JPS6243491B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a cleaning agent used in penetrant testing, and is a novel cleaning agent that allows cleaning operations in penetrant testing to be carried out accurately and efficiently, and that causes extremely few occupational safety and health problems due to inhalation toxicity and flammability. The purpose of this product is to provide a cleansing agent. Penetrant testing is a typical type of non-destructive testing, and is a method for detecting defects that open on the surface of an object to be inspected. Among these, it is especially used as a method for detecting welds or slabs of large parts and structures. Conventionally, solvent-removable dye penetrant testing has been widely practiced. First, to explain the principle of the solvent-removable dye penetrant testing method, a penetrating liquid (a liquid with strong penetrating power containing a visible dye dissolved therein) is applied to the surface to be tested, and is allowed to sufficiently penetrate into the surface opening defects. Next, soak a cloth or paper towel in a cleaning agent (an organic solvent that has excellent compatibility with the penetrant and has a high evaporation rate) and wipe off any excess penetrant other than the penetrant that has penetrated into the surface opening defects. By applying a thin and uniform developer (white inorganic powder dispersed in an organic solvent) to the surface to be inspected, the penetrating liquid remaining in the surface opening defects is sucked up by capillary action.
As a result, the surface opening defect on the surface to be tested appears as an enlarged colored indicator pattern on the developed coating film, making it possible to visually identify the defect. As explained above, the solvent removable dye penetrant testing method is easy to operate, and the penetrant, cleaning agent, and developer are each made into an aerosol, making it easy to carry and handle.
This is currently the most popular method among penetrant testing methods. However, the cleaning agent used in such solvent-removable dye penetrant testing method (hereinafter referred to as "penetrant testing method") has the following drawbacks. First of all, the cleaning agents are generally Ascent, Benzene,
Since volatile low-boiling organic solvents such as rubber volatile oil, trichloroethane, trichlorethylene, etc. are used, there are occupational safety and health problems due to flammability and inhalation toxicity, especially when inspecting inside sealed tanks. is occurring. Second, since the cleaning agent generally has extremely high compatibility with the penetrating liquid, when wiping off the excess penetrating liquid, an excessive wiping operation (cleaning operation) will also wipe out the penetrating liquid remaining in the defective part. Since there is a high risk of so-called over-cleaning, the reliability of flaw detection tends to depend on the skill level of the operator. Thirdly, it is extremely difficult to completely wipe off the excess penetrating liquid that has entered the irregularities of the weld bead because, as mentioned above, it is easy to over-clean the defective parts that exist in the vicinity. Since the liquid also exhibits an indication pattern, a so-called pseudo-indication, it is extremely difficult to distinguish it from a genuine defect indication pattern. The drawbacks explained above are that organic solvents that are highly compatible with the penetrant and have a high evaporation rate (organic solvents that are highly flammable and highly inhalable) This is due to the fact that it is selected as a cleaning agent. Therefore, it has become a challenge in the industry to develop a cleaning agent that has low compatibility with the penetrant, has a high flash point, and has extremely low inhalation toxicity while maintaining the same workability as conventional cleaning agents. . The present invention has been made with the aim of providing a novel cleaning agent for penetrant flaw detection to solve these problems. That is, the present invention provides S-tetrachlorodifluoroethane (hereinafter referred to as "Freon 112"), 1,1,2-trifluoro-1,2,2-trichloroethane (hereinafter referred to as "Freon 113"), or A cleaning agent for penetrant testing characterized by comprising a mixed solvent obtained by diluting the mixed solvent with another organic solvent and at least one type of rust preventive agent dissolved in the mixed solvent, and furthermore, the cleaning agent has a high evaporation rate. The cleaning agent is characterized in that Freon 112, Freon 113, or a mixed solvent thereof is present in the cleaning agent at a concentration sufficient to give a cleaning time of 1 to 3 minutes in a spot test. Here, the spot test refers to dropping a certain amount of solvent onto a filter paper and measuring the time required for the solvent to completely volatilize under certain conditions. The restrictive experimental conditions for the spot test are Toyo Filter Paper No. 2,
