Method and System for Water-Coupled Ultrasonic Nondestructive Testing of Valve Sealing Welds

Abstract

The present invention relates to a method and system for non-destructive testing of valve sealing welds by water-coupled ultrasonic waves. The method includes the following steps: S1, setting a plurality of measuring points on the circumference of the weld; S2, using a special detection probe device to detect each measuring point on the circumference of the weld; S3, adjusting the position and direction of the water immersion focusing probe of the special detection probe device; S4, extracting the detection signals of each measuring point, and measuring the weld thickness and internal defects at the measuring points according to the detection signals of each measuring point. The non-destructive testing system for valve sealing welds by water-coupled ultrasonic waves of the present invention includes a detection unit, a control unit and a calculation unit. The present invention uses a special detection probe device to efficiently transmit the ultrasonic focused beam into the circumferential weld through the water jet of the water spray coupling method. By analyzing the mutual relationship between the pulse characteristics of the detection signal and the weld structure, the weld thickness and internal defects are determined, and the detection sensitivity and detection accuracy are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of valve seal weld detection and repair, and particularly to a method and system for water-coupled ultrasonic non-destructive testing of valve seal welds. Background Art

[0002] All kinds of sealed-weld valves are widely used in nuclear power systems. During operation, in addition to being able to normally block the flow of media and avoid internal leakage, the valve also needs to maintain the integrity and effectiveness of the boundary seal structures such as valve packing and valve bonnet to prevent external leakage of media. Generally, the valve bonnet seal of a globe valve adopts a lip-weld seal structure. By welding the lip-weld groove at the boundary of the valve bonnet, a relatively thin seal circumferential weld is formed to prevent media from leaking through the gap of the valve bonnet. The quality of the seal weld is crucial for ensuring the realization of the sealing function. However, during the welding process, affected by welding process fluctuations, the weld thickness and internal defects may be low, which will inevitably lead to a decline in weld performance and further affect the operation safety of the valve. Therefore, after welding or during service, measuring the thickness and internal defects of the valve seal weld by non-destructive testing technology plays an important role in valve operation and maintenance and ensuring valve safety.

[0003] Since the reinforcement surface of the nuclear power valve seal weld is a convex arc surface and the surface is rough, directly placing the ultrasonic probe on the weld reinforcement will not obtain good acoustic coupling, and ultrasonic waves cannot effectively penetrate into the weld, making it difficult to measure the weld thickness, internal defects and their internal tissue structures. Also, since the valve is installed on the pipeline, although completely immersing the valve and the probe in the coupling liquid can solve the acoustic coupling problem, it is not suitable for on-site detection. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method and system for water-coupled ultrasonic non-destructive testing of valve seal welds in view of the problems of poor surface acoustic coupling performance and difficult wave incidence of valve seal welds in the prior art.

[0005] The technical solution adopted by the present invention to solve its technical problems is to construct a method for water-coupled ultrasonic non-destructive testing of valve seal welds, including the following steps:

[0006] S1. Set a number of measuring points on the weld circumference;

[0007] S2. Use a special detection probe device to detect each measuring point on the weld circumference. The special detection probe device includes a water-immersion focused probe and a water jacket, and the ultrasonic detection beam is incident into the weld through the coupling water jet by the water spraying coupling method;

[0008] S3. Adjust the position and direction of the water-immersion focused probe of the special detection probe device so that the central axis of the water-immersion focused probe is perpendicular to the weld reinforcement surface;

[0009] S4. Extract the detection signals of each measuring point, and measure the weld thickness and internal defects at the measuring point according to the detection signals of each measuring point.

[0010] Preferably, step S1 specifically includes arranging measuring points at intervals of 60° along the circumference of the weld.

[0011] Preferably, before step S2, it further includes discharging the air in the water jacket. After the water jacket is filled with coupling water, gradually reduce the water pressure while keeping the water flow continuous and stable.

[0012] Preferably, step S3 specifically includes:

[0013] S31. Adjust the position and direction of the immersion focusing probe, and observe the waveform amplitude of the detection signal;

[0014] S32. Make the reflected echo from the weld reinforcement surface reach the peak value by fine adjustment, and make the central axis of the immersion focusing probe perpendicular to the weld reinforcement surface.

