Testing of swing type check valves using phased array sequence scanning

A computer with a proper program generates a phased array sequence of signals. In a pulser with delays, the signals are fed through a multiplexor into a water wedge that is attached to a valve being tested. For a sequential operation of the valves from the open to the closed position, ultrasonic signals are transmitted through the fluid contained in the valve and reflected back through piezo-electric crystals to the multiplexor. By summation and merger of the signals, an image can be developed of the operation of the valve to determine if the valve is operating properly. By use of the water wedge, the top plate of the valve appears to disappear because the water wedge has the same refractive angle as the fluid contained in the valve.

BACKGROUND OF THE INVENTION

1. Technical Field

This invention relates to the non-intrusive testing of valves and, more particularly, to the testing of swing-type check valves using phased array sequence scanning.

2. Brief Description of the Prior Art

In the past, if someone wanted to see if a valve was operating properly flow through the valve was the first thing checked. If more information was desired, the valve could be taken apart. As technology advanced, other ways of checking the internal operation of the valve was developed. For example, a magnetic field may be used to determine the position of the disc in a check valve as is shown in U.S. Pat. No. 5,236,011. Also, ultrasonic vibrations have been used to monitor check valves to determine if they are operating properly. Even a combination of acoustic and magnetic techniques have been used in the past to monitor the operation of valves (see U.S. Pat. No. 5,008,841).

In the past, many different techniques of using ultrasonics have been developed to determine either the condition or the position of a valve without taking the valve apart. However, these non-intrusive inspection techniques normally did not give all of the information necessary to determine if a valve is operating properly. For example, the hinge pin on which the clapper of a check valve operates may be worn over a period of time. If this condition is not detected before the hinge pin breaks, a catastrophic failure would result. Typical non-intrusive inspection techniques are not able to detect wear on the hinge pin of a disc-type check valve.

In the last few years, the use of phased arrays to generate a wave front of ultrasonic signals has been used in different types of inspection techniques. For example, phased array has been used to measure flow of a fluid through a pipe as is shown in U.S. Pat. No. 7,503,227. Also variable angle ultrasonic transducers have been used in inspection techniques for pipes, conduit, plates or other foreign metallic members that may have irregularities in the surface of the test member (see U.S. Pat. No. 5,392,652).

As the capability of computers has increased dramatically in recent years, the use of a phased array ultrasonic signal has also been used in the testing of various equipment (see U.S. Patent Publication No. US 2009/0045994 A1). The use of phased array for three-dimensional ultrasonic inspection has also begun to be used in the industry (see U.S. Patent Publication No. US 2009/0293621 A1 and U.S. Pat. No. 7,784,347). Even combinations of laser beams and ultrasonic signals have been used in maintenance programs for testing equipment (see U.S. Pat. No. 7,728,967). Ultrasonic phased array has been used for some time in the testing of weld joints and pipes (U.S. Pat. No. 7,412,890).

As the nuclear regulatory industry has developed, a need has also developed for a very reliable method for non-intrusive inspection of the valves in a nuclear power plant. The operators needs to know with certainty that the valves are operating properly. Also, the operators need to know if a valve has begun to wear to the point where the valve should be serviced or repaired. This cannot be done with the inspection techniques that have been developed and used in the past.

BRIEF SUMMARY OF THE INVENTION

It is an object of the present invention to provide a non-intrusive inspection technique for valves.

It is another object of the present invention to provide for testing of swing-type check valves using phased array sequence scanning.

It is another object of the present invention to use a non-intrusive technique of phased array sequence scanning to determine if a valve is operating properly.

It is yet another object of the present invention to provide the use of phased array sequence scanning in a non-intrusive technique to test the proper operation of a valve.

It is yet another object of the present invention to provide a water wedge in combination with phased array sequence scanning to test the proper operation of a swing-type check valve by use of a non-intrusive technique.

It is another object of the present invention to use a water wedge to transmit a phased array sequence scanning to a valve full of fluid to test proper operation of the valve.

A user setup is provided that consists of a computer properly programmed to create a phased array. The phased array is fed through a pulser with delays to a multiplexor. The multiplexor receives the signals from the pulser and creates a serial set of phased array signals, which phased array signals are sent to a plurality of piezo-electric crystals mounted on a water wedge. A water wedge is a wedge-like structure made from a plastic mixture that has the same refraction index as water.

