JPH11153506A - On-service inspection method for joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To always monitor generation of leak from joint, by detecting leakage of gas containing iodine from color change of adsorbent changing the color by chemical reaction with iodine. SOLUTION: A joint part 3 of inspected object 4 is covered with a sealed vessel 5 and a fluid element 2 containing an adsorbent 1 is connected. The fluid element 2 is made of transparent material or window is provided so as to see the contained adsorbent 1. In the case a defect occurs in the joint 3 of the inspected object 4 and leakage occurs, leaked gas flows to the fluid element 2 as the joint 3 is sealed in the sealed vessel 5 and the iodine contained in the gas is adsorbed in the adsorbent 1. Owing to the chemical reaction to iodine, the color of adsorbent 1 changes and leakage is detected by the color reaction. In the fluid element 2, gas having entered in the inlet fully passes in the fluid element 2 until going out of the outlet and adsorption performance of the adsorbent 1 is fully used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-service inspection method for joints of pipes, equipment, and the like that handle gas containing iodine, and uses an adsorbent so that iodine contained in gas leaking from around the joint is reduced to an adsorbent. And an optical inspection method utilizing the fact that the appearance changes.

[0002]

2. Description of the Related Art Conventionally, in-service inspection methods for joints include:
As non-destructive inspections, those using radiation, lines of magnetic force, ultrasonic waves, etc., and penetrant inspections are known. These are inspection methods for flaw detection after a gas leak is found or before a gas leak is found.

[0003] Originally, adsorbents have been used to obtain a purification effect of removing impurities contained therein, an effect of separating and concentrating a mixture, and a catalytic effect relating to a chemical reaction rate. Alternatively, as is known from Japanese Patent Application Laid-Open No. 7-209147, a gas is adsorbed by an adsorbent, and the gas is taken out and used for sampling.

As a method of detecting gas leakage utilizing discoloration, there is a method of applying a pigment as known in Japanese Patent Application Laid-Open No. 5-107241. Further, as disclosed in JP-A-7-12733 and JP-A-7-83911, there is a gas detection method using a coloring reagent.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide an inspection method capable of always monitoring the presence or absence of leakage from a joint, while the conventional non-destructive inspection method requires an inspection device to be installed each time an inspection is performed. To provide.

It is another object of the present invention to provide an inspection method capable of detecting a gas and removing iodine while the conventional detection method only detects a leak and leaking the gas as it is to the outside. Is provided.

It is a further object of the present invention to provide a simple inspection method capable of visually confirming leakage.

[0008]

According to a first aspect of the present invention, a fluid element is used to secure a residence time of gas, and an adsorbent housed therein is provided. The chemical reaction with iodine is sufficiently performed, and discoloration can be observed remarkably.

Another feature of the present invention to achieve the above object is that, by using a conical container for storing the adsorbent, the conical container starts to come into contact with the adsorbent at the top of the conical container. Therefore, since it starts reacting with a small amount of adsorbent, a small amount of leakage can be detected.

Another feature of the third aspect of the present invention to achieve the above object is that a sample is prepared from the relationship between the amount of iodine adsorbed and the color of the adsorbent, which is measured in advance, and a sample is prepared. By doing so, the amount of adsorption can be measured.

A feature of the invention according to claim 4 that achieves the other object is that the amount of adsorbent stored in one container is kept constant since the adsorbent reacts step by step for each container. Thereby, the amount of adsorption can be measured.

[0012]

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

(Embodiment 1) An in-service inspection method for a joint according to the present invention will be described with reference to FIGS. 1, 4, 6 and 7. FIG. In FIG. 1, the test object 4 is covered with a sealed container 5 so as to include the joint portion 3, and the fluid element 2 containing the adsorbent 1 is connected to the sealed container 5. The fluid element 2 is made of a transparent material, or has a window 14 as shown in FIG. 7 so that the adsorbent 1 contained therein can be seen.

