JPH08247306A - Valve seat - Google Patents

Abstract

PURPOSE: To provide a valve seat furnished with a wide working temperature and corrosion resistance by changing the shape of the valve seat used for a turning valve, etc., hitherto and constituting it with simple parts dispensing with a metal plate spring and 'O' ring. CONSTITUTION: By using a rigid material such as a metal, a nonferrous metal, FRP, FRM, FRG as the constitution material of a valve seat 4, the sliding part 15 of the valve seat for a valve element 3 is formed and machined into a shape by which an elastic effect required to the operation of the valve like compression restoration can be displayed and an adequate surface pressure is held on the sliding part between the valve seat and the valve body to seal a fluid.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve seat of a valve which is excellent in low temperature, high temperature, high pressure and corrosion resistance and can be used in a wide range. More specifically, the present invention relates to a valve seat such as a rotary valve that is mounted and used in a valve box of a valve, in which fluid is sealed at a contact surface with the valve box and a sliding surface with a valve body. It concerns the structure and material of the seat.

[0002]

2. Description of the Related Art A typical valve seat of a rotary valve, such as a ball valve or a butterfly valve, which is mounted and used in a valve box has a contact surface with the valve box and sliding with a valve body. A valve seat (hereinafter, simply referred to as “valve seat”) that seals a fluid on a surface is required to have a compression restoring property and an elastic function. The various properties required for the valve seat sealing function are: (1) The friction coefficient between sliding members is small and impermeable. (2) It has hardness and mechanical strength capable of suppressing wear. (3) It has excellent compressibility and resilience that can follow pressure fluctuations. (4) The above performance is maintained in a wide temperature range. (5) Excellent corrosion resistance against chemicals ...
… And so on.

In order to satisfy the various performances of the valve seat as described above, various attempts have hitherto been made on the material and structure of the valve seat. When a material having poor elasticity such as a metal material or a carbon material is used for the valve seat, a valve seat having a structure as shown in FIG. 15 has been used. In FIG. 15, 1 is a valve box, 3 valve body, 4 is a valve seat, 5 is a valve rod, 18 is an "O-ring", and 19 is a leaf spring.

In the valve seat structure of FIG. 15, the seal between the valve body and the valve seat is achieved by the sliding surface between the valve seat body 4 and the valve body 3, and the seal between the valve box 1 and the valve seat 4 is " This is done by the O ″ ring 18. The elasticity of the metal leaf spring 19 follows the fluctuation of the pressure applied to the valve seat.

The structure of this valve seat is that the "O" ring is made of fluorocarbon rubber or a polymer material such as PTFE.
In a high temperature region, the sealing function is lost due to deterioration and thermal decomposition. Also, with high-pressure fluid, the "O" ring is significantly deformed and a seal cannot be achieved.

Further, since the leaf spring is a metal plate, it deteriorates in a high temperature region and the elastic function is impaired. Therefore, when it is necessary to shut off the fluid in an emergency such as a fire, "O"
There is a problem that the fluid cannot be closed due to damage to the ring or deterioration of the leaf spring.

There is also a problem with the material of the valve seat. Metallic materials have excellent strength and heat resistance, but have a large friction coefficient. If there is no hardness difference between the valve seat and the valve body, problems such as seizure and galling may occur, and the valve may become inoperable. Therefore, the valve seat and the valve body must be subjected to surface treatment such as plating.

Furthermore, since both the valve body and the valve seat are made of metal,
In order to ensure a seal on the sliding surface, both surfaces must be finished to be smooth and dimensional accuracy and sphericity must be extremely high. Further, since both of them are rigid bodies, compression recovery and elasticity cannot be expected at all, so that it is necessary to follow the fluctuation of the pressure applied to the valve seat by using a spring such as a leaf spring as described above.

Further, recently, a carbon material, which is widely used as a material for a valve seat, is itself used as a solid lubricant, and has a friction coefficient and heat resistance much higher than those of metal materials. However, the solid carbon material has drawbacks such as permeability, insufficient mechanical strength, insufficient sealing surface pressure, and relatively large wear.

For this reason, a method of impregnating the voids and pores of the carbon material with a thermosetting resin such as phenol resin has been used, but the effect is such that it normally withstands a use temperature of 200 ° C to 250 ° C. Even if it is further heat-treated to improve heat resistance, it cannot withstand use in a temperature range of 300 ° C. or higher.

Such high-precision machining and heat-resistant processing impose a great economic burden. On the other hand, polytetrafluoroethylene resin (hereinafter simply referred to as “PT
(Referred to as "FE") is the first because PTFE itself is an elastic body.
It is used as a valve seat with the single material shown in FIG. In FIG. 16, 1 is a valve box, 3 is a valve body, 4 is a valve seat, and 5 is a valve stem. The PTFE valve seat 4 has excellent friction coefficient, impermeability, chemical resistance, and elasticity, but lacks other requirements.

