JP2011179533A - High-pressure gas container valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-pressure gas container valve 10 in which damage in a screw part due to a galling phenomenon is inhibited. <P>SOLUTION: A cylinder part 12 is formed in an upper side of a container valve body 11 of the high-pressure gas container valve 10, and a plug 13 is arranged to be screwed in the cylinder part 12. A gas flow passage 19, through which, for example, hydrogen chloride or the like flows, is formed on the lower side of the container valve body 11, and the gas flow passage 19 is opened/closed by turning the plug 13. In the high-pressure gas container valve 10, a male screw part 30 screwed in and contacting a high-pressure gas container 20 is aluminized, and then, is acid-treated. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a high-pressure gas container valve mounted on a high-pressure gas container, and more particularly to a technique for suppressing the caulking phenomenon of the container valve.

  FIG. 1 shows an example of a conventional high-pressure gas container valve 10, and this high-pressure gas container valve 10 is attached to an opening 21 of a high-pressure gas container 20. The high-pressure gas container valve 10 includes a container valve main body 11, a plug 13 screwed into a cylinder portion 12 formed on the upper side of the container valve main body 11, and a spindle 14 at the upper end of the plug 13. And a handle 15 attached thereto. A sheet disk 16 made of ethylene trifluoride chloride resin is provided at the lower end of the plug 13. A gas outlet 17 for extracting gas from the high-pressure gas container 20 is formed on the side surface of the container valve body 11, and an outlet cap 18 is disposed in the gas outlet 17.

  An L-shaped gas flow path 19 is formed on the lower side of the container valve main body 11, one end of the gas flow path 19 is connected to the high pressure gas container 20, and the other end of the container valve main body 10. Connected to the outside from the side. Then, the gas channel 19 can be opened and closed by rotating the plug 13 via the handle 15 and moving it up and down. That is, when using the gas in the high-pressure gas container 20, the plug 13 is raised to open the gas flow path 19, and the gas passes through the gas flow path 19 and is taken out from the gas outlet 17. become. When the use of the gas in the high-pressure gas container 20 is stopped, the plug 13 is lowered to close the gas flow path 19. Moreover, although the lower part of the container valve main body 11 is not shown in FIG. 1 for convenience, the screw is cut as shown in FIG.

  The high-pressure gas container 20 is made of, for example, chromium molybdenum steel (alloy steel in which chromium and molybdenum are added to iron and improved in durability and resilience). On the other hand, the high-pressure gas container valve 10 is generally manufactured using brass, which is an alloy in which zinc and copper are mixed. In the case of high-purity gas used in a semiconductor manufacturing apparatus or the like, a semiconductor is used. In order to suppress contamination on the wafer as much as possible, great corrosion resistance is required, and therefore, it is manufactured using stainless steel which is steel to which Ni, Cr, Mo, etc. other than carbon is added. In particular, when anhydrous hydrogen chloride gas is used, moisture enters the container valve 10 from the outside when the outlet cap 18 is removed. If anhydrous hydrogen chloride gas is present in this state, hydrochloric acid is generated and large. Corrosion will work.

  By the way, when the contact pressure of the screw portion is high, a phenomenon called galling may occur. This galling is a phenomenon in which metals adhere and adhere to each other. Here, since the stainless steel container valve 10 has a higher coefficient of friction than the brass container valve 10, the male screw part 30 formed at the lower part of the container valve main body 11 shown in FIG. The sliding resistance (contact pressure) at the meshing surface with the female screw portion 22 formed in the high-pressure gas container 20 is increased. Further, since stainless steel has a low thermal conductivity, heat is not easily dissipated and the temperature tends to be high locally, and the contact pressure on the meshing surface of the screw tends to increase due to the large thermal expansion.

  As shown in FIG. 2 (b), the male screw portion 30 is inclined downward, and the female screw portion 22 is similarly inclined so that it can be screwed therewith. When combined, the contact pressure becomes higher due to the error of the inclination angle. Further, the container valve 10 chamfering the peripheral part of the front end of the male screw part 30 (a configuration in which the height of the spiral gradually increases from the front end toward the other end) is also widely distributed. Half of 10 shows galling. Therefore, the torque value cannot be increased.

  On the other hand, since the torque value for attaching the container valve 10 to the container valve main body 11 tends to increase in order to respond to the claims of gas leakage on the user side, the stainless steel container valve 10 has the male screw portion 30 and the female screw. The oxide film of the portion 22 is destroyed, and a galling phenomenon is likely to occur due to the exposure of the fresh metal surface. Especially for highly toxic gases, the torque value has been raised to deal with gas leaks, but as a result, the number of claims was reduced but the problem of galling occurred.

