JP2004245331A - High-precision safety valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-precision safety valve in which action can be easily recognized and secured. <P>SOLUTION: This safety valve is installed on a steam boiler, a water boiler, a pressure container, etc. It employs a weld junction structure to prevent invasion of intake air through a valve element both on the primary side and the secondary side even in a condition where secondary side pressure is changed from atmospheric to vacuum, or when stopped. The valve element 64 is connected to a valve rod 66, and a lever 86 capable of pulling up the valve rod 66 is provided. In a state where pressure is not added to a device, action of the valve element 64 can be recognized or secured from the external while maintaining seal performance by pulling up the lever 86. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention is a high-precision safety valve that is easy to confirm operation and ensure operation, in particular, improves the operating characteristics of the safety valve and disassembles the safety valve in the event of a problem such as malfunction of the valve element. The present invention relates to a high-precision safety valve that can be inspected and repaired without any problem. INDUSTRIAL APPLICABILITY The high-precision safety valve of the present invention can be widely applied to applications in which the fluid is not limited to steam, but is flammable gas, toxic gas, or the like, and is not preferably released to the atmosphere or released to the atmosphere.
[0002]
[Prior art]
Although safety valves are installed on steam boilers, hot water boilers, and other pressure vessels, conventional safety valves are generally designed so that the secondary side is open to the atmosphere, so there is no pressure change at the outlet side. , Had been produced. However, it cannot be released to the outside when operating conditions are restricted, when a built-in substance, a substance or an object which is difficult to blow out to the outside is handled.
[0003]
If such an operating condition is conceivable, the conventional safety valve cannot cope with it. In particular, under operating conditions in which the secondary side changes from atmospheric pressure to vacuum, the set pressure may fluctuate depending on the operating conditions, making it difficult to continue stable operation. In order to satisfy these conditions, it is necessary to form a welded structure as a whole. By giving importance to sealability, the safety valve has been inferior in operability and maintenance workability.
Further, in the case of a safety valve having a welded structure, the operation of the valve cannot be confirmed, and once a problem occurs, the safety valve needs to be replaced. Also, in the case of a safety valve with a lever, the valve could not be operated unless the pressure of the device was 75% or more of the set pressure.
[0004]
FIG. 2 shows an example of a conventional safety valve. 50 is a valve body, 52 is a seat (valve seat), 58 is a blowdown ring, 80 is a ring fixing bolt, 78 is a lock nut, 62 is an upper ring, 60 is a valve guide, 64 is a valve body (valve), and 68 is Bellows, 82 is a spring, 66 is a valve stem, 54 is a protective cylinder, 56 is a cap, 76 is an adjusting screw, 72 is a lift limiting plate, 74 is a spring receiver, 84 is a hexagon bolt, 90 is an inlet, and 92 is an outlet It is. The outlet portion 92 is connected to another container or device that has a lower pressure than the inlet portion, and when the set pressure is reached, the valve 64 rises against the spring force and is opened, so that the inlet portion 90 flows in. The discharged fluid is discharged from the outlet 92 to another container or device.
[0005]
Conventionally, as a high-precision safety valve, a safety valve equipped with a bellows attached to a steam boiler, a hot water boiler, a pressure vessel, etc., when the secondary pressure fluctuates from atmospheric pressure to vacuum pressure or when the valve is stopped, It has been proposed that both the primary side and the secondary side have an air-tight welded joint structure so that gas does not enter from the outside through the valve body, and the secondary side is welded and connected to a sealed portion such as a container (for example, Patent Documents) 1).
[0006]
[Patent Document 1]
JP 2001-295952 A (page 2, FIG. 1)
[0007]
[Problems to be solved by the invention]
In the above-mentioned conventional high-precision safety valve, when no pressure is applied to an external device to which the safety valve is connected, it is not possible to externally check the operation of the valve body and secure the operation while maintaining the sealing performance.
[0008]
The present invention has been made in view of the above points, and an object of the present invention is to use a steam inlet and a steam outlet which are connected to a container that fluctuates from an atmospheric pressure or more to a vacuum pressure to ensure safety. The object of the present invention is to provide a high-precision safety valve having a structure and a function capable of improving the slidability of the valve, and confirming operation, securing operation, checking and maintaining, and finely adjusting the pressure at the start and stop of blowing. .
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the high-precision safety valve of the present invention is a safety valve attached to a steam boiler, a hot water boiler, a pressure vessel, or the like, which stops even under conditions where the secondary pressure fluctuates from atmospheric pressure to vacuum pressure. Even at times, both the primary side and the secondary side of the valve are safety valves that adopt a welded joint structure to prevent the intrusion of air from the outside through the valve body, connect the valve body and the valve stem, and pull up the valve stem. That the lever can be pulled up even when pressure is not applied to the device, so that the operation of the valve body can be checked and the operation can be secured from the outside while maintaining the sealing performance. It is characterized by.
