JP2003028315A - Manufacturing method of nuclear/thermal power plant valve device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a valve having excellent corrosion/erosion resistance and maintainability by joining corrosion/wearing resisting alloy wherein eutectic carbide is discontinuously distributed to a sliding portions of various apparatus and valves by brazing, to improve the maintainability of thermal power plant and a nuclear power plant, and to provide the nuclear power plant being excellent in the safety of work and having a system for circulating primary cooling water. SOLUTION: In this valve and apparatus such as a nuclear power plant using the valve, eutectic carbide in alloy having a casting organization basic material portion and the eutectic carbide is formed in plural lumps or plural particles. corrosion/wearing resisting alloy wherein the eutectic carbide is discontinuously distributed is joined to a sliding portion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve in which a sliding portion is joined with a corrosion / wear resistant alloy and a nuclear / thermal power plant using the valve.

[0002]

2. Description of the Related Art In recent years, in turbine power generation facilities and the like, chemicals such as hydrogen peroxide solution and hydrazine have been injected into the circulating water system for adjusting the quality of the circulating water, and the chemicals dissolved downstream from the injection point of the chemicals. The amount of oxygen increases, and as a result, the valve seat surface of the valve is damaged by erosion and galling.

Japanese Unexamined Patent Publication No. 59-179283 discloses C
r30-45 wt%, Ti3.0-8.0 wt%, Mo
A valve in which a valve seat composed of 0 to 10% by weight and the balance Ni is diffusion-bonded to a valve body and a valve box is disclosed.

Valves such as a globe valve, a sluice valve, and a butterfly valve are corrosion and corrosion resistant in order to prevent erosion damage due to fluid near the valve seat during actual operation or to prevent galling during valve operation. High hardness cobalt (C
Surface-welding alloys such as o) base alloys, nickel (Ni) base alloys, and iron (Fe) base alloys are used by overlaying the sliding portion and / or the valve seat portion of the valve.

However, eutectic carbides such as cobalt (Co) -based alloys which are built up on the sliding portion and the valve seat portion of the valve are selectively corroded and damaged. The fluid in the circulating water system has a high temperature, high pressure, and high speed, and following the above-mentioned corrosion damage, the matrix portion of the casting structure may fall off, and erosion may occur.
(Thermal power generation: Vol. 30, No. 5, p. 67 and "Damage to machinery": 1982, No. 2, p. 90).

As a result, the leakage resistance of the valve is lowered,
Problems such as changes in valve control characteristics and operating characteristics occur,
The frequency of valve overhauls increases, and the maintainability of the plant decreases.

Particularly in the nuclear power generation equipment, when the above-mentioned event occurs in the sliding parts in contact with the reactor water and the valves of the system equipment for supplying the cooling water into the reactor, the high hardness of the high hardness accumulated in these parts. Co base, Ni base, Fe alloy, etc.
There is a risk that it will fall off due to erosion and enter the system.

In Japanese Patent Laid-Open No. 59-179283, C
r30-45 wt%, Ti3.0-8.0 wt%, Mo
It is proposed that a valve seat composed of 0 to 10% by weight and the balance Ni be diffusion-bonded to the valve body and the valve box. In addition, JP-A-6
In 0-86239, Cr 30 to 45 wt%, A
at least one of l and Ti 1.5 to
It is proposed that a valve seat consisting of 6.0 wt%, Mo 20 wt% or less, and the balance being Ni is diffusion-bonded to the valve body and the valve box.

[0009]

As described above, Co having a conventional cast structure matrix and a network-like eutectic carbide is used.
Corrosion resistance and erosion resistance of base-based, Ni-based, and Fe-based overlay metals are not sufficient. The purpose of the present invention is to obtain these Co
Corrosion-resistant / wear-resistant alloy in which eutectic carbides of base, Ni-based and Fe-based alloys are discontinuously distributed in the form of lumps and particles is joined to the sliding parts of valves of nuclear power plants and thermal power plants by brazing for corrosion resistance / Provide a valve with excellent erosion resistance and maintainability.