Place a 12.5 cm diameter beaker on a 500 ml beaker, drop 5 drops of solvent onto it using a 1 ml volumetric pipette, and raise the temperature to 20.
The time taken for the solvent to completely volatilize was measured under conditions of ±1°C, humidity of 60±5%, and no wind. The workability of the cleaning operation in penetrant testing is closely related to the evaporation rate of the cleaning agent, so the inventors measured the evaporation rate of the cleaning agent using a simple method and calculated the value and the cleaning operation. As a result of various studies on the relationship between flaw detection and workability, it was found that, in normal flaw detection, if a cleaning agent with an evaporation rate of 1 minute to 3 minutes is used in a spot test, the cleaning operation can be carried out necessary and sufficiently, and a good result can be achieved. They reached the conclusion that the method has good workability. In other words, 1 spot test was performed during the above cleaning operation.
If a cleaning agent that lasts for less than 3 minutes is used, it is highly volatile and causes a large amount of scattering, which is uneconomical.If a cleaning agent that lasts for more than 3 minutes is used, it wastes time until the object to be inspected dries. Not only is this wasted time, but also the defect indication pattern becomes unclear and inaccurate due to the staining effect of the penetrating liquid remaining in the defect area. Solvents that can be spot tested for 1 to 3 minutes include hexane, heptane, isooctane, rubber volatile oil,
benzine, isopropyl ether, methyl acetate,
There are many such substances, such as ethyl acetate, isopropyl acetate, acetone, methyl ethyl ketone, trichloroethylene, and trichloroethane, but they all have extremely strong flammability or inhalation toxicity, and it is not preferable to use them alone as a cleaning agent. On the other hand, high boiling point solvents generally have a high flash point and slow evaporation rate, and low boiling point solvents have a low flash point and high evaporation rate, so by mixing the two, the flash point and evaporation rate can be adjusted. It is well known that this is possible. Therefore, the inventors of the present invention mixed a low boiling point solvent with a relatively high boiling point solvent and conducted a spot test to determine the change in the evaporation rate, and obtained the results shown in FIGS. 1 to 6. In addition, the horizontal axis in the figure is the mixed composition of the mixed solvent (weight%)
, the vertical axis indicates the spot test value, CFC 112, CFC 113, ethyl ether, hexane, acetone, and methylene chloride. The experimental results show that Freon 113 is equivalent to ethyl ether, hexane, or acetone for solvents whose evaporation rate is 3 minutes or more in a spot test for hydrocarbons, chlorinated hydrocarbons, alcohols, ethers, ketones, and esters. 112 is the strongest, and it can be seen that the mixed solvent of Freon 112 and Freon 113 has the effect of accelerating the evaporation rate. Furthermore, as shown in Figure 7, Freon 112 has a stronger effect on accelerating the evaporation rate of solvents (high boiling point solvents) that have a slower evaporation rate when compared to similar solvents, and as shown in Figure 8, the effect of accelerating the evaporation rate is stronger. For solvents whose evaporation rate is less than 1 minute, the evaporation rate slows down. Therefore, among all the organic solvents in general use, Freon has the ability to mix with other organic solvents and adjust the evaporation rate of the mixed solvent to 1 to 3 minutes in a spot test. It can be seen that 112 is the strongest. The present invention utilizes the above-mentioned effects of Freon 112 and Freon 113. Next, both Freon 112 and Freon 113 have a molecular structure in which all the hydrogen in ethane is replaced with chlorine and fluorine, so there is no danger of ignition or explosion.
Furthermore, when this is mixed with a flammable solvent, it has the effect of raising the flash point or eliminating the flash point, depending on the mixing ratio. In other words, Freon 112 or Freon 1 is used as a flammable solvent.
As 13 or a mixed solvent thereof is added, the flash point gradually rises, and when the mixing ratio exceeds a certain level, the flash point disappears (the boiling point of the flammable solvent becomes the combustion point), and at a certain mixing ratio, the flash point increases. If the solvent has an azeotropic composition, Freon 112 or Freon 113
Due to its flame retardant effect, flammability and combustibility can be eliminated. This relationship is shown in Table-1 and Table-2.