The water wedge is mounted on a steel plate forming the top of a check valve. If the check valve is full of liquid, phased array sequence scanning can be used to monitor the operation of the check valve by receiving reflected signals back through the water wedge via receiving piezo-electric crystals, which receiving piezo-electric crystals provide serial input into the multiplexor. The output of the multiplexor sends parallel signals to a receiver with delays, which received signals are summed in a summation device. The summed signals feeds through a phase array acquisition and control to an image development and display. In the image development and display, the operation of the check valve can be monitored to determine if it is operating properly, or if repairs are necessary.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now toFIG. 1, a swing-type check valve10is being tested by phased array sequence scanner illustrated generally by the reference numeral12. The phased array sequence scanner12has a user setup14that will include a computer that is programmed to generate a wave front to be used in testing the swing-type check valve10. If some other type of valve is being tested, the user setup14can be varied and the program changed to generate the particular type of wave front desired for the valve under test.

The wave signal from the user setup14feeds to a phased array acquisition and control16. The phased array acquisition and control16takes the instructions from the software contained in the user setup14and fires the voltages in a timing sequence as determined by the computer program. The signals from the phased array acquisition and control16feed through a pulser with delays to generate spike signal voltages20that are fed through multiplexor22. In the illustration as shown inFIG. 1, a total of eleven voltage spike signals20are generated, but this number can vary depending upon design of the phased array sequence scanner12.

The multiplexor22manages the outgoing pulses24which fires transmit piezo-electric crystals26. In the present embodiment, because there are eleven spike voltage signals20being received from the pulser with delays18, there will be eleven transmit piezo-electric crystals26. In this preferred embodiment, the number of piezo-electric crystals26is eleven. However, the number of piezo-electric crystals can vary according to the preference of the end user.

The number of piezo-electric crystals could be as few as three, but the upper end is controlled only by the number of discreet signals that can be transmitted and received. Twenty or thirty piezo-electric crystals could be used almost the same as eleven are being used in this preferred embodiment. The piezo-electric crystals can be naturally occurring such as quartz, but man-made lattices that form a piezo-electric crystal are better because of the quality control.

The transmit piezo-electric crystals26are attached to the inclined angle28of water wedge30. The inclined angle28can vary from 0° to 70°, but Applicant has found approximately 20° to be ideal. Water wedge30is not actually made from water, but is made from a plastic mixture that has the same refraction index as water. Also, the water wedge30as illustrated inFIG. 1, is not to scale, but is illustrated in a manner that is approximately ten times its actual size when compared to the swing-type check valve10located there below. The water wedge30is enlarged for illustration purposes only.

During a normal test, the swing-type check valve10will be full of liquid. Because the water wedge30has the same refraction index as water, during a test, it will appear as if the top plate32of a check valve10is not present. This gives a much better signal. Therefore, the water wedge30is specifically designed to have approximately the same refraction index as the fluid contained inside of swing-type check valve10.

In normal operation, the user setup14with the computer and program contained therein will cause the phased array acquisition and control16to generate signals that fed to the pulse with delays18that creates timed spike voltage signals20that feed through multiplexor22. From multiplexor22, the outgoing pulse signals24fire the transmit piezo-electric crystals26which generate a wave front in water wedge30. The wave front flows through top plate32and into the chamber34of swing-type check valve10. The wave front36is illustrated by the pie-shaped shaded area within chamber34. The wave front36encompasses the disc38suspended from pin40through the disc arm42. The wave front36will be sequenced over time to follow an entire cycle of a disc38within swing-type check valve10.

Referring now toFIG. 2, in response to the wave front36, acoustic signals will be received back through the top plate32and water wedge30to the receiving piezo-electric crystals44. While the same piezo-electric crystal could be used to receive or transmit, in this preferred embodiment, the receiving piezo-electric crystals44are different from the transmitting piezo-electric crystals26. The acoustic signals received via the receiving piezo-electric crystals44through water wedge30generate reflection signals46. The reflection signals46are processed through multiplexor22to generate return parallel signals48that feed into receiver with delays50. From the receiver with delays50, reflected signals52feed into a summation device54, which gives a summed output56to the phased array acquisition and control16. The phased array acquisition and control16provides an image signal58to image development and display60. The image development and display60gives a visual image of what is happening inside of swing-type check valve10through its normal operation if phased array sequence scanning is used.