That is, in the cryogenic region, liquid nitrogen gas, L
When used as a NG or LPG fluid, or when used as a fluid at a temperature of 250 ° C. or higher, which is a high temperature region, PTEF causes a dimensional change due to a high expansion coefficient, and the sealing function as a valve seat cannot be achieved.

Furthermore, in the event of a fire such as an emergency, when exposed to a high temperature of several hundreds of degrees Celsius or more, PTFE thermally decomposes and sublimes, making it difficult to close the flammable fluid, which may cause a great disaster. .

In the extremely low temperature range, the valve seat contracts remarkably, the sealing function is lost, the elasticity is lost, and the valve seat becomes brittle, so that it easily breaks due to pressure. Further, since PTFE causes cold flow due to pressure even in the normal temperature region, it is difficult to maintain the sealing property, and when temperature is applied, the elongation further increases at an accelerated rate, and a pressure up to 20 Kg / cm ² at 150 ° C. is a permissible range.

In order to make up for the above-mentioned drawbacks, PTFE is filled with asbestos, glass fiber, carbon fiber or the like, or a metal outer ring is attached to prevent cold flow and improve its heat resistance and mechanical strength. The situation is that is only slightly improved.

Further, improved graphite products having excellent heat resistance, impermeability and mechanical strength have also been developed. However, when a graphite material contains a specific chemical, the graphite material is also a characteristic of the graphite material. Chemicals permeate between layers to form intercalation compounds,
The temperature range used in the fluid that collapses the graphite structure or produces intercalation compounds becomes extremely narrow.

[0017]

SUMMARY OF THE INVENTION The object of the present invention is that the valve seat used in a conventional rotary valve and the material and structure used for the valve seat cannot fully satisfy the requirements for the valve seat. The purpose is to provide the existing valve seat as a valve seat that has various requirements to be satisfied.

More specifically, various requirements and performances required for the valve seat are determined by using a rigid material, structurally fixing with a screw seal,
By mounting the valve seat so that it can be easily fixed or detached and the sliding part with the valve body is subjected to molding so that elasticity such as compression resilience can be exerted, it is possible to use the rigid material for the necessary valve seats. The purpose of the present invention is to be achieved by exerting the effect as a requirement.

[0019]

In order to solve the above-mentioned problems, the present invention changes the shape of the valve seat itself so that the valve seat has a sealing function and an elastic spring function. That is, it is proposed that the valve seat is formed in a lip type that seals the valve body in sliding contact, and the elasticity of the lip portion is used for sealing.

That is, the present invention is a valve seat that is used by being screwed into a valve box of a valve, fitted with a tapered surface, or easily attached and detached, and has a contact surface with the valve box and a sliding surface with a valve body. In a valve seat that seals fluid, the valve seat is made of a rigid material, the contact surface with the valve box is sealed with a screw seal, a taper seal, or the back surface of the valve seat, and the sliding surface with the valve body is also a rigid body. The present invention relates to a material and a structure of a valve seat, which is characterized by a structure made of a material and capable of exerting an elastic function such as compression recovery as a valve seat.

The metal material, the non-ferrous metal material, and the reinforced composite material which are the valve seat members of the present invention have excellent wear resistance, mechanical strength and impermeability. These properties can be maintained up to the high temperature range.

The soft valve seat, which is most often used in rotary valves such as ball valves, and which is easily attached and detached, has no flexibility even if an attempt is made to replace it with a rigid material. However, since it can not be expected at all, if it is used alone as a valve seat, excessive surface pressure will be required to achieve fluid sealing, and there is a risk of galling on the valve body and valve seat surface. It becomes very difficult to open and close.

Therefore, it is unavoidable that an elastic function such as compression restoring property is imparted in consideration of joint use with other members. Therefore, a valve seat has been proposed in which the sliding member with the valve body is made of a carbon material or a metal material, and the contact member with the valve box also seals the fluid with a soft material, but it is not satisfactory due to lack of elasticity such as compression recovery. .

The valve seat of the present invention, as shown in FIG.
The O "ring, leaf spring, and valve seat do not have to share the sealing function with three types of materials, and various requirements as a valve seat can be satisfied with a single material, which is not possible with conventional valve seats. Be effective.

The present invention will be described in more detail with reference to the drawings. FIG. 1 is a sectional view of a ball valve as an example of the valve. In the figure, 1 is a valve box, 2 is a valve box cover, 3 is a valve body, 4 is a valve seat, 5 is a valve rod, 6 is a gasket, 7 is a packing retaining ring, 8 is a packing retaining ring, 9 is a gland packing, 10 Is a bolt and nut, and 11 is a handle.

The valve seat of the ball valve as shown in FIG. 1 is annular (ring-shaped), and its cross section is illustrated in FIGS. 2 to 13.

The valve seats shown in FIGS. 2 to 4 are valve seats provided with a threaded portion on the annular outer peripheral surface and press-fitted.
Is a valve body, 4 is a valve seat, 12 is a valve seat mounting jig hole for fitting a threaded portion, 13 is a male screw, 14 is a contact portion between a valve box and a valve seat, and 15 is a valve body and a valve seat. A sliding portion, 16 is a seat chamber, 17 is a seal lip, and 20 is a spring.