An object of the present invention is to improve the maintainability of nuclear power plants and thermal power plants by improving the corrosion resistance and erosion resistance of the sliding parts of valves used in the facilities of nuclear power plants and / or thermal power plants. In particular, it is to provide a nuclear power plant having a primary cooling circulating water system excellent in work safety.

[0011]

The gist of the present invention is as follows.

The first means is to subject the alloy having the cast structure matrix and the eutectic carbide to plastic working by forging or rolling and heat treatment to form the eutectic carbide in a discontinuous lump or granular form to form a lump. It is a valve in which a corrosion-resistant / wear-resistant cobalt-based alloy in which a eutectic carbide having a diameter or particle size of 30 μm or less is distributed is brazed to a sliding portion. Cobalt-based alloys are, for example, C1-3% by weight, Si2% or less, Cr10-32%,
W4-15%, Fe3% or less, Ni3% or less, Mo5%
Those that include the following are preferred.

A corrosion-resistant and wear-resistant alloy in which the eutectic carbide is lumped or granular in a discontinuous distribution by applying plastic working by forging or rolling and heat treatment to the alloy having the cast structure matrix and the eutectic carbide It is preferable that the sliding portion is joined by brazing. Further speaking, the brazing and joining of the foil and the flux of the insert material having a lower melting point than the base material,
It is preferable to perform a brazing joint by inserting a brazing paste material or the like into the combined joint interface. By setting the lump diameter or the grain diameter to 30 μm or less, it is possible to maintain better toughness than the conventional hardfacing alloy.

A second means is a nuclear power plant in which a pipe having a valve is installed in a system in which primary cooling water of a nuclear reactor circulates, and a sliding portion of the valve has a cast structure base portion and a eutectic carbide. A nuclear power plant having a corrosion-resistant and wear-resistant alloy in which the eutectic carbides in the alloy are discontinuously distributed in a lump or granular form. A corrosion-resistant and wear-resistant alloy is brazed to form an alloy having a cast structure matrix and eutectic carbide, which is plastically processed by forging or rolling and heat-treated to form the eutectic carbide in a lumped or granular form with a discontinuous distribution. Is preferably joined to the sliding portion.

A third means is a Co-based, Ni-based, and Fe-based corrosion-resistant corrosion-resistant Co-based alloy in which a eutectic carbide is formed in a lump or a grain in a discontinuous sliding portion of a feed valve which comes into contact with reactor water of a nuclear power plant.
A nuclear power plant in which wear-resistant alloys are joined by brazing.

A fourth means is a Co-based, Ni-based and Fe-based corrosion-resistant corrosion-resistant Co-based, Ni-based and Fe-based alloy which forms a lumpy or granular eutectic carbide in the sliding portion of the feed valve which comes into contact with the reactor water of the nuclear power plant. A nuclear power plant in which wear-resistant alloys are joined by friction welding.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is a Co-based alloy, N, which is used as a wear resistant material for sliding parts of equipment, valve seats of valves and the like.
Of the matrix of the casting structure and the eutectic carbides that form the surface-deposited metal such as i-based alloys and Fe-based alloys, the eutectic carbides that are continuously distributed in the form of a mesh are discontinuous in the form of lumps or particles to prevent corrosion and resistance. The wear alloy is joined to the sliding parts of various devices and valves by brazing or friction welding to suppress the increase of the friction resistance of the sliding parts of the devices and valves. The present invention relates to a device and a valve which are characterized in that the deterioration of the leakproof performance due to the roughening of the material is suppressed.

In order to discontinue the eutectic carbide continuously distributed in the form of a mesh in the form of lumps or particles, for example, the surface welding alloy for overlay welding is subjected to plastic working such as forging and rolling and heat treatment (annealing). However, the method is not limited to this.

The joining of the corrosion-resistant and wear-resistant alloy having the discontinuous eutectic carbide to the sliding portion can be realized by brazing. In brazing, an insert material (brazing material) with a melting point lower than that of the base material (non-bonding material) is inserted into the joint interface, the insert material melts at the time of joining, and the chemical bonding force between the base material and the bonding material increases. Brazing and joining can be performed by utilizing physical adhesive strength. The deformation due to joining can be suppressed to a small level. In addition, brazing can be performed with a machined finish accuracy of the joint surface of about 30 μm.

