Liquid penetrant testing method

Abstract

To provide a liquid penetrant method which can be stably performed without requiring expertise, while maintaining detection accuracy for a minor defect by expanding practical applications and removing excess penetrant more easily and accurately.SOLUTION: A liquid penetrant testing method using an oily penetrant includes steps of: adhering and penetrating the penetrant to a detection object part on a surface of a cleaned test piece; removing most the excess penetrant adhering to the surface of the detection object part from the test piece surface by spraying water onto the surface of the detection object part; applying developer; observing an emerged penetration indication pattern; and removing the developer, in this order.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a penetrant inspection test method for detecting defects on the surface of a test piece, which is a test object, such as cracks, laps, wrinkles, porosity, poor fusion, etc. In particular, it relates to a flaw detection test using an oily penetrant, that is, a solvent-removable penetrant inspection test in an oily penetrant that does not use a surfactant or an emulsifier.

Background Art

[0002] Conventionally, as a non-destructive inspection method for detecting opening defects such as fine cracks and pinholes on the surface of metals, etc., for example, a method using a penetrant that penetrates the surface of the test piece with an oily penetrant to detect defects has been implemented. Also, a method using a penetrant containing an oil-soluble fluorescent dye that emits a yellow-green color when irradiated with ultraviolet light has been implemented (see Patent Document 1).

[0003] When using a dye penetrant, first, the surface of the test piece is cleaned, and then the dye penetrant is applied to the surface and allowed to penetrate. Next, the excess dye penetrant on the surface is wiped off with a wipe, and then wiped off and removed with a wipe to which a removing liquid is attached. Thereafter, a developer is applied to the surface of the test piece to form a thin layer of inorganic chamber white powder on the surface of the test piece, so that the penetrant that has penetrated into the opening defect part is sucked out to the surface of the thin layer. As a result, the defective part appears as a red pattern. Observe under natural light or white light, and detect the presence and position of the opening defect part by the red pattern (penetrant indication pattern) sucked out to the thin layer (see Patent Document 1).

[0004] When the penetrant indication pattern tends to be greatly enlarged when it appears on the thin layer during the development process, attempts have been proposed to suppress the spread of bleeding by devising the formulation of the powder of the developer, etc. (see Patent Document 1).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Now, in a penetrant inspection test, a common penetrant is an oil-based solvent-removable penetrant that needs to be removed with an oil-based solvent. For example, in a dye penetrant inspection test, it is necessary to attach and penetrate a red oil-based penetrant to the surface of the test piece. This is because, in order to detect unknown flaws, especially harmful unknown flaws judged as defects, by nature, the penetrant must be applied and penetrated widely onto the surface of the area to be explored. Then, the penetrant will be applied and adhered to the surface of areas other than the flaws. However, in order to reveal the penetrant that has penetrated into the gaps of the flaws on the open surface, it is necessary to remove the oil-based penetrant adhered to other normal areas in advance with a remover using a wipe. As a test procedure, it is essential to perform an operation of once applying it to the whole and then wiping it off with a remover. Only by thoroughly wiping off the penetrant other than the penetrant that has penetrated into the flaws from the surface of the test piece using the remover can only the penetrant that has penetrated into the flaws be left, making it detectable as a pattern in the developing process.

[0007] That is, in a penetrant inspection test, surplus penetrant inevitably adheres to the test piece. However, in order to avoid false detections such as pseudo patterns during the test, it is important to carefully wipe off the surplus penetrant with a wipe containing a small amount of remover before development. However, due to its nature, the oil-based penetrant is easy to penetrate and spreads well and wets the surface of metals, etc. Therefore, wiping with a wipe with a remover is not easy in terms of workability.

[0008] Therefore, although the penetrant inspection test using an oil-based penetrant is an excellent test method, there are suitable test specimens and unsuitable test specimens. Suitable test specimens were limited to objects that could be easily wiped off as a surface, such as large articles and structures, whose surfaces were finished smoothly to a certain extent. Therefore, it has been desired to expand the scope of test specimens. That is, test specimens that have been difficult to wipe off until now, such as welded joints with rough beads and small castings, could not be applied in solvent-removable penetrant inspection tests because they were difficult to wipe off with a waste cloth. A practically applicable dye penetrant inspection test method has been demanded.

