JPH08193502A - Stem free testing device of main steam stop valve - Google Patents

Abstract

PURPOSE: To provide a simply constructed stem free test device of a main steam stop valve, with which if the closing operation of a valve steam is assuredly executed or not if the main steam stop valve is required to be urgently closed when steam to a steam turbine is urgently shut off during turbine operation. CONSTITUTION: A switching solenoid valve 33 arranged in an oil intake/exhaust pipe 16 connected to an oil pressure cylinder 30, is energized by a change-over switch 37, pressure oil in a cylinder 31 is discharged from an oil exhaust pipe 35 so as to move a valve stem 4 in the closing direction, and a detection opening in an opening detector 40 is comparatively operated with a predetermined test opening in a comparative operation part 41. When the detection opening is below the test opening, the switching solenoid valve 33 is deenergized by the change-over switch 37, the pressure oil is led to flow into the cylinder 31 so that the valve stem 4 is returned in a fully opening position, thus the reciprocating motion of this valve stem 4 is monitored.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a main steam stop valve for confirming during operation of a turbine that a main steam stop valve for shutting off steam supplied to a steam turbine can surely shut off steam in an emergency. Stem free test equipment.

[0002]

2. Description of the Related Art A main steam stop valve is used for inflowing and shutting off steam into a steam turbine, and it is necessary to surely shut off the steam when the turbine is in an emergency such as an accident. However, in the main steam stop valve, the operation of the valve rod (also referred to as a stem) may be hindered during the turbine operation due to the increase in scale or the sticking due to the trapping of foreign matter, making the emergency shutoff impossible. For this reason, in order to confirm that the main steam stop valve can be shut off in an emergency, operate the valve stem of the main steam stop valve during turbine operation to confirm that the main steam stop valve is reliably closed during an emergency shutoff. A stem-free test device is installed on the main steam stop valve.

FIG. 7 is a block diagram of a main steam stop valve equipped with this type of stem-free test device and opened and closed by a hydraulic cylinder. A conventional technique will be described with reference to the drawing. Figure 7
In the main steam stop valve 1, a valve body 2, a valve body 4 to which the valve body 2 is attached, and a piston 3 is connected to an end different from the valve body 2, and the valve body 4 penetrates the valve body 2 Valve seat 5 on which is seated
And a valve casing 7 provided with a steam inlet 6.

The hydraulic cylinder 9 is penetrated by a valve rod 4 to which the piston 3 is connected, and the piston 3, a test piston 12 having a test piston 10 having a diameter larger than the diameter of the piston 3, and a cylinder surrounding the piston 3. It is composed of a body 13a and a cylinder 13 having a side wall made of a cylindrical body 13b surrounding the test piston 10. Here, the test piston 12 is attached to the test piston 10,
A rod 15 that contacts the rear surface of the piston 3 is provided.
An oil supply / discharge pipe 16 for supplying / discharging pressure oil to / from the cylinder 13a of the cylinder 13 is connected to a side wall of the cylinder 13a of the cylinder 13, and a three-way valve 18 is provided on a bottom plate 17 of the cylinder 13.
And an oil supply / discharge pipe 20 for supplying / discharging pressure oil between the test piston 10 and the bottom plate 17 is connected. An oil supply pipe 21 and an oil discharge pipe 22 are connected to the three-way valve 18.

The closing spring 23 is provided between the spring seat 24 provided on the valve rod 4 and the upper plate 25 of the cylinder 13. When the main steam stop valve 1 is closed, the closing force of the valve spring causes the valve rod to close. Move to. With this configuration, during turbine operation,
By switching the three-way valve 18, the piston 3 in the cylinder 13
The pressure oil between the bottom plate 17 and the bottom plate 17 flows from the oil supply / discharge pipe 20 to the oil discharge pipe 2
2 and the pressure oil is discharged from the oil supply / exhaust pipe 16 to the cylinder 1
By being supplied into the valve 3, the piston 3 connected to the valve rod 4 moves to the right against the force of the closing spring 23, and the main steam stop valve 1 is fully opened.

In such a state, the valve stem 4 of the main steam stop valve 1
When confirming the movement of the test piston, the three-way valve 18 is switched and the pressure oil is supplied from the oil supply pipe 21 through the oil supply / discharge pipe 20 into the cylinder 13 on the rear side of the test piston 10 of the test piston 12 to perform the test. Move the piston 12 for
The piston 3 is moved in the closing direction of the valve rod 4 via the rod 15. The stroke of the valve rod 4 at this time is a stroke s until the test piston 10 comes into contact with the stepped portion of the connecting portion of the cylinders 13a and 13b of the cylinder 13.