According to the present invention, in a normal state, eutectic carbides are continuous in a network and are used for overlaying Co group, Ni group, Fe.
Corrosion resistance of discontinuous eutectic carbides by changing the eutectic carbides into agglomerates or granules for welded alloys such as bases
It becomes a wear resistant alloy. By brazing and joining this corrosion- and wear-resistant alloy to the sliding parts of valves and equipment, the amount of dissolved oxygen is increased by injecting chemicals such as hydrogen peroxide and hydrazine into the circulating water system, Suppresses the corrosion damage of existing eutectic carbides in the sliding parts of valves and equipment, and at the same time suppresses the increase in the friction resistance of sliding parts and the deterioration of the leakage resistance due to the roughness of the valve seat surface, etc. Valve and equipment can be provided. Further, according to the present invention, a plate material that has been subjected to plastic working such as forging or rolling and heat treatment (annealing), a Co-based material having a lump or granular eutectic carbide cut out from a bar material, a Ni-based material, and Fe.
By brazing a corrosion resistant / wear resistant alloy such as a base to a valve seat or the like, it is possible to provide a safety valve, a sluice valve, a sphere valve or the like in which corrosion damage or erosion damage of the valve seat or the like caused by dissolved oxygen is reduced.

Further, according to the present invention, it is possible to suppress the scattering and diffusion of Co due to the corrosion, erosion, wear, etc. of the Co-based alloy used in the valves of nuclear power generation facilities, and the nuclear power plant with excellent maintainability. Can be provided.

Conventionally, in order to prevent erosion and galling, for example, high hardness of 1.3% by weight C, -27.7% by weight Cr is applied to the sliding portion of the valve, the valve seat portion and the sliding portion of the equipment. ,
A Co-based alloy containing -4.9 wt% W is used as the surface welding alloy. These are gas welding, PTA (Plas
It is built up by electric arc welding such as ma transfer arc). However, in the above Co-based alloy, the eutectic carbides containing Cr and C as the main components are continuous in a matrix form in the matrix of the cast structure containing Co as the main component, and their corrosion and erosion are dissolved. Oxygen corrodes the network-shaped eutectic carbide, and the matrix portion of the cast structure is likely to drop off and progresses.

In the Co-based corrosion resistant and wear resistant alloy of the present invention, a step of performing plastic working such as forging and rolling and subsequent heat treatment (annealing) or a step of hot forging and hot rolling at high temperature is added. Therefore, the eutectic carbides are discontinuously distributed in the cast structure matrix in the form of lumps or grains, and the corrosion damage of the carbide due to dissolved oxygen is limited to only the carbide on the surface in contact with the dissolved oxygen. Dropout is suppressed.

The above effect is obtained by Co-1.3% C- having a eutectic carbide in the form of a mesh or a eutectic carbide in the form of lumps or particles.
It can be confirmed by a grain boundary corrosion test (Strauss test: JIS G0575) of a 27.7% Cr-4.9% W alloy. When the eutectic carbide is in the form of a mesh, the corrosion depth in the Strauss test is 1/3 when it is in the form of lumps or grains.
It is suppressed to about 00.

The valve to which the present invention is applied is not particularly limited and can be applied to various safety valves, sluice valves, lens valves and the like. (Example 1) In this example, a grain size of 30 μ was obtained by hot forging at 1050 to 1150 ° C. and hot rolling at the same temperature.
1. With high hardness, which formed lumpy or granular carbides of m or less.
A corrosion-resistant and wear-resistant Co-based alloy containing 1 wt% C, 27.7 wt% Cr, and 4.5 wt% W was joined by brazing to the valve seat of a sluice valve used in a dissolved oxygen atmosphere.

