JPH0484742A - Method and apparatus for detecting underwater defect - Google Patents

Abstract

PURPOSE:To make it possible to detect a minute defect by tightly closing a defective part, evaporating water content in the inside in the vacuum state, and facilitating the penetration of a penetrant. CONSTITUTION:The apparatus is set on the surface of an underwater structure 3. A cover 9 and the surface of the structure 3 are tightly sealed with a sealing material 15. The water in the inside is drained with an air exhausting and water draining device 41. Then the inside is dried with hot air through a drying nozzle 27. Evacuation is performed with the device 41. Carbon dioxide gas as a penetrant is supplied through a penetration nozzle 23. After the penetration of about 10 minutes, air is supplied. The excessive gas is removed. A developer is atomized toward a defective part 5 through a developing nozzle 25. Then the carbon dioxide which is penetrated into the defective part and phenolphthalein are brought into contact, and discoloring occurs in the developer. Thus, the minute defect can be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a method and apparatus for detecting defects such as cracks in underwater structures.

(Prior art) Conventional methods for detecting defects in the atmosphere include: ■ Visual inspection method, ■ Optical observation method using a lens or fiberscope instead of the human eye, and ■ X-ray and other methods. A method of detecting defects inside a structure using radiation; ■ A method of detecting defects by reflection or transmission of ultrasonic waves from the defect; ■ A method of detecting defects by utilizing the fact that magnetic lines of force skip at the defect. Magnetic particle flaw detection method to detect,■ When liquid or gas is leaking from a defective part of a structure such as a vibrator, a leak test (helium leak lid) method that detects the defective part by injecting tracer gas into the leaking part , ■ Penetrant testing method, in which a penetrant is poured into the defect and the penetrant is developed.

In the method of detecting defects underwater, since water becomes an obstacle to the inspection, 1. Of the non-destructive defect detection methods (1) to (3) described above, those that can be applied underwater are limited. The best ways to see the defect indication pattern in its original form are: * Visual method, * Visual method using a tool such as a fiberscope, and * Penetrant flaw detection method. However, with the visual method and the method using a fiberscope, it is difficult to distinguish between grinder marks and defects on the surface of a metal structure due to the influence of light.
Since it may not stick under water, it is preferable to use penetrant testing when targeting underwater structures. It is also conceivable to use liquid or gaseous carbon dioxide as a penetrant.

(Problem to be Solved by the Invention) In general, the penetrant flaw detection method is widely used because the defect is visible as a defect pattern.

However, since water becomes an obstacle for both penetration and development underwater, it is difficult to apply penetrant testing as it is.

Therefore, it is conceivable to seal the underwater defective part with a cover and perform penetrant testing within this cover. That is,
Drain the water in the cover and apply penetrant to the defect.

Then, when a developer is applied after removing the excess penetrant, the penetrant that has entered the defective area comes into contact with the developer, and the color of the developer changes in accordance with the pH value, revealing the defect pattern.

However, if the defective part was submerged in water before the test,
Even if the defect is sealed with a cover and water is removed, the moisture within the defect is not removed and it is difficult for the penetrant to enter the defect, reducing the ability to detect the defect.

The present invention has been made in consideration of these points, and is an underwater defect detection method that allows penetrant to sufficiently penetrate into defects and detect even minute defects even when penetrant testing is performed underwater. An object of the present invention is to provide a method and apparatus.

[Structure of the invention]

(Means for solving departmental problems) The present invention has been made to achieve the above object, and the first invention provides a method for detecting a defective part of an underwater structure. This method detects even the smallest defects by sealing and covering the defect area to evaporate the moisture in the defect area in a vacuum, making it easier for the penetrant, which is an indicator, to penetrate into the defect area.

Furthermore, the second invention includes a cover that seals and covers a defective part of an underwater structure, a vacuum drain port that drains the water inside the cover and leaves it empty, and evaporates the remaining water; a penetrating nozzle that supplies a penetrant as an indicator to the defective part, a developing nozzle that supplies a developer that changes color when it comes into contact with the penetrant that has penetrated into the defective part, and a monitor camera that observes this color change. It is equipped with the following.

(Function) By sealing and covering the defective area and evaporating the moisture in a vacuum, the moisture inside the defective area can also be removed. Therefore,
The penetrant penetrates into the defect in the container.

