KR20130017885A - The test equipment of friction coefficient of valve packing and method thereof - Google Patents

Abstract

PURPOSE: A device and a method for testing a frictional coefficient of a valve packing are provided to accurately measure gland stress by directly measuring stress added on a gland stud. CONSTITUTION: A method for testing a frictional coefficient of a valve packing is as follows. A packing gland is fixed to the upper part of a packing unit mounted inside a valve by a medium of a gland stud and a gland nut, and the initial height of the packing gland(S1). The gland nut fixed to the upper part of the packing unit is fastened so that gland stress corresponding to a preset stress value is generated(S2). The gland stress and a packing frictional force are measured by using a strain gauge after driving unit make a valve stem vertically reciprocate once with an applied driving force(S3). Previous steps are repeated until a difference between stress values before and after a reciprocating motion of the valve stem reach a preset range, so that the packing units are compressed(S4). The gland stress and the packing frictional force are successively measured by performing the vertically reciprocating motion of the valve stem several times after measuring the final height of the packing gland and the frictional coefficient of the valve packing is calculated by using the measured gland stress and the packing frictional force(S5). [Reference numerals] (AA) Start; (BB) End; (S1) Fixing a packing gland to the upper part of a packing unit mounted inside a valve by the medium of a gland stud and a gland nut and the initial height of the packing gland; (S2) Tightening the gland nut fixed to the upper part of the packing unit to generate gland stress corresponding to a preset stress value; (S3) Vertically reciprocating a valve stem once with an applied driving force and measuring the gland stress and a packing frictional force by using a strain gauge; (S4) Compressing packings by repeating the step S3 until the difference between gland stress values before and after the reciprocating motion of the valve stem reach a preset range; (S5) Measuring the final height of the packing gland, successively measuring the gland stress and the packing frictional force by vertically reciprocating the valve stem several times, and calculating a packing frictional coefficient by using the measured gland stress and packing frictional force

Description

Valve packing friction coefficient test apparatus and its method {THE TEST EQUIPMENT OF FRICTION COEFFICIENT OF VALVE PACKING AND METHOD THEREOF}

The present invention relates to a valve packing friction coefficient test apparatus and a method thereof, and more particularly, to a technique for calculating an accurate friction coefficient for each material by directly measuring the friction coefficient for each material of the valve packing by gland stress.

In nuclear power plants, safety-related valves must be operable to operate in an accident. The operability of the valve means that the available power, which is the driving force of the driver, is greater than the required power of the valve required to operate the valve.

The required force of the valve includes frictional force due to the packing, and it is necessary to reinforce the airtight force of the packing part by retightening the packing gland to prevent leakage of the packing part.

Since the frictional force of the packing increases when re-tightening the gland of the packing part, it is necessary to directly measure the frictional force of the packing through the diagnostic test or to predict the operation of the valve by predicting the packing frictional force.

As described above, in order to predict the frictional force of the packing, the frictional coefficient of each packing must be derived, but only the general frictional coefficient of the packing is disclosed, and the absence of data verified through empirical tests for each packing material and manufacturer. Therefore, there is a disadvantage that the exact coefficient of friction of the packing is not known.

In addition, in order to accurately calculate the friction coefficient of the packing during the test, the packing gland must accurately measure the gland stress and packing friction force that presses the packing. Since the gland stress and the friction of the packing cannot be accurately measured, the coefficient of friction of the packing is difficult. It is difficult to calculate the situation.

In order to improve this problem, various research and development have been made in the industry, and many are disclosed in addition to Japanese Patent Laid-Open No. 2004-100740 (Gland Packing Performance Diagnosis Device for Control Valve).

Prior art documents have a structure that detects the axial load of the valve shaft and determines the performance of the gland seal even during operation of the control valve. A technique for detecting and determining the performance of each seal by separately calculating the lateral pressure of the packing material using the sliding resistance value in the no-load state between the gland packing and the valve shaft is specified.

However, in the prior literature, the performance of each seal is determined using the sliding resistance value in the no-load state between the gland packing and the valve shaft. The direct load on the gland is not known. Occurs, and there is an inconvenience of having to measure again in response to the material and shape change of the packing.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and provides an apparatus and method for testing friction coefficient of valve packing that can accurately calculate friction coefficient of packing so that gland stress can be directly measured to predict packing friction force. There is a purpose.

In addition, another object of the present invention, by directly measuring the gland load in the gland studs, to eliminate the errors generated during the calculation of the friction coefficient of the packing, regardless of the material and shape of the packing used for each valve The present invention provides an improved friction coefficient testing apparatus and method for predicting the frictional force of a packing to more accurately predict the operation potential of the valve.

