JP2003185027A - Shaft seal device of valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shaft seal device capable of shortening a gland packing replacement working time by performing a gland packing replacement operation without removing a valve from a pipe by the cassette system of a gland packing part. <P>SOLUTION: In this shaft seal of a valve, the packing part is cassetted by housing gland packings 9 pressed by a gland retainer 5 in a gland packing box 6 to facilitate the gland packing replacement operation. A spring 11 is installed between the lower end part of the cylindrical part of the gland retainer 5 surrounding a valve stem 3 and the upper end part of the gland packings 9. Grooves 12 are provided, by multiple slitting, in the peripheral surface of the valve stem 3 near the upper end face of the gland retainer 5 allowing the valve stem 3 to be inserted therein. The fitted surface of the outer gland packing box 6 housing the gland packings 9 therein to a valve body 1 is sloped so that the upper part thereof is increased in diameter more than the lower part. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a cassette for a gland packing part, that is, a gland packing pressed by a gland pressing plate is housed in a gland packing box to form a packing part for cassettes, which is used for maintenance work. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve shaft sealing device that facilitates packing replacement work and shortens maintenance work time, and more particularly to a valve shaft sealing device that can be replaced without removing the valve from a pipe.

[0002]

2. Description of the Related Art In the case of a general valve (valve), as a structural feature, a space for accommodating the gland packing is provided in the valve rod hole penetrating portion of the main body, and the gland packing is placed in the accommodating position after inserting the valve rod. It has a mechanism to prevent leakage of the gland by arranging it in direct contact with the rod and applying pressure to the gland packing with a gland pressing plate to obtain compression of the gland.

In general, a soft material of graphite type is generally selected for the gland packing, and wear due to rotation of the valve shaft and leakage due to progress of wear often occur.

When leakage occurs due to progress of wear, the initial compression to the packing input from the gland pressing plate is low, and the inspector re-tightens the bolts and nuts of the gland pressing plate. Hold the compression of the gland packing. If leakage cannot be prevented by retightening, replace the packing.

Conventionally, there is JP-B-62-22709 as an example of using a cassette system. In order to simplify the work of replacing the gland packing, this product uses a thin-walled cylindrical gland packing box in which the pressure receiving diameter of the seal part on the inner end side is less than the inner diameter of the packing accommodating part on the outer end side. In preparation for this, the inner diameter of the gland press to be fitted with the split gland push is larger than the outer diameter of the gland packing box, and the packing is mounted in the gland packing box, and the O ring is also attached. Is a shaft seal device that can be installed between the valve box body and the valve stem by forming a cassette by providing it on the outer circumference of the gland packing box. The purpose is to replace the cassette by removing the valve shaft. That is, according to the explanation, when disassembling work, for example, when replacing the packing, loosen the tightening nut and move the gland retainer upward, remove the two split gland bushes fitted to it, and then loosen the upper stem bushing. , Turn the handle to the open side and pull up the stem, that is, the valve shaft, the packing box, and the valve body. Then, if the handle is removed, the valve shaft, the gland packing box and the valve body can be manually pulled out and simultaneously removed. That is, the purpose is to replace the cassette by removing the valve shaft.

[0006]

The above-mentioned conventional example is one in which the cassette is replaced by removing the valve shaft. As in the present invention, it is possible to perform the replacement work without removing the valve from the pipe. Is different.

Further, generally, as a problem of the valve shaft sealing device, (i) when the fluid used in the pipe is of high pressure / high temperature, due to the influence of thermal expansion of each component and the reduction of the laplinance effect of the packing under high pressure, There are many opportunities to tighten the bolts and nuts of the gland presser plate at the initial stage of valve use.