[0009] In addition, when an oil-based penetrant is applied to the surface of a test specimen, it is not easy to completely remove the excess penetrant. If there is uneven wiping, it may appear as a false indication pattern. Therefore, in order to appropriately maintain the detection accuracy, proficiency is required for wiping with a waste cloth attached with a solvent. If the wiping itself becomes excessive, the target defect will not be detected, while if it is insufficient, a pseudo pattern will be generated. Since pseudo patterns will be mixed if the wiping itself is not appropriate, from the perspective of detection accuracy, it has to be a task that requires proficiency.

[0010] In addition, when removing the excess penetrant, it is likely to adhere to the hands of the operator in a large amount. Because of its penetrability, a burden such as the stain of the oil-based penetrant on the hands will not come off without using a solvent. Therefore, the work burden on the wiping operator is not only the proficiency of wiping, but also contamination of the operator, so overall, it becomes an even heavier burden.

[0011] Note that the penetrant targeted by the present invention is oil-based and has high penetrability. Therefore, even if a waste cloth or paper that does not fluff or produce lint is used, it is difficult to completely remove the attached penetrant from the surface of the test specimen only by dry wiping. In the case of an oil-based dye solution, if soap, surfactant, emulsifier, etc. are directly used for wiping, it will penetrate into the defect and even remove the penetrated dye solution. Therefore, it is not possible to perform rough operations such as spraying the removal liquid easily.

[0012] Therefore, after the operator attached the removal liquid to the waist, it was necessary to wipe off the oily excess penetrant on the surface of the test piece. Therefore, the wiping operation had to be sequentially removed in a time-consuming procedure. Since such a wiping operation is time-consuming, it is one of the factors that require skill in the operation when properly performing the wiping.

[0013] Therefore, the problem to be solved by the present invention is to expand the practical application target of the penetrant inspection test by ensuring the ease of removing the excess penetrant without applying a surfactant or an emulsifier in the dye penetrant inspection test using an oily penetrant, and to provide a means for more simply and accurately removing the excess penetrant from the surface of the test piece, so as to provide a penetrant inspection method that can maintain the detection accuracy for fine defects and can be stably implemented without requiring skill.

Means for Solving the Problem

[0014] As a result of intensive studies, the inventor of the present application found that before developing the indication pattern, instead of wiping off the excess oily penetrant (excess penetrant) applied to the surface of the test piece with a cloth attached with a remover as before, the procedure of removing the oily excess penetrant only by spraying water or steam, while saving the labor of those wiping operations and without using a surfactant or an emulsifier, and keeping the penetrant that has penetrated into the defect as it is, was pursued. By doing so, it is difficult to contaminate the hands of the operator, the difficulty of the operation that required skilled workers such as wiping was reduced, and the practical application range of the penetrant inspection test could also be expanded, and the following method was conceived.

[0015] That is, a first means for solving the problems of the present invention is, in a penetrant inspection test using an oily penetrant, a step of attaching and infiltrating the penetrant to a detection target site on the surface of the cleaned test piece, a step of removing most of the excess penetrant adhering to the surface of the detection target site from the surface of the test piece by spraying water on the surface of the detection target site, a step of applying a developer, a step of observing the developed penetrant indication pattern, and a step of removing the developer, in this order, which is a penetrant inspection test method using an oily penetrant.

[0016] A second means thereof is that the water sprayed on the surface of the detection target site is water at 10 to 40°C, which is a penetrant inspection test method using an oily penetrant according to the first means.

[0017] A third means thereof is that the water sprayed on the surface of the detection target site is steam, which is a penetrant inspection test method using an oily penetrant according to the first means.

[0018] A fourth means thereof is that the water sprayed on the surface of the detection target site is sprayed at 0.1 to 0.3 MPa, which is a penetrant inspection test method using an oily penetrant according to any one of the second or third means.

Advantages of the Invention

[0019] According to the means of the present invention, since the penetrant adhering while penetrating the surface of the test piece is oily, by spraying water droplets or steam without using a surfactant or an emulsifier, only the excess penetrant on the surface of the test piece can be efficiently blown off and removed. However, the oily penetrant itself that has penetrated into the gaps of the defects opened on the surface repels water moderately and can remain in the gaps of the defects without being blown off. Therefore, while the excess penetrant on the surface of the test piece can be efficiently and significantly removed by spraying water droplets or steam, it is difficult to damage the penetrant inside the defect, so it is less likely to result in excessive cleaning, and the penetrant that has penetrated into the defect at the detection site can be appropriately retained. After spraying water droplets or steam and wiping off the moisture, if a developer is sprayed on the test piece from which the moisture has been wiped off for development, the defective part will become an indication pattern and appear appropriately, so the penetration indication pattern can be detected without any problem.

