JPH08128545A - Leakage suppressing method for ball valve and ball valve - Google Patents

Abstract

PURPOSE: To surely suppress leakage by supplying detergent liquid with a viscosity lower than that of grease in a sealing part and sequentially opening/closing a ball several times when leakage is generated in the sealing part in a seal member brought into contact with the surface of the ball over the whole circumference. CONSTITUTION: While opening a ball 4, foreign matter such as dust and rust in fluid penetrates a clearance between a sheet retainer 21 and the ball 14, and afterward, the foreign matter may be bitten in opening/closing operation of the ball 14. If leakage is generated between a sheet 22 and the ball 14 because of biting of such a foreign matter, detergent liquid is injected from a sealant supplying device 28 instead of sealant so as to be fed to the sealing part via sealant supplying units 10a, 21a. Then, the ball 14 is sequentially opened/closed several times, and the foreign matter is washed away. After washing, the sealant is fed via the same path from the sealant supplying device 28, and the ball 14 is opened/closed, and consequently, the leaking part, is sealed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of suppressing leakage in a ball valve installed in a pipeline for natural gas, crude oil, water, etc., and a ball valve.

[0002]

2. Description of the Related Art Generally, in a ball valve which is opened and closed by the rotation of a ball inside a body, a seal member is provided between the inner surface of the body and the outer surface of the ball, and a seal is made at a contact portion between the seal member and the outer surface of the ball. However, a leak may occur at the seal portion. The main cause of this leak is foreign matter such as dust, sand, rust, and welding scale in the line that enters between the seal member and the outer surface of the ball when the valve is opened, and the foreign matter seals with the ball by the subsequent opening / closing operation. It is to be caught between the members.

Conventionally, as a countermeasure after such a leak occurs, grease (a semi-solid or solid form in which a thickener is dispersed in lubricating oil is dispersed) is injected into the above-mentioned seal portion to remove foreign matter. Block the communication hole generated by biting,
Alternatively, a method of suppressing leakage by filling a communication part due to damage of a sheet is well known.

As a means for preventing the occurrence of the above leak, as shown in Japanese Patent Publication No. 4-49415, an elastic lip is provided on the ball side, and the elastic lip is used for the ball and the sealing member. By covering the gap between the inside and the inside from the inside, it is possible to prevent foreign matter from entering the seal portion, or as disclosed in Japanese Patent Publication No. 20542/1990.
In the seat retainer that holds the sealing sheet, attach a wiper to the portion radially inward of the sheet,
A method is known in which the wiper is pressed against the surface of the ball by the elastic force of a spring so that foreign matter is scraped off by the wiper when the ball is opened and closed.

[0005]

According to the method of the invention, since the fluidity of the grease is low, the grease may not be able to fully penetrate the details of the leak portion, and the leak may not be surely suppressed. Further, since the foreign substance that causes the leak is not removed, the leak is likely to occur again when the grease dries.

In the method of (1), since the elastic lip projects into the line, when the pig (cleaning device having a diameter substantially equal to the inner diameter of the line) is run in the line for the purpose of cleaning the inside of the line, the elasticity is increased. The lip greatly hinders traveling, and on the contrary, the elastic lip may be damaged during traveling with a pig. Also, since the elastic lip is fixed to the inner wall of the ball and moves together with the ball, it is possible to cover the sealing portion from the inside when the ball is in the closed position, but when the ball is in the open position. It is not possible to prevent the entry of foreign matter into the seal portion.

In the method of (1), a considerable distance remains between the wiper and the inner diameter of the pipe due to the fact that the wiper is arranged immediately inside the seat. Therefore, the foreign matter cannot be prevented from entering between the ball and the seat retainer at a portion radially inward of the wiper, and the foreign matter may be caught in the seal portion during the ball opening / closing operation.

In view of such circumstances, it is an object of the present invention to provide a method capable of more reliably suppressing the leak after or before the leak occurs, and a ball valve suitable for the method.