(Ii) If a ground leak is found,
The inspector tightens the bolts and nuts on the gland presser plate to keep the packing compressed, but the tightening of the packing cannot be quantitatively evaluated. Further, a decrease in the compression amount of the packing due to wear and deterioration due to rotation of the valve shaft is a condition that is confirmed by leak detection, and there are many points of concern for safety. Especially when the fluid used in the pipe is highly toxic, it is necessary to consider the effect on the human body.

(Iii) Since the gland packing is arranged directly in the valve rod through hole of the main body, the packing should be replaced with one
You need to remove each one. Further, when the valve is used, a part of the gland packing is always in contact with the fluid, and the packing may be fixed to the main body part or the valve rod due to deterioration or sliding wear. Usually, the removal work should be done with a packing hook or a drawing recommended by the packing manufacturer, as shown in Fig. 3 (a).
Even if a jig such as a tamper as shown in 3 (b) is used, it takes a long time to perform the work including removing the packing and cleaning the fixed surface.

There is a problem that

The present invention solves the above-mentioned problems, and by the cassette system of the gland packing, the valve can be replaced without removing it from the pipe, thereby obtaining a shaft sealing device that can be shortened in time. This is a technical issue.

[0012]

In order to solve the above-mentioned problems, the means adopted by the present invention is to store the gland packing pressed by the gland pressing plate in a gland packing box to form a packing portion cassette, In a valve shaft sealing device that facilitates gland packing replacement work, a spring is interposed between the lower end of the cylindrical portion surrounding the valve rod of the gland pressing plate and the upper end of the gland packing.

Further, it is characterized in that a groove formed by slitting a plurality of ridges is provided on the valve rod peripheral surface near the upper end surface of the gland pressing plate through which the valve rod is inserted.

Further, the fitting surface of the outer gland packing box, which accommodates the gland packing inside, with the valve body is provided with a slope having a larger diameter from the lower part to the upper part.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of the present invention will be described with reference to the examples shown in the drawings. 1 is a sectional view showing an overall view of a valve (eccentric butterfly valve) equipped with a shaft sealing device according to an embodiment of the present invention in a fully closed state, and FIG.
FIG. 3 is an enlarged cross-sectional view of a valve shaft sealing device.

In FIG. 1, an actuator (eg gear box) and a plate 2 which are not shown in the valve body 1 are removed, and the valve rod 3 is projected. First, the gland bolt / nut 4 and the gland pressing plate 5 are removed. Then, a spanner or the like is inserted between the gland packing box 6 and the main body 1, and the entire box 6 is pulled out in a lever-like manner. Reference numeral 7 in the drawing denotes an eccentric valve body.

Next, referring to FIG. 2, the structure of the shaft sealing device will be described in accordance with the procedure at the time of assembling. With the valve rod 3 incorporated in the main body 1, a metal O-ring 8 provided on the bottom surface, packings 9 (braided packing 9a, graphite packing 9b)
Etc.) and a spring 11 between two disc-shaped shim plates 10.
Then, the gland packing box 6 temporarily assembled from the lower part to the upper part is assembled in the packing box part of the valve rod hole penetrating part of the main body 1. At this time, since an inclination (about 5 °) is provided on the outer peripheral surface of the gland packing box 6 so that the lower part has a small diameter and the upper part has a large diameter, the cassette can be easily taken in and out. In addition, the metal O on the bottom
The ring 8 prevents leakage from the outer periphery of the gland packing box 6.

The shim plate 10 is used for preventing damage to packings and for transmitting the force of the spring 11 uniformly to the gland packing 9. Further, by incorporating a plurality of stages of the gland packings 9 in the gland packing box 6, the amount of the fluid directly catalyzing each of these packings is small, and the deterioration due to the fluid temperature is reduced.

Finally, the gland pressing plate 5 consisting of the cylindrical portion surrounding the valve rod 3 and the flange portion at a right angle is tightened using the gland bolts and nuts 4. At this point, the spring 11 is compressed by the torque input to the bolt / nut 4, and a certain amount of force is applied to the gland packing 9.
(For example, when the valve rod diameter is 35 mm, the packing tightening surface pressure is 40
It is preferable to input 0 kgf / cm ² from the gland nut. At the same time, by providing a gap between the gland pressing plate 5 and the gland packing box 6, it becomes possible to leave a space in which the bolt and nut 4 of the gland pressing plate 5 can be tightened further.

