JPH09242895A - Ball valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent nonmetallic seal material such as an elastic seat from damage due to welding heat at the time of welding in a wholly welded type trunnion ball valve where a welded part for connecting a body to a cap does not directly face a body cavity. SOLUTION: In a wholly weided type trunnion ball valve 1, an elastic seat 5 accommodated between a seat retainer 6 and an outer ring 7 is pressed against a ball 4 supported through upper and lower stems 9, 10 by the elastic spring force of a spring 8 acting on a seal ring 12 to seal among a ball 4, a body 2 and a cap 3, and the body 2 and the cap 3 are connected by welding, and the cap 3 is provided with an annular empty part 14 formed between the back of the outer ring 7 and the inner circumference of the cap 3 and a supply port or a discharge port 11 being a conducting port to communicate with the outside of the cap 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an all-welded ball valve which is mainly used by being mounted on a pipeline for transporting fuel gas and the like.

[0002]

2. Description of the Related Art FIG. 2 is a longitudinal sectional view showing an example of a conventional large-diameter all-welded trunnion ball valve, in which a seat ring 21 is housed in a seat retainer having an outer ring and an outer ring. By the elastic force of
By pressing the ball 25 supported by the lower stems 23 and 24, the space between the ball 25 and the body 26 and the ball 2
5 and the cap 27 are sealed.

The body 26 and the cap 27 of this ball valve are connected by welding, and FIG.
It is an expanded partial longitudinal cross-sectional view showing the periphery of the welded portion 28. When constructing the welded portion 28, a large amount of welding heat is applied to raise the temperature in the vicinity of the welded portion where the body 26 and the cap 27 are welded, and this temperature rise is caused by the sheet 21 made of a non-metallic material, Around the seat retainer 22,
A sealing material such as an O-ring used around the upper and lower stems 23 and 24 or around the upper and lower covers 29 and 30 is deteriorated or damaged by the heat during welding,
There is a problem that makes the ball valve 31 defective.

In order to prevent this problem, when the welded portion 28 is applied, the interlayer time, which is the time interval from the formation of one welded layer to the superposition of the next welded layer, is lengthened to increase the welded portion 2.
Suppress the rise due to the accumulation of temperature of 8 or ball 2
It is also practiced to remove welding heat by sending air or the like from the outside of the valve 31 through a supply port 33 provided in the body cavity 32 with the valve 5 half-opened.

[0005]

However, in the former method, it takes a long time to construct the welded portion 28, which is extremely uneconomical. In the latter method, the welded portion 28 directly contacts the body cavity 32. However, it is effective when the welded portion does not directly face the body cavity, and the welded portion 13 does not directly face the body cavity. When it is close to the sealing material, it is impossible to solve the above-mentioned problem due to the temperature rise even if the latter method is applied.

The present invention was developed in view of the above-mentioned conventional problems, and an object of the present invention is to provide a welded portion connecting a body and a cap not directly facing the body cavity. An object of the present invention is to provide an all-welded ball valve capable of welding while cooling non-metallic parts such as seat rings and O-rings without damaging them.

[0007]

In order to achieve the above object, the present invention supports a ball with upper and lower stems, presses a seat of a seal ring against the ball with a spring, and welds a body and a cap. In the all-welded trunnion type ball valve, a supply port or a discharge port formed in the cap is provided in the space between the back surface of the seal ring on the outer side of the seat and the inner surface of the cap. A single piece or a plurality of pieces are made to communicate with each other, and cooling air or the like is passed through the conduction port to prevent damage to the seal material such as the seal ring sheet or the O ring due to welding heat.

Another invention is a fully welded trunnion type ball valve in which a ball is supported by upper and lower stems, a seat of a seal ring is pressed against the ball by a spring, and a body and a cap are welded. The space between the back surface of the seal ring on the outer side and the inner surface of the cap is connected to a supply port for supply formed in the cap, and a discharge port is provided in the body cavity for cooling from the port. Air is supplied from the outlet through the fitting gap between the outer peripheral surface of the seal ring and the inner peripheral surface of the body or cap, and the seal of the seal ring sheet or O-ring due to welding heat. I tried to prevent the damage of the material.