[0020] Also, according to the means of the present invention, while only the oily excess penetrant can be efficiently removed with water or steam, since water and oil are difficult to mix due to the difference in intermolecular forces, even when water is sprayed, the penetrated oily staining liquid remains held in the gaps inside the defect, so it is difficult to fall off from the fine gaps, and it is possible to detect a fine indication pattern.

[0021] Different from wiping with a cloth that is good at wiping smooth surfaces, according to the means of the present invention, even for articles that are difficult to wipe with a cloth, such as welded parts with rough beads, soiled surfaces, parts with unevenness, and small castings, the excess penetrant can be removed. Therefore, not only can the labor of wiping the excess penetrant be greatly saved, but also the practical application target can be substantially expanded. In addition, false detection of pseudo-indications near the boundary of the welded bead part can be suppressed, and the dye penetrant inspection test can be applied practically.

[0022] By spraying water or steam at an appropriate pressure, only the excess penetrant adhering to the surface can be efficiently removed. However, by spraying moderately at a pressure that is not too strong, such as 0.1 to 0.3 MPa, the oil-based penetrant that does not mix with water can be left inside the defect. Therefore, compared to manual wiping using a remover with a cloth, the removal operation of the excess penetrant can be significantly advanced in a short time.

[0023] In addition, if it is spraying of water or steam, the requirement for skill can be reduced compared to wiping using a remover with a cloth. Therefore, the work can be stably and practically advanced regardless of the operator. And by the means of the present invention, troubles such as the excess penetrant adhering to the operator's hand during wiping with a cloth can be greatly reduced.

Brief Description of the Drawings

[0024]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0025] Prior to the implementation of the present invention, an oily penetrant (solvent-removable penetrant) used in the present invention will be described. The oily penetrant referred to here is a solvent-removable penetrant for flaw detection, that is, a penetrant that does not contain a surfactant component or an emulsifying component among oily red dye penetrants or oily fluorescent flaw detection agents. The oily red dye solution is the most common standard penetrant in solvent-removable dye penetrant flaw detection tests and can be removed with an organic solvent. As long as it is a general oily penetrant, the manufacturer is not particularly limited, and any of them can be suitably applied. That is, the means of the present invention is a reasonable method that can be implemented by using a general oily penetrant without requiring a particularly special penetrant.

[0026] The procedure of the penetrant flaw detection test method using the oily penetrant (solvent-removable penetrant) in the present invention will be described. It should be noted that each step described in the procedure of the present invention is to be carried out in order during the penetrant flaw detection test, but it does not exclude the possibility that other procedures can be combined before, after, or during each step. For example, it is also possible to appropriately combine procedures such as pre-treatment cleaning of the penetrant and final wiping after most of the excess penetrant has been removed.

[0027] Now, an example of the procedure of a dye penetrant inspection test using an oil-based penetrant by means of the present invention will be described in detail. A. Pretreatment (pre-cleaning) ↓ B. Drying ↓ C. Application of penetrant C1. Application of an oil-based penetrant (solvent-removable penetrant) to the test piece C2. Retention for penetration ↓ D. Removal of excess penetrant D1. Spraying of water (D1’. Spraying of vapor) ↓ E. Drying ↓ F. Development F1. Application of developer F2. Retention of development time ↓ G. Observation of the revealed indication pattern ↓ ↓ H. Post-cleaning ↓ I. Further, if necessary, perform surface protection treatment as appropriate.

[0028] Each step will be described in detail below.

[0029] A. Pretreatment The pre-cleaning in the pretreatment is to remove contamination by scale, rust, oils and fats, dust, paint, etc. so that the penetrant can penetrate into the defects on the surface of the test piece. In addition to cleaning with organic solvents or petroleum-based solvents, contaminants can also be removed by brushing, polishing, blasting, etc.