The valve seats shown in FIGS. 5 to 7 are, like the valve seats shown in FIGS. 2 to 4, a valve seat 4A which is a valve seat retaining ring. 8 to 10 show a valve seat in which the annular outer peripheral surface of the valve seat is provided with a taper, and the taper surface is also provided in the valve box.
Is a valve body, 4 is a valve seat, 14 is a contact portion between the valve box and the valve seat, 15 is a sliding portion between the valve body and the valve seat, 16 is a seat chamber, and 17 is a seal lip.

Further, the valve seats shown in FIGS. 11 to 13 are valve seats which are used by being easily detachably fitted into the valve housing of the valve, where 1 is a valve housing, 3 is a valve body, and 4 is a valve. Seat, 14 is a contact portion between the valve box and the valve seat,
15 is a sliding portion between the valve body and the valve seat, 16 is a seat chamber,
Reference numeral 17 is a seal lip.

FIG. 14 is a sectional view of the valve seat of FIG. 2 assembled into a ball valve. FIG. 17 is a cross-sectional view of a butterfly valve as another example of the valve, and FIGS. 18 to 20 show cross-sectional views of aspects of a valve seat used in this valve.
1 is a valve box, 32 is a valve box lid, 33 is a valve body, 34 is a valve seat, 3
5 is a valve rod, 36 is a gasket, 39 is a gland packing, 40 is a bolt, 41 is a handle, 42 is a jig hole for fitting a valve seat, 43 is a screw part, 44 is a contact part between a valve box and a valve seat Reference numeral 45 is a sliding portion between the valve body and the valve seat, and 46 is a seat chamber.

The material of the valve seat 4 is appropriately selected from the following materials. a) Metal materials b) Non-ferrous metal materials c) Reinforced composite materials.

The contact portion 14 between the valve box 1 and the valve seat 4 and the sliding portion 15 between the valve body 3 and the valve seat 4 are appropriately selected from metal materials, non-ferrous metal materials and fiber reinforced composite materials depending on the use conditions. . Valve seats for valves are roughly classified into high pressure, medium pressure, low pressure, high temperature, normal temperature, and low temperature depending on the application.

In the case of a high pressure valve, the valve seat is the portion most susceptible to corrosion and wear by a high speed fluid, and in consideration of this, chromium-based corrosion resistant steel and nickel-based corrosion resistant steel are preferable. Further, in the case of a high temperature valve, high carbon high chromium steel or austenitic stainless steel is used to prevent seizure and galling.

However, in 18: 8 stainless steel, etc., 5
Carbide may be precipitated at grain boundaries around 00 ° C to cause grain boundary corrosion. As a preventive measure, a metal material having high corrosion resistance, for example, high nickel stainless steel such as Aloyco 20, Hastelloy B, or Monel is used. High nickel alloy etc.
Alternatively, in order to prevent heat resistance, wear resistance, seizure, etc., stellite alloy (cobalt-chrome, dungsten alloy), coromonoy (nickel-chrome, boron alloy) or T, W, C alloys (tungsten, carbide)
Weld alloys etc.

Such a metal deposit is a surface hardening treatment, which is a preferable treatment for carrying out the present invention, even when it is not used at a high temperature. In the case of a medium pressure and normal temperature valve, 13 chrome steel is preferable because it has excellent wear resistance and corrosion resistance, and the mechanical strength does not almost drop from 400 ° C to 450 ° C.

In the case of low pressure, when the fluid is water, warm water, air, etc., aluminum bronze, phosphor bronze, etc. are used, but stainless steel is preferable from the viewpoint of corrosion resistance and rigidity. Further, austenitic stainless steel having high safety is preferable for the low temperature valve.

In addition to the above, any material such as aluminum, aluminum alloy, copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, ferritic stainless steel, martensitic stainless steel can be used.

The material can be selected as appropriate according to the fluid used, temperature and pressure. Mechanical factors such as friction coefficient, wear resistance to fluid and valve body, hardness, yield point, tensile strength, etc. The optimum material is selected in consideration of properties, chemical properties such as oxidation resistance and corrosion resistance, thermal expansion coefficient, thermal conductivity, structural stability, mechanical workability and economic efficiency.

Further, as the valve seat material of the present invention, in addition to the above-mentioned metallic materials and non-ferrous metal materials, fiber reinforced resin composite materials (FRP) and fiber reinforced metal composite materials (FR. M) and fiber reinforced glass composite (FRG) materials can be used.

The fiber used in the main valve seat of the fiber-reinforced resin composite material (hereinafter simply referred to as FRP) is preferably carbon fiber or silicon carbide fiber, but other fibers are glass fiber, aramid fiber, boron fiber. It is possible to use asbestos fibers and many fibers, and epoxy resin, polyimide resin, or phenol resin is used as the resin base material.

