JP2001208217A - Valve and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a valve realizing very effective corrosion resistance performance, preventing operation failure and leakage caused by corrosion when used in a production plant for corrosive gas or liquid of halogen such as chlorine or fluorine or a facility consuming or utilizing these gasses, and also provide its manufacturing method. SOLUTION: A fluoride passive film having a thickness of 0.1-5 μm is formed on the surface of a metal film formed on the base surface of the valve. The manufacturing method for the valve comprises a process for forming a metal film on the base surface of the valve, forcedly oxidizing the surface with an oxidizing material, and reacting the forcedly oxidized film with fluoride gas, and an assembly process for connecting structure components of the valve.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plant for producing a halogen-based corrosive gas or liquid such as chlorine or fluorine, a valve used in a facility for using and consuming such a gas, and a method for producing the valve.

[0002]

2. Description of the Related Art Halogen-based gases such as chlorine and fluorine are highly corrosive and toxic high-pressure gases.
A safety structure that does not leak those gases and a corrosion resistance that prevents corrosion by corrosive gases are required. In chlorine (soda) industrial equipment, a gland-type globe valve has been used for many years, and has a feature that the structure is simple and can flow a large flow rate. FIG. 1 shows the structure of a typical globe valve. With this gland seal globe valve structure, when a stem (valve rod) required for opening and closing a valve element moves up and down, the valve box is closed. There is a problem that the leakage of chlorine gas from the gap caused by the fatigue of the gland packing from the penetrating gland part is inevitable, and the seal with the outside (atmosphere) is an O-ring seal of the rotating shaft part. Due to the gland packing seal, the amount of external leakage is extremely large.

Various measures have been implemented for many years as a measure to prevent this gas leakage. FIG. 2 shows an example of such a case. In general, a method is adopted in which the ground portion is made long and four types of packings are superposed in multiple layers to reduce leakage. However, since the packing is inevitably deteriorated due to fatigue, deformation, wear and the like, and it is essentially impossible to completely stop the leakage, it is necessary to replace the packing by performing frequent maintenance. In addition, because the valve seat is sealed at the sliding part between the metal stem and the Teflon-based resin or metal sheet, the valve seat cutoff surface pressure is small and the valve seat leak amount is extremely high.
There is a problem that many particles are generated. It is difficult to prevent the generation of the particles, and the particles accumulate on the sheet portion, making it impossible to completely shut off the particles. Here, if retightening is repeated in order to prevent leakage, a great deal of labor is required for opening and closing work, which eventually causes thread cutting and malfunction. Further, when a conventional ball valve is used in a chlorine production line, when chlorine leaks to the outside, the chlorine reacts with moisture in the atmosphere to generate hydrochloric acid. Forged steel is mainly used for the body and components of the valve. Corrosion occurs rapidly due to the generated hydrochloric acid, and the gland, the stem and the like malfunction, and frequent maintenance and replacement of parts are required. Accordingly, there is a need for a valve that is less likely to leak gas and is less likely to corrode, especially in soda industrial equipment.

[0004] For the above reasons, the following characteristics (1) to (6) are required for valves used for manufacturing and consuming facilities of halogen-based corrosive gas such as chlorine or fluorine gas. I have. (1) Completely shut off from outside and no external leakage. (2) No generation of particles and little generation of particles. (3) Good gas replacement characteristics. (4) Good initial valve seat closing performance. (5) Desorption of released gas and adsorbed moisture from the gas flow path surface of the valve component is good. (6) Good corrosion resistance to halogen-based gas such as chlorine or fluorine.

[0005] That is, (1) is to eliminate the leak from the outside and reduce the contamination of the atmosphere as much as possible. The amount of the leak is determined by the detection limit of the helium (He) leak detector which has the highest sensitivity with the current measuring instrument. Is 2 × 1
^0-8 Pa · m ³ / s / m ² or less is required. This value indicates that the sealing is reliably performed from the outside under conditions such as repeated operation, pressure load, and corrosive atmosphere.
(2) In order to prevent deposits due to abrasion and corrosion products from causing malfunction of the valve, it is necessary to minimize particles generated mainly from the valve seat, which is a sliding portion, particularly by repeated operation. Is shown.
(3) indicates that the valve component needs to have a structure designed to use a component having good gas exchangeability and not to have a stagnation portion (dead space). In addition, (4) shows that there is little leakage from the valve seat immediately after assembly, and that the valve seat has a function that can be completely closed. Quantitatively, 10 ⁻⁶ Pa · m ³ / s / m Must be reduced to ² or less. (5) indicates that since the fluid (gas, liquid) flowing inside is a high-pressure gas having corrosiveness, it is required that the released gas and the adsorbed moisture from the inner surface of the valve be well desorbed. . This is because chlorine gas is hydrolyzed to change into hydrogen chloride and hydrochloric acid, and fluorine gas is changed to hydrofluoric acid to further increase the corrosiveness and accelerate the corrosion because of the permeability. (6) Either use a material with high corrosion resistance or have a surface treatment to increase the corrosion resistance, and use a material with a good balance between corrosion resistance in consideration of price and workability. It is necessary to select a surface treatment method. These (1) to (6)
Since the required characteristics are severe, various types of valves have been proposed.

