JPH0552269A - Structure of valve body seat part - Google Patents

Abstract

PURPOSE:To prevent the seat crack of a filling-up part by lightening the thermal stress of a seat part by forming an annular groove on the outer periphery of the filling-up metal of a valve seat, at the seat part of a valve body for handling the fluid having high temperature, low temperature, or high pressure. CONSTITUTION:The thermal stress at a seat part can be lightened by forming a U or V shaped annular groove on the outer periphery of a filling-up metal 24a of a valve seat 24 installed on the same axis line, in opposed contact with a disc 22 which is fitted in slidable manner in a valve body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a valve seat portion, and particularly to a rapid thermal stress acting on the valve seat portion when collecting or flushing a fluid having a high temperature or a fluid having a low temperature in a power plant or the like. The present invention relates to the structure of a valve body seat portion configured to reduce the above.

[0002]

^2. Description of the Related Art Generally, as a valve for handling high-temperature and high-pressure fluid (for example, 500 ° C., 300 kgf / cm ² ), a connection type valve as shown in FIG. 3A is used. That is, the valve body 10 is composed of the upper valve body 1
The protrusion 12a provided at the center of 2 is fitted in the recess 14a provided at the center of the lower valve body 14, the joint surfaces of both valve bodies 12 and 14 are butted, and the outer peripheries thereof are welded to be integrally formed. Has been done.

The stem 16 is a gland packing 1.
8 and the packing seat 20 so as to be liquid-tightly inserted into the upper valve body 12 and its protrusion 12a so that the disc 22 provided at the tip of the stem 16 is seated on the valve seat 24 provided in the lower valve body 14. It is configured.

In such a valve, the valve seat 24 is the most important part of the valve structure, and the valve seat 24 is provided in the valve body 10 in order to prevent leakage due to physical damage due to foreign matter or the like as much as possible. In comparison, a hard material is used by applying a metal deposit 24a to this portion.

[0005]

However, since the heap metal 24a of the valve seat 24 has a difference in linear expansion coefficient due to the difference in material from the valve body 10, thermal stress and fatigue due to repeated rapid heating and cooling ( There is a problem that cracks (sheet breakage) occur in the deposit due to heat fatigue). That is, the seat crack of the metal deposit due to thermal shock is caused by a sudden high temperature and high pressure load when the valve is first opened and a large thermal stress is generated there, and the load is repeatedly acted upon by opening and closing the valve. .. It is presumed that a large amount of energy consumed by the material causes rapid damage in a short period of time, which causes sheet cracking.

[0006] As a structure of a valve having such a measure for preventing sheet breakage of a heap metal, for example, a structure as shown in Fig. 3B has been proposed. That is, in order to reduce the heat capacity of the valve seat 32 provided with the heap metal 32a, it is separated into the seat member 26 and the pressing member 28 for pressing the seat member 26, and a large number of gland packings 30 and the like are attached to the pressing member 28. Use to ensure the seal. However, since such a valve structure has a separated structure, the number of parts is large, the structure is complicated, and much time is required for disassembling and assembling work, which makes maintenance difficult, which causes a rise in manufacturing cost. Was there.

Therefore, an object of the present invention is to apply a metal harder than the material of the valve body to a seat portion of a valve that handles high-temperature, high-pressure or low-temperature fluid, and form an annular groove on the outer periphery of the seat portion metal. Thus, the structure of the valve body seat portion is provided, which is capable of reducing the thermal stress in the seat portion and has a simple structure and can significantly reduce the number of disassembling / assembling work steps.

[0008]

In order to achieve the above object, in a valve handling a high or low temperature fluid, a disc is slidably inserted in the valve body in an axial direction so as to open / close a fluid outlet / inlet of the valve. Then, a helix that is harder than the material of the valve body is applied to the periphery of the fluid inlet of the seat portion that is provided on the same axis as the tip of this disc, and an annular groove is formed around the helix of this valve seat. Is formed.

In this case, in the valve body, the upper valve body and the lower valve body are welded to each other and a recess is formed in the abutting surface of the lower valve body connecting portion, and the fluid inlet is communicated with the recess. It is preferable that a convex portion is formed on the contact surface of the upper valve body connecting portion and the disc is slidably fitted on the same axis as the convex portion.

Further, it is preferable that the annular groove has a U-shaped or V-shaped cross section.

[0011]

According to the structure of the valve seat portion according to the present invention, the disc is slidably inserted in the valve body in the axial direction so as to open and close the fluid outlet / inlet of the valve, and is brought into contact with the tip of the disc. By applying a metal harder than the material of the valve body to the periphery of the fluid inlet of the seat provided on the same axis as this and forming an annular groove on the outer circumference of the metal of the valve seat, In addition to reducing stress, the structure is simple and the disassembling and assembling work can be significantly reduced.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the structure of a valve body seat portion according to the present invention will be described below in detail with reference to the accompanying drawings. For the sake of convenience of explanation, the same components as those shown in FIG. 3 are designated by the same reference numerals, and detailed description thereof will be omitted.

FIG. 1A shows an embodiment of the structure of the valve body seat portion according to the present invention, FIG. 1B is a sectional view of the essential parts showing another embodiment, and FIG. It is a comparison explanatory view of the valve seat part which concerns on this invention, and the conventional valve seat part.