However, among the above-mentioned fibers, asbestos fiber is a material that is inexpensive, relatively easy to obtain, and extremely excellent in heat resistance, but its influence on the human body is always regarded as a problem. It was decided to exclude it from the fiber for valve seat material.

In the FRP, the physical properties are different depending on the arrangement direction of the fibers and their oblique angles. Therefore, if the unidirectional prepregs are simply laminated in one direction, a molded product that is strong in the longitudinal direction but extremely weak in the lateral direction can be obtained. When used as a material, it is rare that the stress applied to the molded body is in only one direction, and stress in multiple directions is applied. Therefore, it is necessary to stack the molded body and the fibers at a plurality of angles.

FRP is manufactured by whiskers, felts, chops, strands instead of unidirectionally aligned fibers or woven or non-woven fabrics such as plain weave and satin weave.
Fibers such as tows and mats are impregnated with a base resin such as epoxy resin or polyimide resin to make a prepreg, which is laminated in multiple directions and thermocompressed by a hot press or an autoclave. , FRP molded body is obtained.

As another method, the fiber bundle is passed through a resin bath, wound around a mandrel with a spiral wound, and then heat-cured. Further, an injection mold using short fibers or a spray method may be used as a material. You can get it.

In this method, since the basic performance of the composite material such as the morphology, orientation and volume content of the reinforcing fiber is determined, it is essential to design the material in any direction depending on the application. is there. The FRP thus obtained has extremely high strength and elastic modulus, excellent fatigue properties and creep properties, better vibration damping properties than metals, thermal dimensional stability, cryogenic temperature, and chemical resistance. It is an excellent material.

On the other hand, in order to improve heat resistance which is the only weak point of FRP, the heat treatment temperature of the epoxy resin and the polyimide resin as the base materials is 120 ° C. (250 ° C.) in the former case.
F) By heat-curing the latter at 180 ° C (350 ° F), 150 ° C to 200 ° C and 250 ° C to 300, respectively.
It is possible to obtain long-term heat resistance at a temperature of ° C.

Fiber-reinforced metal composite (hereinafter referred to simply as "FR
Carbon fiber or silicon carbide fiber is preferable as the fiber for which M) is used for the valve seat, but other fibers such as glass fiber, aramid fiber, boron fiber and many other fibers are used. However, carbon fibers and silicon carbide fibers are preferable among them.

In the case of FRP, the operating temperature is 2 to 2
Although used with the expectation of mechanical properties that cannot be obtained with metals in the temperature range of 50 ° C., FRM composite material is used to obtain a valve seat that can be used in a high temperature region.

In the FRM, a bundle of carbon fibers and silicon carbide fibers are arranged in parallel in one direction and fixed with a sizing resin to form a fiber sheet. This sheet and aluminum plates are stacked alternately to form a laminate, which is placed in an autoclave and heated at high temperature under reduced pressure.The sizing resin component is removed by thermal decomposition, and then reheated again under reduced pressure. The molten aluminum is permeated between fibers to obtain a fiber-reinforced aluminum composite material.

By laminating the fiber sheets on the aluminum plate in a plurality of directions so as to be at right angles to each other, a composite material that is strong in a plurality of directions can be obtained. A composite material can be obtained by fiber-chopping the above material and using aluminum as a base material.

A billet is produced by compounding fiber chops and aluminum by a high pressure casting method. By extruding this billet material at high temperature, a round bar of fiber chop reinforced aluminum composite material can be produced.

In addition to the above, a bundle of fibers is put into molten aluminum to make a preformed wire. Using this preformed wire as an intermediate material, it is possible to obtain various shapes of materials such as round bars and pipes.

However, since FRM is often used for the purpose of exerting various mechanical properties in a high temperature region, FR
When the fiber used for M is a carbon fiber, it has excellent chemical resistance such as acid and alkali, but its greatest drawback is that it is weak against oxidation at high temperature.

Oxidation of carbon material often proceeds mainly from defects, and carbon has an oxidizing atmosphere of 400-400.
Oxidation consumption starts at 450 ° C, and as the temperature increases, the rate of oxidation consumption also increases.

Since the structure of the fiber itself changes variously depending on the arrangement state of the graphite crystals, and various defects are inherent in the composite material, the silicon carbide fiber should be used especially when used in a high temperature region. FRM used as a reinforcing material is desirable.

The silicon carbide fiber is produced by using polycarbosilane, which is an organic silicon polymer, as a starting material, followed by melt spinning and firing. This fibrous silicon carbide fiber has high strength and elastic modulus, retains high strength even at high temperature, has low reactivity with metal, and has good wettability, so it is most effective as a reinforcing fiber for FRM. Is.

Silicon carbide fibers are currently manufactured and sold by Nippon Carbon Co., Ltd. under the trade name of Nicalon. This fiber is an inorganic fiber excellent in oxidation resistance and high heat resistance without lowering its strength up to 1273 ° K in air and up to 1523 ° K in a non-oxidizing atmosphere.