The structure of the sluice valve is shown in FIGS. Figure 1
Shows a sectional view of a sluice valve according to the present embodiment. Figure 2
Shows an enlarged view of the valve body, and FIG. 3 shows an enlarged view of the valve box. FIG. 1 is a vertical cross-sectional view of a sluice valve made of a cast of SCPH2 (S25C equivalent product). First, the ring 100 in which the eutectic carbide is discontinuously lumped or granulated to the valve body 50 of FIG.
a was joined. FIG. 3 shows an enlarged view of the valve box. Valve box 511
A ring 100b in which a eutectic carbide was discontinuously distributed and which was in the form of lumps and granules was joined. A flux-coated insert material is placed on the joint surface, and the above-mentioned corrosion-resistant and wear-resistant Co-based alloy in the form of a ring plate having a thickness of 6 mm in which eutectic carbide is lumped or granular is brazed on the insert material. Joined. The insert material has a thickness of 0.5 mm, and its solidus temperature and liquidus temperature are about 650 ° C. and 690 ° C., respectively.
℃. The brazing and joining conditions are brazing and joining temperature: 8
00 ° C, holding time: 1 hour, vacuum degree: 2 × 10 ^-4 Tor
r, applied pressure: 100 g / cm ² .

After the brazing and welding, the cross-section of the joint interface was observed.
When applied, almost no bonding defects such as voids were observed.
However, a good brazed joint state was exhibited. In addition, this embodiment
The sluice valve manufactured by
Of the base material in the casting structure is suppressed
Therefore, the corrosion of the valve seat 1 and the progress of erosion are suppressed.
As a result, the leakage resistance is prevented from deteriorating. (Example 2) In this example, at 1050 ° C to 1100 ° C
Eutectic carbides were made into lumps or granules by hot forging
1.1% by weight of hardness C-29.7% by weight Cr-4.5 weight
Corrosion-resistant / wear-resistant Co-based alloy containing amount% W for brazing
Therefore, attach it to a reverse valve that is used in a dissolved oxygen atmosphere.
It was FIG. 4 shows a cross-sectional view of the check valve according to this embodiment.
It Bonding conditions: 800 ° C in air, holding time: 1 hour
Pressure, 100 g / cm ²And Brazing joint
When the cross section of the surface was observed, junction defects such as voids
It was not observed so much and showed a good bonding state. Also,
The check valve manufactured in this example is a eutectic carbide due to dissolved oxygen.
Corrosion is suppressed and the base material of the casting structure is prevented from falling off.
Therefore, corrosion of the valve seat surfaces 1a and 1b is suppressed,
The deterioration of the leakage resistance performance is prevented.

Although the flux is applied to the insert material and the Co-based alloy is brazed and joined in the above-mentioned Examples 1 and 2, the Ni-based alloy and the Fe-based alloy can be similarly applied. (Example 3) In this example, a grain size of 30 μ was obtained by hot forging at 1050 to 1150 ° C. and hot rolling at the same temperature.
1. With high hardness, which formed lumpy or granular carbides of m or less.
Corrosion- and wear-resistant Co-based alloy containing 1 wt% C, 29.7 wt% Cr, and 4.5 wt% W is used for the valve seat of a small sluice valve used in a control system in a dissolved oxygen atmosphere by friction welding. Joined. As a welding condition for friction welding, the fixed side is SCPH2.
(S25C equivalent product) Corrosion resistance of valve body and ring side on the rotating side
Wear-resistant Co-based alloy, friction pressure 5-10 kg / mm ² ,
A partition valve body having an upset pressure of 10 to 20 kg / mm ² , a friction time of 10 to 20 S, a rotation speed of 2500 to 3000 rpm, and a diameter of 50 mm was manufactured. The valve seat side was also manufactured under the above conditions.

As a result of observing the cross section of the joining interface after friction welding, no joining defects such as joining defects, cracks, and fused parts were observed, and a good friction welding joining state was shown. Further, since the sluice valve manufactured in this example suppresses the continuous corrosion generation of the eutectic carbide due to the dissolved oxygen and the falling of the base material portion of the cast structure, the corrosion / erosion of the valve seat 1 is suppressed. The progress is suppressed, and the deterioration of the leakproof performance is prevented.