  Therefore, in order to suppress the caulking phenomenon, a sealing tape using, for example, PTFE (polytetrafluoroethylene) (not shown) is wound around the male screw portion 30 of the container valve 10, and the container valve 10 is interposed via this sealing tape. And the high-pressure gas container 20 are in indirect contact with each other, so that the galling phenomenon can be suppressed. However, when the container valve 10 and the high-pressure gas container 20 are joined, a part of the seal tape may be damaged and fall off into the high-pressure gas container 20. There is no sealing tape on one mountain. For this reason, there is a high possibility that the tip portion of the male screw portion 30 of the container valve 10 is damaged.

  The inventor has also studied nitriding treatment to harden the surface of the male screw portion 30 and prevent galling. However, when the base material of the container body is stainless steel, chromium which is a useful component of stainless steel is used. Is segregated, and the corrosion resistance is significantly reduced. Therefore, it cannot be used when corrosive gas such as hydrogen chloride is stored in the high-pressure gas container 20.

  In Patent Document 1, the third thread tip of the male thread part is the standard thread part that contacts the thread of the female thread part, and the other thread part in the male thread part is slightly smaller in diameter than the standard thread part. The screw component which suppresses a cabbage phenomenon by reducing the friction with the internal thread part in the screw thread of is described. However, in this threaded part, the galling phenomenon in this part is not suppressed because the standard threaded part is in contact with the female threaded part. Further, Patent Document 2 discloses a container valve that suppresses corrosion of a metal part and suppresses a galling phenomenon by configuring a container valve body and a cylinder part with Hastelloy, which is a material having excellent corrosivity. However, since this container valve is only for the purpose of preventing corrosion, it has not been made directly to suppress the caulking phenomenon.

JP-A-7-260096 JP 2001-343209 A

  The present invention has been made under such circumstances, and an object of the present invention is to provide a high-pressure gas container valve capable of suppressing a caulking phenomenon at a portion screwed with the high-pressure gas container.

  The high-pressure gas container valve of the present invention is characterized in that at least a surface portion of a screw portion screwed into the high-pressure gas container is subjected to an aluminizing process and then an acid treatment. For example, the screw portion is made of stainless steel.

  According to the present invention, the surface of the portion of the high-pressure gas container valve that is screwed with the high-pressure gas container is aluminized and then acid-treated to form a film. The galling phenomenon can be suppressed by this film.

It is a longitudinal cross-sectional view of the high pressure gas container valve which concerns on embodiment of this invention. It is the schematic diagram which showed typically the part which a high pressure gas container valve and a high pressure gas container contact. It is explanatory drawing which showed a mode that the surface of an external thread part changed by each process. It is a longitudinal cross-sectional view of the high pressure gas container valve which concerns on other embodiment. It is the graph which showed the relationship between reaction time when each sample was immersed in hydrochloric acid aqueous solution, and mass change.

  An embodiment of a high-pressure gas container valve according to the present invention will be described. Since the high-pressure gas container valve according to this embodiment is substantially the same as the high-pressure gas container valve 10 described in the background art section, the description of the same portions will be omitted and only different portions will be described. The container valve main body 11 of the high-pressure gas container valve 10 is made of stainless steel, and the male screw portion 30 of the container valve main body 11 is subjected to an acid treatment after being subjected to an aluminizing process. In addition, a laminated film composed of a passive film 42 having excellent corrosion resistance and an intermetallic compound layer 41 is formed. Even if a large contact pressure is applied to the laminated film, the laminated film is not easily broken and the fresh surface of stainless steel is difficult to be exposed.

  Next, each process for forming the laminated film will be described with reference to FIG. 3 showing how the surface of the male screw portion 30 changes. FIG. 3A shows the surface of the male screw portion 30 before performing the aluminizing process.

  The aluminizing process is a method of forming an intermetallic compound of iron and aluminum by coating aluminum (Al) on the steel surface. This intermetallic compound has high hardness and is effective in preventing galling. However, both aluminum and iron are vulnerable to acids and cannot be used in corrosive environments. When stainless steel is aluminized, chromium (Cr) and nickel (Ni) are included in the intermetallic compound consisting of iron (Fe) and aluminum formed at the interface with the base material, improving toughness. Is done.

FIG. 3B shows the surface of the male screw portion 30 after the aluminizing treatment, and the intermetallic compound layer 41 formed by the treatment is composed of FeAl, FeAl (Cr), or the like. As a specific method of the aluminizing treatment, for example, the male screw portion 30 is immersed in a plating bath, and the male screw portion 30 is electroplated with aluminum. As a plating solution used in this plating bath, a conventionally known one is used. For example, AlCl ₃ and 1-methyl-3-propylimidazolium bromide mixed and melted at a molar ratio of 2: 1 with various additives added, AlCl ₃ and butyl viridinium bromide Can be used in which 4 g / l of polystyrene (MW5000) is added to a bath obtained by mixing and melting these at a molar ratio of 2: 1.

