characterized by leveling the layer surface and detecting leakage at the capillary edge of the tube in the tube sheet and leakage inside the capillary by suction changes in the foam layer under reduced pressure in the condenser.