(Example) An example of the present invention will be described below with reference to FIGS. 1 and 2. FIG. 1 is a longitudinal cross-sectional view of an underwater defect detection device that seals and covers a defective portion of an underwater structure, and FIG. 2 is a flowchart showing a defect detection procedure by the device of FIG. 1.

This device is installed on the surface of a structure 3 existing in water 1. A defective portion 5 exists on this surface. The device has a cover 9 supported on the underside of a cylindrical support 7 passing through the water surface.

This cover 9 has two stages, and the upper first force t<
-9A and a lower second cover 9B. A rotating inner container 11 that rotates with respect to the cover 9 is present inside the second cover 9B. Both the rotating inner container 11 and the cover 9 have a cylindrical shape, and the rotation is performed around the cylindrical axis and is rotationally driven by a motor 13 provided within the first cover 9A. In addition, rotating inner container 1
The rotational position of the motor 1 is detected by a rotational position detector 14 connected to the motor 13 through gears.

A skirt-shaped seal 15 is provided at the lower edge of the second cover 9B, that is, at a position in contact with the surface of the structure.

Inside the second cover 9B, there is a cleaning liquid removal nozzle 19 provided at the tip of the vacuum drain port 17 for draining water inside the cover 9, removing cleaning liquid, evacuation, etc., a cleaning nozzle 21 for spouting cleaning liquid, etc. A penetrating nozzle 23 supplies penetrant, and a developing nozzle 2 supplies developer.
5. Drying nozzle 2 to send hot air or dry air to remove enough water from inside the cover before vacuum evacuation
7. A marking port 29 for marking the original where the exact position of the defective part has been detected, and nozzles such as a glass surface cleaning nozzle 37 for cleaning the glass surface of the transparent glass 35 that protects the monitor camera 31.33. Classes are provided.

In addition to the cleaning liquid removal nozzle 19, a vent 39 for draining and exhausting water is provided. Further, the vacuum drain port 17 is connected to a drain exhaust device 41. Further, a pressure gauge 43 is provided inside the cover 9.

The operation of this embodiment will be explained below with reference to FIG. 2.

First, the entire device is inserted into water and installed at a position where a defective portion of the surface of the structure 3 is likely to exist. At this time, it is preferable to check the installation position using the central monitor camera 31 of the two monitor cameras 31 and 33 in the device.

In the installed state, the seal 15 seals the cover 9 and the surface of the structure 3 in a fluid-tight manner. In this state, the inside of the cover 9 is filled with water.

Then, the water in the cover 9 is drained by operating the drain exhaust device 41 and using the vacuum drain port 17 and the cleaning liquid removal nozzle 19. After draining, clean the surface of the structure if necessary. At this time, cleaning is performed by jetting cleaning liquid from the cleaning nozzle 21, but if the pressure inside the cover 9 increases due to this jetting, the vent 39 is opened to prevent the pressure inside the cover 9 from increasing. Otherwise cover 9
If the internal pressure rises above the outside water pressure, the entire device will become stiff and there is a risk that the dirty cleaning fluid inside will mix with the outside water, so care must be taken.

The dirty cleaning liquid is removed by a cleaning liquid removal nozzle 19.

Dry with hot air to remove sufficient moisture. This hot air is sent from the drying nozzle 27. At this time, the hot air creates a temperature difference between the lower and upper surfaces of the transparent glass 35, causing water droplets to adhere to the glass surface and making it cloudy, so it is desirable to flow dry air from the drying nozzle 27 after the hot air.

Furthermore, in order to evaporate the water in the defective part, a drainage exhaust device 4 is installed.
1, the inside of the cover 9 is evacuated using the vacuum drain port 17 and the cleaning liquid removal nozzle 19. and,
Observe the pressure with the pressure gauge 43, and when the pressure is about 75 mmHg,
Vacuuming is performed for 5 minutes to completely evaporate the moisture in the defective portion 5. At this time, the seal 15 is in an internal vacuum state fi (approximately 1
0 mm 1 g or less). However, if necessary, the inside of this seal 15 may be evacuated using a separately provided exhaust device (not shown).

Next, while the cover 9 is in a vacuum state, the vacuum drain port 17 is
Close the valve. Then, a penetrating agent, which is carbon dioxide gas, is supplied from the penetrating nozzle 23. This allows carbon dioxide gas to penetrate into the defective portion. By supplying carbon dioxide gas,
The pressure inside the cover will be high, but it must be lower than the water pressure outside.