When the main steam stop valve 1 is fully opened after moving the valve rod 4 in the closing direction, the three-way valve 18 is switched to supply the pressure oil between the test piston 10 and the bottom plate 17. By discharging from the oil discharge pipe 22 via the discharge pipe 20, the piston 3 returns to the original position, and the main steam stop valve is fully opened. By monitoring the reciprocating movement of the valve rod 4 by the test piston 12 at the stroke s, it is confirmed that the main steam stop valve is reliably closed in an emergency.

In the above prior art, confirmation of the closing of the main steam stop valve 1 in an emergency is performed by monitoring the reciprocating motion of the valve rod 4 at the stroke s which is a partial stroke. If multiple turbines are installed and one of the main steam stop valves does not interfere with the operation of the turbine even if the main steam stop valve is fully closed, open and close the valve stems by opening and closing the main steam stop valves sequentially. By monitoring the reciprocating motion of all strokes to closing, it is confirmed that all main steam stop valves can be reliably closed in an emergency.

[0009]

In order to confirm whether or not the fully opened main steam stop valve can be closed in an emergency during turbine operation, a test piston 12 for reciprocating the valve rod 4 of the main steam stop valve is provided. Since it is necessary to provide the provided stem-free test device in the hydraulic cylinder of the main steam stop valve, there are problems that the structure becomes complicated and the cost increases.

When a plurality of main steam stop valves are installed in the steam turbine, one main steam stop valve is sequentially opened and closed as described above even if the test piston 12 is not provided. Since it can be confirmed that the steam stop valve can be reliably closed in an emergency, depending on the number of main steam stop valves installed, the structure of the hydraulic cylinder differs depending on whether the test piston is required or not. There is a problem in that it is disadvantageous in terms of standardization and series of cylinders.

The object of the present invention is to provide a simple structure without a test piston, and to reciprocate the partial stroke of the main steam stop valve up to the partial opening and the full stroke up to full closing. It is an object of the present invention to provide a stem-free test device for a main steam stop valve, which can confirm by monitoring that the main steam stop valve can be reliably closed in an emergency.

[0012]

In order to solve the above-mentioned problems, according to the present invention, a valve rod connected to a piston of a hydraulic cylinder is supplied to a cylinder of pressurized oil via an oil supply / discharge pipe connected to the cylinder. In the stem-free test device of the main steam stop valve that confirms the movement of the valve rod of the main steam stop valve that reciprocates by discharging to inject and shut off the steam to and from the steam turbine, in the oil supply and discharge pipe The formation of a flow path that is provided to allow the pressure oil supplied to the hydraulic cylinder to flow into the cylinder by switching between excitation and non-excitation and to prevent the formation of this flow path and to discharge the pressure oil from the cylinder. A switching solenoid valve that switches between formation and switching, a switching switch that is turned on and off to energize and de-energize the electric circuit connected to this switching solenoid valve, and the opening of the main steam stop valve is detected by the stroke of the valve stem. With the opening detector, this When this opening below compared to predetermined test opening a predetermined detection angle in degrees detector,
It is assumed that a comparison calculation unit that outputs a signal for switching the changeover switch is provided.

Further, in the above stem-free test device for a main steam stop valve, instead of a comparison calculation unit that compares the detected opening degree of the opening degree detector with a predetermined test opening degree, the detected opening degree is Compare the test opening to be compared with the test opening setter that sets the desired opening from fully closed to fully open, and compare the detected opening with the opening detector with the set test opening from the test opening setter. A comparison calculation unit that outputs a signal for switching the changeover switch when the lever opening is equal to or less than the lever opening is provided.

In the stem-free test device for the main steam stop valve described above, a throttle is provided in the flow passage for discharging the pressure oil in the cylinder of the hydraulic cylinder from the switching solenoid valve.

[0015]

[Function] The piston of the hydraulic cylinder, to which the valve rod of the main steam stop valve is connected, reciprocates in the cylinder to open and close the main steam stop valve. The switching solenoid valve is energized and de-energized by turning on and off the electric circuit connected to the solenoid valve by a changeover switch.
At this time, the switching solenoid valve forms a flow path through which pressure oil supplied to the hydraulic cylinder flows into the cylinder by either excitation or non-excitation, and the formation of this flow path is blocked to prevent the pressure oil in the cylinder from being formed. To form a flow path for discharging the gas to the outside.