Further, in the contact area (about 10 mm) between the valve rod 3 and the gland pressing plate 5, a groove 12 is formed by slitting at 1 mm intervals.
By providing the, the initial setting position of the gland pressing plate 5 becomes clear, and the amount of compression when the gland bolts and nuts 4 are retightened can be quantitatively confirmed, and according to the number of the reduced slits 12, It becomes possible to tell the replacement time.

Although the structure of the eccentric butterfly valve has been described in the above embodiment, the invention can be similarly applied to other valves.

[0022]

As described above, according to the present invention,
In the valve shaft sealing device that stores the gland packing pressed by the gland holding plate in the gland packing box to make the packing part a cassette, and facilitates gland packing replacement work, the cylindrical part surrounding the valve rod of the gland holding plate. By interposing the spring between the lower end of the gland packing and the upper end of the gland packing, the following effects can be obtained.

(I) A certain amount of compressive force is applied to the gland packing, and minute wear and thermal deterioration can be absorbed by the spring force, leading to a reduction in the frequency of inspection by the inspector.

(Ii) Further, since the shaft sealing device is of the cassette type as described above, if the flow direction is limited and the valve is fully closed to prevent leakage, in the case where pressure is applied in the pipe But the packing can be replaced.

(Iii) Further, at the time of reassembly, the gland packing can be easily incorporated by performing the assembly according to the first assembly procedure (procedure).

Further, since a groove formed by slitting a plurality of grooves is provided on the valve rod peripheral surface near the upper end surface of the gland pressing plate through which the valve rod is inserted, the packing is worn when the gland bolts and nuts are retightened. The quantity becomes clear, and the packing replacement timing can be quantitatively determined according to the number of slits reduced.
It is also excellent in safety.

Further, the fitting surface of the outer gland packing box having the gland packing accommodated therein with the valve body is provided with a slope having a larger diameter from the lower part to the upper part, so that the gland packing box can be replaced when the gland packing is replaced. You can put something like a wrench between the main body and the main body and pull out the box like a lever.

[Brief description of drawings]

FIG. 1 is a sectional view showing an overall view of a valve provided with a shaft sealing device showing an embodiment of the present invention.

2 is an enlarged sectional view of the valve shaft sealing device of FIG. 1. FIG.

3 (a) and 3 (b) are explanatory drawings showing a usage procedure of a jig that has been conventionally used for removing a packing.

[Explanation of symbols]

1 body 2 plates 3 valve rod 4 Ground bolts and nuts 5 Ground presser plate 6 gland packing box 7 valve body 8 metal O-rings 9 packing 9a Braided packing 9b Graphite packing 10 shim boards 11 spring 12 grooves

Claims (3)

[Claims] 1. A shaft seal device for a valve, wherein a gland packing pressed by a gland holding plate is housed in a gland packing box to form a packing part cassette, and a gland packing replacing operation is facilitated. A valve shaft sealing device characterized in that a spring is interposed between the lower end of a cylindrical portion surrounding a rod and the upper end of a gland packing to reduce the pressing work of the gland pressing plate. 2. A groove formed by slitting a plurality of ridges is provided on the valve rod peripheral surface near the upper end face of the gland pressing plate through which the valve rod is inserted so that the amount of wear of the packing and the replacement time can be easily confirmed. The shaft sealing device for a valve according to claim 1, wherein: 3. A gland packing box having a gland packing housed therein is fitted with a valve body with a slope having a larger diameter from the lower part to the upper part to facilitate replacement of the gland packing box. Claim 1 or 2
A shaft sealing device for the described valve.