[0010]
In this high-precision safety valve, even if the primary side pressure is equal to or higher than the atmospheric pressure and the secondary side pressure is vacuum, if the primary side pressure exceeds the set pressure, it operates to release the expanded gas. It is configured as follows. In addition, the valve body and the valve stem are connected to each other, and the bush is inserted into a sliding portion between the valve stem and the plate supporting the valve stem, thereby improving the movement of the valve body.
In addition, in these high-precision safety valves, a ring stopper bolt provided on the valve body and a ring stopper bolt for improving the sealing performance between the outside air and the adjusting ring provided for improving the accuracy of the blowing pressure, the pre-leakage pressure, and the closing pressure are provided. Is preferably provided.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described. However, the present invention is not limited to the following embodiments, and can be implemented with appropriate modifications. FIG. 1 shows a high-precision safety valve according to a first embodiment of the present invention.
The high-precision safety valve according to the present embodiment has a structure in which the bellows 68 and the valve body (valve) 64 are sealed by welding so that the set pressure of the primary side pressure does not fluctuate due to the fluctuation of the secondary side pressure. Is sealed and fixed to the safety valve body 50 by welding, so that operation failure due to a pressure difference between the secondary side pressure and the atmospheric pressure is hardly caused. Further, the valve body 64 and the valve stem (spindle) 66 are connected, and the bush 70 is inserted into the sliding portion of the valve stem to ensure the operability of the valve body 64, and the valve body 64 and the valve stem 66 may malfunction. The structure is difficult to raise.
[0012]
In order to improve the sealing property and operability of the ring stopper bolt 80, a welding cover 94 is provided to cover the ring stopper bolt 80. Normally, the bolt cover is covered with the welding cover 94 to secure the sealing property and to perform fine adjustment. Only when it becomes necessary, the cover 96 of the welding cover portion is removed so that the bolt can be operated and adjusted. Fine adjustment may need to be performed on rare occasions. However, it is usually difficult to make fine adjustments after the installation of the safety valve.
[0013]
The valve body 64 and the valve stem 66 are connected to each other, and a lever 86 capable of lifting the valve stem 66 is provided. By raising the lever 86, the valve body 64 can be easily moved from the outside while maintaining the sealing property. Is configured to be possible. By rotating the lever 86 with the pin 87 as a fulcrum, the valve body 64 can be slid up and down via the valve rod 66 to open and close the valve.
Accordingly, even if a foreign matter is mixed or bitten into the valve body 64 and an operation failure occurs, the operation of the valve body 64 can be confirmed and the operation can be ensured by pulling up the lever 86. Maintenance and inspection work can be performed while maintaining the sealing property. That is, the operation of the valve can be ensured by raising the lever 86 regardless of the presence or absence of the pressure applied to the device.
[0014]
The lever attached to the conventional safety valve is used for pressing down the valve element using the force of a spring, and is not attached for the purpose of lifting the valve element.
The high-precision safety valve according to the present embodiment employs a structure in which a spring for pressing the valve body 64 is tightened and adjusted by a pressure adjusting screw 76 provided separately. Is newly provided in order to easily and surely perform the operation.
[0015]
Further, in order to improve the sealing performance against high temperature fluid to the outside air, a gasket and rubbers are not used, and all have a welded structure. However, in general, operation instability due to thermal distortion during welding and valve seat leakage were raised as concerns, but the safety valve in this example has a structure in which welding distortion does not cause concerns about performance. I have. As an example, for welding the valve body 64 and the bellows 68, (1) a distance is provided between the welded portion and the valve body 64. (2) A part of the steel material between the welded portion and the valve body 64 is made thinner to reduce the heat transmission area, thereby making it difficult to transmit the influence of heat to the valve body 64. Such a structure is adopted so that heat is hardly transmitted to the valve body 64 and thermal distortion is not applied.
[0016]
Further, the valve body 64 is connected to the valve stem 66 so that the valve body 64 can be operated by sliding the valve stem 66. At this time, a bush 70 is inserted between the valve stem 66 and the lift limiting plate 72 so that the valve body 64 and the valve stem 66 operate smoothly.
[0017]
In order for the safety valve to exhibit high accuracy, the bellows used must be soft and have excellent pressure resistance and durability, so a welded bellows is used instead of the conventional molded bellows. In addition, when adjusting rings (upper ring 62, blow-down ring 58) which are indispensable for improving the accuracy of the blowout pressure, the pre-leakage pressure, and the stoppage pressure, ring stop bolts 80, 80 are required, A finely adjustable bolt is provided as a retaining bolt.
At this time, as a means for improving the sealing performance between the screw portion and the outside air, the ring cover bolt 80 is covered with the welding cover 94. No space is provided in the ring fixing bolt portion as in the above-mentioned Patent Document 1 or welding is performed.
