JP2000097355A - Valve seat material or valve element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To have a bending strength a prescribed value or more, to have a mechanical strength enduring the abrupt clamping of stress, and to have impermeability to liquid and fluid of gas by using composite material formed by impregnating synthetic resin such as phenol resin and furan resin to a high- strength carbon fiber reinforced carbon material. SOLUTION: A composite material formed by impregnating a synthetic resin such as phenolic resin and furan resin to a high-strength carbon fiber reinforced carbon material is used for a member for a pipe valve seat or a valve element for a chemical plant of high temperature and high pressure. The mechanical strength is enhanced by the combined effects of the strength of a fiber material and the impregnating material, for example, the bending strength 100 MPa and Charpy impact value 5 kg/cm or more, so that the valve seat or the valve element can endure the impact of the additional tightening works in leakage and the valve seat or the valve element can be prevented from split or damaged. This constitution can provide with stable exhaustion resistance by chemical reaction and give the effect of the service life prolongation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve seat (valve seat) or valve body of a valve (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 or valve body such as a rotary valve used by being mounted in a valve box of a valve, wherein a fluid seal is provided on a contact surface with the valve box and a sliding surface with the valve body. It relates to the material of the valve seat or the valve element to be performed.

[0002]

2. Description of the Related Art Conventionally, a valve seat of a typical rotary valve such as a ball valve or a butterfly valve, which is mounted in a valve box and used, has a contact surface with the valve box and a sliding surface with the valve body. JP-A-8-247306 describes that a valve seat for sealing a fluid (hereinafter referred to as a valve seat) requires the following performance. (1) The coefficient of friction between the sliding members is small and impermeable. (2) Hardness and mechanical strength that can suppress wear. (3) It has excellent compression recovery that can follow pressure fluctuations. (4) The above performance must be maintained over a wide temperature range. (5) It has excellent corrosion resistance against chemicals and the like.

In order to satisfy the above requirements for the valve seat,
Conventionally, various attempts have been made on the structure and material of the valve seat. When a non-elastic material such as a synthetic polymer elastic body is used as the main body of the valve seat, such as a metal material or a carbon material, it is configured in combination with an elastic O-ring, a metal leaf spring, or the like.

In the structure of the valve seat, the seal between the valve body and the valve seat is achieved by a contact surface between the valve body and the valve body, and the seal between the valve box and the valve seat is achieved by an O-ring or the like. The purpose of the pressure fluctuation applied to the valve seat is achieved by the elasticity of a metal leaf spring inserted between the valve seat and the valve box.

[0005] The carbon material itself is used as a solid lubricant, and is excellent in friction coefficient and heat resistance. However, since a small diameter open pore (hole) exists, a gas or liquid fluid is used. However, there are drawbacks such as that it is permeable to water, that it cannot have a sufficient sealing surface pressure due to its low mechanical strength, and that it has relatively large wear.

In order to solve this drawback, there has been obtained a high-strength, impervious material in which pores and pores of a carbon material are impregnated with a thermosetting resin such as a phenol resin or a metal.

However, the mechanical strength of a metal-impregnated steel sheet has a maximum bending strength of 220 MPa, and that of a resin-impregnated steel sheet has a bending strength of about 90 MPa. When leakage occurs, additional tightening is performed to maintain the sealing property of the valve seat.

In this case, there is a case where the valve seat is broken due to a sudden tightening stress, and the solution is disclosed in, for example, Japanese Patent Publication No. 58-18554, Japanese Patent Publication No. 62-40592 and Japanese Utility Model Publication No. 58-51475. As described above, there is a method of designing a material to be used by a structural design. However, if a carbon-based material having a high cost and a bending strength of 100 MPa or more is developed, it can be used for a valve seat or a valve body at a low cost as a whole.

[0009]

In view of the above problems, the present invention has a bending strength of 100 MPa or more, and has a mechanical strength capable of withstanding sudden tightening of stress,
Further, the present invention provides a valve seat material or a valve body of a valve which is impermeable to a liquid or a gaseous fluid and is suitable in terms of cost.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention has been developed to replace a conventional carbon material with a high-strength carbon fiber reinforced carbon material (hereinafter referred to as C / C material or CCM).
A composite material impregnated with a synthetic resin such as a phenol resin and a furan resin is used for a valve seat or a valve body.

[0011] By using the composite material according to the present invention as a valve or a member of a valve body, the mechanical strength can be reduced to a bending strength of 100 MPa by the combined effect of the strength of the fiber material and the impregnating material.
a) The Charpy impact value is 5 kgcm / cm ² or more, and the shock of the tightening work at the time of leakage of the valve seat or the valve body can withstand, and the breakage of the valve seat or the valve body can be prevented.