If a defect occurs in the joint 3 of the test object 4 and the joint 3 leaks, the leaked gas flows to the fluid element 2 because the joint 3 is sealed in the sealed container 5. Is adsorbed by the adsorbent 1 stored therein. As the iodine contained in the gas leaked to the adsorbent 1 is adsorbed, the color of the adsorbent 1 changes, and the leak can be detected from the change to confirm the soundness of the joint. The fluid element 2 used here is
The inlet and outlet are mounted vertically, and the body is circular, so that the fluid entering from the inlet passes through the fluid element 2 sufficiently until the fluid exits from the outlet to improve the adsorption performance of the adsorbent 1. Can be pulled out sufficiently. As shown in FIG. 4, when three fluid elements 2 are connected, the amount of adsorption can be measured since the color changes sequentially from the front stage. Since the fluid element is used as the adsorbent storage container, the gas and the adsorbent sufficiently come into contact with each other in each stage, and an adsorption reaction occurs. Therefore, a clear difference in the adsorption reaction occurs in each stage of the fluid element. From this, almost no adsorption reaction occurs in the second and subsequent stages until the first stage reaches saturation.

By utilizing this fact, when silver silica gel is used as the adsorbent, when the adsorbent reaches 13 cc, the amount of adsorbed iodine is about 1 g. 0.54g when storing the adsorbent
It means that it was adsorbed. Here, it is necessary to determine that the first stage has reached saturation. However, as shown in FIG. 6, the relationship between the iodine adsorption amount and the color is not necessarily proportional, and the discoloration proceeds as the adsorption proceeds. , Eventually becoming reddish brown. Therefore, it can be determined that saturation has been reached when the color becomes reddish brown.

(Embodiment 2) A method of in-service inspection of a joint according to the present invention will be described with reference to FIGS.

FIG. 2 shows the fluid element 2 in the configuration of FIG.
Instead, a conical container 6 is provided. Similarly to the fluid element 2, the conical container 6 is made of a transparent material or provided with a window 14 as shown in FIG.

By making the container for storing the adsorbent into a conical shape, the amount of the adsorbent 1 existing on the inlet side becomes small, and the adsorption reaction is generated by the adsorbent 1 which is extremely limited. Leaks can be detected early.

When three conical containers 6 are connected, the same effect as described in the first embodiment can be obtained.

(Embodiment 3) An in-service inspection method for a joint according to the present invention will be described with reference to FIGS. 3, 7 and 8. A method as shown in FIG. 3 can be adopted in a joint of a piping system through which a gas containing radioactive iodine passes, such as a nuclear facility. A room called a cell, which cannot be accessed by a person, is separated from a room, which can be accessed by a person, by a shielding wall 11, and the joints therein cannot be directly inspected. Therefore, as shown in FIG. The sealed container 5 is installed so as to cover the portion 3, and is drawn out of the sealed container 11 by piping into a room outside the shielding wall 11, connected to the adsorbent storage container 7, and ejected by the ejector 8 to release air in the sealed container 5 therefrom. Is returned to the cell through a pipe and sent to a waste liquid tank.

In a facility including a radioactive material such as a nuclear facility, a negative pressure is generally maintained so that the internal material does not go out even if a defect occurs. It is important to extract gas from each volume. Here, the adsorbent storage container 7 refers to the fluid element 2 or the conical container 6 described above.

When gas containing iodine leaks from the joint portion 3, the gas is drawn by an ejector 8 connected downstream and sent to an adsorbent storage container 7,
When the adsorbent 1 and iodine contained therein are adsorbed, the light is changed from light gray to yellow and finally to red-brown, and is adsorbed by silver silica gel or the like, and sent to the waste liquid tank 10 via the ejector 8.

At this time, the gas containing the leaked iodine passes through the iodine adsorbent 1 stored in the adsorbent storage container 7, and the iodine is removed. The gas sent to 10 is almost free of iodine. Further, in order to replace the adsorbent 1, a decontamination liquid is first injected from a decontamination liquid inlet provided in a pipe connected to the adsorbent storage container 7 so as to lower the radiation dose, and the radiation dose is reduced. Replace the adsorbent 1.

The ejector 8 used in the present embodiment forcibly draws gas even when the joint portion 3 is slightly damaged, so that gas leakage can be detected at an early stage. In place of the ejector 8, a vacuum pump or the like capable of drawing air can be provided. In addition, adsorbent 1
Is replaced, the valve A12 is closed so that the atmosphere from inside the cell does not come.

The adsorbent 1 used in this embodiment is a porous substance such as alumina, which is obtained by chemically reacting iodine such as Ag or Pb with a substance which forms a compound, and is attached, deposited or coated. When detecting leakage of other gaseous substances, it is possible to select and use a substance suitable for them, assuming that the produced substance has a different color from the original substance.