Further, since it is a thin fiber, it has flexibility and can be woven into various kinds of fabrics such as plain weave, satin weave and three-dimensional weave. As an application, rather than as a heat resistant material
Rather, it is a very effective fiber as a reinforcing fiber for FRM.

An aluminum composite material reinforced with silicon carbide whiskers is manufactured by the following method. Since the silicon carbide whiskers are obtained in a entangled state, they are thoroughly disentangled, then mixed with aluminum powder, and then the molten metal pressure molding method is performed to obtain silicon carbide whiskers / aluminum billets.

This billet material can be pressed under high pressure to produce silicon carbide whisker / aluminum plates, rods and pipes. This composite material has a Vf of 35% by volume, a tensile strength of 56 Kg / mm ^{2 and an} elastic modulus of 12,000 Kg /
mm ² .

The elasticity is particularly high and has a higher value than the aluminum composite material reinforced with other fibers. Further, since this composite material can be rolled, it can be processed into various shapes by hot pressing or the like.

Besides this, boron fiber reinforced aluminum composite materials and silicon carbide fiber reinforced titanium composite materials can be obtained by the same method as the above-mentioned silicon carbide fiber reinforced aluminum composite materials, but the biggest defect is that the price is high. However, the general molding requires diffusion bonding under high pressure of several tens of Kg / cm ² up to 803 ° K for boron fiber reinforced aluminum composites. As a result, the cost will increase significantly.

Boron fiber / titanium alloy has a problem because it is highly reactive with the titanium alloy base material. In order to overcome this drawback, boron carbide-coated boron fibers have been developed, and the high temperature stability of boron-based fibers has been improved, but the material price becomes very expensive due to the advanced multi-layer treatment.

Further, in these composite materials, since the hardness of boron fiber is extremely hard as Mohs hardness of 9 or more, it is difficult to perform cutting work, and it is necessary to rely on grinding, and a special tool using diamond is required. Economic burden is large.

On the other hand, ceramic materials such as silicon carbide, silicon nitride, alumina, and zirconia retain strength at high temperatures of 800 ° C. or higher, but the brittleness peculiar to ceramics is not improved, so they are used as valve seat materials. Hard to be put to practical use.

Therefore, the most promising materials for high temperature heat resistance are fiber reinforced glass (FRG) and fiber reinforced ceramics (FRC). Among them, FRG composite material has excellent features such as high strength at high temperature, high toughness, and light weight.
Promising as a heat resistant material.

The reinforcing fibers of this fiber-reinforced glass composite material include graphite fiber, alumina fiber, silicon carbide fiber and the like. The graphite fiber-reinforced glass composite material has a high level of strength and fracture toughness. As mentioned above, the fibers are 400
Since it is consumed by oxidation at temperatures above 450 ° C, it loses its function as a heat resistant material in a high temperature oxidizing atmosphere.

Further, in the alumina fiber reinforced glass composite material, alumina reacts with glass at a high temperature to vitrify, so that the fibers are eroded and strength and toughness cannot be obtained. However, in the silicon carbide fiber reinforced glass composite material, the silicon carbide itself has an oxidation resistance even in high temperature air, maintains excellent strength and does not react with glass, so at high temperature, it has high strength and high strength. A material having toughness and oxidation resistance can be obtained.

This silicon carbide fiber-reinforced glass composite material is obtained by impregnating glass powder with a resin such as polyvinyl alcohol into a silicon carbide fiber to form a silicon carbide fiber / glass preform body. A molded product can be obtained by subjecting to a predetermined shape and then heat-molding.

Fiber-reinforced ceramic composite materials (FRC) can be narrowed down to existing heat-resistant materials such as carbon fibers, silicon carbide fibers, and alumina fibers, when classified according to the type of material constituting the composite material. However, all types of ceramics can be used as the base material. When the main base materials are listed in ascending order of use temperature, they are glass, glass ceramics, oxide ceramics, nitride ceramics, and carbides.

Among the above-mentioned fibers, the carbon fiber and the alumina fiber have the problems of oxidation resistance and the cost as described above.
Not suitable as a reinforcing fiber for FRC. Among them, the silicon carbide fiber reinforced ceramics composite material is an inorganic binder for fibers such as whiskers, cloths, felts, chops, strands, mats, fabrics, and aligned products, instead of woven and non-woven fabrics made of silicon carbide fibers. As a result, fine particles of crystalline silica were dispersed in colloidal silica.

A paste-like liquid is applied by brushing or the like, and this is molded and fired to obtain a silicon carbide fiber-reinforced ceramic composite material. The silicon carbide fiber adopted here is a fiber having a fiber diameter of 50 μm or less, which is manufactured by using an organic silicon compound as a raw material.

Conventionally, nickel, cobalt, tungsten, iron, chrome-based alloys, titanium alloys, etc. have been used as heat-resistant materials capable of withstanding 800 ° C. or higher. However, this metal material has a strength of 50% or less at high temperatures, often 10% or less.
The current situation is that the percentage falls to 20%.

