JP3465561B2 - Under-film corrosion inspection method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting under-film corrosion of, for example, a coated or lined steel sheet from a film or a lining film. [0002] In order to inspect the corrosion of a metal material by measuring the roughness of the metal surface, a visual inspection, a stylus inspection and an optical inspection have conventionally been performed. If there is a coating on the surface, it is peeled off and inspected. To inspect without removing the coating, there are methods using eddy current method and magnetism. As a method of using X-ray reflection, X
There are a line diffraction method and a fluorescent X-ray method. [0003] In the conventional visual inspection, stylus-type inspection and optical inspection method, it is not possible to inspect through a coating film or a lining film, and the corrosion of a metal material under the coating film cannot be inspected. Not applicable for detection. In these inspection methods, it is necessary to peel off the coating film and the like, and it takes a lot of labor and time to peel off the metal surface to the extent that it can be inspected. In addition, the eddy current method and the magnetic method for detecting surface defects of steel plates and pipes from the above-mentioned coating film or lining film detect corners formed by cracks or dents, thereby reducing corrosion. Detection and measurement of the increase in surface roughness due to corrosion cannot be performed. Further, as a method utilizing the reflection and scattering of X-rays, the above-mentioned X-ray diffraction and X-ray fluorescence methods (Japanese Patent Laid-Open No.
No. 40407), these methods use microscopically at the stage of crystal structure and are incompatible with macroscopic inspection of the surface. An object of the present invention is to provide a method for inspecting the corrosion state of the surface of a metal material such as a steel plate or a pipe from a coating film or a lining film by utilizing X-ray reflection in order to solve the above-mentioned problems. It is in. Means for Solving the Problems In order to solve the above problems and achieve the object, the present invention uses the following means. (1) In the method of the present invention, an X-ray is incident on a metal film under a coated or coated metal coating film or a lining film at an angle at which a reflected dose intensity ratio becomes 70 to 100%. A step of measuring a reflected dose rate with respect to the incident X-ray, and a step of measuring the roughness of the metal surface based on a relationship between the reflected dose rate of the X-ray and the metal surface roughness obtained in advance from the dose rate. And inspecting the presence or absence of corrosion and the degree of corrosion of the metal surface under the coating film based on the relationship between the metal surface roughness and the degree of corrosion determined in advance from the roughness of the metal surface. A method for inspecting corrosion under a coating film, characterized in that: (2) In the method of the present invention, in the reflected dose rate measuring step, a plurality of dose rates are measured by changing an angle at which the X-ray reflected dose rate is measured with respect to an incident angle of the X-ray. The method for inspecting corrosion under a coating film according to the above (1), wherein the reflected dose rate is measured by setting a measurement angle at which the dose rate is maximized. DETAILED DESCRIPTION OF THE INVENTION The present inventors have obtained a method for inspecting the corrosion state of the surface of a metal material such as a steel plate or a pipe from a coating film or a lining film by utilizing X-ray reflection. In order to do so, we conducted intensive research. As a result, the inventors of the present invention apply X-rays at an angle of total reflection determined by the applied X-rays and the metal to be reflected or at an angle close to this angle, increase the reflection intensity, and apply the X-rays to a metal surface such as a steel plate. Reflect and measure the surface roughness from the degree of scattering (reflection dose rate) on the surface, measure the surface roughness of metal materials such as steel plates and pipes from the coating or lining film,
A method for inspecting the degree of corrosion corresponding to the surface roughness was found, and the present invention was completed. The method for inspecting corrosion under a coating film by X-ray reflection according to the present invention comprises applying a X-ray to a metal film under a coated or coated metal coating film or a lining film at a reflected dose intensity ratio of 70%. And a step of measuring a plurality of dose rates by changing the angle at which the X-ray reflected dose rate is measured with respect to the X-ray incident angle, and measuring the dose rate to be the maximum. Setting the angle, measuring the reflected dose rate, and inspecting the metal surface roughness based on the relationship between the X-ray reflected dose rate and the metal surface roughness obtained in advance from the dose rate. And inspecting the presence or absence of corrosion on the metal surface under the coating film and the degree of corrosion based on the relationship between the metal surface roughness and the degree of corrosion determined in advance from the roughness of the metal surface. X-rays are reflected at a reflected dose intensity ratio of 70 to 100.
