JP4294968B2 - High precision safety valve - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is a high-accuracy safety valve that is easy to check and ensure operation, and more specifically, improves the operating characteristics of the safety valve and disassembles the safety valve in the event of problems such as malfunction of the valve body. This relates to a high-precision safety valve that can be inspected and repaired without any problems. The high-accuracy safety valve of the present invention can be widely applied to applications where the fluid is not limited to vapor but is flammable gas, toxic gas, etc., and the release to the atmosphere and release to the atmosphere are not preferable.
[0002]
[Prior art]
Safety valves are attached to steam boilers, hot water boilers, and other pressure vessels, but the conventional safety valves are normally designed to be open to the atmosphere on the secondary side, so the pressure on the outlet side does not change. It was made. However, when handling operating conditions, built-in items, substances that are difficult to blow out to the outside, objects, etc., they cannot be released to the outside.
[0003]
When such operating conditions are conceivable, the conventional safety valve cannot cope. In particular, under operating conditions where 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. And in order to satisfy those conditions, it is necessary to make the whole into a welded structure, and it has become a safety valve inferior in operability and maintenance workability by placing importance on the sealing performance.
Further, in a safety valve having a welded structure, the operation of the valve cannot be confirmed, and once a problem occurs, it is necessary to replace the safety valve. Further, even in a safety valve with a lever, the valve could not be operated unless the device had a pressure of 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 blow-down ring, 80 is a ring retaining bolt, 78 is a lock nut, 62 is an upper ring, 60 is a valve guide, 64 is a valve body (valve), 68 is Bellows, 82, spring, 66, valve stem, 54, protective cylinder, 56, cap, 76, adjustment screw, 72, lift limit plate, 74, spring support, 84, hexagon bolt, 90, inlet, 92, outlet It is. The outlet portion 92 is connected to another container or device having a pressure lower than that of the inlet portion. When the set pressure is reached, the valve 64 rises against the spring force to be in an open state and flows in from the inlet portion 90. 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, hot water boiler, pressure vessel, etc., under conditions where the secondary side pressure fluctuates from atmospheric pressure to vacuum pressure, An airtight welded joint structure is proposed so that gas does not enter from the outside through the valve body on both the primary side and the secondary side, 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]
Japanese Patent Laid-Open No. 2001-295952 (second page, FIG. 1)
[0007]
[Problems to be solved by the invention]
In the conventional high-precision safety valve, the operation of the valve body cannot be confirmed and ensured from the outside while maintaining the sealing performance when no pressure is applied to the external device to which the safety valve is connected.
[0008]
The present invention has been made in view of the above points, and an object of the present invention is to be used as a safety device in which a steam inlet and a steam outlet are connected to a container that fluctuates from an atmospheric pressure or higher to a vacuum pressure to ensure safety. It is a safety valve to improve the slidability of the valve, and to provide a high-precision safety valve with a structure and function that can check the operation, ensure operation, check and maintain, and finely adjust the start and stop pressure. .
[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, hot water boiler, pressure vessel, etc., and stops even under conditions where the secondary side pressure varies from atmospheric pressure to vacuum pressure. Even at times, both the primary and secondary sides of the valve are safety valves that employ a welded joint structure that prevents intake air from entering from the outside through the valve body, connecting the valve body and the valve stem, and pulling up the valve stem A lever that can be used, and even when no pressure is applied to the device, by pulling up the lever, the operation of the valve element can be confirmed and 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 greater than 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. Configured as follows. Further, the valve body and the valve stem are connected, and the bush is inserted into the sliding portion between the valve rod and the plate supporting the valve stem, thereby improving the movement of the valve body.
Also, in these high-precision safety valves, in order to improve the sealing performance between the ring retaining bolt of the adjusting ring and the outside air provided to increase the accuracy of the blowing pressure, pre-leakage pressure, and blowing stop pressure, the ring retaining bolt is attached to the valve body. It is preferable to provide a welding cover that covers.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below, but 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 fluctuations in the secondary side pressure. Is sealed and fixed to the safety valve main body 50 by welding so that a malfunction due to the pressure difference between the secondary pressure and the atmospheric pressure is unlikely to occur. 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, so that the valve body 64 and the valve stem 66 malfunction. The structure is difficult to occur.
[0012]
In order to improve the sealing performance and operability of the ring retaining bolt 80 part, a welding cover 94 that covers the ring retaining bolt 80 is provided, and the sealing performance is usually secured by covering the bolt part with the welding cover 94 to make fine adjustments. Only when it is necessary to remove the welding cover cover 96, the bolt can be operated and adjusted. Although it may be necessary to make fine adjustments rarely, 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, and a lever 86 that can lift the valve stem 66 is provided. By lifting the lever 86, the valve body 64 can be easily moved from the outside while maintaining the sealing performance. Is configured to be possible. By rotating the lever 86 around 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 foreign matter is mixed in or bites into the valve body 64 and malfunction occurs, it is possible to confirm the operation of the valve body 64 and ensure the operation by pulling up the lever 86. Maintenance and inspection work can be performed while maintaining sealing performance. In other words, the operation of the valve can be ensured by pulling up the lever 86 regardless of the pressure applied to the apparatus.
[0014]
The lever attached to the conventional safety valve is used for pressing the valve body using the force of the spring, and is not attached for the purpose of lifting the valve body.