[0012] Compared with the conventional carbon material, the tensile strength is C
/ C improves with the favorable effect of the fiber strength of the material.

[0013] The strength characteristics required as mechanical parts are empirical values, but are 100 MPa or more. In contrast, carbon-based materials have self-lubricating properties, but have a compressive strength of 1%.
Then, the bending strength is 0.5 and the tensile strength is 0.25. For example, EG of Nippon Carbon's isotropic graphite material
F-264, HC-30, NC-07 for carbon materials for machinery
Table 1 shows the typical characteristics of EG-50, a graphite material for machinery.

[Table 1]

Considering the use of the graphite material shown in Table 1 as a mechanical part, it cannot be used alone because the bending strength is less than 100 MPa.

As a solution to this problem, Nippon Carbon reinforces the product with metal retainers and conventionally strengthens the product by resin impregnation under the trade name of Nikaseal ^R , bearings, mechanical seal materials, piston rings of oilless air compressors, Rod seal packing has been manufactured and sold since 1959.

The carbonaceous material obtained by impregnating the carbon material with a resin is a carbonaceous material HC-3E3 or NC-0 manufactured by Nippon Carbon.
Table 2 shows representative characteristics of 7E and the graphite material EG-5E3.

[Table 2]

The carbon material impregnated with the resin has improved strength, but is used dynamically, for example, in 3
At a high sliding temperature of 50 ° C. or higher and a high sliding speed of 10 m / s or higher, the bending strength cannot clear 100 MPa.

In response to this, Nippon Carbon Co., Ltd. has developed a joint development with Toyo Kogyo (currently Mazda), and used a metal-impregnated carbon material as an apex seal material for a rotary engine. Table 3 shows the representative characteristics.

[Table 3]

Each of the metal-impregnated carbon materials shown in Table 3 has a flexural strength exceeding 100 MPa and can be used as an apex seal material for a rotary engine.

The above-mentioned carbon material is obtained by kneading pitch or tar with a carbon material obtained by pulverizing pitch coke or the like as a filler, kneading, molding, firing and, if necessary, a high temperature treatment of 2000 ° C. or more (graphitization). .

On the other hand, according to the present invention, in order to solve the above-mentioned problems, a phenol resin is used instead of a conventional carbon material instead of a high-strength carbon fiber reinforced carbon material (hereinafter referred to as C / C material or CCM). A composite material impregnated with a synthetic resin such as furan resin is used for a valve seat or a valve body. Table 4 shows the representative characteristics.

[Table 4]

The above-mentioned CCM base material obtained by melting and impregnating a metal material with a bending strength of 100 MPa or more can be obtained.
Since the fibers constituting the skeleton of the M base material are cut, the strength is reduced. Impregnating an expensive CCM material with a metal material has little merit.

As described above, the present invention has a bulk specific gravity of 1.25.
The above CCM material is impregnated with resin and the bending strength is 180MPa
The composite material described above is applied to a valve seat material or a valve body.

As a result, the high strength properties of the CCM material are subjected to a resin sealing treatment, impermeability is added, and the strength can be further increased. The resin-impregnated CCM substrate having a bulk specific gravity of less than 1.25 has a thermosetting resin content of 25% by volume or more, which has a large resin content and has a problem of causing breakage when used at a high temperature of 200 ° C. or more. A CCM substrate of 1.7 or more has a drawback that the cost is increased because the densification process is increased.

[0025]

EXAMPLE A terephthalic acid (raw material for tetron) was used in a valve seat for piping as shown in Table 5 in a plant for producing terephthalic acid. NC-07E, a high-strength carbon material, suffered breakage, but the CCM material was impregnated with resin. All are endurable.

[Table 5]

[0026]

According to the present invention, a valve seat for piping of a high-temperature and high-pressure chemical plant and a valve body obtained by impregnating a C / C material with a resin have excellent high-temperature strength without causing breakage. It is stable against wear due to the reaction and has the effect of extending the life. An excellent valve seat material or valve body can be provided in consideration of product characteristics, productivity and cost in a comprehensive manner, which is extremely useful in industry.

Claims (1)

[Claims] 1. A valve seat material or valve body in which a valve seat material or valve body of a valve requiring high temperature, high pressure and corrosion resistance is made of a composite material in which a carbon fiber reinforced carbon material is impregnated with a resin.