[0015] Preferably, after step S3, it further includes: adjusting the gain of the test instrument to make the reflected echo from the weld reinforcement surface reach a set value, adding a compensation value on the basis of the set value for detection sensitivity, and recording the detection signal.

[0016] Preferably, the characteristic pulses of the detection signals of each measuring point include the probe-end reflected echo F 1 , the water reflected echo F 2 , the slit-end reflected echo F of the weld 3 , and the weld bottom reflected echo F 4 .

[0017] Preferably, measuring the weld thickness and internal defects at the measuring point according to the detection signals of each measuring point includes: according to the slit-end reflected echo F of the weld 3 , obtaining the weld thickness where c is the longitudinal wave sound velocity in the weld, t 3 is the peak time of the slit-end reflected echo F 3 , t 2 is the peak time of the water reflected echo F 2 .

[0018] Preferably, to ensure that the weld thickness meets the requirements, determine the final evaluation value T of the weld thickness 评定 = T - 0.06.

[0019] Preferably, the longitudinal wave sound velocity c in the weld is corrected by comparing with the measurement result of the metallographic method.

[0020] The present invention also constructs a water-coupled ultrasonic non-destructive testing system for valve sealing welds, including:

[0021] A detection unit for detecting each measuring point on the circumference of the weld seam;

[0022] A control unit for adjusting the position and direction of the immersion focusing probe of the special detection probe device so that the central axis of the immersion focusing probe is perpendicular to the weld reinforcement surface;

[0023] A calculation unit for extracting the detection signals of each measuring point and measuring the weld thickness and internal defects at the measuring points according to the detection signals of each measuring point.

[0024] Implementing the present invention has the following beneficial effects: The present invention utilizes a special detection probe device, and through the water spray coupling method, the ultrasonic focused sound beam is efficiently transmitted into the circumferential weld seam along the coupling water jet. By analyzing the mutual relationship between the pulse characteristics of the detection signal and the weld structure, the weld thickness and internal defects are determined, improving the detection sensitivity and detection accuracy. Description of the Drawings

[0025] The present invention will be further described below in conjunction with the drawings and embodiments. In the drawings:

[0026] Figure 1 is a schematic diagram of the water-coupled ultrasonic non-destructive testing method for the valve seal weld of the present invention;

[0027] Figure 2 is a schematic diagram of the measuring point selection of the water-coupled ultrasonic non-destructive testing method for the valve seal weld of the present invention;

[0028] Figure 3 is a schematic diagram of the structure of the special detection probe device of the present invention;

[0029] Figure 4 is a detection schematic diagram of the water-coupled ultrasonic non-destructive testing method for the valve seal weld of the present invention;

[0030] Figure 5 is a schematic diagram of the installation position of the special detection probe device of the present invention;

[0031] Figure 6 is a detection principle diagram of the water-coupled ultrasonic non-destructive testing method for the valve seal weld of the present invention;

[0032] Figure 7 is a detection signal characteristic diagram of the 3rd measuring point of the water-coupled ultrasonic non-destructive testing method for the valve seal weld of the present invention;

[0033] Figure 8 is a detection signal characteristic diagram of the 4th measuring point of the water-coupled ultrasonic non-destructive testing method for the valve seal weld of the present invention;

[0034] Figure 9 is a weld metal phase diagram of the 3rd measuring point for comparison with the present invention;

[0035] Figure 10 It is the weld metal phase diagram of the 4th measuring point for comparison with the present invention;

[0036] Figure 11 It is the comparison diagram of the measurement results of the water-coupled ultrasonic non-destructive testing method and the metallographic method for the valve seal weld of the present invention;

[0037] Figure 12 It is the schematic diagram of the water-coupled ultrasonic non-destructive testing system for the valve seal weld of the present invention. Specific embodiments

[0038] In order to have a clearer understanding of the technical features, objectives and effects of the present invention, the specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings. In the following description, it should be understood that the orientation or positional relationships indicated by "front", "rear", "upper", "lower", "left", "right", "longitudinal", "transverse", "vertical", "horizontal", "top", "bottom", "inner", "outer", "head", "tail", etc. are based on the orientation or positional relationships shown in the drawings, and are in a specific orientation structure and operation, only for the convenience of describing the present technical solution, rather than indicating that the indicated device or element must have a specific orientation, so it cannot be understood as a limitation to the present invention.