Still another aspect of the present invention is a fully welded trunnion type ball valve in which a ball is supported by upper and lower stems, a seat of a seal ring is pressed against the ball by a spring, and a body and a cap are welded. In the space between the back surface of the seal ring on the outer side of the seat and the inner surface of the cap, a supply port for supply formed in the cap is communicated, and cooling air or the like is supplied from the connection port. In addition, through the fitting gap between the outer peripheral surface of the seal ring and the inner peripheral surface of the body or cap, the balls of intermediate opening are discharged into the flow path from the balls of the intermediate opening, and the seal ring seat or O-ring due to welding heat, etc. Prevents damage to the sealing material. The seal ring in each of the above-described inventions is composed of an elastic sheet, a seat retainer and an outer ring, a set ring, an O ring, and the like.

With the above-mentioned structure, at the time of welding for connecting the body and the cap, a conduction port is formed in the annular space formed between the back surface of the outer ring of the seal ring and the inner peripheral surface of the cap. Coolant such as air and water is sent from a certain supply port and discharged from a discharge port that is a conduction port to prevent the temperature of the seal ring and the body and cap parts in the vicinity from rising, and to prevent the sheet and O Prevents damage to the sealing material such as rings.

Further, when the body cavity is provided with a discharge port such as a drain hole, the coolant sent from the supply port to the space portion is inserted into the body through the fitting gap between the cap and the outer ring. Since it flows out into the cavity and is discharged from this discharge port, in this case, only the supply port needs to be provided between the space and the outside. Furthermore, if the ball is opened halfway, the coolant sent from the supply port into the space flows out into the body cavity through the fitting gap between the cap and the outer ring, and is discharged into the flow path. Also in this case, only the supply port may be provided between the space and the outside.

[0012]

1 is a longitudinal sectional view showing an embodiment of a ball valve according to the present invention, in which 1 is a valve body of the trunnion ball valve of this all-welded type, 2 is a body, and 3 is a body.
Is a cap, and the body 2 and the cap 3 constitute a valve body. 4 is a ball having a through hole 4a,
5 is an elastic ring-shaped seat, 6 is a seat retainer, 7 is an outer ring, 8 is a spring such as a coil spring or a leaf spring,
9 is the upper stem, 10 is the lower stem, 11 is the cap 3
It is a supply port or a discharge port which is a conduction port formed in 1., and one or a plurality of this conduction port 11 are provided. Reference numeral 12 is a seal ring, and the seal ring 12 is composed of a seat 5, a seat retainer 6, an outer ring 7, a set ring 7a, an O ring 17, and the like.

The elastic sheet 5 of the seal ring 12
Is housed between the seat retainer 6 and the outer ring 7, and the elastic force of the spring 8 acts on the seal ring 12 to press the seat 5 against the ball 4 and the space between the ball 4 and the body 2. , And the space between the ball 4 and the cap 3 is sealed.

The body 2 and the cap 3 are welded to each other at the welded portion 1.
Welded in 3. Further, an annular space portion 14 is formed between the back surface of the outer ring 7 of the seal ring 12 and the inner peripheral surface of the cap 3, and this space portion 1
4 and the outside of the cap 3 supply and discharge ports 11
Is provided on the cap 3. Reference numeral 15 is an O-ring mounted between the seat retainer 6 and the body 2 or the cap 3, 16 is an O-ring mounted on the upper stem 9, and 17 is an O-ring mounted on the lower stem 10.