In the high-accuracy safety valve according to this embodiment, a spring that presses the valve body 64 is tightened and adjusted by a pressure adjusting screw 76 provided separately. Is newly provided in order to enable easy and reliable operation.
[0015]
In addition, in order to improve the sealing performance against high temperature fluid against the outside air, a gasket or rubber is not used, and all have a welded structure. However, in general, unstable operation and valve seat leakage due to thermal distortion during welding were raised as concerns, but the safety valve in this example has a structure in which welding distortion does not cause anxiety on performance. Yes. As an example, for the welding of the valve body 64 and the bellows 68, (1) a distance is placed 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 thin, and the heat transfer area is reduced to make it difficult to transmit the influence of heat to the valve body 64. Such a structure is adopted that the heat is not easily transmitted to the valve body 64 so as not to give thermal distortion.
[0016]
Further, the valve body 64 and the valve stem 66 are connected, and the valve body 64 can be operated by sliding the valve stem 66. At that 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 to be used must be soft and have excellent pressure resistance and durability. Therefore, a welded bellows is used instead of a conventional molded bellows. Further, in order to employ adjustment rings (upper ring 62, blow-down ring 58) that are indispensable for increasing the accuracy of the blow-out pressure, the pre-leak pressure, and the blow-off pressure, ring retaining bolts 80 and 80 are required. A bolt that can be finely adjusted is provided as a stop bolt.
At that 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 weld cover 94. No space is provided or welded to the ring retaining bolt portion as in Patent Document 1 described above.
[0018]
When the primary side pressure of the inlet portion 90 rises, the valve body 64 is pushed up and the pressure is released to the secondary side of the outlet portion 92 in the normal operation of the safety valve, and the spring 82 pushing down the valve body 64. Further, the secondary side of the valve body 64 is also in contact with the outside air, and usually atmospheric pressure is applied.
However, when the secondary side is connected to a container whose pressure fluctuates, it is necessary to seal by welding so as not to be affected by atmospheric pressure, and in this example, a sealing structure by welding or flange is used. In this case, atmospheric pressure is applied only to the outside air side of the valve body 64. If it does in this way, the valve body 64 will operate | move by the difference of a primary side pressure and atmospheric pressure, and will not receive the pressure fluctuation of a secondary side.
[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 set operating point does not change or malfunctions. Since the valve body 64 operates with a pressure difference from the primary side with reference to the atmospheric pressure on the outside air side, the operating point that operates due to the rise of the primary side pressure is stable and is affected by the pressure fluctuation on the secondary side. There will be no. 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】
Since this invention is comprised as mentioned above, there exist the following effects.
(1) The high-precision safety valve of the present invention is suitable for use as a safety valve that is not easily affected by the pressure on the outlet side of the safety valve and is attached to a system that requires high-precision operating characteristics. In addition, the selection of bellows and the use of a welded structure that is less likely to cause thermal distortion over the prior art makes 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 side pressure, and the primary side pressure is released to another container or device connected to the secondary side without opening it to the atmosphere. As an apparatus including the side and the secondary side, there is an effect of maintaining the sealing performance.
(3) By the above (1) and (2), it becomes possible to release the pressure of contents that are not preferable to be released into the atmosphere not only with steam but also with flammable gas, toxic gas, etc. Yes, the effect is enormous.
(4) In addition, by providing a valve body and a lever that is directly connected to the valve stem, it is possible to easily check and secure the movement of the valve body, improving workability such as inspection and maintenance while maintaining the sealing performance. Is done.
(5) Furthermore, when providing a ring retaining bolt that makes it possible to readjust the upper ring and blow down ring that finely adjust the blow start / stop pressure, if necessary, cover the ring retaining bolt. By providing the welding cover, it is possible to maintain the sealing performance and improve the function.
[Brief description of the drawings]
FIG. 1 is an explanatory view of a longitudinal section of a high-precision safety valve according to a first embodiment of the present invention (showing a state in which the valve is closed).
FIG. 2 is a 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 Protection cylinder 56 Cap 58 Blow-down ring 60 Valve guide 62 Upper ring 64 Valve body (valve)
66 Valve stem (spindle)
68 Bellows 70 Bush 72 Lift limit plate 74 Spring receiver 76 Pressure adjusting screw 78 Lock nut 80 Ring retaining bolt 82 Spring 84 Hexagon bolt 86 Lever 87 Pin 88 Four-sided nut 90 Inlet portion 92 Outlet portion 94 Weld cover 96 Cover

Claims (1)

For safety valves attached to steam boilers, hot water boilers, pressure vessels, etc., both on the primary and secondary sides of the valve, both under the conditions where the secondary pressure varies from atmospheric pressure to vacuum pressure, and when stopped This is a safety valve that employs a welded joint structure that prevents intrusion of air from the valve, and a lever that connects the valve body and the valve stem and allows the valve stem to be pulled up is provided so that no pressure is applied to the device. Even in the state, the lever can be pulled up to maintain the sealing performance and to confirm the operation of the valve body from the outside and to ensure the operation. The primary pressure is above atmospheric pressure and the secondary pressure is vacuum. Even if the pressure on the primary side exceeds the set pressure, it operates to release the expanded gas, connects the valve body and valve stem, and slides between the valve stem and the plate that supports the valve stem. Insert the bush into In order to improve the movement of the valve body and improve the sealing performance between the ring retaining bolt of the adjustment ring and the outside air provided to increase the accuracy of the blowing pressure, the pre-leakage pressure and the blow-off pressure, A high-precision safety valve characterized in that a cover that covers the ring retaining bolt is provided by welding .

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