DE102018111010B3 - Method for setting a closing force of a fitting and fitting measurement method - Google Patents

Abstract

Method for setting a closing force on a valve which can be driven linearly by means of a drive via a transmission element (2), comprising a valve body and a valve seat, comprising the steps:
Retracting the valve in a closed position in which the drive has moved to a Weganschlag, the valve body just touches its valve seat powerless, and
Loading a predefined thrust force by means of a change in length of the transmission element or adjusting the travel stop, wherein the thrust force acting on the transmission element (2) when approaching is measured.

Description

The invention relates to a method for setting a closing force on a linearly driven via a transmission element by means of drive valve with a valve body and a valve seat. Furthermore, the invention relates to a valve measuring method for quality inspection of the valve during operation.

To control fluid flows in piping systems fittings, in particular shut-off or control valves are used in the industry. The fluid flows to be controlled may be gases or liquids, but it is also possible for the flowing fluids to be granules, shot, powder or dusts as well as flowing plastic masses. In many cases, the proper functioning of the control or shut-off valves is an indispensable prerequisite for the efficiency and safety of the operating or process sequence to be controlled. This applies in particular to operating and process sequences of the chemical industry. In particular, safety-relevant fittings must be checked at regular intervals for their functionality. Often, however, it is not possible to expand safety-relevant valves from the affected line system for the purpose of functional testing. Although known test methods, which can be used during operation of the valve, provide important information about the movement sequence of the valve, but nothing about the internal quality status. It is also often necessary to interrupt the process and operations for the development of the test valve to undergo a detailed functional check.

From the DE 44 39 230 C2 a method for determining the state of fittings is known, in which a torsional torque proportional to the transmitting torque is measured on the fitting by means of optical triangulation.

Furthermore, from the DE 102 09 545 A1 a method for the online detection of valve data is known in which operating parameters and / or state parameters are detected and closed on the technical functional state of the valve. It is proposed that to obtain the state parameters during operation small oscillations or deflections are excited around the operating point around.

Another method for safety inspection of valves with electric actuator is in the DE 42 07 643 A1 disclosed. When the valve is actuated, the method uses the recorded active power curves of the actuator to draw conclusions about the acting torque.

The Applicant has recognized the need for a technical condition test of rotary drivable fittings and a related method for rotary drivable fittings according to DE 10 2012 111 883 A1 developed.

To carry out this measurement method, a special Torsionsmesskupplung according to DE 20 2010 010 267 U1 used.

Furthermore, there are many applications in industry in which the valves are linearly driven, so called lift valves are installed. With the aforementioned methods and devices, however, no precise statement about the technical condition of globe valves, for example gate valves or wedge gate valves, in which a spindle as a transmission element transmits a linear movement to a valve body, for example a wedge, can be taken.

Accordingly, the describes US 5,140,853 a dynamic load measuring system for monitoring and measuring the variable dynamic thrust exerted by the drive on the valve stem.

A corresponding force measuring device for receiving in a valve stem is in the US 2015/0082902 A1 described.

Therefore, the object of the invention is to develop a fitting measuring method for such drivable fittings for adjustments and quality checks on it.

This object is achieved with a method according to claim 1 and a fitting measuring method according to claim 2.

By measuring the force acting on the transmission element (spindle or shaft) of the valve thrust force with a force measuring device, the acting thrust is detected directly, so a very fine resolution and a direct assignment is possible. In a further embodiment, the same force measuring device preferably measures the tensile force acting on the spindle even when the lifting valve is driven up. Accordingly, an immediate tensile force measurement is possible for the Auffahrvorgang.

If in a closed position of the valve, a predefined thrust force is applied in the direction of the closed position of the valve and a travel for the linear drive is limited, so that the predefined thrust repeatable in the closed position is reached, the Armature via the drive by linear movement of the transmission element (spindle or shaft) brought in repeated actuation in the geometrically same closed position and - at least for a non-worn valve - a predefined thrust in the closed position and thus the valve body are loaded on the valve seat.

In order to apply the closed position and a predefined thrust in the direction of the closed position, so load of the valve body on the valve seat, touches the definition of the closed position via the transmission element adjustable valve element of the valve just his valve seat powerless, then the predefined thrust on the Transfer element is applied.