  Next, the acid treatment will be described. This acid treatment is performed by immersing the aluminized male screw portion 30 in an acidic solution such as an aqueous hydrochloric acid solution. The inventor has inferred that the passive film 42 is formed by the following reaction process by this acid treatment based on the experiment described below.

  Immediately after the male screw part 30 is immersed in a hydrochloric acid aqueous solution, the intermetallic compound layer 41 is dissolved as shown in FIG. 3C, and Fe, Cr, and Al constituting the intermetallic compound layer 41 are eluted in the aqueous hydrochloric acid solution. To do. Thereafter, the aluminum dissolved in the hydrochloric acid aqueous solution becomes aluminum oxyhydroxide (AlO (OH)) and adheres to the surface of the intermetallic compound layer 41.

  Subsequently, iron and chromium dissolved in the hydrochloric acid aqueous solution gradually become iron oxyhydroxide (FeO (OH)) and chromium oxyhydroxide (CrO ((OH)), covering the surface of the AlO (OH), and these AlO A passive film 42 made of (OH), CrO ((OH)) and FeO (OH) is gradually formed, and the dissolution of the intermetallic compound layer 41 is reduced, and the intermetallic compound layer 41 becomes the passive film 42. The dissolution of the intermetallic compound layer 41 is stopped (FIG. 3D).

  According to the above-described embodiment, the laminated film composed of the passive film 42 made of oxyhydroxide and the metal compound layer 41 is formed on the surface of the male screw portion 30 of the container valve 10 and cured. Therefore, when the high-pressure gas container valve 10 and the high-pressure gas container 20 are screwed together, the caulking phenomenon is suppressed, and the male screw portion 30 and the female screw portion 22 are not damaged, so that gas leakage can be prevented more reliably. Further, the corrosion resistance of the male screw portion 30 can be obtained. As the corrosion resistance of the passive film 42, when SUS316 is used as a base material of the high-pressure gas container valve 10, it has a corrosion resistance equivalent to that of the base material.

  By the way, the aluminizing treatment is not limited to using a plating bath, and includes, for example, performing plating by spraying aluminum. Moreover, in performing the aluminizing process, components other than aluminum, such as chromium, may be mixed in the aluminum covering the male screw portion 30.

  In addition to hydrochloric acid, other acids such as sulfuric acid may be used as the acid used for the acid treatment. And as a method of an acid treatment, if an acid is supplied to the intermetallic compound 41, it is not restricted to being immersed in an acidic solution as mentioned above. For example, mist of an acidic solution may be sprayed on the male screw portion 30.

  The present invention is not limited to the above-described embodiment, and can be applied to a diaphragm-type high-pressure gas container valve described below. The configuration of this high pressure gas container valve will be described. As shown in FIG. 5, the upper side of the container valve main body 61 constitutes a cylinder part 62, and an opening / closing element 63 is provided in the cylinder part 62. The opening / closing element 63 is maintained at the upper limit position so that the L-shaped gas flow path 64 is opened by a coil spring (not shown). An opening at the upper end of the cylinder portion 62 is hermetically closed by a leaf spring 65 that is a circular diaphragm, and a peripheral portion of the leaf spring 65 is connected to the cylinder by a bonnet 66 that is screwed into the container valve body 61. It is pressed against the part 62.

  A spindle 68 that is rotated by a handle 67 that is an operation unit is screwed into the bonnet 66. The spindle 68 presses the central portion of the leaf spring 65 downward, whereby the switch 63 is pressed against the elastic force of the coil spring, and the gas flow path 64 is closed. The lower side portion of the container valve main body 61 is formed as a male screw portion 69. And since the container valve main body 61 is acid-treated after an aluminizing process and the film | membrane is formed in the surface, the effect similar to the above-mentioned embodiment is acquired.

Evaluation Experiment Next, an evaluation experiment was performed to confirm the effect of the high-pressure gas container valve 10 of the present invention. As an example, ten new high-pressure gas containers 20 having a volume of 47 L and made of CrMo steel were prepared. Also, a high pressure gas container made of SUS316 (stainless steel made of an alloy of iron, chromium and nickel, containing 18% chromium and 12% nickel and adding molybdenum to these to improve corrosion resistance). Ten valves 10 were prepared, and the male screw portion 30 was aluminized in the same manner as in the embodiment and then acid-treated. This container valve 10 is designated as sample 1. Each sample 1 was screwed into each high-pressure gas container 20 with a specified torque value, and the sample 1 was removed from these 10 sets of high-pressure gas containers 20 with container valves the next day.