【table】

[Table] Even if it is a flammable solvent, Freon 11
By adding an appropriate amount of fluorocarbon 2 or Freon 113 or a mixed solvent thereof, the mixed solvent can be made nonflammable or the flash point of a flammable solvent can be raised. Incidentally, the term "non-flammable" here refers to the absence of a flash point, and is defined as including cases where the boiling point of the flammable solvent is the combustion point. Therefore, if the above-mentioned mixed solvent is used as a cleaning agent for penetrant flaw detection, the cleaning agent becomes non-flammable or maintains a high flash point, so it is extremely unlikely to cause labor safety problems due to ignition. 1
This has the effect of making it possible to produce cleaning agents with various characteristics depending on the physical or chemical properties of the flammable solvent mixed with Freon 12 or Freon 113 or a mixed solvent thereof. As explained above, Freon 112 or Freon 1
13 or a mixed solvent thereof has the effect of making a mixed solvent of this and a flammable solvent nonflammable, but a chlorinated hydrocarbon solvent also exhibits the same effect. However, chlorinated hydrocarbon solvents have extremely strong inhalation toxicity, and as mentioned above, it is not preferable to use them as the main component of cleaning agents. Incidentally, Table 3 shows the maximum allowable concentrations of Freon 112, Freon 113, chlorinated hydrocarbon solvents, and alcohol solvents.

[Table] Since Freon 113 has been shown to have a maximum allowable concentration value equivalent to that of ethyl alcohol, it can be considered a solvent with almost no inhalation toxicity. Although Freon 112 has a maximum permissible concentration value equivalent to that of methylene chloride, its inhalation toxicity is extremely low compared to other chlorinated hydrocarbon solvents, and the cleaning agent according to the present invention has a maximum allowable concentration value equivalent to that of methylene chloride. Since Freon 112 is not used alone but is used in combination with other organic solvents, if Freon 112 is mixed with a solvent with low inhalation toxicity, the cleaning agent can be evaluated as having extremely low toxicity. Furthermore, as shown in Figures 1 to 6, Freon 112 has an adjustment effect that adjusts the evaporation rate of the mixed solvent to 1 to 3 minutes in spot tests when mixed with other organic solvents, compared to methylene chloride. It has the advantage of being extremely resistant to all organic solvents. Next, the solubility of Freon 112 and Freon 113, that is, their compatibility with the penetrating liquid will be explained. Generally speaking, there is no single absolute measure of the solubility of a solvent, so it is desirable to conduct a cleaning test each time the substance is to be removed. However, the cowributanol value (KB value) is often used as a measure of relative dissolution ability. This value is an empirical method for estimating the solubility of a solvent, and it is believed that the larger the KB value, the greater the dissolving power. Therefore, Table 4 shows the KB values of chlorinated hydrocarbon solvents, Freon 112, and Freon 113, which are the main components of nonflammable penetrant cleaning agents currently used.

[Table] As shown in Table 4, the KB values of Freon 112 and Freon 113 are both lower than those of chlorinated hydrocarbon solvents, indicating that their solubility is low. However, this KB value is only a guide to solubility, and it is difficult to discuss the exact results of compatibility with the penetrant unless you actually perform the cleaning operation for each penetrant. Can not. Therefore, we decided to use a sandblasted board (100 mesh sandblasted on a stainless steel plate) with two currently commercially available solvent-removable dye penetrants (A and B) and solvent-removable fluorescent penetrant C at an angle of 45 degrees. After dropping 2 ml onto the surface and leaving it for 15 minutes, immerse it in rubber volatile oil ) was measured. The results are shown in Table-5.