After this permeation is performed for about 10 minutes, the supply of carbon dioxide gas is stopped, the vent 39 is opened, and at the same time, air is supplied from the permeation nozzle 23.

By supplying this air, excess carbon dioxide gas inside the cover 9 is removed. Note that if air is supplied forever, the carbon dioxide gas in the defective portion 5 will also escape, so only a few seconds is enough.

Next, develop. That is, a developer mixed with phenolphthalein is sprayed toward the defective portion 5 by the developing nozzle 25 . As a result, the carbon dioxide gas that has permeated into the defective portion 5 comes into contact with phenolphthalein, and the color of the developer changes due to the change in pH. This color change causes the defect to appear as a pattern. This pattern was captured by the monitor camera 31.
Observe at 33.

Note that the color change occurs when the colorless developer turns red. Once the exact location of the defective part 5 has been determined, carefully observe the location using the monitor camera 31, 33 and remember it.
Marking paint is sprayed onto the defective portion 5 or its vicinity from the marking port 29 to perform marking.

Observation of the defective portion 5 and supply of developer can be carried out using the monitor camera 31 .
By moving the positions of the developing nozzle 33 and the developing nozzle 25, this can be done over a wide range. This rotational position is detected by a rotational position detector 14 connected to the motor 13 through gears. In addition, if the surface of the transparent glass 35 that protects the monitor cameras 31 and 33 becomes dirty, the glass surface cleaning nozzle 3
It is also possible to spray out cleaning water from 7 for cleaning.

Next, the developer is removed. Similar to the cleaning of the defective portion 5 described above, water is strongly jetted from the cleaning nozzle 21 to wash away the developer, and the cleaning liquid removal nozzle 19 is used to drain the developer.

After the developer has been completely removed, the seal 15 is removed and the water is introduced into the cover 9 to eliminate the pressure difference with the outside.
Remove the entire device.

In the above embodiment, the drainage and exhaust inside the case 9 are 1
Although the description has been made assuming that the vacuum drainage port 17 and the drainage/exhaust device 41 are used, in other embodiments, the drainage and exhaustion may be performed using completely different systems.

Further, although the penetration nozzle 23 is used to supply air for removing excess penetrant, another air nozzle may be provided. Also, the developer was explained as one containing phenolphthalein, but
It may also be a mixture of other indicators.

Further, although the developer is removed using water spouted from the cleaning nozzle 21, in other embodiments, it is also possible to use a cleaning agent instead of water. Further, the transparent glass 35 may be a transparent plate made of plastic. Further, although carbon dioxide gas was used as the penetrating agent, other chemicals may be used in other embodiments. Furthermore, in the above embodiments, the device is installed on the surface of the structure, but in other embodiments, for example, the device can be installed in a ring shape around a cylindrical structure. The invention can be implemented.

〔Effect of the invention〕

As explained above, according to the present invention, a defect existing in an underwater structure is sealed and covered, and the water contained in the defect is evaporated in a vacuum, thereby making it easier for the penetrant to penetrate into the defect. This makes it possible to detect minute defects even underwater.

19...Cleaning liquid removal nozzle, 21...Cleaning nozzle,
23... Penetration nozzle, 25... Development nozzle, 27.
...Drying nozzle, 29...Marking port, 31.33
...Monitor camera, 35...Transparent glass, 37...
・Glass surface cleaning nozzle, 39... Ventro, 41...
- Drain exhaust system, 43...pressure gauge.

Claims (1)

[Claims] 1. In a method for detecting a defective part of a structure underwater, the defective part is hermetically covered, moisture contained in the defective part is evaporated in vacuum, and a penetrating agent as an indicator is added to the defective part. An underwater defect detection method that detects even the smallest defects by making it easier to penetrate. 2. The method according to claim 1, wherein gaseous or liquid carbon dioxide gas is used as the penetrant, and upon contact with the carbon dioxide gas, the color of the developer containing phenolphthalene changes to indicate the shape of the defect. Underwater defect detection method. 3. A cover that seals and covers the defective part of the underwater structure, a vacuum drain port that drains the water inside the cover and creates a vacuum state to evaporate the remaining water, and an indicator to the defective part where the water inside has evaporated. An underwater defect that is equipped with a penetration nozzle that supplies a certain penetrant, a development nozzle that supplies a developer that changes color when it comes into contact with the penetrant that has penetrated into the defect, and a monitor camera that observes this color change. Detection device.