[0030] B. Drying After removing contaminants in the pretreatment, it is desirable to thoroughly dry the test piece so that no water or organic solvent remains.

[0031] C. Application of penetrant C1. Apply an oily penetrant (solvent-removable penetrant) to the surface of the test piece. The application can be done by any method such as brushing, spraying, dipping, or pouring, but it is important that the penetrant wets the area to be tested. In the case of a dye penetrant, since it is visible in red, it can be visually confirmed whether the penetrant has spread over the surface. In order to avoid condensation, it is preferable to carry out the operation in an atmosphere of about 10 to 50 °C. C2. To ensure proper penetration of the penetrant, a holding time may be ensured. The holding time is set to about 5 to 60 minutes according to the test piece and the nature of the defect, the required sensitivity of the penetrant, and the temperature so as to obtain detection accuracy.

[0032] D. Removal of excess penetrant D1 Spraying of water To remove the excess penetrant on the surface of the test piece, water is sprayed as fine droplets toward the surface of the test piece with a nozzle, and the excess penetrant is peeled off from the surface by the momentum of the water energized by the injection from the nozzle. Nozzles such as full-cone type, hollow-cone type, flat type, etc. can be appropriately applied. If the temperature of the sprayed water is too high, the test piece may subsequently cause condensation due to a rapid temperature change. Considering the workability of not getting burned, it is preferably, for example, 10 to 40 °C. Also, the water pressure when spraying from the nozzle is preferably, for example, 0.1 to 0.3 MPa. Depending on the type and size of the defect, it may be possible to increase the efficiency by removing the penetrant by spraying at a higher pressure. While the excess penetrant can be peeled off and removed from the surface of the test piece, a balance is achieved such that the penetrant in the gap of the opened defect is not washed away, so the penetrant in the fine defect can be retained. As a result, the excess penetrant can be efficiently and significantly removed, and even in a situation where it is difficult to wipe off on a wet surface, most of the excess penetrant can be removed.

[0033] D1’ Spraying of vapor Instead of spraying water as droplets with a nozzle, steam generated from heated water may be sprayed from the nozzle to wash away the excess penetrant. The cleaning of the test piece with steam is not a cleaning by spraying over time, but a quick and rapid washing, so the test piece is not overheated. The pressure of the steam when ejected from the nozzle is preferably, for example, 0.1 to 0.3 MPa. While the excess penetrant can be peeled off and removed from the surface of the test piece, it is balanced so that the penetrant in the gaps of the opened defects is not washed away, so the penetrant in the fine defects can be retained.

[0034] In the conventional penetrant testing procedure for applying an oily penetrant, the standard procedure for removing the excess penetrant was to manually wipe it off with a cloth using a small amount of remover. That is, since it is an oily penetrant (solvent-removable penetrant), it is not washed with water. The solvent of the remover is attached to a cloth (a cloth or paper that does not shed lint or dust) to wipe off the excess penetrant on the surface of the test piece with the solvent. Although the oily penetrant is removed with a solvent, if the solvent is directly sprayed, it may wash away the penetrant in the defect. Therefore, after impregnating the cloth with the solvent, it is reciprocated and manually wiped to remove the excess penetrant from the surface while leaving the penetrant inside the defect. According to the method of the present invention, the wiping operation with the cloth containing the solvent, which was performed manually, can be significantly reduced or labor can be saved.

[0035] According to the procedures of D1 and D1' of the present invention, the excess penetrant in the oily penetrant (solvent-removable penetrant), for which solvent removal has generally been considered necessary, is detached and removed from the surface of the test piece by spraying water without using a solvent despite being an oil. Therefore, the manual work that required time and skill with these cloths can be greatly omitted. In addition, since it can be applied to locations where wiping is not suitable in the first place, only the excess penetrant on the surface can be removed while leaving the penetrant in the fine and accurate defects using the oily penetrant, so the indication pattern of the fine defect can be detected.