[0009]

As a means for solving the above-mentioned problems, the present invention provides a body between a body and a ball for opening and closing a valve which is rotatably housed in the body about a predetermined axis. This is a method of suppressing leakage in a ball valve in which a ring-shaped sealing member that makes contact with the entire surface of the ball and seals at this contact portion is interposed, in which a leakage occurs at the sealing portion by the sealing member. At this time, a cleaning liquid having a viscosity lower than that of grease is supplied to the seal portion, and the ball is continuously opened and closed a plurality of times (claim 1).

More specifically, as the cleaning liquid,
A liquid (more preferably oil; claim 3) having a viscosity at 40 ° C of less than 200 centistokes is preferred (claim 2).

Further, after the opening / closing operation, by supplying a fluid having a viscosity higher than that of the cleaning liquid to the sealing portion and then opening / closing the ball, more excellent effects as described later can be obtained ( Claim 4).

This fluid is preferably oil having a viscosity lower than that of grease (claim 5). In particular, after the cleaning liquid having a viscosity of 200 centistokes or less at 40 ° C. is used, the fluid has a viscosity of 200 centistokes at 40 ° C. Above all, oil of 300 centistokes or less is preferable (claim 6).

Further, according to the present invention, between the body and the ball for opening and closing the valve, which is rotatably housed in the body about a predetermined axis, the surface of the ball is in contact with the ball over the entire circumference, and the contact portion is provided. In a ball valve in which a ring-shaped sealing member for sealing is provided, the angle formed by the tangent line of the ball surface at the sealing portion and the surface of the sealing member in a region radially outside the sealing portion formed by the sealing member is set. 5
It is set to be equal to or more than ° (Claim 7).

Further, according to the present invention, between the body and the ball for opening and closing the valve which is rotatably housed in the body about a predetermined axis, the surface of the ball is in contact with the entire circumference of the ball and the contact portion is provided. A method of suppressing leakage in a ball valve having a ring-shaped sealing member for performing sealing, wherein the ball and the seal are provided in a region radially inward of a sealing portion by the sealing member before using the ball valve. Grease is interposed between the member and the member (Claim 8).

[0015]

According to the method of claim 1, after a leak occurs,
Supply a cleaning liquid with a viscosity lower than that of grease (that is, with high fluidity) to the leaked seal area,
By successively opening and closing the ball a plurality of times, the cleaning liquid permeates into the leaked portion in detail, and the foreign matter causing the leak is washed away.

More specifically, in the method according to claim 2,
By using a liquid having a viscosity of less than 200 centistokes at 40 ° C. as the cleaning liquid, sufficient fluidity for the cleaning can be secured.

Therefore, the cleaning liquid may be water,
In order to effectively carry out the above-mentioned washing, it is preferable that it has high fluidity and an appropriate viscosity. Therefore, it is more preferable to use oil as the cleaning liquid as described in claim 3.

Further, in the method according to claim 4, after the foreign matter is removed by the opening / closing operation, a fluid having a viscosity higher than that of the cleaning liquid is supplied to the seal portion, so that the leak occurrence portion after the foreign matter is removed. The fluid is sealed and the leak is more effectively suppressed.

Grease may be used as the fluid, but since this grease has extremely low fluidity and it is difficult to permeate into the leaked portion, it is more difficult than the grease as described in claim 5. Using oil with low viscosity
More preferable.

More specifically, when a liquid having a viscosity of less than 200 centistokes at 40 ° C. is used as the cleaning liquid as described in claim 2 or 3, then, the viscosity of the sealing portion at 40 ° C. It is advisable to supply oil not less than 200 centistokes and not more than 300 centistokes.

In carrying out the above method, if the gap between the ball surface and the surface of the seal member is too small in the region radially outward of the seal portion, the surface tension in this portion causes the cleaning liquid to be removed. The foreign matter is less likely to be washed out to the outside in the radial direction even when supplied, but in the ball valve according to claim 7, the tangent line of the ball surface at the seal portion in the region outside the seal portion by the seal member in the radial direction. Since the angle with the surface of the seal member is 5 ° or more, the foreign matter is smoothly washed out to the outside in the radial direction.