  As Comparative Example 1, ten high-pressure gas containers 20 similar to those in the example were prepared. Moreover, ten high pressure gas container valves 10 made of SUS316 were prepared. This container valve 10 is designated as sample 2. Then, each sample 2 was screwed into each high-pressure gas container 20 with a specified torque value in the same manner as in the example, and the sample 2 was removed from these 10 sets of high-pressure gas containers 20 with container valves the next day.

Experimental Results and Discussion Regarding the examples, no galling phenomenon occurred in any of the samples 1 and the high-pressure gas container 20. That is, no damage was observed in either the male screw part 30 of the sample 1 or the female screw part 22 of the high-pressure gas container 20. In Comparative Example 1, galling phenomenon was observed in the seven samples 2 and the seven high-pressure gas containers 20, and the sample 2 and the high-pressure gas container 20 were damaged. Further, no caulking phenomenon was observed in the three samples 2 and the three high-pressure gas containers 20, but the screw ends of the two ends of the male screw portion 30 of the sample 2 were deformed in a erosion shape. . Further, when the sample 2 and the high-pressure gas container 20 are screwed together, the sixth thread from the upper end of the female screw part 22 of the high-pressure gas container 20 with which the tip part of the male screw part 30 of the sample 2 is in direct contact is the surface. I was seen rough. From the above, by subjecting the high pressure gas container valve 10 to an aluminizing treatment and an acid treatment, it is possible to suppress the caulking phenomenon and prevent the male screw portion 30 and the female screw portion 22 from being damaged. I can see it.

  Further, as Comparative Example 2, an experiment was performed in which the surface of the high-pressure gas container valve 10 was modified by a method different from the present invention. The material of the high-pressure gas container valve 10 is SUS316 that is not plasma-treated, and the surface of the container valve 10 is made of an amorphous material such as titanium nitride (TiN), chromium nitride (CrN), or diamond-like carbon (DLC). Carbon was formed as Sample 3. However, in this method, since SUS316 is soft, titanium nitride, chromium nitride, or diamond-like carbon is affected by the properties thereof, and these are affected by the contact pressure between the high-pressure gas container valve 10 and the high-pressure gas container 20. Was peeled off, the surface of the high-pressure gas container valve 10 was exposed, and a galling phenomenon occurred.

  Subsequently, an experiment conducted by the present inventor and obtained as a knowledge leading to the present invention will be described. A sample 1 made of FeAl, a sample 2 made of FeAl (Cr), a sample 3 made of SUS316, and a sample 4 made of CrMo steel were prepared. The mass ratio of the composition of sample 1 is Al: Fe = 28.3: 71.7, and the mass ratio of the composition of sample 2 is Cr: Al: Fe = 11.9: 24.9: 64.2. Each sample 1-4 was immersed in hydrochloric acid aqueous solution, and the mass variation | change_quantity of each material per unit surface area with respect to immersion time was measured.

FIG. 5 shows the result. The horizontal axis of the graph indicates the immersion time, and the unit is kilosecond. The horizontal axis indicates the amount of mass change per unit surface area, and the unit is kg / m ² . As shown in the graph, immediately after the immersion, the mass change amounts of the sample 1 and the sample 2, that is, the corrosion rate, are larger than those of the sample 3 and the sample 4. However, the mass change amount of the samples 1 and 2 decreases with time. As described above, in Samples 1 and 2, the amount of mass change greatly varies with the elapsed time as compared with Samples 3 and 4.

  From this experimental result, it is conceivable that in Samples 1 and 2, a certain film having corrosion resistance against the aqueous hydrochloric acid solution is formed over time. When X-ray diffraction was performed on Samples 1 and 2 and the obtained spectrum was analyzed, a peak indicating AlO (OH) was confirmed in the spectrum obtained from Sample 1. In the spectrum obtained from Sample 2, peaks indicating AlO (OH) and CrO (OH) were confirmed. From this experimental result, the present inventor has reached the present invention.

DESCRIPTION OF SYMBOLS 10 High pressure gas container valve 11 Container valve main body 13 Plug 17 Gas extraction port 19 Gas flow path 20 High pressure gas container 22 Female thread part 30 Male thread part 41 Intermetallic compound layer 42 Passive film

Claims (2)

  A high-pressure gas container valve, wherein at least a surface portion of a screw portion screwed into a high-pressure gas container is subjected to an acid treatment after being aluminized.   The high-pressure gas container valve according to claim 1, wherein the screw portion is made of stainless steel.

Images