Therefore, light and strong high-strength fiberized composite materials and ceramics materials have been studied, and widespread use of these materials has been planned. Among them, fiber-reinforced metal composite materials are currently silicon carbide. Fiber-reinforced aluminum alloys are the mainstay, and the heat resistance is less than 500 ° C, but the heat resistance of valve seats such as rotating valves is over 450 ° C, and the seat selection depends on the operating conditions. It is important to select the most suitable material from the materials mentioned above.

[0075]

As described above, the valve seat of the present invention is made of a rigid material that cannot be expected to have the various properties of the conventional rotary valve such as the ball valve and the soft valve seat often used for butterfly valves. It is an epoch-making valve seat that can be used for a rotary valve valve seat and can select a structure and material that can exhibit various characteristics required for the valve seat.

A valve incorporating this valve seat functions as a valve seat in a wide range from extremely low temperature to high temperature and from low pressure to high pressure by selecting the material and structure of the valve seat according to usage conditions. It is something to demonstrate.

[0077]

The present invention will be described in more detail with reference to Examples and Comparative Examples. (Examples 1 to 6, Comparative Examples 1 to 3)

The nominal diameter of the structure shown in FIG. 1 is 2 inches (5
0A) ball valves having the structure and material shown in Table 1 were prepared. The valve seat structures and materials used in Examples 1 to 3 and the valve seat structures and materials used in Examples 4 to 5 were obtained by the following method.

[0079]

[Table 1]

[0080]

[Table 2]

[0081]

[Table 3]

[0082]

[Example 1] The material of the valve seat in Example 1 is 18% chrome, 12% nickel, and 2.5% molybdenum for the standard composition of austenitic stainless steel in which chrome and nickel are added to iron. Therefore, it is called 18-12 steel and has a very high corrosion resistance and acid resistance, and is a stainless steel JIS-G-4303, SU that does not dissolve in most acids and alkalis at room temperature.
As shown in Fig. 4, using the steel material of S-316, a metric fine parallel female screw is machined on the outer peripheral surface of the valve seat ring on the annular inner surface of the valve seat housing part of the valve box, and a male screw matching it is machined. It was

Further, the seat chamber 16 has a thickness of the seal lip 17 which is most likely to exhibit the sealing property and the elastic effect in consideration of the surface pressure applied to the valve seat of the ball valve. (See Figure 4)

[0084]

Example 2 As the material of the valve seat in Example 2, a commercially available round bar equivalent to titanium steel rod JIS-H-4650 type 4 TB-550H was used. Titanium steel has a small specific gravity, and is very excellent in mechanical strength such as tensile strength and elastic modulus, its characteristics are almost unchanged up to about 500 ° C., and it is also excellent in corrosion resistance.

Similar to the first embodiment, this material is machined with the same male screw as the first embodiment, which matches the metric fine parallel screw provided on the valve seat accommodating portion of the valve box, as shown in FIG. It was In addition, the seat chamber 16 and the seal lip 1
As for No. 7, the structure having the most elastic effect is prepared in consideration of the surface pressure of the ball valve, the elastic modulus of the titanium material, and the like as in the first embodiment. (See Figure 2)

[0086]

[Embodiment 3] In Embodiment 3, the valve seat is made of nickel-copper alloy (70Ni-30Cu) JIS-H-455.
A commercially available 3 NCuB round bar was used. It is a nickel-copper alloy steel generally known as monel metal. Like titanium, monel metal retains mechanical strength even at high temperatures and has excellent corrosion resistance to many chemicals such as seawater, neutral salt solutions, alkaline solutions, and organic acid gasoline.

This material is used to form a taper surface in the valve seat accommodating portion of the valve box, and the taper surface that matches the taper angle and can seal the fluid is formed on the outer peripheral surface of the valve seat ring as shown in FIG. Which is machined to the thickness of the seat chamber 16 and the seal lip 17 which are easy to exert the sealing property of the fluid required for the valve seat and the elastic effect by utilizing the material characteristics of Monel metal similarly to the first and second embodiments. Prepared. (See Figure 10)

[0088]

Example 4 In Example 4, the valve seat material used was FRM which is a silicon carbide fiber reinforced metal composite material. The silicon carbide fiber was a fiber manufactured and sold by Nippon Carbon Co., Ltd. under the trade name of Nicalon, and aluminum was used as the base material (Matrix). Short-forms of silicon carbide fibers were mixed and dispersed in molten aluminum in an amount of 30 to 35% by weight, and a molded body was obtained by a casting method of injecting into a valve seat-shaped mold, and finishing processing was performed. (See FIG. 5) The valve seat retaining ring 4A is made of SUS-
304 was used.

[0089]

Fifth Embodiment In the fifth embodiment, the valve seat material is FRG which is a silicon carbide fiber reinforced glass composite material. As in the case of Example 4, the silicon carbide fiber was Nicalon fiber and the base material was lithium aluminosilicate (crystallized glass).
(See FIG. 6) The valve seat retaining ring 4A is made of SUS-304.
And

The ball valve incorporating this valve seat has been confirmed to be safe as a valve seat for a wide temperature range by various performance evaluation tests. Typical test contents and results are as follows. .