As described above, the grease is less effective if it is supplied to the seal portion after the leak occurs, but as described in claim 8, before the ball valve is used, the grease is preliminarily used before the seal portion by the seal member. By interposing a sealant between the ball and the seal member in the radially inner region, the grease can effectively prevent foreign matter from entering the seal portion and prevent leakage. In this case, since it is necessary to keep the sealant in the above area for a long period of time, it is more advantageous to use grease having extremely low fluidity than oil having high fluidity.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS.

The ball valve shown in FIG. 2 has a cylindrical body 10 in which a ball 14 is housed at a position between its fluid inlet 11A and fluid outlet 11B. A fluid passage 12 that penetrates the ball 14 in the horizontal direction is formed in the ball 14, and the ball 14 itself is supported by the body 10 so as to be rotatable about a vertical axis. Specifically, a vertical support shaft 16 is provided on the bottom of the body 10.
Is fixed, the bottom of the ball 14 is rotatably fitted to the upper end of the support shaft 16, and the ball 14
An operation shaft 18 in the vertical direction is fixed to the upper part of the body 10, and the operation shaft 18 penetrates the upper part of the body 10.
It is rotatably supported by. The rotation of the ball 14 causes switching between an open position in which the fluid inlet 11A and the fluid outlet 11B communicate with each other via the fluid passage 12 and a closed position in which the fluid inlet 11A and the fluid outlet 11B are shut off. ing.

A seal member 20 is provided between the body 10 and the ball 14 on the inlet side and the outlet side of the ball valve. The seal member 20 includes a seat retainer 21 as shown in FIG. 1, and an elastic sheet 22 is fitted on the outer peripheral surface of the seat retainer 21, and the elastic sheet 22 is pressed by an outer ring 24 from the outside in the radial direction. It is rare. The outer ring 24 has a screw hole 2 that opens on the side opposite to the ball 14 (on the left side in FIG. 1).
4a, and the presser ring 25 is disposed on the opening side, and the bolt insertion hole 2 provided in the presser ring 25 is provided.
The outer ring 24 is fastened to the seat retainer 21 by screwing the bolts 5 through 5a into the screw holes 24a. A compression spring 27 is interposed between the outer ring 24 and the inner surface of the body 10.
The elastic sheet 22 is pressed against the surface of the ball 14 by the elastic force of 7, and a seal is made at this pressure contact point.

In FIG. 1, 23 is an O-ring for sealing.

The seat retainer 21 is formed with a sealant supply passage 21a that penetrates the seat retainer 21 in the axial direction (the left-right direction in FIG. 1), and the body 10 penetrates it in the radial direction (the up-down direction in FIG. 1). A sealant supply passage 10a is formed, and both supply passages 21a and 10a are in communication with each other. A sealant supply device 28 is connected to the sealant supply passage 10a from the outside of the body 10.

In this ball valve, the ball 14 is open, that is, as shown in FIG.
In the state where the fluid inlet 11A and the fluid outlet 11B are communicated with each other through the dust, dust in the fluid flowing in the ball valve,
Foreign matter such as sand, rust, and welding scale may enter a slight gap between the seat retainer 21 and the ball 14, and may be caught during the subsequent opening / closing operation of the ball 14. Then, the sheet 2 is caught by such foreign matter.
When a communication path is formed between the ball 2 and the ball 14, a leak occurs.

Therefore, in this embodiment, after the above-mentioned leak occurs, a cleaning liquid is sprayed from the sealing agent supply device 28 instead of the sealing agent, and the sealing portion (the surface of the elastic sheet 22 and the ball 14 is passed through the sealing agent supply paths 10a and 21a). Supply it from the inner side in the radial direction. As the cleaning liquid, it is important to use a fluid having a viscosity lower than that of grease. Specifically, by using a liquid having a viscosity at 40 ° C. of less than 200 centistokes, the cleaning effect described below (that is, It has been confirmed that the foreign matter removing effect) can be obtained. Therefore, although water can be used as the cleaning liquid, it is preferable that the cleaning liquid has a certain degree of viscosity in order to obtain the above-mentioned foreign matter removing effect. Therefore, the cleaning liquid has a viscosity of 200 centistokes at 40 ° C. Less than oil is optimal.