FIG. 5 is an example of a piping system diagram of a nuclear power plant in which the valve of the present invention is used for system equipment for circulating primary cooling water.

The valve according to the present invention is present in a large number in the system equipment in which the primary cooling water circulates, and therefore the illustration is omitted.

In the nuclear power plant shown in FIG. 5, the primary cooling water is heated in the reactor pressure vessel 14 and becomes high-temperature high-pressure steam, which is introduced into the high-pressure turbine 18 through the main steam pipe 15. Next, the exhaust steam from the high-pressure turbine 18 is introduced into the low-pressure turbine 19 to drive the generator 20. Exhaust steam from the high-pressure turbine 18 and the low-pressure turbine 19 passes through the main water cover 10, and then through the water supply system 6 having many valves of the present invention, the water supply pump 30, the high-pressure water supply heater 31, and the water supply pipe 9.
Water is reciprocated to and from the reactor pressure vessel 14 through.

The present invention is effective in extending the life of the equipment and valves in a nuclear power plant, and can reduce the radiation exposure of workers in the plant.

Further, the method of the present invention is applied not only to the sluice valve and the check valve described above but also to sliding parts such as valve seats of safety valves, target valves, etc., to reduce the leakage resistance performance and controllability. -It has the effect of suppressing the deterioration of operating performance.

By using the above valves in combination, this is performed in plant equipment such as turbine power generation equipment. Corrosion and erosion of sliding parts such as valve seats of valves due to the influence of dissolved oxygen due to injection of hydrogen peroxide water for the purpose of water quality control can be suppressed, and it is effective in improving the safety of plant equipment such as turbine power generation equipment. is there.

In particular, in nuclear power generation equipment, the eutectic carbides of Co-based alloys such as valve seats and cages of valves of system equipment for supplying cooling water to the sliding parts in contact with the primary cooling water and corrosion of the eutectic carbides are removed. Providing a nuclear power plant that suppresses the outflow and diffusion of Co into the system, and also suppresses the removal of the base of the casting structure mainly composed of Co, which has reduced erosion resistance due to the corrosion loss of eutectic carbides. To do.

[0037]

As described above, according to the apparatus and valve of the present invention, the sliding portion or valve seat portion of the valve is less rough due to the corrosion damage of the eutectic carbide due to the dissolved oxygen in the fluid, and the sliding It is possible to reliably maintain the increase in frictional resistance at the valve seat and the valve seat, and the prevention of leakage at the valve seat.

Further, the nuclear power plant of the present invention can prolong the life of the equipment and valves in the plant, and can reduce the radiation exposure of workers in the plant.

[0039]

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a sluice valve.

FIG. 2 is an enlarged view of a valve body portion of a gate valve.

FIG. 3 is an enlarged view of a valve box valve seat portion of the sluice valve.

FIG. 4 is a vertical sectional view of a check valve.

FIG. 5 is a piping system diagram of a nuclear power plant using the valve of the present invention for a water supply system.

[Explanation of symbols]

50 ... Valve body, 100a ... Co that is made of lumps and particles of carbide
Base alloy ring, 511 ... Valve box valve seat, 100b ... Cobalt alloy ring in block shape, 5 ... Cooling water purification system heat exchanger, 6 ... Water supply valve system, 7 ... Water supply heater, 8 ... Recirculation system Piping, 9 ... Water supply pipe, 10 ... Main condenser, 11 ... SLC tank, 12 ... SLC pump, 13 ... Containment vessel, 14 ... Reactor pressure vessel, 15 ... Main steam pipe, 16 ... Water supply pipe, 17 ... Wet Minute analyzer, 18 ... high-pressure turbine, 19 ... low-pressure turbine,
20 ... Generator, 21 ... Main transformer, 22 ... Exhaust pipe, 23 ...
Off-gas treatment system, 24 ... Air extractor, 25 ... Low-pressure condensate pump, 26 ... Grand steam condenser, 27 ... Condensate storage tank,
28 ... Condensate filtration device, 29 ... Condensate desalination device, 30 ... Water supply pump, 31 ... High pressure water heater, 32 ... Control rod drive system,
33, 36 ... Heat exchanger, 34 ... Filtration demineralizer, 35 ... Reactor isolation cooling system.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshihisa Kiyoshi             3-1-1 Sachimachi, Hitachi City, Ibaraki Prefecture Stock Association             Hitachi, Ltd. Nuclear Business Division (72) Inventor Akira Sakamoto             3-1-1 Sachimachi, Hitachi City, Ibaraki Prefecture Stock Association             Hitachi, Ltd. Nuclear Business Division (72) Inventor Yoshiteru Chiba             Hitachi, 3-10-3 Bentencho, Hitachi City, Ibaraki Prefecture             Kyowa Engineering Co., Ltd. (72) Inventor Shizuo Matsushita             Hitachi, 3-10-3 Bentencho, Hitachi City, Ibaraki Prefecture             Kyowa Engineering Co., Ltd. F-term (reference) 3H052 AA02 BA23 CA38 CA39 CB38                       CB39 EA10                 3H054 AA01 BB13 CA39 CA40 CC08                       CC09 GG10