[0018]
When the primary pressure of the inlet portion 90 increases, the valve body 64 is pushed up and the pressure is released to the secondary side of the outlet portion 92. This is a normal operation of the safety valve, and the spring 82 pushing down the valve body 64 is operated. Also, the secondary side of the valve body 64 is in contact with the outside air, and is normally under atmospheric pressure.
However, when the secondary side is connected to a container that fluctuates in pressure, it is necessary to seal by welding so as not to be affected by atmospheric pressure. In this example, a sealing structure by welding or a flange is used. In this case, the atmospheric pressure is applied only to the outside air side of the valve body 64. In this case, the valve element 64 operates at the difference between the primary pressure and the atmospheric pressure, and does not receive the secondary pressure fluctuation.
[0019]
For this reason, even if the pressure on the secondary side fluctuates and the differential pressure between the primary side pressure and the secondary side pressure fluctuates, there is a characteristic that the operating point at which the pressure is set does not change or malfunctions. Since the valve element 64 operates based on the pressure difference between the primary side and the atmospheric pressure on the outside air side, the operating point operated by increasing the primary side pressure is stable, and is affected by the pressure fluctuation on the secondary side. Will not be. 52 is a seat (valve seat), 54 is a protective cylinder, 56 is a cap, 60 is a valve guide, 74 is a spring receiver, 78 is a lock nut, 84 is a hexagon bolt, and 88 is a four-sided nut.
[0020]
【The invention's effect】
The present invention is configured as described above, and has the following effects.
(1) The high-precision safety valve of the present invention is less likely to be affected by the pressure on the outlet side of the safety valve, and is suitable for use as a safety valve to be attached to a system that requires high-precision operating characteristics. In addition, the selection of the bellows and the adoption of a welding structure that does not easily cause thermal distortion as compared with the conventional technology have made it possible to provide a relatively inexpensive and highly accurate safety valve.
(2) The safety valve of the present invention has the effect of a safety valve that releases the pressure without abnormally increasing the primary pressure, and releases the primary pressure to another container or device connected to the secondary without releasing the primary pressure to the atmosphere. The device including the side and the secondary side has an effect of maintaining the sealing property.
(3) According to the above (1) and (2), it is possible to release the pressure of contents that are not desirable to be released to the atmosphere by not only steam but also flammable gas, toxic gas, etc., and practicality in a wide range of applications. Yes, the effect is enormous.
(4) In addition, by providing a lever directly connected to the valve body and the valve shaft, it is possible to easily confirm and secure the movement of the valve body, thereby improving workability such as inspection and maintenance while maintaining the sealing property. Is done.
(5) Further, if a ring stop bolt is provided so that the upper ring and blow down ring for finely adjusting the blow start / stop pressure can be readjusted as necessary, cover the ring stop bolt. By providing the welding cover, the sealing performance can be maintained and the function can be improved.
[Brief description of the drawings]
FIG.
It is a longitudinal section explanatory view of a high-precision safety valve by a 1st embodiment of the present invention (it shows the state where a valve was closed).
FIG. 2 is an explanatory longitudinal sectional view showing an example of a conventional safety valve (showing a state in which the valve is closed).
[Explanation of symbols]
50 Valve body 52 Seat (valve seat)
54 Protective cylinder 56 Cap 58 Blow down ring 60 Valve guide 62 Upper ring 64 Valve (valve)
66 Valve stem (spindle)
68 Bellows 70 Bush 72 Lift limiting plate 74 Spring support 76 Pressure adjusting screw 78 Lock nut 80 Ring fixing bolt 82 Spring 84 Hex bolt 86 Lever 87 Pin 88 Four-sided nut 90 Inlet 92 Outlet 94 Weld cover 96 Cover

Claims (4)

For safety valves attached to steam boilers, hot water boilers, pressure vessels, etc., both under the condition that the secondary pressure fluctuates from atmospheric pressure to vacuum pressure and at the time of stoppage, both the primary and secondary sides of the valve are external through the valve body. A safety valve that adopts a welded joint structure that prevents the intrusion of air from the valve.It has a lever that connects the valve body and the valve rod, and allows the valve rod to be pulled up, so that no pressure is applied to the device. A high-precision safety valve characterized in that the operation of the valve body can be checked and the operation can be secured from the outside while maintaining the sealing performance by raising the lever even in the state. 2. An operation for releasing expanded gas when the primary pressure exceeds a set pressure even if the primary pressure is equal to or higher than the atmospheric pressure and the secondary pressure is vacuum. High precision safety valve described. 2. The high-precision safety valve according to claim 1, wherein the valve body and the valve stem are connected to each other, and a bush is inserted into a sliding portion between the valve stem and the plate supporting the valve stem to improve the movement of the valve body. Claims: A valve body is provided with a welding cover for covering the ring stopper bolt in order to improve the sealing performance between the ring stopper bolt of the adjustment ring and the outside air provided for improving the accuracy of the blowing pressure, the pre-leak pressure, and the closing stop pressure. The high-precision safety valve according to 1, 2, or 3.

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