[0036] In order to perform dye penetration inspection on areas that are difficult to wipe off, there is a flaw detection test that uses other water-washable penetrants or emulsified penetrants different from the present invention and uses water washing to remove excess penetrant. However, with those methods, the dye solution in the flaw is also easily removed by water washing, making them unsuitable for detecting fine flaws or flaws that are too large. The accuracy is not necessarily high, and it was inevitably a trade-off with workability. In the method of the present invention, the excess penetrant of an oily penetrant (solvent-removable penetrant) is removed by spraying water or steam without using a solvent. Since it is a combination of removing oil with water, when the excess penetrant on the surface of the test piece is removed by the force of the spray, the oil inside the flaw repels without mixing with water and remains inside the flaw. Therefore, contrary to water-washable or emulsifiable penetrants, the penetrant penetrates into fine flaws with a width of several micrometers, so that the indication pattern of fine flaws can also be detected.

[0037] Note that prior to D1 and D1', the excess penetrant may be gently wiped off with a dry wipe and then water may be sprayed. This is because if the application of the excess penetrant is too much, wiping it off in advance with a dry wipe can improve work efficiency.

[0038] Note that most of the excess penetrant can be removed by spraying water or steam. After most of it has been removed, if necessary, it may be wiped with a wipe containing a solvent for further finishing. Since most of the excess penetrant has already been removed by spraying water, it is only for finishing and is just a matter of wiping with a wipe. This can save significantly more labor than repeatedly wiping with a wipe from the beginning, and by performing the final wiping, unevenness and variations such as missed wiping can be reduced, making it easier to ensure stable accuracy without requiring skill.

[0039] E. Drying Before applying the dry developer, dry the excess moisture. It can be left to stand, but for a quick test, it is desirable to quickly remove water droplets and puddles. That is, even after removing the excess penetrant, after spraying water or steam, the surface of the test piece is wet, so it may be wiped up appropriately with a dry cloth and dried. In addition to wiping with a cloth, forced air circulation or drying at a high temperature with hot air or the like may be used, and as long as the surface of the test piece is not overheated, they can be appropriately combined. By drying quickly, it is possible to quickly move on to the next developing process. In addition, when the excess penetrant is removed by spraying steam, drying progresses quickly.

[0040] F. Development Developers include dry, quick-drying, and wet developers. Any procedure for applying dry, quick-drying, or wet developers can achieve the purpose as long as a uniform film can be formed and a penetration indication pattern can appear on the surface. Hereinafter, a quick-drying developer will be described as an example.

[0041] F1. Application of Developer The penetrant that has penetrated into the scratches on the surface of the test piece from which the excess penetrant has been removed is difficult to confirm as it is when observed from the surface. Therefore, a quick-drying developer is sprayed onto the test surface with a spray or the like to thinly and uniformly cover the surface. The developer contains inorganic white fine powder such as magnesium carbonate powder and calcium carbonate powder. In the case of quick-drying properties, the white fine powder is suspended in a volatile organic solvent, and when this is sprayed, a thin film is formed with quick-drying properties without the need for special drying. As long as the surface can be thinly covered as uniformly as possible, any method such as spraying, electrostatic spraying, spraying with a nozzle, or dipping method can be applied in the case of a dry developer.

[0042] F2. Ensuring the Holding Time (Development Time) for Development After thinly covering with the developer, it is held in a dry state for, for example, 10 to 30 minutes for development. That is, after the quick-drying developer dries, sufficient development time is ensured for the penetration pattern to appear on the surface. As the development time elapses, the penetrant (such as a red dye) that has penetrated into the gaps of the defect can be sucked up by the white inorganic fine powder and made to appear as an indication pattern on the thin film of the developer.

[0043] G. Observation Visually observe the penetration indication pattern that appears to float on the thin layer of the white inorganic powder under illumination of an appropriate brightness (under ultraviolet illumination if it is fluorescence). Record the shape, dimensions, and position of the defect of the indication pattern by writing a description, or record it as a sketch or an image. In addition, it may be observed before the development time has elapsed, and the result may be used as an aid in the interpretation of the penetration indication pattern. For visual confirmation, in addition to visual inspection, a magnifying glass or the like may be appropriately used.

[0044] H. Post-cleaning After observation, remove the developer, the penetrant used for flaw detection, etc. from the surface of the test piece.

[0045] I. Protection treatment Furthermore, if necessary, perform a protection treatment to prevent corrosion, etc. of the surface of the test piece.

[0046] (Examples and Comparative Examples) Using a test piece consisting of three steel plate weld joints, a penetrant flaw detection test was conducted using an oil-based dye penetrant (solvent-removable penetrant) to confirm the soundness of the joint. This test piece is made of steel with a length of 40 cm and a width of 20 cm. The joints of these test pieces are ordinary build-up welds, and visually, there are no harmful defects judged to be in the welded part.