[0039] It should also be noted that, unless otherwise clearly defined and limited, terms such as "installation", "connection", "connection", "fixation", "setting" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two elements or the interaction relationship between two elements. When an element is referred to as being "on" or "under" another element, the element can be "directly" or "indirectly" located above the other element, or there may also be one or more intermediate elements. Terms such as "first", "second", "third", etc. are only for the convenience of describing the present technical solution, and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, features defined with "first", "second", "third", etc. can explicitly or implicitly include one or more of such features. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0040] In the following description, specific details such as specific system structures and technologies are presented for the purpose of illustration rather than limitation, in order to thoroughly understand the embodiments of the present invention. However, those skilled in the art should clearly understand that the present invention can also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid unnecessary details from hindering the description of the present invention.

[0041] As Figure 1 shown, the present invention discloses a method for ultrasonic non-destructive testing of the water coupling of valve sealing welds, which includes the following steps:

[0042] S1. Set a number of measuring points on the circumference of the weld; specifically, the measuring points are selected as Figure 2 shown, and one measuring point is set every 60° along the circumference of the weld.

[0043] S2. Use a special detection probe device to detect each measuring point on the circumference of the weld. As Figure 3 shown, the special detection probe device 1 includes a water immersion focusing probe 11 and a water jacket 12; the special detection probe device injects the ultrasonic detection beam into the weld through the coupling water jet by means of water spraying coupling, effectively improving the detection sensitivity and detection accuracy. The ultrasonic detection beam is coupled and incident into the circumferential weld through the water spraying jet, having good and stable acoustic coupling characteristics. Using a focusing probe to emit a focused beam can further improve the sound field ability, jointly realizing high-sensitivity and high-precision measurement of the weld thickness and internal defects.

[0044] As Figure 4 shown, specifically, the special detection probe device 1 is connected to the main body of the test instrument 100 through a radio frequency signal line and is fixed on the handwheel connecting rod of the valve 200 through a connecting mechanism 2, and the direction of the special detection probe device can be adjusted through the connecting mechanism. Water is transported to the water jacket 12 through a water pump and sprayed from the water spraying end onto the surface of the weld; the ultrasonic probe 11 in the water jacket 12 emits ultrasonic waves and is incident into the weld through the coupling water. Here, the ultrasonic probe can be a water immersion focusing probe; the coupling water collector 3 is suspended on the pipeline, and the coupling water flows from the front end of the probe 11 along the valve 200 into the coupling water collector 3 and is pumped back into the water tank 4 through a water pump to realize water circulation.

[0045] Further, before step S2, it also includes discharging the air in the water jacket. Connect a water pump and the water jacket through a hose, turn on the water pump and adjust the water pressure to the maximum to discharge the air in the water jacket 12. After the water jacket 12 is filled with coupling water, gradually reduce the water pressure and maintain the continuity and stability of the water flow; discharge the air in the water jacket 12; after the water jacket 12 is filled with coupling water, gradually reduce the water pressure to the minimum, and at the same time, it is necessary to maintain the continuity and stability of the water flow.

[0046] S3. Adjust the position and direction of the water immersion focusing probe of the special detection probe device so that the central axis of the water immersion focusing probe is perpendicular to the weld reinforcement surface;

[0047] As Figure 5 shown, further, step S3 specifically includes:

[0048] S31. Adjust the position and direction of the water immersion focusing probe and observe the amplitude of the detection signal waveform;

[0049] S32. Through fine adjustment, make the reflected echo of the weld reinforcement surface reach the peak value, so that the central axis of the water immersion focusing probe is perpendicular to the weld reinforcement surface.

[0050] After step S3, it also includes: adjusting the gain of the test instrument to make the reflected echo of the weld reinforcement surface reach the set value, that is, 80% of the full screen, and adding a compensation value of 12 dB on the basis of the set value for detection sensitivity, and recording the detection signal.