In order to push the valve body into the valve seat with a predefinable thrust force, the predefined thrust force is then applied by means of a change in length of the transmission element.

Alternatively, the predefined thrust can be applied by means of an adjustable travel stop for the linear drive of the transmission element.

If the thrust force during retraction and / or the traction force when the valve is being started are recorded continuously, the recorded thrust and traction curves can be compared continuously or as needed. Thus, it is possible to determine a wear on the valve based on changes in the force curves.

Particularly preferably, a reference curve of the pushing and pulling force during opening and closing is recorded before or during (re-) start-up of the valve, and the pushing and pulling force is measured during operation of the valve, whereby the course of the pushing and pulling force during erection. and in-running operation is compared to the reference history and, in the event of deviations greater than a predetermined error threshold, errors are reported, thereby enabling automated error output. In this case, the predetermined error thresholds can be set so that, although still a sufficiently safe valve operation is possible, but in a next production interruption, the relevant valve is replaced in the industrial plant, prepared or repaired.

Accordingly, the fitting measuring method can be used for quality testing of the fitting during operation. The state of the valve can thus be determined during operation without production interruption and without removal and installation costs.

According to the device, the force measuring device for determining the tensile or shear force between the drive for the valve and the transmission element (spindle or shaft) is arranged. Favor this is a pull and pressure transducer.

Hereinafter, an embodiment of the invention will be described with reference to the accompanying drawings.

• 1 ein Hubventil in schematischer Ansicht in Offenstellung,
• 2 das in 1 dargestellte Hubventil in Schließstellung,
• 3 eine Kraftmesskurve als Zeitreihe über einen Messzyklus „auf/zu“ im Neuzustand,
• 4 in einem ersten Verschleißzustand,
• 5 in einem zweiten Verschleißzustand und
• 6 in einem dritten Verschleißzustand.

It shows:

• 1 a lift valve in a schematic view in the open position,
• 2 this in 1 illustrated lifting valve in the closed position,
• 3 a force measurement curve as a time series over a measurement cycle "open / close" in new condition,
• 4 in a first state of wear,
• 5 in a second state of wear and
• 6 in a third state of wear.

In 1 is a schematic, partially sectioned view of a globe valve 3 with a schematically indicated valve housing 30 and a transmission element 2 represented in the form of a spindle. At the in 1 oriented upper end of the transmission element 2 is a drive 1 for linear movement of the transmission element 2 along the punctiform longitudinal axis, namely the spindle axis X , The drive 1 can be done pneumatically, hydraulically or electrically via corresponding actuators. Furthermore, a load by means of spring force, for example for safety valves is conceivable.

At the lower end of the transmission element 2 is a valve cone 31 arranged with a valve seat 32 interacts. In 1 is the lift valve 3 shown in the open position. Accordingly, the fluid flow F over valve body 31 and valve seat 32 flow. In 2 is the same valve in the closed position, ie the valve drive 1 linear along the dot-dashed spindle axis X is shown adjusted down. In this position, the valve body sits 31 on the valve seat 32 on and blocks the fluid flow F in the valve housing 30 from.

The trained as a spindle transmission element 2 leads from the outside through the valve body 30 in the valve interior, wherein at this end of the valve body 31 inside the valve body 30 is arranged. To avoid unwanted medium leakage is a stuffing box 23 arranged on this housing feedthrough. The valve spindle 2 further comprises a biasing means 4 on the for example, from a union nut 41 with left and right threads exists in which the spindle 2 in two sections, an upper section 21 and a lower section 22 , Is connected to a respective right and left-hand thread. Accordingly, by turning the nut 41 the total length of the valve stem 2 to be changed. The upper section 21 the spindle 2 has a force measuring device 5 on, the tensile and compressive loads in the direction of the spindle axis X can measure. For example, the upper section 21 the spindle 2 here separated and over a Zug- and pressure load cell 51 be connected. To the measuring device 5 To install the linear-driven valves, there are many possibilities. So it is also possible to install the pull and pressure cell in the diaphragm plate or valve disc in the drive.