[0047] For these test specimens, as shown in Figs. 1 to 6(a) for the examples, a penetrant flaw detection test using an oily dye penetrant was conducted by the method of the present invention in which water spraying was used to remove the excess penetrant. Also for comparison, as shown in Figs. 1 to 6(b) as comparative examples, a penetrant flaw detection test with an oily dye penetrant was also conducted by the method of manually wiping with a waste cloth containing a conventional solvent.

[0048] First, as a pretreatment, after removing the surface dirt with a cleaning solution, as shown in Fig. 1, for both the test specimens of the example in (a) and the comparative example in (b), an oily red dye penetrant was applied to the welded part on the surface of the test specimen with a brush at room temperature.

[0049] After ensuring a sufficient penetration time, next, in order to remove the excess penetrant on the surface of the test specimen (1), in the example, as shown in Fig. 2, due to the water potential of the water droplets sprayed from the tip of the nozzle (3), the excess penetrant applied above the welded part (2) was detached from the surface of the test specimen (1) and most of it was removed. For the water spraying, for example, a full-cone spray nozzle manufactured by Spraying Systems Co. was used, and the water pressure to the nozzle was set to about 0.1 to 0.3 MPa. As shown in Fig. 3(a), most of the excess penetrant was removed only by the water spraying. In the example, as shown in Fig. 4(a), as a finishing step, it was lightly wiped with a waste cloth attached with a remover.

[0050] On the other hand, as shown in Fig. 3(b), in the comparative example, the excess penetrant on the surface of the test specimen (1) was wiped off with a dry waste cloth, but as shown in Fig. 3(b), the excess penetrant could not be completely removed from the surface. Therefore, in the comparative example, the excess penetrant was substantially removed by wiping with a waste cloth attached with a small amount of the solvent of the remover. As shown in Fig. 4(b), it remained faintly red on the surface of the steel plate. It can be seen that the removal by wiping with a conventional waste cloth attached with a remover requires skill, and the wiping with a waste cloth is not necessarily an easy operation. On the other hand, in the example, it was confirmed that not only the finishing in Fig. 4(a) but also only the water spraying in Fig. 3(a) could almost remove it.

[0051] When applying the developer, a quick-drying developer was sprayed onto the surface of the test piece (1) from which the excess penetrant had been removed, and a thin film layer of white inorganic fine powder was formed on the surface thereof. The state immediately after applying the quick-drying developer is shown in Fig. 5. Fig. 5(a) is an example, and Fig. 5(b) is a comparative example.

[0052] After holding for a certain period of time (15 minutes) necessary for the indication pattern to appear in the thin film layer by development, the surface of the test piece was observed as shown in Fig. 6 and Fig. 7(A)(I)(U), and the presence or absence of the appearance of the test pattern, the position, shape, size, etc. of the test pattern that appeared in red were observed and recorded in the image.

[0053] Penetrant flaw detection using an oil-based dye penetrant, which is a solvent-removable penetrant, is a non-destructive inspection that can detect minute and fine defects and is widely used in practice. However, the removability of the excess penetrant is not always high, and conventionally, it was necessary to remove it with a solvent-wiped wipe. However, according to the method of the present invention, as shown in Fig. 3(a) and Fig. 4(a), most of the excess penetrant can be efficiently washed off by spraying water. On the other hand, as shown in Fig. 6(a) and Fig. 7(A)(I)(U), it was confirmed that in the method of the example, even minute defects at sites such as welded joints can accurately show the penetration indication pattern (4). All the defects that appeared as the penetration indication pattern (4) were minute cracks, which were not easy to visually distinguish with the naked eye in the state before penetrant flaw detection.

[0054] Since these test pieces are made by welding three steel plates together, the joint surface of the welded part has large irregularities and poor smoothness. Therefore, when applying an oil-based dye penetrant, since the solvent removability of the excess penetrant is poor, as shown in Fig. 3(b) and Fig. 4(b) of the comparative example, it is not easy to wipe off the excess penetrant with a wipe, and it is easy for the excess penetrant to remain slightly, etc., and it was reconfirmed that it is difficult to apply it to the welded part with a wipe using a conventional remover.