The reason for incidence at an angle of% is that most of the incident X-rays are totally reflected. In other words, at this time, most of the emitted X-rays are reflected on the metal surface and do not penetrate into the metal, so that the reflection of the X-rays from the metal inside or the metal back surface affects the radiation monitor (dosimeter), An error can be prevented from occurring. The reason why the reflected dose rate is set at a measurement angle at which the dose rate is maximized and measured is to measure the maximum value of the reflected dose rate and improve the measurement accuracy of the reflected dose rate. is there. As described above, from the measured reflected dose rate, the surface roughness of the metal is identified and measured based on the relationship between the X-ray reflected dose rate and the surface roughness obtained in advance.
Based on the previously determined relationship between the metal surface roughness and the degree of corrosion, the presence or absence of corrosion and the degree of corrosion on the metal surface under the coating film can be inspected. Hereinafter, examples of the present invention will be described to demonstrate the effects of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for inspecting corrosion under a coating film according to the present invention will be described with reference to FIG. An X-ray generator 4 controlled by a controller 3 is provided on the surface of the coating or lining coating 2 applied to the metal 1.
Radiate incident X-rays 5. The incident X-ray 5 has an incident angle 7 set at an angle at which the reflection intensity reflected on the surface of the metal 1 is maximized or at an angle in the vicinity thereof (range of ± 5 °).
The line 6 is reflected at a reflection angle 8 and a radiation monitor (dosimeter) 9
Is measured by the controller 10. A shielding plate (lead plate) 11 is provided on one metal surface so that the incident X-ray 5 does not directly enter the radiation monitor (dosimeter) 9. The angle at which the reflection intensity at which the incident X-ray 5 is reflected on the surface of the metal 1 is maximized is determined by the type of the target metal 1 and the type of the incident X-ray 5. When the incident angle 7 was changed for the steel sheet and the reflected dose was measured, the maximum reflected dose was shown when the incident angle 7 was 10 °.
The intensity ratio of the reflected dose of the reflected X-ray 6 is defined as 100% when the incident angle 7 indicating the maximum reflected dose is 10 °.
2 is shown in FIG. By setting the incident angle 7 to 10 ° or an angle in the vicinity thereof (range of ± 5 °), most of the emitted X-rays (soft X-rays) are reflected. At this time, most of the emitted X-rays are reflected on the metal surface and do not penetrate inside the metal, so that the reflection of the X-rays from the metal inside or the metal back surface
It is possible to prevent the radiation monitor (dosimeter) 9 from being affected and causing an error. In this manner, the incident angle 7 of the X-ray is set to an angle at which the reflection intensity reflected on the surface of the metal 1 is maximized or an angle in the vicinity thereof (a range of ± 5 °). Further, the coated steel sheet was exposed in various environments and periods to prepare several kinds of steel sheets having different degrees of corrosion on the steel sheet surface under the coating film. X-rays were incident on these steel plates at an incident angle 7 of 10 °, and the reflected dose rate of the reflected X-rays 6 was measured by changing the angle measured by a radiation monitor (dosimeter) 9. On the other hand, the coating film of the coated steel sheet is removed with care so as not to impair rust and surface irregularities due to corrosion of the steel sheet surface, and the surface roughness of the steel sheet is measured with a stylus type measuring instrument, and the average roughness is measured. I asked for it. Table 1 shows the relationship between the corrosion state of the steel sheet and the average roughness of the steel sheet surface.
