JPH1130601A - Underwater paint film soundness measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure the soundness of a paint film coating the surface of an underwater structure early and quantitatively by placing an electrode face to face with the underwater structure made of steel and coated with the paint film, with a fixed space to measure the resistance value and electric capacity between the electrode and the underwater structure, and obtaining a loss factor from a specific expression. SOLUTION: A support plate 21 is fitted to a bar-like support body 24 through a universal joint 23. A coil spring 26 is disposed between the support plate 21 and a collar body 25 so as to prevent the tip of the universal joint 23 from hanging down. A coil spring 28 is disposed between the collar body 25 and a bearing stand 27 slidably fitted with the support body 24, so as to prevent a holder 20 from being damaged due to being pressed to an underwater structure. The bearing stand 27 is fastened to a submerged robot 30. Electric resistance R and electric capacity C between the underwater structure 10 and an electrode face 6a fitted to the support plate 21 are measured by an impedance measuring apparatus 1, and a loss factor D is computed from an expression D=1/(2πfCR), where (f) is frequency (Hz) of an alternating current.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring the soundness of a coating film applied on the surface of a steel underwater structure.

[0002]

2. Description of the Related Art In many cases, various tanks installed on large ships, various tanks on land, large underwater structures, and the like are coated on their surfaces for corrosion protection. As a method of inspecting the soundness of such a coating film in water, there is known a method of measuring underwater T
Visual inspection using a V camera or a diver has become mainstream. Visual inspection is to check for rust and swelling.However, visual inspection in water is not reliable in turbid water. From the viewpoint of soundness, it is desired to be able to diagnose the deterioration of the coating film earlier and more reliably because it is a terminal symptom.

On the other hand, a method for measuring the soundness of a coating film in the atmosphere has been established to some extent. It is adopted relatively often because quantitative numerical data can be obtained. In addition, in water, a technique of measuring an anticorrosion potential using an underwater electrode is known for managing the anticorrosion of a steel structure. However, in this method, the performance of the coating film itself cannot be known.

[0004]

SUMMARY OF THE INVENTION The present invention has been devised to solve such a conventional problem, and has as its object the purpose of making steel steel irrespective of the degree of turbidity of water. An object of the present invention is to provide an underwater coating film soundness measuring device capable of early and quantitatively measuring the soundness of a coating film coated on the surface of an underwater structure.

[0005]

According to a first aspect of the present invention, there is provided an underwater coating film soundness measuring apparatus according to the present invention, wherein an electrode is provided to face a steel underwater structure covered with a coating film at a predetermined interval. And the resistance R between the electrode and the underwater structure
And a measuring instrument for measuring the electric capacity C, an underwater electric cable connecting the measuring instrument and the electrode, a ground wire connecting the measuring instrument and the underwater structure, and a loss coefficient from the following equation (1) (Tan delta) and a computer for determining D.

D = 1 / (2πfCR) (1) where f is a frequency. According to the first aspect of the present invention, the soundness of the coating film covering the surface of the steel underwater structure can be measured early and quantitatively regardless of the degree of turbidity of the water. Can be.

According to a second aspect of the present invention, in the underwater coating film soundness measuring device, the electrodes are mounted on a support plate provided with three tentacles of a fixed length, and the support plate is connected via a universal joint. A coil spring coaxial with a universal joint may be provided between the support plate and the support plate. According to the second aspect of the present invention, even if the support is inclined, the electrodes can be opposed (facing) with a predetermined interval to the painted underwater structure.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 1 denotes an impedance measuring instrument, and a ground wire 3 attached to a steel underwater structure 10 is inserted into one terminal 2 of the impedance measuring instrument. The attachment point of the ground wire 3 is located above the sea surface W. The surface of the underwater structure 10 is covered with a coating film 11.

An underwater electric cable 5 attached to an electrode, which will be described later, is inserted into the other terminal 4 of the impedance measuring instrument 1. This electrode is attached to the tip of the underwater robot 30 via the holder 20.

The underwater robot 30 includes a robot body 31 formed of a pressure vessel, an observation device 32 such as a TV camera for observing the state of the underwater, a propulsion device 33 for moving the underwater robot 30 forward or backward, and an underwater robot 30. It comprises a thruster 34 for elevating and lowering, a thruster 35 for sliding the underwater robot 30 to the side, and the like. Also,
The underwater robot 30 is controlled by a control device (not shown) on land or on a mother ship connected via a tether cable 36. In addition, images captured by the observation device 32 can be displayed on the display 46 on land or on the mother ship, similarly to the control device.

As shown in FIG. 2, the electrode (made of titanium) 6 has a disk shape (diameter of 25 mm), and one end of the underwater electric cable 5 is connected to the back surface 6b. An electrically insulating resin 8 is filled between the electrode 6 and the cylindrical electrode case 7 so that only the front end face 6a of the electrode 6 is exposed.

The electrode 6 is, as shown in FIG.
0 is attached to a support plate 21 which is one of the components that constitutes the reference numeral 0. As shown in FIG. 4, the support plate 21 has an isosceles triangle, and is provided with a columnar tentacle 22 at each corner (corner), and the front end surface 6 a of the electrode 6 and the front end surface 2
2a is maintained at a constant distance L (= 5 mm).

The support plate 21 is mounted on a rod-shaped support 24 via a universal joint 23. The flange 2 attached to the support plate 21 and the support 24
5, a first coil spring 26 coaxial with the universal joint 23 is provided so that the tip of the universal joint 23 does not hang down. Further, a second coil spring 28 coaxial with the support 24 is disposed between the flange 25 and a bearing stand 27 on which the support 24 is slidably mounted.
When pressed to zero more than necessary, the rod-shaped support 24 retreats and prevents the holder 20 from being damaged.
When attaching the holder 20 to the underwater robot 30, the bearing stand 27 is fixed to the underwater robot 30.