In the figure, reference numeral 34 indicates a fluid inlet of a valve that handles high-temperature, high-pressure or low-temperature fluid, and the fluid introduced from this fluid inlet 34 passes through the inside of the valve body by repeated opening of the valve. It is intermittently discharged from the fluid outlet 36.

The fluid inlet 34 is formed on the vertical central axis of the lower valve body 14 so as to communicate with the inlet 34a formed in the horizontal direction from the side surface of the lower valve body 14.
b, the inflow port 34b communicates with the seat part 40, and the tip of the disk 22 liquid-tightly inserted into the protruding part 12a of the upper valve body 12 on the same axis as the valve part is located at the periphery of the inflow port 34b. When the tip of the disc 22 is repeatedly seated on the valve seat 24 in contact with the seat 24, the valve seat portion is prevented from leaking to the valve seat 24 as much as possible due to physical damage or the like due to physical damage. The deposit 24a is made of a material harder than the above material. Then, in FIG.
As shown in FIG.
The V-shaped annular groove 38 or the V-shaped annular groove 42 shown in FIG. 1B is formed.

Next, the structure of the valve seat portion will be described in comparison with the structure of the conventional valve seat portion with reference to FIG. That is, (a) of FIG. 2 shows a cross-sectional view on one side from the center of the conventional seat portion, and (b) of FIG. 2 shows a half-sectional view of the seat portion of the present invention. In FIGS. 2A and 2B, the inner and outer radii r ₁ and r ₂ of the valve seat helix and the bottom surface of the seat portion 40 provided at the center of the lower valve body 14 forming the valve seat 24 The inner radii R are the same, and in FIG. 2 (a), the metal deposit 24a of the valve seat 24 on the bottom surface of the seat of this radius R is
A U-shaped annular groove 38 having a width R-r ₃ is formed on the outer circumference.

By forming the annular groove 38 having a U-shaped cross section in this manner, the heat capacity of the seat portion 40 is reduced, and thermal stress and fatigue due to repeated rapid heating and cooling (thermal fatigue) are reduced to reduce thermal shock. Can be softened and the cracking of the sheet of the heap metal 24a can be prevented. With this structure, when a high-temperature or low-temperature fluid flows into the valve, the tensile or compressive stress due to the difference in the linear expansion coefficient between the metal plate and the valve body rapidly repeats in proportion to the size of the valve body. However, by forming the annular groove in the sheet portion on the outer periphery of the metal deposit, it is possible to significantly reduce the thermal stress related to the metal deposit.

[0018]

As is apparent from the above-described embodiments, according to the structure of the valve body seat portion of the present invention, the disc is axially slidably inserted into the valve body to open and close the fluid outlet / inlet of the valve. The valve seat is placed in contact with the front end of the disc and is provided on the same axis as the fluid inlet port of the seat. By forming the groove, it is possible to reduce the thermal stress in the seat part, and the structure is simple so that the disassembling and assembling man-hours can be greatly reduced, the maintenance can be facilitated and the manufacturing cost can be reduced. And so on.

While the preferred embodiment of the present invention has been described above, the structure of the valve body seat portion of the present invention has been described, for example, as the annular groove having a U-shaped or V-shaped cross section, but is not limited to this shape. Of course, various design changes can be made without departing from the spirit of the present invention.

[Brief description of drawings]

FIG. 1A is a sectional view of an essential part of a valve body seat portion according to an embodiment of the present invention, and FIG. 1B is a valve according to the present invention. FIG. 11 is a cross-sectional view of a main part of the valve seat portion, showing another embodiment of the body seat portion.

FIG. 2 is a comparative explanatory view of the structure of the valve body seat portion of the present invention and the structure of the conventional valve body seat portion, and FIG. 2 (a) is an explanatory view of the conventional valve body seat portion. (B) is an explanatory view of the valve body seat portion of the present invention.

FIG. 3 is a cross-sectional view of essential parts showing a conventional valve structure in which a valve body seat is covered with a metal harder than the material of the valve body.

[Explanation of symbols]

10 valve body 12 upper valve body 14 lower valve body 16 stem 18,30 gland packing 20 packing sheet 22 disc 24,32 valve seat 24a, 32a deposit 26 sheet member 28 pressing member 34, 34a, 3
4b Fluid inlet 36 Fluid outlet 38 U-shaped annular groove 40 Seat portion 42 V-shaped annular groove

Claims (3)

[Claims] 1. In a valve for handling a high or low temperature fluid, a disc is slidably inserted in the valve body in an axial direction so as to open and close a fluid outflow port of the valve, and the disc is brought into contact with the tip of the disc. A valve body seat portion characterized by forming a metal harder than the material of the valve body on the periphery of the fluid inlet of the seat portion provided on the same axis and forming an annular groove on the outer periphery of the metal of the valve seat. Structure. 2. The valve body, wherein an upper valve body and a lower valve body are welded to each other, a recess is formed in an abutting surface of a lower valve body connecting portion, and a fluid inlet is communicated with the recess. 2. The structure of the valve body seat portion according to claim 1, wherein a convex portion is formed on the contact surface of the upper valve body connecting portion, and the disc is slidably fitted on the same axis as the convex portion. 3. The annular groove has a U-shaped or V-shaped cross section.
The structure of the valve body seat part according to claim 1, which is formed in a V shape.