Valve packing coefficient of friction test apparatus of the present invention for achieving the above technical problem, the valve is provided on the support is fixed via a valve fixing nut, the at least one packing is coupled to be received in the stuffing box; A packing gland seated on an upper side of the packing and coupled to penetrate the gland stud; A gland nut securing the packing gland to an upper side of the valve to impart gland stress; A valve stem fitted to the packing so as to be lifted up and down so as to interlock with an actuator stem provided at an upper side thereof through a stem connector; A first strain gauge disposed on the valve stem to measure packing frictional force; And a second strain gauge provided between the packing gland and the valve to measure gland stress.

On the other hand, the valve packing coefficient of friction test method of the present invention based on the above-described device, the packing gland is fixed to the upper side of the packing mounted in the valve via the gland stud and gland nut, the initial of the packing gland (A) measuring the height; (B) tightening the gland nut fixed on the packing side to generate gland stress corresponding to the preset stress value; (C) measuring the gland stress and the packing friction force through the strain gauge after the driver reciprocates the valve stem up and down once through the driving force applied from the motor; (D) compressing the packings by repeating step (c) until the gland stress difference before and after the up and down reciprocation of the valve stem reaches a preset range; And after measuring the final height of the packing gland, the valve stem is reciprocated up and down a plurality of times to continuously measure the gland stress and the packing friction force, and the packing friction coefficient is calculated using the measured gland stress and the packing friction force ( e) step.

According to the present invention as described above, it is effective to directly measure the stress applied to the gland stud to provide an accurate gland stress measurement.

In addition, according to the present invention, by reducing the gland stress difference before and after the reciprocating operation of the actuator stem to calculate the accurate friction coefficient of each packing, the possibility of operation of the power plant safety-related valve based on the packing friction coefficient information for each packing material It has the effect of accurately predicting.

1 is a block diagram showing an apparatus for diagnosing performance of a gland packing used in a conventional control valve.
Figure 2 is a flow chart illustrating a valve packing friction coefficient test method according to the present invention.
Figure 3 is a flow chart showing the detailed process of the valve packing friction coefficient test method according to the present invention.
Figure 4 is a flow chart showing a process after step S30 of the valve packing coefficient of friction test method according to the invention.
Figure 5 is a schematic view showing a valve packing coefficient of friction test apparatus according to the present invention.
Figure 6 is a use state showing the combined state of the packing and packing gland of the valve packing coefficient of friction test apparatus according to the present invention.
7 is a flow chart showing the operation of the valve packing coefficient of friction test apparatus according to a first embodiment of the present invention.
8 is a view showing the gland stress difference before and after reciprocating operation by the operating mode of the valve packing coefficient of friction test apparatus according to the first embodiment of the present invention.
Figure 9 shows the coefficient of friction of the packing calculated by the operating mode of the valve packing coefficient of friction test apparatus according to the first embodiment of the present invention.
10 is a flow chart showing the operation of the valve packing coefficient of friction test apparatus according to a second embodiment of the present invention.
11 is a view showing the gland stress difference before and after reciprocating operation by the operating mode of the valve packing coefficient of friction test apparatus according to the second embodiment of the present invention.
12 shows the coefficient of friction of the packing calculated by the operating mode of the valve packing coefficient of friction testing apparatus according to the second embodiment of the present invention.

Specific features and advantages of the present invention will become more apparent from the following detailed description based on the accompanying drawings. Prior to this, terms and words used in the present specification and claims are to be interpreted in accordance with the technical idea of the present invention based on the principle that the inventor can properly define the concept of the term in order to explain his invention in the best way. It should be interpreted in terms of meaning and concept. It is to be noted that the detailed description of known functions and constructions related to the present invention is omitted when it is determined that the gist of the present invention may be unnecessarily blurred.

Referring to the valve packing coefficient of friction test method according to the present invention with reference to Figure 2, first, the gland stud 41 and the gland nut 43 on the upper side of the packing 100 mounted in the valve 50 through The packing gland 40 is fixed and the initial height of the packing gland 40 is measured (S1).

Subsequently, the gland nut 43 fixed on the packing 100 is tightened to generate a gland stress corresponding to the preset stress value (S2).

Subsequently, after the driver 10 operating by the driving force of the motor 11 reciprocates the valve stem 30 up and down once, the gland stress and the packing friction force are measured through the strain gauge (S3).

Subsequently, the packing 100 is compressed by repeating step S3 until the gland stress difference before and after the up and down reciprocation of the valve stem 30 reaches a preset range (S4).

After the final height of the packing gland 40 is measured, the valve stem 30 is reciprocated up and down a plurality of times to continuously measure the gland stress and the packing friction force, and by using the measured gland stress and the packing friction force. The packing friction coefficient is calculated (S5).