[0006]

SUMMARY OF THE INVENTION The present invention has been made under such a background, and is directed to a plant for producing a halogen-based corrosive gas or liquid such as chlorine or fluorine, and a facility for utilizing or consuming the gas. It is an object of the present invention to provide a valve that realizes extremely effective corrosion resistance when mounted on a valve, and that prevents operation failure and leakage due to corrosion, and a method of manufacturing the valve.

[0007]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have found that a metal film formed on a substrate surface has a thickness of 0.1 to 5 μm. Using a valve having a fluorinated passivation film formed thereon, it has been found that malfunctions due to corrosion or gas leakage can be prevented, and the above problem can be solved, and the present invention has been completed. The present invention relates to the following valves (1) to (25) and a method for producing the same.

(1) A ball type valve characterized in that a fluorinated passivation film having a thickness of 0.1 to 5 μm is formed on the surface of a metal film formed on the base material surface of the valve. (2) The above (1), wherein the metal film is a nickel film.
Ball-shaped valve according to 1. (3) The ball valve according to the above (1) or (2), wherein the fluorinated passivation film is fluorinated after the metal film is forcibly oxidized. (4) The ball valve according to any one of (1) to (3), wherein rotation of the stem is prevented by a swivel stopper. (5) The above (1) in which the valve structure is a bellows seal structure.
The ball valve according to any one of (1) to (4). (6) The ball valve according to (5), wherein the bellows has a seamless structure. (7) The ball valve according to (5) or (6), wherein the bellows is Hastelloy C-22. (8) The ball valve according to any one of (1) to (7), wherein the valve seat has a soft seal structure, and the soft seal is PTFE. (9) The ball valve according to any one of the above (1) to (8), wherein the gas flow path is S-shaped. (10) The above (1) in which the valve opening is 1/3 or less of the nominal diameter.
The ball type valve according to any one of (1) to (9).

(11) The ball valve according to any one of (1) to (10), which is used for a halogen-based corrosive gas or liquid. (12) On the surface of the metal film formed on the base material surface of the valve,
A gate valve having a fluorinated passivation film having a thickness of 0.1 to 5 μm. (13) The gate valve according to (12), which is used for a halogen-based corrosive gas or liquid. (14) On the surface of the metal film formed on the base material surface of the valve,
A check valve, wherein a fluorinated passivation film having a thickness of 0.1 to 5 μm is formed. (15) The check valve according to (14), which is used for a halogen-based corrosive gas or liquid. (16) A step of forming a metal film on the base material surface of the valve, forcibly oxidizing the surface with an oxidizing substance, and then reacting the forced oxide film with a fluorinated gas, and assembling the structural components of the valve. A method for producing a valve, comprising a step. (17) The method for manufacturing a valve according to the above (16), wherein the metal film is formed by electrolytic or electroless plating of nickel or a nickel alloy.

(18) The valve according to the above (16) or (17), wherein the oxidizing substance is at least one of oxygen, nitrous oxide, nitrous oxide, ozone, and a mixed gas containing these gases. Manufacturing method. (19) The valve manufacturing method according to the above (16) or (17), wherein the oxidizing substance is a solution containing nitric acid or hydrogen peroxide. (20) The method for producing a valve according to the above (16) or (17), wherein the oxidizing substance is oxygen generated at an anode by an anodizing method. (21) The production of a valve according to any of (16) to (20), wherein the fluorinated gas contains at least one gas selected from the group consisting of fluorine, chlorine trifluoride, and nitrogen trifluoride. Method. (22) The valve according to any one of (16) to (21), wherein the assembling step of connecting the structural parts of the valve includes a step of welding the bellows to the bellows ring and welding the bellows ring to the bellows flange. Manufacturing method. (23) The method for producing a valve according to any one of (16) to (22), wherein the valve is a ball valve. (24) The method for producing a valve according to any one of (16) to (22), wherein the valve is a gate valve. (25) The method for manufacturing a valve according to any one of (16) to (22), wherein the valve is a check valve. That is, the present invention provides a “valve characterized in that a fluorinated passivation film having a thickness of 0.1 to 5 μm is formed on the surface of a metal film formed on the base material surface of the valve” and “valve of the valve”. After forming a metal film on the surface of the base material and forcibly oxidizing the surface with an oxidizing substance, the method includes a step of reacting the forced oxide film with a fluoride gas and an assembling step of connecting structural parts of the valve. Characteristic Valve Manufacturing Method ".