Therefore, if the switching solenoid valve is operated by operating the changeover switch so as to form a flow path through which pressure oil supplied to the hydraulic cylinder flows into the cylinder when it is de-excited, the flow path allows the hydraulic cylinder to operate. The pressure oil to be supplied can be supplied to and discharged from the cylinder, and the piston connected to the valve rod reciprocates by the supply and discharge of the pressure oil to open and close the main steam stop valve. Therefore, when the pressure oil flows into the cylinder, the piston moves the valve rod connected to the piston in the opening direction, and the main steam stop valve is fully opened.

When the main steam stop valve is fully opened and the changeover switch is changed over to excite the changeover solenoid valve, formation of the flow passage is blocked and a flow passage for discharging the pressure oil in the cylinder is formed. The pressure oil in the cylinder flows through this flow path and is discharged to the outside, and the piston moves the valve rod connected to the piston in the closing direction. At this time, the stroke of the valve rod, that is, the opening degree of the main steam stop valve is detected by the opening degree detector, and the signal of the detected opening degree is input to the comparison calculation unit. In this comparison calculation unit, the input detected opening is compared and calculated with a test opening that is a predetermined partial stroke of the valve rod, and a signal is output when the detected opening is less than or equal to the test opening. By inputting this signal to the changeover switch, the changeover switch is changed over to change the switching solenoid valve from the excited state to the non-excited state. By this non-excitation, the flow path of the switching solenoid valve is switched and the pressure oil supplied to the hydraulic cylinder flows into the cylinder, so the valve rod closed to the specified test opening moves again in the opening direction and the main steam The stop valve is fully opened.

Therefore, since the valve stem is opened and closed from the full opening to a predetermined test opening, it is confirmed by monitoring the movement of the valve stem associated with this opening and closing that the main steam stop valve can be reliably closed in an emergency. To be done. In addition, the above-mentioned predetermined test opening is set as a test opening set by a test opening setting device that sets an arbitrary opening from fully closed to fully opened, and the set test opening and the opening detection When the detected opening is equal to or less than the set test opening by comparing and calculating with the comparison opening of the detector, the changeover switch is switched to open and close the valve rod from full open to the set test opening as described above. Check the movement of the main steam stop valve to confirm that the closing operation of the valve stem will be performed reliably when the main steam stop valve is closed suddenly.

Further, by providing a throttle in the passage for discharging the pressure oil in the cylinder of the hydraulic cylinder from the switching solenoid valve, the pressure oil in the cylinder can be discharged when the valve rod of the main steam stop valve is moved in the closing direction. Since the speed at which the main steam stop valve is operated is slowed, it is possible to prevent the main steam stop valve from being closed to a predetermined test opening that is set in advance or an opening that is smaller than the set test opening due to a calculation delay in the comparison calculation unit.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a system diagram of a main steam stop valve that is equipped with a stem-free test device according to an embodiment of the present invention and that is opened and closed by a hydraulic cylinder. In FIG. 1 and FIGS. 2 to 6 described later, the same parts as those of the conventional example of FIG. 7 are designated by the same reference numerals, and the description thereof will be omitted. 1 is different from the conventional example of FIG. 7 as follows.

The cylinder 31 of the hydraulic cylinder 30 is formed so as to surround the piston 3 to which the valve rod 4 is connected. The oil supply / discharge pipe 16 connected to the cylinder 31 has a switching solenoid valve 33.
Is provided. The switching solenoid valve 33 forms a flow path that allows the pressure oil supplied to the hydraulic cylinder 30 without excitation to flow into the cylinder 31 through the oil supply / discharge pipe 16, and the pressure oil supplied to the hydraulic cylinder 30 by excitation. It is switched to the formation of a flow path that prevents the pressure oil in the cylinder 31 from flowing into the cylinder 31 and discharges the pressure oil in the cylinder 31 to the outside through an oil discharge pipe 35 having a throttle 34.

An electric circuit 36 for energizing the solenoid valve is connected to the switching solenoid valve 33, and the changeover switch 37 is turned off.
The switching solenoid valve 33 is non-excited or excited in response to the input. A lever 38 is attached to the valve rod 4, and the lever 38 is attached to a sensor rod 39 of the opening detector 40.
0 detects the stroke of the valve rod 4, that is, the opening degree via the lever 38.