Next, the operation will be described with reference to FIG. When the body 2 and the cap 3 are welded and connected to each other at the welded portion 13, a coolant such as air and water is fed into the space portion 14 from the supply port 11 which is a conduction port, and a position different from the port 11 is provided. The seal ring 12 is discharged from the discharge port 11 provided in
It prevents the temperature of the cap 3 and the body 2 around the welded portion 13 from rising and prevents the elastic sheet 5 and the sealing materials such as the O-rings 15, 16 and 17 from being damaged.

Further, in the case of sour gas having corrosiveness as a fluid to be applied to the ball valve, if there is a tensile residual stress due to welding, stress corrosion cracking occurs. However, according to the present invention, cooling is performed by passing air or water through the supply port 11 at the time of welding to change the residual compressive stress to prevent stress corrosion cracking,
It becomes possible to protect the seat, the O-ring, and the like.

When the body cavity 18 is provided with a discharge port 19 such as a drain hole, the supply port 1
Since the coolant sent from 1 to the space portion 14 flows out from the fitting gap 20 between the cap 3 and the outer ring 7 into the body cavity 18 and is discharged from the discharge port 19, in this case, the space Supply port 11 between the portion 14 and the outside
Only provide. Furthermore, if the ball 4 is in a half open state,
Since the coolant sent from the supply port 11 into the space 14 flows out from the fitting gap 20 between the cap and the outer ring 7 into the body cavity 18, and is discharged into the flow path.
Also in this case, only the supply port 11 is provided between the space 14 and the outside.

[0018]

From the above, according to the present invention, there are the following excellent effects. That is, when the body and the cap are welded and connected, a coolant such as air or water is fed from a supply port and discharged from a discharge port, etc., so that a non-metallic sealing material such as an elastic seat ring or an O-ring. It is a very economical ball valve that can be efficiently welded without damaging the.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of a ball valve of the present invention.

FIG. 2 is a vertical cross-sectional view showing an example of a conventional large-diameter all-welded trunnion ball valve.

FIG. 3 is an enlarged partial vertical sectional view showing the periphery of the welded portion in FIG.

[Explanation of symbols]

 1 Valve Body 2 Body 3 Cap 4 Ball 5 Elastic Seat 6 Seat Retainer 7 Outer Ring 8 Spring 9 Upper Stem 10 Lower Stem 11 Conduction Port (Supply Port, Discharge Port) 12 Seal Ring 13 Welding Part 14 Space Part 19 Discharge Port

Claims (3)

[Claims] 1. An all-welded trunnion type ball valve in which a ball is supported by upper and lower stems, a seat of a seal ring is pressed against the ball by a spring, and a body and a cap are welded to the outer side of the seat. In the space between the back surface of the side seal ring and the inner surface of the cap, one or a plurality of supply or discharge passages formed in the cap are communicated with each other, and cooling air is supplied to the passage. Ball valve designed to prevent damage to the sealing material such as the seal ring seat and O-ring due to welding heat. 2. An all-welded trunnion type ball valve in which a ball is supported by upper and lower stems, a seat of a seal ring is pressed against the ball by a spring, and a body and a cap are welded to each other. In the space between the back surface of the seal ring on the side and the inner surface of the cap, a supply port for supply formed in the cap is communicated,
An exhaust port is provided in the body cavity, cooling air or the like is supplied from the conduction port, and is discharged from the exhaust port through a fitting gap between the outer peripheral surface of the seal ring and the inner peripheral surface of the body or cap, Seal ring sheet and O by welding heat
Ball valve designed to prevent damage to the sealing material such as rings. 3. An all-welded trunnion type ball valve in which a ball is supported by upper and lower stems, a seat of a seal ring is pressed against the ball by a spring, and a body and a cap are welded to the outer side of the seat. The space between the back surface of the seal ring on the side and the inner surface of the cap is connected to a supply opening for supply formed in the cap, and cooling air or the like is supplied from the connection opening. Damage to seal materials such as seal ring seats and O-rings due to welding heat discharged from the body cavity into the flow path from the intermediate opening balls through the fitting gap between the outer peripheral surface and the inner peripheral surface of the body or cap Ball valve designed to prevent