[Table] From this experimental result, the cleaning agent according to the present invention is A.
It can be seen that its compatibility with any of the penetrating liquids B and C is lower than that of rubber volatile oil and trichlorethylene. As mentioned above, Freon 112 and Freon 113 have various beneficial effects on cleaning agents for penetrant testing, but when mixed with an alcohol solvent or mixed with water, if left for a long time, iron, magnesium, zinc, etc. It has the disadvantage of reacting with other metals and corroding storage containers. Therefore, the inventors of the present invention have repeatedly studied various rust preventive agents that can eliminate this drawback and maintain the evaporation rate of the cleaning agent within 1 to 3 minutes in a spot test. It has been found that this meets the requirements. The rust inhibitors are nitromethane, nitroethane,
These include nitropropane, nitrobenzene, ethylenediamine, ethylenediaminetetraacetate, triethanolamine, and triethylenediamine. The present invention will be explained below based on examples. <Example> (Example 1) Freon 112 38%, Freon 113 48%, ethyl alcohol 13%, nitromethane 1% (spot test 1 minute 45 seconds) (Example 2) Freon 112 62%, methylene chloride 37%, Nitroethane 1%, (spot test 1 minute 30
(Example 3) Freon 112 34%, Freon 113 35%, Sec butyl acetate 30%, nitromethane 1% (Spot test 2 minutes 30 seconds) (Example 4) Freon 112 33%, Freon 113 33%, toluene 33%, ethylenediamine 1% (spot test 2 minutes 15 seconds) (Example 5) Freon 112 26%, Freon 113 53%, methyl ethyl ketone 20%, nitromethane 1%
(Spot test 1 minute 15 seconds) A cleaning agent according to the present invention was manufactured with the above mixing ratio (wt%), and the defect detection sensitivity was compared using this and a conventional cleaning agent (conventional product) made of trichlorethylene. I went there. That is, three types of commercially available solvent-removable dye penetrants were applied to the butt overlay welds (one containing aromatic hydrocarbons/vegetable oil as the main component [A], one containing chlorinated hydrocarbon as the main component [B], and saturated). After performing a penetration treatment using a detergent (C) whose main components are fatty acids, esters, and alcohol, soak a rag in the cleaning agent of the present invention or a conventional product, completely wipe off the excess penetrant, and clean it naturally. After drying, development was performed and defects indicating patterns were compared. This experiment was repeated and the following results were obtained. That is, the defect indicating pattern is not related to the types of the three types of penetrant liquids mentioned above, but is related to the cleaning process. In other words, if the cleaning process is carried out by a skilled person,
The disappearance of defective indication patterns and the appearance of false indications due to over-cleaning are relatively rare both when using the cleaning agent according to the present invention and when using the conventional product, and they exhibit good and equivalent detection sensitivity. However, when the cleaning process was carried out by a beginner using a conventional product, there were so many false indications and defective indication patterns disappeared due to over-cleaning that they were almost undetectable. On the other hand, when the cleaning process was performed by a beginner using the cleaning agent according to the present invention, a relatively large number of false indications appeared, but almost no defect indication pattern disappeared due to overcleaning. From the above results, it can be understood that if cleaning treatment is performed using the cleaning agent according to the present invention, the reliability of the flaw detection test is extremely unlikely to be influenced by the skill level of the operator. At the same time, the compatibility of the cleaning agent according to the present invention with the penetrating liquid is equivalent to the three types of penetrating liquids A, B, and C, and the compatibility is lower than that of trichlorethylene. It can be understood. As explained above, the cleaning agent according to the present invention solves the problems faced in the industry: ``While maintaining the same workability as conventional cleaning agents, it has low compatibility with penetrants, has a high flash point, and has low inhalation toxicity.'' It satisfies all the requirements of "cleaning agents," and its practical effects are extremely large.

[Brief explanation of the drawing]

Figures 1 to 6 are evaporation rate curves of mixed solvents in which a solvent with a slow evaporation rate is mixed with a solvent with a high evaporation rate, Figure 7 shows the effect of accelerating the evaporation rate of the mixed solvent, and Figure 8 is an evaporation rate curve diagram showing a conversely slowing effect. In the figure, indicates Freon 112, indicates Freon 113,
indicates ethyl ether, indicates hexane, indicates acetone, and indicates methylene chloride.

Claims (1)

[Claims] 1 S-tetrachlorodifluoroethane or 1,
Penetrant flaw detection characterized by comprising a mixed solvent obtained by diluting 1,2-trifluoro-1,2,2-trichloroethane or a mixed solvent thereof with another organic solvent, and at least one type of rust inhibitor dissolved in this. cleaning agent. 2 The cleaning agent contains S-tetrachlorodifluoroethane or 1.
The cleaning agent for penetrant flaw detection according to claim 1, characterized in that 1,2-trifluoro-1,2,2-trichloroethane or a mixed solvent thereof is present.