(1) Antistatic Ball valve uses PTFE for the valve seat and gland packing.
When an insulator such as resin is used, static electricity is generated due to friction between the valve body and the valve seat resin, which is dangerous when used for gasoline, natural gas, LPG, etc., which have a particularly low flash point.

A valve using a conventional soft valve seat is a valve rod or
A mechanism for removing static electricity is provided in the fitting portion between the valve rod and the valve body.However, since the valve seat itself is a good conductor of electricity in this valve seat, static electricity is excellent as it is without charging the valve body. Since it has an antistatic mechanism, it is economical because there is no need to pay attention to antistatic.

All of Examples 1 to 5 and Comparative Examples 1 to 3 passed. However, Comparative Example 3 had no problem because the valve seat was made of PTFE resin but the antistatic mechanism was attached.

(2) Water pressure test As a water leak test of a valve seat, 18 Kg / cm ² , 21 Kg / cm ²
cm ² , 53 Kg / cm ² , 105 Kg / cm ² , 15
The test was conducted at each pressure of 5 Kg / cm ² .

Water pressure corresponding to each of the above pressures is applied to the inside of the valve, one end is released to eliminate water, and then each of the above test pressures is increased and held for 5 minutes to maintain the valve seat and the valve disc. The presence or absence of water leakage or bleeding from the sliding surface and the back surface was inspected. As a result, all of Examples 1 to 5 and Comparative Examples 1 to 3 passed.

(3) Airtightness test A blind flange is attached to one end of the valve and 2K from the other end.
^{g / cm 2, 6Kg / cm} 2, 10Kg / cm 2, 16
After addition of air pressure of each test pressure ^{Kg / cm 2, 20Kg / cm} 2, closing the valve, the valve, inside and encapsulates the air pressure, from both end flange surface, a valve body of the valve seat by soapy water The presence or absence of leakage from the sliding surface and the back surface of the above was inspected.

In the valve of Comparative Example 1, a leak of 0.01% or more of the total flow rate was confirmed at a pressure of 10 kg / cm ² or more, but this leak amount was within the allowable leak amount. All of the other valves, Examples 1 to 5 and Comparative Examples 2 to 3, passed.

(4) Steam test 6 kg / cm ² (164 ° C.) as steam, 10 kg / c
m ² (183 ° C.), 15 Kg / cm ² (200 ° C.), 2
Using saturated steam of 0 kg / cm ² (214 ° C.), the temperature of the entire valve is raised stepwise until it becomes almost isothermal, and at each of the above temperatures, the sliding surface and back surface between the valve seat and the valve body Leakage from
It was inspected with a mirror.

The valves of Comparative Examples 2 and 3 were 20 kg / cm ²
There was a leak in the inspection at (214 ° C). When the members were inspected, the valve seat and the O-ring were thermally deformed. All other valves passed. In addition, a valve opening / closing operation test was also conducted, but the valve rod, valve seat, valve body, etc. could be operated smoothly without seizing or galling.

(5) Low temperature test After substituting air with liquid nitrogen gas into the inside of the valve, the valve was immersed in a refrigerant (-55 ° C) and kept at a pressure of 6 Kg / cm ² , and the inside of the valve body and valve box, etc. Is cooled to the above temperature, and after holding the time necessary for the temperature to stabilize further, the temperature is checked, and the valve is repeatedly opened and closed to perform operation tests such as the valve opening force and valve closing force. It was

After the operation test, in order to stabilize the temperature, it was left for another 20 minutes, liquid nitrogen gas was sealed inside the valve to close the valve, and a pressure of 6 Kg / cm ² was applied from the upstream side.
After holding for 5 minutes, the downstream valve seat was inspected for leakage. As a result, in the valve of Comparative Example 3, the valve seat contracted because of the PTFE resin, and leakage was recognized. The valves of the other Examples and Comparative Examples all passed.

(6) Fire-safe test In a normal ball valve, a nonmetal material such as PTFE resin or rubber is often used as a sealing material such as a valve seat, a gland packing and a gasket. Therefore, if the valve is exposed to fire or the like and it is burned out, the fire will increase significantly by causing leakage from the gland or gasket to the outside, valve seat leakage, or malfunction. It is important that the valve does not become a weak point because it is a ball valve and it interferes with the operation of the valve.

In this fire-safe test, after the primary side of the valve was filled with water and it was confirmed that no air remained inside,
The water pressure of 3.5 Kg / cm ² was applied and the secondary blind flange on the opposite side was removed, and 760 ° C (1400 ° F) to 980 ° C using two LPG (liquefied propane gas) burners.
10 minutes after reaching a temperature of 595 ° C (1100 ° F) on the valve surface for 30 minutes in a (1800 ° F) flame.
Burning was continued for a minute, and valve seat leakage from the secondary side was confirmed.