[0051] S4. Extract the detection signals of each measurement point, and measure the weld thickness and internal defects at the measurement points according to the detection signals of each measurement point. Analyze the mutual relationship between the pulse characteristics of the detection signal and the weld structure, and accurately measure the weld thickness and internal defects by accurately positioning the peak time position of the pulse in the detection signal;

[0052] Specifically, as Figure 6 shown, the characteristic pulses of the detection signals of each measurement point include the probe-end reflected echo F 1 , the water reflected echo F 2 , the slit-end reflected echo F 3 of the weld, and the weld bottom reflected echo F 4 . Correspondingly, the pulse arrival time of the probe-end reflected echo F 1 is set as t 1 , the pulse arrival time of the water reflected echo F 2 is set as t 2 , the pulse arrival time of the slit-end reflected echo F 3 of the weld is set as t 3 , and the pulse arrival time of the weld bottom reflected echo F 4 is set as t 4 , and the pulse arrival time is the peak time of the pulse wave.

[0053] Further, measuring the weld thickness and internal defects at the measurement points according to the detection signals of each measurement point specifically includes: according to the slit-end reflected echo F 3 of the weld, obtaining the weld thickness

[0054]

[0055] where c is the longitudinal wave sound velocity in the weld, and t 3 is the reflected echo F at the slit end3 Peak time, t 2 is the peak time of the water reflected echo F 2 .

[0056] Furthermore, according to the detection test analysis, 0.06 mm is the average error between the measured value and the metallographic value (actual value) measured by the metallographic method. Therefore, to ensure that the weld thickness meets the requirements, the final evaluation value of the weld thickness

[0057] T 评定 = T - 0.06 (2);

[0058] According to Equation (2), the evaluated value of the weld thickness T 评定 is shown in Table 1

[0059] Table 1 Measured value T and evaluated value T of weld thickness 评定 (mm)

[0060]

[0061]

[0062] Furthermore, by comparing with the measurement results of the metallographic method, the longitudinal wave sound velocity c in the weld is corrected to reduce the detection error and ensure the reliability of the evaluated values of the weld thickness and internal defects. After correction, the longitudinal wave sound velocity c in the weld is 5120 m / s

[0063] As Figures 7-8 shown, for the thickness measurement result using the method of the present invention, the t 3 - t 2 calculated for the 3rd measurement point is 0.7 μs, and the t 3 - t 2 calculated for the 4th measurement point is 0.77 μs. The average sound velocity c measured in the test is 5120 m / s. According to Equation (1), the weld thickness T at the 3rd measurement point is 1.79 mm, and the weld thickness T at the 4th measurement point is 1.97 mm. Similarly, the weld thicknesses of other measurement points can also be measured using the same method

[0064] Using the existing technology, the circumferential weld is cut, and the weld thickness and internal defects of each measurement point are measured by the metallographic method to verify the thickness measurement result of ultrasonic non-destructive testing. The cross-sectional metallographic diagrams of the 3rd and 4th welds are as Figures 9-10 shown, and the metallographic measurement results of the 3rd and 4th welds are 1.79 mm and 1.91 mm respectively

[0065] As Figure 11As shown in the figure, by comparing the ultrasonic measurement values and metallographic measurement values of each measuring point of the weld, it can be seen that the ultrasonic thickness measurement values and metallographic measurement values have good consistency, with a maximum error of 0.11 and an average error of 0.06 mm. The special probe and detection method for water-coupled ultrasonic non-destructive thickness measurement of valve sealing welds proposed can measure the thickness and internal defects of valve sealing welds well, meeting the detection requirements for the thickness and internal defects of nuclear power valve sealing welds.

[0066] Completely, a set of water-coupled ultrasonic non-destructive detection system for valve sealing welds can also be formed by integrating software and hardware. The system is applied and demonstrated in a pilot power plant, tested through on-site joint debugging in a nuclear power plant, and gradually optimized and improved according to the feedback results to form a set of system solutions.