The impedance measuring device 1 measures an electric resistance R (Ω) and an electric capacitance (capacitance) C (F) when an alternating current is applied between the electrode 6 and the underwater structure 10. I have. Further, the computer 40 connected to the impedance measuring device 1 via the electric wiring 41 calculates the loss coefficient D from the following equation (1). This loss factor D is expressed by the tan delta (tan
δ).

D = 1 / (2πfCR) (1) where f is the frequency (Hz) of the alternating current. Furthermore,
A display 43 is connected to the computer 40 via an electric wiring 42, and a printer 45 is connected to the computer 40 via an electric wiring 44. The above-mentioned loss coefficient D has a correlation with the soundness of the coating film. According to the experiment, the loss coefficient D is 0.2 or less for a healthy coating film, and 2 or more for a coating film in which pinholes are generated. There is a difference of one or more digits. Therefore, the soundness of the coating film can be represented by the value of the loss coefficient D.

When the soundness of the coating film 11 of the underwater structure 10 is measured, the three tentacles 22 of the holder 20 attached to the tip of the underwater robot 30 are operated by operating the underwater robot 30. The electrode 6 is opposed to the underwater structure 10 by pressing against the surface of the underwater structure 10, and the distance between the electrode 6 and the underwater structure 10 is kept constant (L = 5 mm).

Next, an electric resistance R and an electric capacity C between the electrode 6 and the underwater structure 10 are measured by the impedance measuring device 1 while an alternating current is passed between the electrode 6 and the underwater structure 10. The value is input to the computer 40. The computer 40 calculates the loss coefficient D from the following equation (1).
Is calculated, and the value is displayed on the display 43. D = 1 / (2πfCR) (1) where f is the frequency of the alternating current.

Therefore, the soundness of the coating film 11 of the underwater structure 10 can be quantitatively grasped from the loss coefficient D displayed on the display 43. If desired, the loss coefficient D displayed on the display 43 by the printer 45 can be printed.

Since the holder 20 has the universal joint 23, the three tentacles 22 are brought into contact with the underwater structure 10 even if the underwater robot 30 is not correctly facing (correcting) the underwater structure 10. Thus, the electrode 6 can correctly face (correct) the underwater structure 10.

When the underwater robot 30 separates from the underwater structure 10, the universal joint 23 returns to the initial state by the spring force of the coil spring 26. That is,
The universal joint 23 becomes straight.

The state of the coating film 11 of the underwater structure 10 photographed by the observation equipment 32 such as a TV camera can be displayed on another display 46. It is possible to perform reliable maintenance of the coating film.

In the above description, the case where the electrode 6 is mounted on the submersible-type underwater robot 30 has been described. However, the present invention is not limited to this. Any device that can move along the surface of the underwater structure 10 can be used instead of the underwater robot.

[0023]

As described above, the underwater coating film soundness measuring apparatus according to the first aspect of the present invention faces a steel underwater structure covered with a coating film at a predetermined interval. Resistance between the electrode and the electrode and the underwater structure R
And a measuring instrument for measuring the electric capacity C, an underwater electric cable connecting the measuring instrument and the electrode, a ground wire connecting the measuring instrument and the underwater structure, and a loss coefficient from the following equation (1) (Tan Delta) Because it is composed of a computer that calculates D, regardless of the degree of turbidity of water,
The soundness of the coating film covering the surface of the steel underwater structure can be measured early and quantitatively. Also,
Since the result can be obtained in combination with the visual inspection by the TV camera of the underwater robot, reliable maintenance of the coating film of the underwater structure becomes possible.

D = 1 / (2πfCR) (1) where f is a frequency. Further, in the underwater coating film soundness measuring device according to the present invention, the electrode is mounted on a support plate provided with three tentacles of a fixed length, and the support plate is supported via a universal joint. Attached to the body,
In addition, since a coil spring coaxial with the universal joint is disposed between the support plate and the support, even if the support is inclined, the electrodes are arranged at a predetermined interval with respect to the painted underwater structure. Can face each other (facing).

[Brief description of the drawings]

FIG. 1 is a schematic view of an underwater coating film soundness measuring device according to the present invention.

FIG. 2 is an explanatory diagram of an electrode.

FIG. 3 is a side view of a holder on which electrodes are mounted.

FIG. 4 is a front view of a holder on which electrodes are mounted.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Impedance measuring device 3 Ground wire 5 Underwater electric cable 6 Electrode 10 Underwater structure 11 Coating 40 Computer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kitao Yamamoto 5-6-4 Tsukiji, Chuo-ku, Tokyo Inside Mitsui Engineering & Shipbuilding Co., Ltd. (72) Inventor Hirotaka Ohashi 5-6-4 Tsukiji, Chuo-ku, Tokyo Mitsui Engineering & Shipbuilding Co., Ltd. (72) Inventor Takeshi Kawaguchi 3-1-1 Tama, Tamano-shi, Okayama Pref.

Claims (2)

[Claims] An electrode facing a steel underwater structure covered with a coating film at a predetermined interval, and a resistance value R and a capacitance C between the electrode and the underwater structure are measured. It consists of a measuring device, an underwater electric cable connecting the measuring device and the electrode, a ground wire connecting the measuring device and the underwater structure, and a computer for obtaining a loss coefficient D from the following equation (1). Underwater coating soundness measurement device. D = 1 / (2πfCR) (1) where f is a frequency. 2. An electrode is mounted on a support plate provided with three tentacles of a fixed length, and the support plate is attached to a support via a universal joint, and a gap between the support plate and the support is provided. The underwater coating film soundness measuring device according to claim 1, wherein a coil spring coaxial with the universal joint is disposed in the underwater coating.