After extinguishing the LP gas, the valve was set to 100 ° C (2
The test was conducted in the following order after being naturally cooled to 12 ° F.) or lower. The operability was confirmed by repeatedly opening and closing the valve several times. The valve was closed and hydraulic pressure of 3.5 Kg / cm ² was applied to the primary side to confirm valve seat leakage. The inside of the valve was subjected to a high pressure cutoff test at a water pressure of 10 kg / cm ² to confirm the presence or absence of leakage.

In this test, in both the valves of Examples and Comparative Examples, in order to guarantee the heat resistance of the parts other than the valve seat, the materials of the gland packing and the gasket were expanded graphite moldings made by Nippon Carbon Co., Ltd. A certain trade name Nika film was used for each.

After the above test, each valve was disassembled and each member was inspected. The valves of Examples 1 to 5 all passed the test under the above-mentioned severe conditions. Regarding Comparative Example 1, there was significant leakage from the valve seat. As a result of inspecting the members, "O-ring was severely damaged, the rubber was carbonized and the sealing function was completely lost. Also, the metal leaf spring was annealed and lacked elasticity, so that the proper surface pressure was applied. Could not be held.

Similar to Comparative Example 1, there was a significant leakage in Comparative Example 2. The O-ring of the member was carbonized as in Comparative Example 1. Further, the valve seat did not serve as a valve seat in which many fine cracks were observed on the sliding surface due to carbonization of the phenol resin impregnated in the carbon material.

In Comparative Example 3, there was more severe leakage than in the valves of other Comparative Examples. As a result of inspecting the members, the PTFE resin, which is the material of the valve seat, was thermally decomposed due to the high temperature and disappeared without remaining the shape of the valve seat.

[0109]

[Brief description of drawings]

FIG. 1 is a sectional view of a ball valve as an example of the valve. 2 to 13 are sectional views illustrating various aspects of the valve seat of the present invention, and FIG. 14 is a sectional view when the valve seat of FIG. 2 is incorporated into a valve. FIG. 15 is a sectional view of an example of a conventional valve seat having an “O-ring” metal leaf spring, FIG. 16 is a sectional view of an example of a conventional valve seat of a PTFE valve seat, and FIG. 17 is an example of a valve. View of a butterfly valve as a. 18 to 20 are cross-sectional views illustrating various aspects of the valve seat of the present invention.

[Explanation of symbols]

1. Valve box 2. Valve box lid 3. Valve body 4. Valve seat 4A. Valve seat retaining ring 5. Valve rod 6. Gasket 7. Packing retaining ring 8.
Packing foot 9. Gland packing 10. Bolt nut 11. Handle 12. Valve seat mounting jig hole 13. Male screw 14. Valve box and valve seat contact part 15. Sliding part between valve body and valve seat 16. Seat chamber 17. Seal lip 18. O-ring 19. Leaf spring 20. Coil spring 31. Valve box 32. Valve box lid
33. Valve body 34. Valve seat 35. Valve stem 36. Gasket 37. Packing retaining ring 38. Packing foot 39. Grand Pakin 40. Bolt 41. Handle 42. Valve seat mounting jig hole 43. Male screw 44.44A. Valve box and valve seat contact part 45. Sliding part between valve body and valve seat 46. Seat chamber 47. Seal lip

Claims (5)

[Claims] 1. A valve seat, such as a rotary valve, which is mounted and used in a valve housing of a valve, wherein a fluid is sealed at a contact portion between the valve housing and the valve seat and a sliding portion between the valve body and the valve seat. In the seat, the sliding part of the valve seat with the valve body is molded and processed into a shape that can exert the elastic effect necessary for valve operation such as compression restoration, and a suitable surface for the sliding part of the valve seat and the valve body. A valve seat characterized by holding pressure and sealing fluid. 2. The F.V. wherein the valve seat is a reinforced composite material made of metal or non-ferrous metal, carbon fiber, silicon carbide fiber or the like.
R. P (Fiber ReinforcedPlast)
ics), F.I. R. M. (Fiber Reinfor
ced Metal) or F.C. R. G. (Fib
er Reinforced Glass) or the like, and the valve seat according to claim 1. 3. The valve seat fixing method and sealing method are such that a female screw portion provided in a valve box is fitted and fixed to a male screw provided on an outer peripheral surface of the valve seat, and a back surface of the valve seat is made a valve box surface. Either press-contact and seal, or provide a taper on the valve seat storage part, and also provide a taper surface on the outer peripheral surface of the valve seat that matches the taper provided inside the valve box. Patent that seals the contact part between the valve seat and the valve seat, or seals fluid on the back surface and sliding surface of the valve seat by the contact surface pressure between the valve body and the valve seat, which is used by being easily installed and removed in the valve box. The valve seat according to claims 1 and 2. 4. A chamber provided in the valve seat to assist the elasticity of the sliding portion of the valve seat with the valve body.
The valve seat according to any one of claims 1 to 3, wherein a spring is attached to r). 5. The valve seat according to any one of claims 1 to 4, wherein the retaining ring of the valve seat according to claim 3 is combined with a different material using a general-purpose metal.