The comparison calculation unit 41 sets a predetermined partial stroke of all strokes from full opening to full closing of the valve rod 4, that is, a partial opening as a test opening, and the opening detector 40.
The detected opening is compared with the test opening, and when the detected opening is equal to or smaller than the test opening, a signal for switching the changeover switch 37 is output. With such a configuration, when the main steam stop valve 1 switches the switching switch 37 to open the electric circuit 36 and de-energize the switching solenoid valve 33, inflow of pressure oil to the oil discharge pipe 35 is blocked, The pressure oil flows from the oil supply / discharge pipe 16 into the cylinder 31 of the hydraulic cylinder 30 through the switching solenoid valve 33. The inflowing pressure oil causes the piston 3 connected to the valve rod 4 to move in the right opening direction against the spring force of the closing spring 23, so that the main steam stop valve 1 is fully opened. In this fully opened state, steam is supplied to the steam turbine through the main steam stop valve 1.

A test for confirming that the closing operation of the valve rod 4 is surely performed when the main steam stop valve 1 is suddenly closed when the main steam stop valve 1 is fully opened is performed as follows. The changeover switch 37 is changed over to close the electric circuit 36, and the changeover solenoid valve 33 is changed from non-excitation to excitation. By exciting the switching solenoid valve 33, the pressure oil supplied to the cylinder 31 of the hydraulic cylinder 30 is blocked by the flow direction of the switching solenoid valve 33 shown in FIG. 2, and the pressure oil in the cylinder 31 is throttled from the oil discharge pipe 35. By 34, the discharging speed becomes slower and the discharging is performed. By the discharge of the pressure oil, the piston 3 connected to the valve rod 4 moves at a gentle speed in the closing direction to the left by the force of the closing spring 23. At this time, the opening detector 40 detects the stroke of the valve rod 4, that is, the opening, and the signal of the detected opening is input to the comparison calculation unit 41.

In the comparison calculation unit 41, the input detected opening is compared with the test opening, which is a predetermined partial stroke of the valve stem, and when the detected opening is less than or equal to the test opening, A signal is output, and the changeover switch 37 is switched by this signal to open the electric circuit 36. Therefore, the switching solenoid valve 33 is de-energized by opening the electric circuit 36,
The piston 3 to which the valve rod 4 is connected moves in the right opening direction, and the main steam stop valve 1 is fully opened.

The discharge of the pressure oil at a slow speed by the throttle 34 provided in the oil discharge pipe 35 is performed by reducing the closing speed of the valve rod and delaying the calculation in the comparison calculation unit 41, thereby opening the opening smaller than the test opening. I try not to close it. By monitoring the reciprocating movement of the valve rod 4 from the full opening to the test opening as described above, it is possible to confirm that the valve rod 4 is surely closed when the main steam stop valve 1 is emergency closed.

In this embodiment, the pressure oil in the cylinder 31 is discharged when the switching solenoid valve 33 is excited, but the pressure oil in the cylinder 31 is discharged when the switching solenoid valve 33 is not excited, and the cylinder 31 is discharged when excited. The pressure oil may be supplied to. FIG. 3 is a flow chart showing the flow of the test for confirming the movement of the valve rod 4 of the main steam stop valve 1 described above, and the flow will be further described with reference to FIG. 1 based on FIG.

In FIG. 3, step 5 is executed during turbine operation.
When the changeover switch 37 is turned off at 0, the changeover solenoid valve 33 is de-energized at step 51 due to this changeover, and the flow path of the pressure oil flowing through the changeover solenoid valve 33 is the pressure oil supplied to the hydraulic cylinder 30. Is a flow path through which the oil flows into the cylinder 31 via the oil supply / discharge pipe 16 (indicated by the switching solenoid valve opening in step 51 in FIG. 3)
Then, the pressure oil flows into the cylinder 31 to move the piston 3 connected to the valve rod 4 in the opening direction, and the main steam stop valve 1 is fully opened. At this time, the signal of the opening degree detected by the opening degree detector 40 is not input to the comparison calculation unit 41.