When the cleaning liquid is supplied in this way and the ball 14 is continuously opened and closed a plurality of times, the highly liquid cleaning liquid permeates even the details of the leak portion to wash away the foreign matter that causes the leak. , This effectively prevents recurrence of leaks.

Further, after such cleaning, a sealing agent composed of a fluid having a viscosity higher than that of the cleaning liquid is supplied from the sealing agent supply device 28 through the same path, and the balls 14 are washed.
When the opening / closing operation is performed, the reoccurrence of leak can be prevented more surely by causing the sealant to spread over the leak occurrence location (that is, the communication passage occurrence location) and seal this location. Grease may be used as this sealant, but since this grease has extremely low fluidity and does not easily penetrate into details, oils with a relatively high viscosity other than this grease, more specifically, at 40 ° C. Viscosity is 200
It is more preferable to use oil of not less than 300 centistokes and not more than centistokes.

Next, a second embodiment will be described with reference to FIG.

In the ball valve of FIG. 1, if the gap between the surface of the outer ring 24 and the surface of the ball 14 in the region radially outward of the seal portion is too small, a high surface tension is generated in this portion, and This prevents foreign substances from being washed out to the outside in the direction. Therefore, in this second embodiment,
As shown in FIG. 3, the angle θ formed between the surface 24b of the outer ring 24 facing the ball 14 and the tangent line at the seal portion of the surface of the ball 14 is 5 ° or more (about 1 ° in the past). The inclination angle of the surface 24b is set.

With such a structure, foreign matter can be washed out more smoothly in the radial direction, and a higher leak suppressing effect can be obtained.

Next, a third embodiment will be described with reference to FIG. In the above-described embodiment, the method for suppressing the leak after the leak has been described, but in this embodiment, before the leak occurs, more specifically, before the ball valve is used, the seal agent supply device 28 and the seal agent supply are supplied. The grease 30 is provided between the seat retainer 21 and the ball 14 by supplying the grease 30 from the outside of the pipe using the passages 10a and 21a or by applying the grease 30 from the inside of the pipe.
According to this method, the foreign matter in the line is sealed by the seal portion (elastic sheet 22 and ball 14) without using a special member.
With the presence of the grease 30, it is possible to effectively prevent the invasion into the contact portion) with the occurrence of leakage.

In the third embodiment, unlike the case where the processing is performed after the occurrence of the leak as in the first embodiment, it is important to use grease as the sealant. This is because after the sealing agent is supplied, the sealing agent needs to remain between the ball 14 and the seat retainer 21 even during use of the ball valve, and for that purpose, the sealing agent needs to have low fluidity. This is because the sealant does not need to have a high fluidity because it does not seal the portion where the leak actually occurs.

[0037]

As described above, according to the present invention, the following effects can be obtained.

In the method according to the first aspect, after a leak occurs, a cleaning liquid having a viscosity lower than that of grease (that is, a fluidity higher than that of grease) is supplied to the leaked seal portion, and the ball is continuously fed a plurality of times. Because it is operated to open and close,
It is possible to permeate the above-mentioned cleaning liquid into the leak portion in detail to wash away the foreign matter causing the leak, and thereby to prevent the recurrence of the leak more reliably than in the past.

In particular, in the method according to the second aspect, since a liquid having a viscosity at 40 ° C. of less than 200 centistokes is used as the cleaning liquid, it is possible to secure sufficient fluidity for the cleaning. .

Furthermore, in the method according to the third aspect, since oil is used as the liquid, the effect of removing foreign matter can be enhanced as compared with the case of using a liquid having an extremely low viscosity such as water.

Further, in the method according to the fourth aspect, after the foreign matter is removed by the opening / closing operation, a fluid having a viscosity higher than that of the cleaning liquid is supplied to the seal portion, so that the leak occurrence portion after the foreign matter is removed. Can be sealed with the above fluid,
There is an effect that the leak can be suppressed more effectively.