It is clear that the surface roughness of the steel sheet increases. Therefore, by measuring the surface roughness, it is possible to identify the presence or absence and the degree of corrosion. [Table 1] FIG. 3 shows the relationship between the measurement angle of the radiation monitor (dosimeter) 9 and the reflected dose rate corresponding to the surface roughness measured by the above method. It is apparent that there is a difference in the numerical value of the reflected dose rate for each angle measured by the radiation monitor (dosimeter) 9 corresponding to the roughness of the metal surface. In addition, it is clear that the reflected dose rate is maximized when the angle at which the radiation monitor (dosimeter) 9 measures the reflected dose rate is 10 °, which is the same as the incident angle 7. It is appropriate to measure the reflected dose rate of the radiation monitor (dosimeter) 9 at 10 ° because the measurement accuracy of the reflected dose rate is increased. FIG. 4 shows the relationship between the reflected dose rate and the surface roughness when the angle measured by the radiation monitor (dosimeter) 9 is 10 °. It is clear that the reflected dose rate changes linearly with the surface roughness. In this way, the degree of scattering of X-rays (soft X-rays) corresponding to the roughness of the metal surface can be obtained by measuring the reflected dose to obtain the surface roughness, and the numerical value of the surface roughness can be obtained. It is possible to inspect the presence or absence of corrosion on the metal surface and the degree of corrosion. According to the method of the present invention, steel structures such as bridges, piers, towers and the like, buildings such as chimneys, tanks and various plants, and pipelines such as gas, oil, water and sewage, which have been painted or lined by the method of the present invention. For (metals) etc., measure the surface roughness of the metal surface from the surface of the coating or lining film, and then peel off the coating or lining film and use a stylus inspection method for the surface roughness of the metal surface As a result, the same surface roughness value or an error of about 5% can be confirmed, and the corrosion can be inspected from the numerical value of the surface roughness. did it. According to the present invention, X is set at an angle close to total internal reflection.
Injecting rays, increasing the reflection intensity, and measuring the intensity of the reflected X-rays, peeling off the coating or lining coating from the coating or lining coating applied to metal materials such as steel plates and pipes In addition, it is possible to measure the roughness of the metal surface, and to provide an inspection method for determining whether or not corrosion has occurred and the degree of corrosion. By using the inspection method of the present invention, the labor and time required for removing the coating film required by the conventional method, and
The industrial utility value is great, for example, the need for restoration painting is eliminated.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing a surface roughness inspection method according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a relationship between an incident angle and an intensity ratio of a reflected dose according to the embodiment of the present invention. FIG. 3 is a diagram showing a relationship between a radiation monitor measurement angle and a reflected dose corresponding to a surface roughness according to the embodiment of the present invention. FIG. 4 is a diagram showing a relationship between a surface roughness and a reflected dose according to an example of the present invention. [Description of Signs] 1 ... metal, 2 ... coating or lining coating, 3 ... control device, 4 ... X-ray generator, 5 ... incident X-ray, 6 ... reflection X-ray, 7
... incident angle, 8 ... reflection angle, 9 ... radiation monitor (dosimeter), 10 ... control device, 11 ... shield plate (lead plate).

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) G01N 23/00-23/227 JOIS, PATOLIS

Claims (1)

(57) [Claims 1] X-rays are applied to a metal coating under coating or lining or a metal surface under the lining coating in a reflected dose intensity ratio of 70 to 100%. Incident at an angle, measuring the reflected dose rate with respect to the incident X-rays, and calculating the roughness of the metal surface from the dose rate based on the relationship between the X-ray reflected dose rate and the metal surface roughness determined in advance. And measuring the degree of corrosion of the metal surface under the coating based on the relationship between the metal surface roughness and the degree of corrosion determined in advance from the roughness of the metal surface. A method for inspecting corrosion under a coating film comprising the steps of: when measuring a reflected dose rate, with respect to an incident angle of an X-ray,
By changing the angle for measuring the X-ray reflection dose rate, multiple dose rates
Measure, set the measurement angle at which the dose rate becomes the maximum,
A method for inspecting corrosion under coating , characterized by measuring the reflected dose rate .