When it is confirmed that the closing operation of the valve rod 4 is surely performed when the main steam stop valve 1 is fully closed and the main steam stop valve 1 is emergency closed, the changeover switch 37 is set at step 50. Turn on. By this entry, the opening detector 4
The signal of the detected opening at 0 is input to the comparison calculation unit 41.
Then, in the comparison calculation unit 41, the signal of the detected opening is input to the adder 45, and is compared and calculated with a predetermined test opening 53 that is predetermined for monitoring the movement of the valve rod 4, and the opening deviation 54 is calculated. While the opening deviation is larger than 0% in step 54, the switching solenoid valve 33 is opened in step 55.
Is excited, and the passage of the switching solenoid valve 33 is connected to the hydraulic cylinder 30.
The pressure oil supplied to the cylinder 31 is blocked from flowing into the cylinder 31, and the pressure oil in the cylinder 31 serves as a flow path (shown by the closing of the switching solenoid valve in step 55 in FIG. 3) to be discharged from the oil discharge pipe 35. Since the pressure oil inside is discharged from the oil discharge pipe 35, the piston 3 connected to the valve rod 4 moves in the closing direction.
The stroke of the valve rod 4 at this time, that is, the opening degree is detected by the opening degree detector 40, and the detected opening degree is compared and calculated with the test opening degree 53 by the comparison calculation section 41, and the opening degree deviation 54 is 0% or less. , A signal is output, and this signal causes step 50
The changeover switch 37 is turned off, and the changeover solenoid valve 33 is de-excited to open the changeover solenoid valve 33 in step 51 as described above, and the main steam stop valve 1 is fully opened in step 52. At this time, the signal of the opening degree detected by the opening degree detector 40 is not input to the comparison calculation unit 41.

Therefore, by monitoring the reciprocating movement of the valve rod 4 from the full opening of the valve rod 4 to the test opening, it is confirmed that the closing operation of the valve rod 4 is surely performed when the main steam stop valve 1 is emergency closed. it can. FIG. 4 is a system diagram of a main steam stop valve having a stem-free test device according to another embodiment of the present invention and opened and closed by a hydraulic cylinder. In FIG. 4, instead of the predetermined test opening of FIG. 1, a test opening setting device 48 that sets an arbitrary opening from the fully open to the fully closed of the main steam stop valve as a test opening, It is the same as FIG. 1 except that a comparison calculation unit 49 for performing a comparison calculation of the detected opening of the opening detector 40 with the set test opening from the test opening setter 48 is provided.

With such a structure, when it is confirmed that the closing operation of the valve rod 4 at the time of emergency closing of the main steam stop valve 1 is surely performed, the test opening setting device 48 sets the test opening. As a result, the reciprocating movement of the valve rod up to an arbitrary opening between full closing and full opening can be monitored as described above. FIG. 6 is a flow chart showing the flow of a test for confirming the movement of the valve rod 4 of the main steam stop valve 1 based on the system diagram of FIG. In FIG. 6, the test opening setter 48 sets the test opening, which is the reference to be compared by the comparison calculation unit 49, by the main steam stop valve 1
An arbitrary opening degree between the fully closed state and the fully opened state of the valve rod 4 is set as a test opening degree, and the reciprocating movement of the valve rod 4 from the fully opened state to the set test opening degree 57 is performed in the same manner as in FIG. By performing the operation and monitoring the movement of the valve rod 4, it can be confirmed that the closing operation of the valve rod 4 at the time of emergency closing of the main steam stop valve 1 is reliably performed.

By providing the test opening setting device 48, a main steam stop valve is provided in a steam turbine having one main steam stop valve or a plurality of main steam stop valves 1 in the steam turbine 58 as shown in FIG. Effective for stem free test of valve. That is, in the steam turbine having one main steam stop valve, the test opening setting unit 48 can set the opening at which the amount of steam that does not hinder the operation of the turbine to the test opening. Further, as shown in FIG. 5, in the steam turbine 58 including a plurality of, for example, two main steam stop valves 1, the main steam stop valves 1 are fully closed one by one, and a stem-free test of the main steam stop valve 1 is performed. Therefore, it is possible to set the test opening to the fully closed opening by the test opening setting device 48.

[0033]

As is apparent from the above description, according to the present invention, the main steam stop valve in the fully open state is controlled by the above-mentioned configuration according to the opening degree detected by the opening degree detector during the operation of the steam turbine. By monitoring the reciprocating movement of the valve stem of the main steam stop valve up to a predetermined predetermined test opening or a test opening set to any opening from fully closed to fully opened,
It can be confirmed that when the main steam stop valve is suddenly closed when the steam is shut off to the steam turbine, the valve rod is reliably closed. In addition, without providing a test piston that moves the piston of the hydraulic cylinder as in the past, during turbine operation,
Since the movement of the valve stem of the main steam stop valve can be confirmed, the structure is simplified, the cost is reduced, and the standardization and series of hydraulic cylinders can be easily obtained.