Particularly, in the method according to claim 5, as the fluid, oil having a viscosity lower than that of grease (4 in claim 6) is used.
Since the oil whose viscosity at 0 ° C is 200 centistokes or more and 300 centistokes or less) is used, the fluid can be penetrated into the details of the leak occurrence point more reliably than when grease is used, and a more reliable seal is obtained. There is an effect that can be done.

According to another aspect of the ball valve of the present invention, the angle between the tangent to the ball surface and the surface of the seal member at the seal portion is 5 ° or more in the region radially outside the seal portion formed by the seal member. Therefore, it is possible to avoid generation of high surface tension at this portion and to wash out the foreign matter more smoothly in the radial direction.

According to the method of claim 8, grease is previously interposed as a sealant between the ball and the seal member in a region radially inward of the portion sealed by the seal member before using the ball valve. Therefore, the grease can effectively prevent foreign matter from entering the seal portion without providing a special member, and can prevent leakage from occurring.

[Brief description of drawings]

FIG. 1 is a sectional view showing a main part of a ball valve according to a first embodiment of the invention.

FIG. 2 is a sectional view showing the overall structure of the ball valve.

FIG. 3 is a sectional view showing a main part of a ball valve according to a second embodiment of the invention.

FIG. 4 is a sectional view showing an essential part of a ball valve according to a third embodiment of the present invention.

[Explanation of symbols]

 10 body 14 ball 20 seal member 21 seat retainer 22 elastic seat 24 outer ring 25 surface where outer ring faces the ball 30 grease

Claims (8)

[Claims] 1. A body and a ball for opening and closing a valve, which is housed in the body so as to be rotatable around a predetermined axis,
This is a method of suppressing leakage in a ball valve in which a ring-shaped sealing member that makes contact with the entire surface of the ball and seals at this contact portion is interposed, in which a leakage occurs at the sealing portion by the sealing member. At this time, a method for suppressing leakage in a ball valve, characterized in that a cleaning liquid having a viscosity lower than that of grease is supplied to the seal portion, and the ball is continuously opened and closed a plurality of times. 2. The method for preventing leakage in a ball valve according to claim 1, wherein a liquid having a viscosity at 40 ° C. of less than 200 centistokes is used as the cleaning liquid. Method. 3. The method for preventing leakage in a ball valve according to claim 2, wherein oil having a viscosity at 40 ° C. of less than 200 centistokes is used as the cleaning liquid. Method. 4. The ball valve leakage prevention method according to claim 1, wherein after the opening / closing operation, a fluid having a viscosity higher than that of the cleaning liquid is supplied to the sealing portion, and then the ball is opened / closed. Leak suppression method with a ball valve. 5. The method for preventing leakage in a ball valve according to claim 4, wherein oil having a viscosity lower than that of grease is supplied as a fluid having a viscosity higher than that of the cleaning liquid. Leak suppression method. 6. The method for preventing leakage in a ball valve according to claim 2, wherein after the opening / closing operation, oil having a viscosity at 40 ° C. of 200 centistokes or more and 300 centistokes or less is supplied to the sealing portion. A method of suppressing leakage with a ball valve, which is characterized by opening and closing the ball first. 7. A body and a ball for opening and closing a valve, which is housed in the body so as to be rotatable about a predetermined axis,
In a ball valve having a ring-shaped seal member interposed between the surface of the ball and the entire circumference to seal at this contact portion, in the seal portion in a region radially outside the seal portion formed by the seal member. The ball valve characterized in that the angle formed by the tangent line of the ball surface and the surface of the seal member is set to 5 ° or more. 8. Between the body and a ball for opening and closing the valve, which is rotatably housed in the body about a predetermined axis,
A method for suppressing leakage in a ball valve, in which a ring-shaped seal member is provided which makes contact with the surface of the ball over the entire circumference and seals at this contact portion, the seal member being used before using the ball valve. A method for suppressing leakage in a ball valve, characterized in that grease is interposed between the ball and the seal member in a region radially inward of the sealed portion by the above.