Further, for the drive 1 for the linear movement of the transmission element 2 in the direction of the spindle axis X a path stop 11 provided so that a fixed distance L between valve seat 32 and this path stop 11 is predetermined.

Hereinafter, the fitting measuring method and the initial basic settings for carrying out the method with reference to the in the 1 and 2 illustrated lifting valve 3 described.

First, for the exact definition of the closed position of the drive 1 on the path stop 11 driven, the valve body 31 just its assigned valve seat 32 to touch powerless. From this basic position is then by means of the biasing device 4 by turning the union nut 41 a predefined thrust, for example 900 N, on the transmission element formed as a spindle 2 uprated. The acting thrust is via the force measuring device 5 measurable.

In addition, when moving the spindle 2 through the drive 1 when loading and / or driving a load during movement via the force measuring device 5 can be read, this force of friction in the stuffing box 23 be assigned. With the clamping device 4 then becomes the valve cone 31 against the seat 32 pressed. In the example in 3 to about 680 N. Then follows the Auffahrbewegung. The neutral phase is reached where the direction of force changes from pressure to tension. Now, the frictional force of the stuffing box with the pulling motion is measured at about 230 N. It follows the closing process with the neutral phase, where the change from tensile to pressure measurement passes. The friction of the stuffing box is now measured with the pressure measurement, which is also about 230 N. Thereafter, the closing of the valve with the bias of 680 N.

The frictional force on the stuffing box 23 can thus be accurately measured when the valve moves in setting and the bias is canceled. Only when the preload in the closing process is effective, both will find together in the measurement result. Accordingly, the predefined thrust force acting on the transmission element 2 is loaded, so to choose that in the force measuring device 5 measured load less the frictional force (eg 230 N) coming from the stuffing box 23 is received, the desired pressing pressure (eg 680 N) of the valve body 31 on the valve seat 32 equivalent. Once this adjustment is made, then can the mint or reconditioned lift valve 3 a reference curve of the pushing and pulling force during opening and closing of the valve can be recorded. This reference curve corresponds to the force measurement curve according to 3 ,

Now, in each case, the force curve during the opening and closing of the valve is recorded as an "operating curve". In each case, the operating curve is compared with the reference curve and thus any wear made recognizable. As long as there are no or only minor deviations from the reference curve, the operating curve of the fitting has been verified.

In contrast, a clear deviation of the operating curve shown in dashed lines from the reference curve is an example in a later measurement process 4 occurred during the closing process, namely from about 680 N to 830 N. Here, a deposit on the valve seat has formed. The deposit is about 0.1 mm, resulting in the approach of the valve to the stop 11 the higher ballast pressure results. Changes to the frictional force of the stuffing box have not occurred. Accordingly, an error message is output during an automated evaluation of the measured curves.

Likewise, the in 5 dashed curve to qualify as faulty because too low a pressure in the closed position, namely about 490 N from the base of 680 N is displayed. Here, a removal of about 0.1 mm has taken place on the seat, resulting in the approach of the valve on the stop 11 the reduced load pressure results. A leak is the result. Again, an automatic system would give an error message.

In 6 the stuffing box was tightened too tight. The higher frictional force of the stuffing box also reduces the preload on the seat assembly. In this picture has the seat set of the lift valve 3 no mistake. The addition of forces again gives the preload when new. This must be taken into account during the evaluation. The Preload can now be adjusted again. A reduction of the frictional force on the stuffing box has the opposite effect. Measuring the frictional force of the stuffing box is important. If it has changed, it has influence on the bias on the seat. The seat set does not have to be faulty just because the frictional force of the stuffing box has changed.

Thus it can be seen that with the fitting measurement method, a quality control on linear actuated valves during operation can be performed.

In the simplest case, only the defined preload in the closed position, ie on the valve seat 32 seated valve body 31 each compared as a repeated measured variable with the originally set bias voltage. Deposits form between the valve seat 32 and valve body 31 this would increase the preload, since the adjustment is minimally smaller and thus a higher pressure on the valve seat 32 measured at the spindle 2 arises. Should be abrasion or washouts on the valve seat 32 or valve body 31 arise, this would lead to a minimal extension of the travel, so that the bias voltage is lower. Thus, already alone on the spindle 2 by means of force measuring device 5 measured Auflastdruck in the closed position a statement about the quality of the valve, namely in particular the closure on the valve body 31 or valve seat 32 deliver. Accordingly, changes such as abrasion, cavitation damage, erosion, removal of material are already evident when comparing these measured values.