The image development and display60uses a combination of signal amplitude and timing to form an image as to the operation of a swing-type check valve. Therefore, time of flight of a particular pulse inside of the swing-type check valve10is important as well as the amplitude of each signal.

Referring now toFIG. 3, the image being shown is the image that would be recorded over time during the actual operation of the check valve. If a swing-type check valve is operating properly, a valve closed signal62will be generated. As the disc on the valve opens, a valve opening signal64shows the travel of the disc when it goes from the closed position to the full open position. When the valve is full open, a valve open signal66is generated.

The main signal is associated with the color red. Red means there is a lot energy being returned at that point during the cycle.

During the reverse operation, a valve closing signal68is generated which is a downward slope as shown inFIG. 3. When the disc of the swing-type check valve closes, another valve closed signal70is generated. However, for the check valve being tested as illustrated inFIG. 3, there is a valve closure delay signal72between the valve open signal66and the valve closed signal70. This valve closure delay signal72indicates a problem in the valve such as wear of pin40shown in previousFIGS. 1 and 2. The valve closure delay signal72indicates there is a problem with the valve under test which could be due to wear. Therefore, before a catastrophic failure occurs, the valve should be either repaired or replaced.

By looking at the phased array sequence scanning signal shown inFIG. 3, an operator can quickly tell if (1) the valve being tested is operating properly, (2) the valve being tested is worn or has some other defect and (3) the valve may cause problems in the near future. The signal shown inFIG. 3is easily understood by the operator.

Referring now toFIG. 4, the pie-shaped figure is actually a cross-sectional view of the sound beam interacting with the valve and valve disc as previously shown inFIG. 3. However, the cross-sectional view shown inFIG. 4is harder to interpret than the wave form shown inFIG. 3. InFIG. 4, the two red dots74actually show the valve gate moving from the full open to the full closed position. It is much more difficult to get meaningful information out of the pie-shaped cross-sectional view shown inFIG. 4, but the image shown inFIG. 3is easily understood by the operator.

Applicant has found that if the inclined angle28of the water wedge30is 15°, it provides the good data. The view as shown inFIG. 3is a volume corrected sound beam at 15°. The sound energy can either be measured at (1) a single angle or (2) all the sound energy can be merged to form one picture. Each has their advantages and disadvantages.

Referring toFIG. 5, the phased array sequence scanning of four different valves76,78,80and82are shown in cycles1,2,3and4, respectively. Cycle one for valve76has a normal open cycle as is represented by the incline84. The full open position86is also normal for valve76. During the closing cycle88, there is a valve closure delay90caused by wear inside of valve76. The valve closure delay90is typical of wear in the pin40(seeFIGS. 1 and 2) of a swing-type check valve. When fully closed, a closed signal92will again be given.

Cycle two is for a normally operating swing-type check valve78with no signs of undue wear or any other malfunctions.

However, valve80, as is represented by gate open and closing cycle three has numerous problems. The gate or disc38in valve80has a tendency to oscillate near the closed position. The gate oscillation is illustrated by reference numeral94. Also, when fully opened, the valve80again has oscillations at the open position as represented by the numeral96. During the closure cycle of valve80, there is gate oscillation at a midway position of the valve as represented by numeral98. Again, when valve80is fully closed, there is again gate oscillations at the closed position as indicated by reference numeral100. The valve80as shown in cycle three is about to have a catastrophic failure. During catastrophic failure any of a number of things could occur such as the disc coming off of the hinge pin or other types of similar failure. A valve operating similar to valve80should be replaced immediately.

Valve82as represented by cycle four is again a normal functioning valve.

As can be seen by looking atFIGS. 3 and 5, when phased array sequence scanning is used in testing swing-type check valves, the operator can easily see if the valve is functioning properly.

For the phased array sequence scanning to operate properly, the valve being tested should be full of liquid. If there is only liquid upstream of the disc, the valve can still be tested but the water wedge would have to be positioned upstream of the hinge point for the disc.

If it is desired to use the phased array sequence scanning on some other type of valve other than a hinged type check valve, a known signal will have to be generated for a good, properly operating valve. Thereafter, in checking similar type valves, future signals would be compared to the known signal to determine if the valve is operating properly.