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is used in handling a halogen-based corrosive gas such as chlorine or fluorine. In particular, an industrial chlorine gas production plant, a soda electrolysis facility and a facility using chlorine gas, for example, chlorine gas And a valve installed in a chlorine gas bleaching line in a pulp and paper manufacturing facility that sterilizes using water. Specifically, the present invention is a valve in which a fluorinated passivation film having a thickness of 0.1 to 5 μm is formed on the surface of a metal film formed on the base material surface of the valve, and a ball-shaped valve, It can be used as a gate valve or a check valve, and can be used as a valve having various structures such as a ball valve, a butterfly valve, a bellows valve, and a diaphragm valve.

Here, the valve of the present invention will be described by taking as an example a ball valve conventionally used in an industrial chlorine gas production plant and soda electrolysis equipment. First, the lens-shaped valve of the present invention has the following features (1) to (4). (1) A fluoride passivation film having a thickness of 0.1 to 5 μm is formed on the surface of the metal film formed on the base material surface of the valve. (2) The structure of the valve is a bellows seal structure. (3) The valve seat has a soft seal structure, and PTFE is used for the soft seal. (4) The gas flow path is S-shaped, and the valve opening is 1 /
3 or less.

Each of the above features (1) to (4) will be described in detail. (1) The body and components are usually made of low-temperature carbon steel or SUS304. These materials are
Since corrosion countermeasures are required when used for corrosive gas such as chlorine, the present invention provides a metal film formed on a base material surface of a valve with a film thickness of 0.1 to 5 μm, preferably 1 to 5 μm. ~ 3μ
The corrosion resistance is improved by forming a fluorinated passivation film of m, more preferably 1-2 μm. (2) Most leaks from the conventional ball valve are caused by leaks from the gland packing part. Since a general globe valve has a gland seal structure, it is impossible to eliminate leakage structurally. Particularly, toxic gases such as chlorine gas and fluorine gas are dangerous, so it is desirable to structurally eliminate external leakage from the ground portion. For this reason, the present invention employs a bellows seal structure. The bellows, which is the most movable member, is made of Hastelloy, which is seamlessly and hydraulically molded in consideration of corrosion resistance and life, and is preferably made of Hastelloy C-22. Further, the stem usually rotates with the vertical movement, and the rotation causes wear and deterioration of the gland portion, which causes gas leakage. In the present invention, a swivel stopper (rotation stop) is used to prevent the rotation of the stem, the movement of the stem is only up and down movement, and the thin bellows is not twisted,
The life of the valve can be extended. In addition, the sealing property between the seat disk and the seat ring is improved, and a double seal structure with no internal leakage or external leakage is realized.

(3) A soft seal made of PTFE is used to improve the shut-off performance by using a soft seal structure for the valve seat portion and to prevent leakage even if some foreign matter is bitten. As a result, the closing torque of the handle can be reduced, and the structure can be replaced very easily.
The soft seal can be replaced with, for example, a Monel metal sheet, and in this case, the corrosion resistance to liquefied chlorine can be further improved. (4) The flow path of the gas is S-shaped, and the flow rate is secured and the size is reduced. In current commercially available gland seal globe valves, the inlet flow path is arranged linearly in line with the center of the front and rear piping lines, and the outlet has a steeply inclined hole from the top of the valve box Therefore, unless the opening degree of the valve body (disk holder and disk) is made large, the resistance becomes large, so that the pressure loss becomes large and the flow rate cannot be secured. For this reason, the valve is designed so that the valve opening is equal to or more than 呼 び of the nominal diameter. According to the bellows seal globe valve of the present invention, in order to solve the conventional problem, when the valve body is opened by taking a gas flow path in an S shape, the fluid discharged from the valve seat immediately flows to the outlet. As described above, the outlet side oblique hole is directly connected to the valve seat. With this structure, the wrist (valve opening) is reduced to 1/3 of the nominal diameter, the bellows can be stored in the body, and compactness can be achieved.