Specifically, referring to Figure 3 when looking at the detailed process of the valve packing friction coefficient test method according to the present invention.

Looking at the detailed process of the step S1, first, the step of mounting the packing 100 to the valve 50, disassembling the gland nut 43 to the packing gland 40 in the upper side of the valve 50 Separate (S10).

Subsequently, the bushing 200 is inserted into the stuffing box 52 of the valve 50, and the packing 100 is seated on the bushing 200 (S20).

Then, the packing gland 40 is seated on the packing 100 and the gland nut 43 is tightened to fix the packing gland 40 to the packing 100 (S30).

In addition, as shown in FIG. 4, after step S30, the bushing 200 is disposed under the packing 100 to perform a spacer function (S40). At this time, the packing gland 40 penetrates the gland stud 41 disposed above the valve 50 to be seated on the valve 50 and the packing 100, and is fixed by the gland nut 43. .

Subsequently, the second strain gauge 42 is disposed between the packing gland 40 and the valve 50 to directly measure the load and stress applied to the packing gland 40 (S50).

Subsequently, the plurality of packings 100 are inserted to be accommodated in the valve 50, and fitted to the outer circumferential surface of the valve stem 30 (S60).

Then, the first strain gauge 31 is provided in the valve stem 30 to measure the frictional force of the packing (S70).

Here, the setting range of the gland stress is preferably within 10% of the gland stress difference before and after the reciprocating operation, because the difference in the stress transmitted to the packing arranged on the top and the packing arranged on the bottom occurs, In order to reduce the stress difference, the actuator is reciprocated to be lifted up and down a plurality of times in order to accurately measure the frictional force of the packing.

Meanwhile, the surface of the valve packing friction coefficient test apparatus of the present invention for performing the test method described above with reference to FIGS. 5 and 6 is as follows.

First, the valve 50 is provided on the support 60 to be fixed via the valve fixing nut 51, and the at least one packing 100 is coupled to be accommodated in the stuffing box 52. At this time, the support 60 may be installed a plurality of wheels in the lower portion to be movable.

In addition, the packing gland 40 is seated on the upper side of the packing 100 and coupled to penetrate the gland studs 41, and the gland nut 43 is packed gland 40 to impart gland stress. To the upper side of the valve (50).

In addition, the valve stem 30 is fitted to the packing 100 so as to move up and down in conjunction with the driver stem 32 of the driver 10 provided on the upper side through the stem connector 34.

In addition, the first strain gauge 31 is disposed on the valve stem 30 to measure the packing frictional force, and the second strain gauge 42 is provided between the packing gland 40 and the valve 50 to gland stress. Measure

Specifically, the packing 100 is provided to be received in the stuffing box 52 seated on the upper side of the valve 50, and the driver 10 transmits the driving force applied from the motor 11 to the valve stem 30 side. The function of the motor 11 is controlled by the control unit 12.

The yoke 20 is provided above the valve 50 to support the driver 10 and the motor 11, and the torque arm 33 has one end fixed to the driver stem 32 and the other end of the yoke 20. Supported at 20 to prevent rotation of the driver stem 32.

Hereinafter, the operation of the valve packing friction coefficient test apparatus according to the first embodiment of the present invention with reference to FIGS. 7 to 9 are as follows.

As shown in FIG. 7, when the packing material is the braided graphite work and the molded flexible graphite ring, the initial height of the packing gland 40 is measured over the first and second steps (S11).

Subsequently, when the primary height of the packing gland 40 is measured to be 34.80 mm and the secondary height is 35.00 mm, the gland nuts 43 are tightened to form a gland stress to have a predetermined stress value (S12). .

Subsequently, the second strain gauge 42 measures the gland stress and the first strain gauge 31 measures the frictional force of the packing 100 while performing a reciprocating operation of raising and lowering the driver stem 32. (S13).

Subsequently, steps S12 and S13 are repeated until the gland stress difference before and after performing the reciprocating operation of the driver stem 32 is within 10% (S14), and the result is as shown in FIG. 8. .

Then, the actuator stem 32 is operated three times to continuously measure the gland stress and the frictional force of the packing, and after measuring the final height of the packing gland 40, the coefficient of friction of the packing is calculated, and the calculated friction of the packing The coefficient is as shown in FIG. 9 (S15).

On the other hand, with reference to Figures 10 to 12 will be described below the operation of the valve packing friction coefficient test apparatus according to a second embodiment of the present invention.

As shown in FIG. 10, when the packing is Teflon packing, the initial height of the packing gland 40 is measured over the first and second steps (S21).

Subsequently, when the primary height of the packing gland 40 is measured to be 35.00 mm and the secondary height is 35.00 mm, the gland nuts 43 are tightened to form a gland stress to have a predetermined stress value (S22). .