[0055] Similarly, regarding the removal of excess penetrant applied to the test piece by changing the water spray to steam spray, the same effect confirmation was also performed using the test piece. The steam spray used was a general handy-type household steam cleaner, which was of the type that ejects steam boiled at normal pressure in a boiler from the tip of a tapered nozzle. The steam was at a temperature of about 40 to 100°C, and by spraying it on the test piece with excess penetrant adhering thereto, most of the excess penetrant could be removed without wiping the excess penetrant on the surface. On the other hand, it was confirmed that the oily penetrant that had penetrated into the weld defect remained as it was without being mixed with the steam moisture and oil, and appeared as an imitation of a penetration indication after development.

[0056] In addition, when using a water-washable or emulsifiable type of dye solution, which is a type of penetrant different from the oily penetrant (solvent-removable penetrant) of the present invention, for penetrant flaw detection, the excess penetrant applied to the test piece is washed off with shower water. However, this is because the penetrant used in a situation where the excess penetrant is difficult to remove gives priority to water washability, and water-washable or emulsifiable type of dye penetrants are easier to fall off from fingerprints compared to oily dye penetrants. Detection in both fine gaps or overly large gaps is difficult. However, since they are penetrants with enhanced washability, such as being water-washable or emulsifiable, they are likely to fall off, and there is a trade-off relationship, such as the dye solution that has penetrated into the defect gap itself may also flow away due to water. The risk of being washed away from the defect by the shower is high, and in the water wash in these methods, the water flow rate for washing cannot be increased even in the case of washing with a shower. For these reasons, water-washable dye solutions are mainly used in situations where oily dye solutions are not good at detection, and the detection accuracy is not necessarily sufficient. In situations where an oily solvent-removable dye penetrant can be applied, water-washable dye solutions are not the standard for penetrant flaw detection, and in situations where an oily penetrant is applicable, an oily penetrant, which is a solvent-removable penetrant, is still used.

[0057] However, since the method of the present invention uses a solvent-removable penetrant such as a so-called standard red oil-based penetrant, it is possible to detect minute defects. In particular, for a solvent-removable penetrant, the oil-based penetrant itself does not need to be limited to special components and can be widely applied. And even if the excess penetrant is removed by spraying with water, since the oil and water do not mix in the gaps of the defects, it is possible to accurately detect even minute defects in the same way as wiping with a cloth to which a normal remover is attached, so it can be said that it is a method with excellent work efficiency. Since it is possible to use a standard oil-based penetrant, it is very useful.

[0058] By means of the present invention, improving the method of the penetrant inspection test for an oil-based penetrant which is a solvent-removable penetrant is useful because it enhances workability while maintaining the characteristics of the oil-based penetrant that can also detect fine defects. Furthermore, according to the means of the present invention, it becomes possible to apply to members with rough surfaces or small parts where oil-based penetrants have conventionally been unsuitable, etc., and thus the practical application targets of oil-based penetrants can be expanded.

Industrial Applicability

[0059] The penetrant inspection test method of the present invention is suitable for non-destructively checking and inspecting defects on the surface of metal materials, such as castings, forgings, and welded joints, and can also be applied to non-destructive inspection of surface defects of ceramics, etc.

Explanation of Signs

[0060] 1 Specimen 2 Welded joint 3 Nozzle 4 Penetration indication pattern

Claims

1. In penetrant testing using oil-based penetrant liquid, A step of applying and penetrating a penetrant liquid to a detection target portion on the cleaned surface of the test body; removing most of the excess dye penetrant liquid adhering to the surface of the detection target site from the surface of the test specimen by spraying water onto the surface of the detection target site; Applying a developer; Observing the resulting penetration indication; Removing the developer A penetrant testing method using an oil-based penetrant liquid containing the following in order:

2. The method for penetrant testing using an oil-based penetrant liquid according to claim 1, wherein the water sprayed on the surface of the detection target site is water at a temperature of 10 to 40°C.

3. 2. The method for penetrant testing using an oil-based penetrant liquid according to claim 1, wherein the water sprayed onto the surface of the detection target portion is steam.

4. 4. The method for penetrant testing using an oil-based penetrant liquid according to claim 2 or 3, characterized in that the water sprayed on the surface of the detection target portion is sprayed at 0.1 to 0.3 MPa.

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