FIG. 3 shows the structure of a bellows seal ball valve according to an embodiment of the present invention. 25 in the figure is a stem, 2
Reference numeral 1 denotes a swivel stopper, which has a structure for preventing the rotation of the stem 25 as described above. Reference numeral 22 denotes a ground packing, which has a double sealing structure for preventing foreign substances from entering the bellows 24 and preventing gas leakage even if the bellows is damaged. 26 is a soft sheet,
Reference numeral 27 denotes a seat ring, and reference numeral 28 denotes an S-shaped gas flow path. The gas flows from the left side of the valve to the right side of the drawing.

Next, a method for manufacturing the valve of the present invention will be described. The method of manufacturing a valve according to the present invention includes a step of forming a metal film on a base material surface of the valve, forcibly oxidizing the surface with an oxidizing substance, and then reacting the forced oxide film with a fluorinated gas. It is characterized by including an assembling step of connecting the structural parts. Here, after forming a metal film on the base material surface of the valve and forcibly oxidizing the surface with an oxidizing substance,
The inventors of the present invention have disclosed a process of reacting the forced oxide film with a fluorinated gas in Japanese Patent Application Laid-Open No. 11-92912.

That is, in the present invention, first, a metal film is formed on the base material surface of the valve. This metal coating is nickel,
Electroplating, electroless plating, physical vapor deposition (PV) of copper, silver, aluminum or an alloy containing one or more of these
D) and the like. Ni plating, Ni-Cu plating, Ni-W
Plating and the like. For electroless plating, Ni-
P plating, Ni-B plating, Ni-PW plating, Ni
-PB plating and the like. In addition, as the PVD, a sputtering method of Ni or an alloy thereof is used. Preferably, a film formed by electrolytic or electroless plating of nickel or a nickel alloy is preferable. As described above, the base material of the valve for forming the film is usually made of low-temperature carbon steel or SUS304. Before forming the metal film, a known base treatment such as degreasing, pickling, polishing, or shot blasting is performed.

Next, the surface of the metal film is once forcibly oxidized, and then the metal oxide film is reacted with a fluorinated gas. This is because in natural oxidation, the thickness of the oxide film is several tens to several hundred angstroms, and the metal on which a strong oxide film is formed is limited to a specific metal such as aluminum. When fluorination is performed after forced oxidation, a substitution reaction between oxygen and fluorine occurs to form a fluorinated layer. Therefore, the thickness of the fluoride layer increases in proportion to the thickness of the forced oxidation layer, and the thickness of the fluoride layer formed on the surface of the metal film according to the present invention depends on the thickness of the oxide film formed on the surface. By controlling, it is possible to provide a fluoride film having a greater thickness than obtained by so-called passivation. The fluorinated layer thus formed has a level of performance that can withstand practically and sufficiently in corrosion resistance and durability. The fluorinated layer is a layer containing fluorine in a broad sense, but is preferably substantially composed of fluoride. Here, fluoridation has a substantial meaning, and the oxidized metal film is 1
It is not necessary to change to 00% fluoride, but it is preferred that the oxygen be replaced with fluorine below the detection level. The metal does not necessarily need to be uniformly fluorinated, the thickness of the fluorinated layer may be non-uniform, and the fluoride region and the fluorine diffusion region may be mixed. If the fluorination treatment is performed after the forced oxidation, not only is the oxide layer replaced with fluorine to generate fluoride, but also diffusion of fluorine into the metal of the film occurs, and as a result, a thick fluoride layer can be formed. In this case, the fluorinated layer is composed of a first layer substantially made of metal fluoride and a second layer in which fluorine is diffused into a lower layer.

As the forced oxidation means, so-called gas phase oxidation is possible. In this case, oxygen or a mixed gas thereof with a neutral or inert gas is preferable. In addition, nitrous oxide, nitrogen peroxide, ozone, A mixed gas of hydrogen and a neutral or inert gas is also preferable. In this case, these gases are brought into contact with the metal at a high temperature. Another forced oxidation means includes liquid phase oxidation. This can also be carried out by immersion in a solution such as nitric acid or hydrogen peroxide solution. Further, the metal can be anodized using an electrolytic solution such as an alkali to form an oxide film on the surface. As described above, the methods of the forced oxidation treatment can be combined according to the thickness of the oxide film to be formed.