Subsequently, the second strain gauge 42 measures the gland stress and the first strain gauge 31 measures the frictional force of the packing 100 while performing a reciprocating operation of raising and lowering the driver stem 32. (S23).

Subsequently, steps S22 and S23 are repeated until the gland stress difference before and after performing the reciprocating operation of the actuator stem 32 is within 5% (S24), and the result is as shown in FIG. 11. .

Then, the actuator stem 32 is operated three times to continuously measure the gland stress and the frictional force of the packing, and after measuring the final height of the packing gland 40, the coefficient of friction of the packing is calculated, and the calculated friction of the packing The coefficient is as shown in FIG. 12 (S25).

At this time, the final height of the packing gland 40 is measured over the first and second from the upper surface of the valve 50, the primary final height is measured to 29.50mm and the secondary final height is measured to 29.50mm.

As described above, the packing frictional force of the first and second embodiments according to the present invention is derived through Equation 1 below, and the packing friction coefficient is calculated by Equation 2 below.

[Equation 1]

&Quot; (2) "

As described above, the present invention can directly measure the stress applied to the gland studs 41 using a strain gauge, so that accurate stresses can be measured and the exact coefficient of friction of each packing 100 can be calculated. In addition, it is possible to predict the operation possibility of the safety valves related to power plant by obtaining packing friction coefficient information for each packing material.

While the present invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. It will be appreciated by those skilled in the art that numerous changes and modifications may be made without departing from the invention. And all such modifications and changes as fall within the scope of the present invention are therefore to be regarded as being within the scope of the present invention.

10: Driver 11: Motor
12: control unit 20: yoke
30: valve stem 31: first strain gauge
32: driver stem 33: torque arm
34: stem end connection 40: packing gland
41: gland stud 42: second strain gauge
43: gland nut 50: valve
51: nut for fixing the valve 52: stuffing box
60: support 100: packing
200: bushing

Claims (7)

In the valve packing friction coefficient test method,
(a) fixing the packing gland via a gland stud and a gland nut on an upper side of the packing mounted in the valve, and measuring the initial height of the packing gland;
(b) tightening the gland nut fixed above the packing to generate gland stress corresponding to a predetermined stress value;
(c) after the driver reciprocates the valve stem up and down once through the driving force applied from the motor, measuring the gland stress and the packing friction force through the strain gauge;
(d) repeating step (c) to compress the packings until the gland stress difference before and after the up and down reciprocation of the valve stem reaches a preset range; And
(e) After measuring the final height of the packing gland, the valve stem is reciprocated up and down a plurality of times to continuously measure the gland stress and the packing friction force, and the packing friction coefficient using the measured gland stress and the packing friction force. Valve packing friction coefficient test method comprising the step of calculating. The method of claim 1,
The step (a)
(a-1) disassembling the gland nut to separate the packing gland from the upper side of the valve;
(a-2) inserting a bushing into the stuffing box of the valve and seating a packing on the bushing; And
(a-3) seating the packing gland on the packing and tightening the gland nut to fix the packing gland to the packing; valve packing friction coefficient test method comprising the. The method of claim 2,
After the step (a-3),
(i) a bushing disposed below the packing to perform a spacer function;
(j) a second strain gauge is disposed between the packing gland and the valve to directly measure the load and stress applied to the packing gland;
(k) inserting a plurality of packings to be received in the valve, the fitting being fitted to the outer circumferential surface of the valve stem; And
(l) a first strain gauge is provided on the valve stem to measure the frictional force of the packing; valve packing friction coefficient test method comprising the. In the valve packing friction coefficient test apparatus,
A valve provided at an upper portion of the support and fixed through a nut for fixing the valve, the valve being coupled to receive at least one packing in the stuffing box;
A packing gland seated on an upper side of the packing and coupled to penetrate a gland stud;
A gland nut securing the packing gland to an upper side of the valve to impart gland stress;
A valve stem fitted to the packing so as to be lifted up and down so as to interlock with an actuator stem provided at an upper side thereof through a stem connector;
A first strain gauge disposed on the valve stem to measure packing frictional force; And
And a second strain gauge provided between the packing gland and the valve to measure gland stress. The method of claim 4, wherein
The packing is
Valve packing friction coefficient test apparatus characterized in that it is provided to be accommodated in the stuffing box seated on the upper side of the valve. The method of claim 4, wherein
The driver,
A valve packing coefficient of friction test device, characterized in that to perform the function of transmitting the driving force applied from the motor to the valve stem, the motor is controlled by the control unit. The method of claim 4, wherein
A yoke provided above the valve to support a driver and a motor; And
And a torque arm having one end fixed to the driver stem and the other end supported by the yoke to prevent rotation of the driver stem.

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