The waste liquid tank used in the present embodiment is mainly used when replacing the adsorbent 1 in consideration of the safety of the work of the worker.
It receives the decontamination liquid when the adsorbent storage container 7 and the ejector 8 are decontaminated. When a waste liquid tank is installed in the equipment according to a request other than the present invention, it can be shared with the waste liquid tank.

The air used as a drive source of the ejector 8 used in this embodiment is generated by using a compressor 9. By using a large-sized device, it can be supplied to each common inspection device installed in a facility requiring inspection. A compressor 9 can be installed in each common inspection apparatus. In this case, a small one may be used.

Here, the adsorbent 1 generally exhibits good effects at high temperature and low humidity. From this, valve 8
A heater is installed between the gas adsorbent container 2 and the gas adsorbent container 2 so that the gas leaked from the non-inspection body 4 is heated sufficiently to reach the gas adsorbent container. As shown in FIG. 5, in order to sufficiently remove the moisture of the gas leaked from the non-inspection body 4, the inside of the gas adsorbent storage cartridge 11 is divided into two parts, and silica gel or the like is provided on the inlet side of the leaked gas. Is filled with an adsorbent 1 that adsorbs water. Further, by reducing the humidity of the air supplied to the ejector 7, the effect of the adsorbent 1 is increased, and it becomes easy to detect gas leakage.

7 and 8, when the adsorbent is replaced, the adsorbent storage cartridge 16 stored in the fluid element 2 or the conical container 6 is easily taken out by opening the adsorbent storage container lid 15. Material 1 can be replaced. The sealing hook 17 is attached in order to prevent the gas inside from leaking outside during use. A lid hinge 18 is provided to open and close the adsorbent storage container lid 15.

[0030]

The adsorbent can be used effectively by using the fluid element as the adsorbent storage container.

From this, the adsorption reaction is sufficiently performed,
Gas leak detection due to discoloration can be easily performed.

By connecting a plurality of adsorbent storage containers, an adsorption reaction occurs sequentially in each stage, so that the amount of adsorption can be measured.

In addition, the in-service inspection of the joint in a room where no one can enter can be performed, and the adsorbent used once or the adsorbent which has been replaced after a long time can be replaced. By extracting gas with an ejector, even a minute leak can be detected.

[Brief description of the drawings]

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a view for explaining an in-service inspection method for a joint using an adsorbent and a fluid element accommodating the adsorbent according to an embodiment of the present invention.

FIG. 2 is a view for explaining an in-service inspection method for a joint using the adsorbent of the present invention and a conical container storing the adsorbent.

FIG. 3 is a view for explaining the in-service inspection method of the in-cell joint of the present invention.

FIG. 4 is a diagram illustrating a state in which three fluid elements of the present invention are connected.

FIG. 5 is a diagram illustrating a state in which three conical containers of the present invention are connected.

FIG. 6 is a characteristic diagram showing a change in color of the adsorbent of the present invention and a change tendency of an iodine adsorption amount.

FIG. 7 is a diagram illustrating details of a fluid element of the present invention.

FIG. 8 is a diagram illustrating details of a conical container of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Adsorbent, 2 ... Fluid element, 3 ... Joint part, 4 ... Test object, 5 ... Sealed container, 6 ... Conical container, 7 ... Adsorbent storage container, 8 ... Ejector, 9 ... Compressor, 10 ... Waste liquid Tank, 11 ... shielding wall, 12 ... valve A, 13 ... valve B,
14 ... window, 15 ... adsorbent storage container lid, 16 ... adsorbent storage cartridge, 17 ... sealing hook, 18 ... lid hinge.

Claims (4)

[Claims] An in-service inspection method for a joint, comprising: an adsorbent that changes color due to a chemical reaction with iodine; and a fluid element containing the adsorbent, wherein leakage of gas is detected by changing the adsorbent. 2. The in-service inspection method for a joint according to claim 1, wherein a conical vessel is used for the fluid element to improve iodine detection sensitivity. 3. The in-service inspection method for a joint according to claim 1, wherein the amount of leakage is calculated from the amount of the discolored adsorbent. 4. An in-service inspection method of a joint, characterized in that the provision of two or more containers for accommodating the adsorbent according to claim 1 and 2 makes it possible to easily estimate the amount of adsorption visually.