Similarly, the fluorination treatment is performed by using a 100% gas such as fluorine, chlorine trifluoride, or nitrogen trifluoride, or a gas obtained by diluting these gases with an inert gas such as nitrogen, helium, argon, or the like. In this method, an oxide film formed on the outermost layer on the metal surface is reacted with a plasma gas such as the above to obtain a fluorine diffusion layer or a fluoride film. Specifically, the following may be performed. That is, the metal as described above is mounted in a normal-pressure gas-phase flow reactor, the reactor is heated to a predetermined temperature under a flow of an oxidizing gas, held for a predetermined time, and further fluorinated at a predetermined temperature. The surface may be fluorinated by filling with gas and reacting for a predetermined time. In this case, the metal is degreased and dehydrated in a usual manner before being charged into the reaction furnace to increase the purity of the forced oxide film formed thereafter and have no defects. However, the thin native oxide film of several tens of angstroms catabolism remaining on the metal surface is forcibly oxidized together with the bulk, so that it is not necessary to remove it before the forcible oxidation.

Further, the temperature of the reaction furnace is usually from 200 ° C. to 600 ° C., particularly preferably from 300 ° C. to 500 ° C. in the forced oxidation of nickel and copper. The reaction time is usually preferably 1 hour to 48 hours, particularly preferably 3 hours to 24 hours. Aluminum is preferably formed by anodic oxidation. Similarly, the fluorination temperature is usually 100 ° C to 700 ° C under normal pressure,
In particular, 150 ° C to 500 ° C is preferable. Further, the reaction time is usually preferably 1 hour to 48 hours, particularly preferably 3 hours to 24 hours. Below these preferred lower limit temperatures and times, the oxygen in the forced oxidation layer is not sufficiently replaced by fluorine, and the diffusion of fluorine from the outermost surface is not sufficient. And cracks occur in the formed film.

Next, a process of assembling structural parts using the base material of the valve on which the fluorinated passivation film is formed will be described. When a bellows seal structure is adopted for the valve, the bellows is welded in this step. Hastelloy is used for the material of the bellows in consideration of corrosion resistance.
When a Hastelloy bellows is directly welded to stainless steel, there arises a problem that the corrosion resistance of the welded portion is deteriorated. Therefore, in the present invention, a method is used in which a bellows is welded to a bellows ring made of Hastelloy, and the bellows ring is fitted to a bellows flange made of stainless steel and a disk holder and then welded. In the welding, for example, if nickel having high corrosion resistance is used, only the Hastelloy and nickel welds are exposed in the gas contact portion, and a structure in which the corrosion resistance of the weld is not deteriorated can be obtained.

[0023]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. (Formation of Electroless Ni-P Plating Film) After subjecting the body made of forged low-temperature steel and other components made of SUS304 to a pre-treatment by degreasing, pickling, etc., the temperature is raised to 90 ° C.
It was immersed in a plating solution tank adjusted to a predetermined pH. After reacting for a predetermined time, a Ni-P plating film having a thickness of 20 μm was formed on the entire surface. The electroless Ni-P plating used here is called so-called chemical nickel plating, and a commercially available chemical of acidic chemical nickel plating by reduction of hypophosphite has been put to practical use. In this example, a commercially available chemical nickel plating using sodium hypophosphite as a reducing agent, that is, nickel-phosphorus plating (Ni-P alloy plating) was used. These drugs are mainly composed of NiS, which is a metal component.
O ₄ (nickel sulfate) 25 g / L, NaH as reducing agent
It is composed of 20 g / L of PO ₂ (hypophosphorous acid), a complexing agent, a stabilizer and a brightener.

(Formation of oxide film / fluorination treatment) Ni-P
The plated component was mounted inside a normal-pressure gas-phase flow reactor, and heat-treated at 200 ° C. for 5 hours under reduced pressure to release moisture adsorbed on the surface. Thereafter, oxygen gas (99.99
9%), the temperature was raised to 400 ° C., and the temperature was maintained for 12 hours to forcibly oxidize the metal surface. afterwards,
The system was gradually cooled while replacing the oxygen gas with a nitrogen gas. When the temperature reached 350 ° C., the introduction of 20% F 2 gas (diluted with nitrogen) was started, and after the gas was completely replaced, it was kept as it was for 24 hours to fluorinate the surface. After a predetermined time, the fluorine gas is replaced with nitrogen, and
Hold for a time and cool to room temperature. The thickness of the obtained fluorinated passive film was about 1.5 μm.