Further, by providing a throttle in the passage for discharging the pressure oil in the cylinder of the hydraulic cylinder from the switching solenoid valve, the test opening set in advance or the set test opening by the calculation delay in the comparison calculation unit is set. It is possible to prevent the opening degree from being smaller.

[Brief description of drawings]

FIG. 1 is a system diagram of a main steam stop valve that is equipped with a stem-free test device according to an embodiment of the present invention and that is opened and closed by a hydraulic cylinder.

2 is a stem-free main steam stop valve showing the switching state of the switching solenoid valve when discharging the pressure oil in the cylinder of the hydraulic cylinder when confirming the movement of the valve rod of the main steam stop valve in FIG. Partial system diagram of test equipment

FIG. 3 is a flow chart showing a flow when performing a stem-free test of the main steam stop valve of FIG.

FIG. 4 is a system diagram of a main steam stop valve that is equipped with a stem-free test device according to another embodiment of the present invention and that is opened and closed by a hydraulic cylinder.

5 is a system diagram of a steam turbine including a plurality of main steam stop valves to which the stem-free test device for the main steam stop valve of FIG. 4 is applied.

FIG. 6 is a flow chart showing a flow when performing a stem-free test of the main steam stop valve of FIG.

FIG. 7 is a block diagram of a main steam stop valve that is equipped with a conventional stem-free test device and is opened and closed by a hydraulic cylinder.

[Explanation of symbols]

 1 Main Steam Stop Valve 3 Piston 4 Valve Bar 16 Oil Supply / Discharge Pipe 30 Hydraulic Cylinder 31 Cylinder 33 Switching Solenoid Valve 36 Electric Circuit 37 Changeover Switch 40 Opening Detector 41 Comparison Computation Unit 48 Test Opening Setting Unit 49 Comparison Computation Unit

Claims (3)

[Claims] Claim: What is claimed is: 1. A valve rod connected to a piston of a hydraulic cylinder is reciprocated by supplying / discharging pressurized oil to / from the cylinder through an oil supply / discharging pipe connected to the cylinder to inject and shut off steam to / from a steam turbine. In a stem-free test device for a main steam stop valve that confirms the movement of the valve stem of the main steam stop valve during turbine operation, the main steam stop valve is provided in the oil supply / discharge pipe and is supplied to a hydraulic cylinder by switching between excitation and non-excitation. A switching solenoid valve for switching between formation of a flow path for allowing pressure oil to flow into the cylinder and formation of a flow path for preventing the formation of this flow path and discharging pressure oil in the cylinder to the outside, and this switching solenoid valve The changeover switch that is turned on and off to energize and de-energize the electric circuit connected to, the opening detector that detects the opening of the main steam stop valve by the stroke of the valve rod, and the opening detector The detection opening is set to a predetermined value. When this opening below in comparison with test opening, the stem-free test device of the main steam stop valve, characterized in that a comparison operation unit for outputting a signal for switching the selector switch. 2. A valve rod connected to a piston of a hydraulic cylinder is reciprocated by supplying / discharging pressure oil to / from the cylinder through an oil supply / discharging pipe connected to the cylinder, thereby injecting and shutting off steam to / from a steam turbine. In a stem-free test device for a main steam stop valve that confirms the movement of the valve stem of the main steam stop valve during turbine operation, the main steam stop valve is provided in the oil supply / discharge pipe and is supplied to a hydraulic cylinder by switching between excitation and non-excitation A switching solenoid valve for switching between formation of a flow path for allowing pressure oil to flow into the cylinder and formation of a flow path for preventing the formation of this flow path and discharging pressure oil in the cylinder to the outside, and this switching solenoid valve The changeover switch that is turned on and off to energize and de-energize the electric circuit connected to, the opening detector that detects the opening of the main steam stop valve by the stroke of the valve rod, and the opening detector The test opening to be compared with the detected opening From the test opening setter to set any opening from the to full open, and the detected opening in the opening detector is compared with the set test opening from the test opening setter and is less than or equal to this opening, A stem-free test device for a main steam stop valve, comprising: a comparison calculation unit that outputs a signal for switching a changeover switch. 3. A stem-free main steam stop valve according to claim 1 or 2, wherein a throttle is provided in a passage for discharging pressure oil in the cylinder of the hydraulic cylinder from the switching solenoid valve. Test equipment.