Claims (7)

[Claims] 1. A sliding portion is a cobalt-based alloy, a nickel-based alloy or an iron-based alloy having a eutectic carbide in a forged or rolled metallographic structure, and the shape of the eutectic carbide is discontinuously lumpy or granular. And / or a valve seat portion is brazed to the valve seat portion, and a method for manufacturing a valve device for a nuclear / thermal power plant. 2. A cobalt-based alloy, a nickel-based alloy or an iron-based alloy having a eutectic carbide in a forged or rolled metallographic structure portion, the shape of the eutectic carbide being discontinuous and in the form of lumps or particles of 30 μm or less. A method for manufacturing a valve device for a nuclear / thermal power plant, which is brazed to a moving part and / or a valve seat part. 3. Sliding a cobalt-based alloy, a nickel-based alloy or an iron-based alloy having a eutectic carbide in the forged or rolled metal structure, and the shape of the eutectic carbide is discontinuous and is a lump or granularity of 30 μm or less. And / or valve seat portion, which is brazed in a temperature range of 50 ° C. lower than the solidus temperature of the sliding member to 300 ° C., the nuclear / thermal power generation. Manufacturing method of plant valve device. 4. Sliding a cobalt-based alloy, a nickel-based alloy or an iron-based alloy having a eutectic carbide in the forged or rolled metal structure, and the shape of the eutectic carbide is discontinuous and is lumpy or granular with a size of 30 μm or less. Part and / or valve seat part, by brazing with a valve seat member and cobalt-based alloy, nickel-based alloy or iron-based alloy with insert material foil, flux, brazing paste material, etc. A method for manufacturing a device for a nuclear power plant or a thermal power plant. 5. A slidable cobalt-based alloy, nickel-based alloy or iron-based alloy having a eutectic carbide in the forged or rolled metal structure, the shape of the eutectic carbide being discontinuous and in the form of lumps or particles of 30 μm or less. And / or valve seat portion is brazed, the nuclear reactor is characterized by being brazed using an electric furnace in an air atmosphere, an electric furnace in an inert gas atmosphere and / or an electric furnace in a vacuum atmosphere. -Method for manufacturing a thermal power plant device. 6. A slidable cobalt-based alloy, nickel-based alloy, or iron-based alloy having a eutectic carbide in the forged or rolled metal structure, the shape of the eutectic carbide being discontinuous and lumpy or granular with a size of 30 μm or less. When brazing to the valve and / or the valve seat, the pressing load during brazing is 10 kg or more when the weight is more than its own weight.
A method for manufacturing an apparatus for a nuclear power plant or a thermal power plant, which is brazed at a rate of not more than / cm ² . 7. A slidable cobalt-based alloy, nickel-based alloy or iron-based alloy having a eutectic carbide in the forged or rolled metal structure, the shape of the eutectic carbide being discontinuous and in the form of lumps or particles of 30 μm or less. Part and / or valve seat part is joined by friction welding to a nuclear / thermal power plant device manufacturing method.