A structural component such as a bellows seal was assembled by welding or the like to the valve obtained by the above method and having a fluorinated immobilized film formed on the surface, and mounted on a chlorine production line and then actually used. As a result, there was no change in the initial flow rate characteristics in continuous use for one month and three months. Also,
There is no leakage from the valve seat and gland,
The valve was once removed and dismantled to check the internal corrosion, but there was no evidence of corrosion.

[0026]

As described above, the valve of the present invention can be installed in a facility for producing or using a halogen-based high-pressure gas which is highly corrosive and toxic, such as chlorine or fluorine. It is very useful because it can be a safe facility that does not leak those gases and can prevent corrosion by the gases.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a typical gland seal ball valve.

FIG. 2 is a cross-sectional view of the gland seal portion of the improved ball valve.

FIG. 3 is a sectional view of a bellows seal ball valve according to the embodiment of the present invention.

[Description of Signs] 1 Handle 2 Stem 3 Spacer 4 Ground Packing 5 Ground Packing 6 Valve Body 7 Flange 8 Body 11 Stem 12 Spacer 13 Ground Packing 14 Ground Packing 15 Backsheet 16 Valve Body 21 Swivel Stopper 22 Ground Packing 23 Backsheet 24 Bellows 25 Stem 26 Soft seat 27 Seat ring 28 S-shaped channel

Claims (25)

[Claims] 1. A ball-shaped valve comprising a metal passivation film having a thickness of 0.1 to 5 μm formed on a surface of a metal film formed on a base material surface of the valve. 2. The ball valve according to claim 1, wherein said metal film comprises a nickel film. 3. The ball valve according to claim 1, wherein the fluorinated passivation film is fluorinated after a metal film is forcibly oxidized. 4. The ball-shaped valve according to claim 1, wherein rotation of the stem is prevented by a swivel stopper. 5. The ball type valve according to claim 1, wherein the valve has a bellows seal structure. 6. The globe valve according to claim 5, wherein the bellows has a seamless structure. 7. The ball valve according to claim 5, wherein the bellows is Hastelloy C-22. 8. The globe valve according to claim 1, wherein the valve seat has a soft seal structure, and the soft seal is PTFE. 9. The ball-shaped valve according to claim 1, wherein the gas flow path is S-shaped. 10. The globe valve according to claim 1, wherein the valve opening degree is 1/3 or less of the nominal diameter. 11. The ball valve according to claim 1, which is used for a halogen-based corrosive gas or liquid. 12. A gate valve characterized in that a fluorinated passivation film having a thickness of 0.1 to 5 μm is formed on a surface of a metal film formed on a base material surface of the valve. 13. The gate valve according to claim 12, which is used for a halogen-based corrosive gas or liquid. 14. A check valve characterized in that a fluorinated passivation film having a thickness of 0.1 to 5 μm is formed on a surface of a metal film formed on a base material surface of the valve. 15. The check valve according to claim 14, which is used for a halogen-based corrosive gas or liquid. 16. A step of forming a metal film on the base material surface of the valve, forcibly oxidizing the surface with an oxidizing substance, and then reacting the forced oxide film with a fluorinated gas, and connecting the structural parts of the valve. A method for manufacturing a valve, comprising an assembling step. 17. The method according to claim 16, wherein the metal film is formed by electrolytic or electroless plating of nickel or a nickel alloy. 18. The method according to claim 16, wherein the oxidizing substance is at least one of oxygen, nitrous oxide, nitric oxide, ozone, and a mixed gas containing these gases. 19. The method according to claim 16, wherein the oxidizing substance is a solution containing nitric acid or hydrogen peroxide. 20. The method according to claim 16, wherein the oxidizing substance is oxygen generated at an anode by an anodic oxidation method. 21. The method according to claim 16, wherein the fluorinated gas contains at least one gas selected from the group consisting of fluorine, chlorine trifluoride, and nitrogen trifluoride. . 22. The valve according to claim 16, wherein the assembling step of connecting the structural parts of the valve includes welding a bellows to a bellows ring and welding the bellows ring to a bellows flange. Production method. 23. The method for manufacturing a valve according to claim 16, wherein the valve is a ball valve. 24. The method according to claim 16, wherein the valve is a gate valve. 25. The method according to claim 16, wherein the valve is a check valve.