Is the entire push and pull load record evaluated as to the 3 to 9 described, in addition, other impairments of the valve, such as hardening of the stuffing box, declining driving forces, blockages or not fully closing valves during operation without disassembly of the monitored lift valve can be determined by the evaluation of the measured force curves. Thus, it is also possible to determine the frictional forces acting on the glands and to determine the cause of leaks, for example, the cause of heavy gear, failure and too low frictional forces.

Preferably, the force curves, namely the constantly measured operating curves are compared with the reference curve in an automated process such that errors can be determined with a corresponding evaluation software and maintenance requirements can be displayed. The software is preferably controlled via feedback of the valve position at control valves. The evaluation can take place via the control system of the operator of the industrial plant.

Of course, it is alternatively also possible to carry out a manual evaluation via data loggers and / or handheld measuring instruments. Always here is the force measurement on the transmission element (spindle 2 ) for certain operating states of the lift valve or over certain periods of time, for example when driving on and off, a prerequisite for quality control.

It is also possible to monitor linearly moved safety valves with the valve measuring method described here. In the case of safety valves, the valve stem is pressed by means of spring force onto the valve seat of the safety fitting. However, there is no check between the prescribed test cycles as to whether the valve has been actuated in the meantime or whether the spring tension responsible for the contact pressure still fulfills the tasks set. Again, with the invention Armaturenmessverfahren by measuring the on the spindle 2 Lasting force any activities and changes that occur in any operations, be noticed safely.

It is also possible to monitor with the valve measuring method described here also linearly moving hand-operated valves with threaded spindle. As a stop, the threaded spindle, the z. B. by means of lock nuts the way and so serves as a stop. The measuring device is housed in the housing of the spindle nut. Tensile and pressure measurements work here according to the described measuring method. The same applies to electrically operated valves with threaded spindle.

LIST OF REFERENCE NUMBERS

1

drive

11

Weganschlag

2

Transmission element, spindle

21

upper section

22

lower section

23

gland

3

globe valve

30

valve housing

31

Valve body, valve cone, valve element

32

valve seat

4

biasing means

41

Nut

5

Force measuring device

51

Tension / pressure cell or transducer

F

fluid flow

L

Distance stop valve seat

X

spindle axis

Claims (5)

Method for setting a closing force on a valve which can be driven linearly by means of a drive via a transmission element (2), comprising a valve body and a valve seat, comprising the steps: Retracting the valve in a closed position in which the drive has moved to a Weganschlag, the valve body just touches its valve seat powerless, and Loading a predefined thrust force by means of a change in length of the transmission element or adjusting the travel stop, wherein the thrust force acting on the transmission element (2) when approaching is measured. Valve measuring method for the quality testing of a linearly driven by means of a drive transmission via a transmission element (2) during operation with a valve body and a valve seat comprising the steps: adjusting the thrust force in the closed position according to Claim 1 , Measuring the thrust force in the closed position in repeated closing operations, comparing the measured thrust force in the closed position with the predefined thrust force and output of an error message in case of deviations greater than a predetermined error threshold. Valve measuring method according to Claim 2 , characterized in that for traction a tensile force on the transmission element (2) of the valve is transmitted, wherein the tensile force acting on the transmission element (2) when driving on is measured. Valve measuring method according to Claim 2 or 3 , characterized in that the thrust force during retraction and / or the tensile force when driving the valve are recorded continuously. Valve measuring method according to Claim 4 , characterized in that a reference curve of the pushing and pulling force during opening and closing before or during (re-) start-up of the valve is recorded and that the pushing and pulling force is measured during operation of the valve, wherein the course of Schub- and tensile force during startup and shutdown during operation is compared with the reference curve and errors are reported for deviations greater than a predetermined error threshold value.

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