[0067] Therefore, as Figure 12 shown in the figure, the present invention also discloses a water-coupled ultrasonic non-destructive detection system for valve sealing welds, including:

[0068] A detection unit for detecting each measuring point on the circumference of the weld;

[0069] A control unit for adjusting the position and direction of the water immersion focusing probe of the special detection probe device so that the central axis of the water immersion focusing probe is perpendicular to the weld reinforcement surface; the position and direction of the water immersion focusing probe can be adjusted according to the control signal of the control unit. The control unit can record the parameters of the position and direction of the water immersion focusing probe and make fine adjustments according to the parameter data to facilitate accurate alignment of the probe position; and

[0070] A calculation unit for extracting the detection signals of each measuring point and measuring the weld thickness and internal defects at the measuring point according to the detection signals of each measuring point. The calculation unit can pre-enter the calculation formula and calculate according to the data detected by the detection unit; or the calculation unit can directly calculate and process the data detected by the detection unit and adjust the calculation method at the same time to improve the accuracy.

[0071] Implementing the present invention has the following beneficial effects:

[0072] The present invention uses a special detection probe device to realize the detection of valve annular sealing welds; through the water spray coupling method, the ultrasonic focused sound beam is efficiently transmitted into the internal of the circumferential weld along the coupling water jet, greatly improving the detection sensitivity and detection accuracy; deeply analyzing the mutual relationship between the pulse characteristics of the detection signal and the weld structure, accurately measuring the weld thickness and internal defects by accurately positioning the peak time position of the pulse in the detection signal; correcting the measured value by correcting the sound speed and analyzing the measurement error, and the maximum measurement error is less than or equal to 0.06 mm, ensuring the reliability of the evaluation values of the weld thickness and internal defects.

[0073] It can be understood that the above embodiments only represent the preferred embodiments of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent for the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, the above technical features can be freely combined, and several deformations and improvements can also be made, which all fall within the protection scope of the present invention. Therefore, all equivalent transformations and modifications made in accordance with the scope of the claims of the present invention shall fall within the scope covered by the claims of the present invention.

Claims

1. A method for ultrasonic non-destructive testing of valve seal welds by water coupling, characterized in that, it includes the following steps: S1. Set a number of measuring points on the circumference of the weld; S2. Use a special detection probe device to detect each measuring point on the circumference of the weld. The special detection probe device includes a water immersion focusing probe and a water jacket. The ultrasonic detection beam is incident into the weld through the coupling water jet by the water spraying coupling method; S3. Adjust the position and direction of the water immersion focusing probe of the special detection probe device so that the central axis of the water immersion focusing probe is perpendicular to the weld reinforcement surface; S4. Extract the detection signals of each measuring point, and measure the weld thickness and internal defects at the measuring points according to the detection signals of each measuring point; Among them, measuring the weld thickness and internal defects at the measuring points according to the detection signals of the respective measuring points includes: according to the echo reflected from the slit end of the weld , obtaining the weld thickness T = ; where c is the longitudinal wave sound velocity in the weld, is the peak time of the echo reflected from the slit end , is the peak time of the echo reflected from the water ; to ensure that the weld thickness and internal defects meet the requirements, determining the final evaluation value = T - 0.

06.

2. The method for ultrasonic non-destructive testing of valve seal welds by water coupling according to claim 1, characterized in that, the step S1 specifically includes setting measuring points every 60° along the circumference of the weld.

3. The method for ultrasonic non-destructive testing of valve seal welds by water coupling according to claim 1, characterized in that, before the step S2, it also includes discharging the air in the water jacket. After the water jacket is filled with coupling water, gradually reduce the water pressure, and at the same time, it is necessary to keep the water flow continuous and stable.

4. The method for ultrasonic non-destructive testing of valve seal welds by water coupling according to claim 1, characterized in that, the step S3 specifically includes: S31. Adjust the position and direction of the water immersion focusing probe, and observe the amplitude of the detection signal waveform; S32. Through fine adjustment, make the reflected echo of the weld reinforcement surface reach the peak value, so that the central axis of the water immersion focusing probe is perpendicular to the weld reinforcement surface.

5. The method for ultrasonic non-destructive testing of valve seal welds by water coupling according to claim 1, characterized in that, after the step S3, it also includes: adjusting the gain of the test instrument to make the reflected echo of the weld reinforcement surface reach a set value, and adding a compensation value on the basis of the set value for detection sensitivity, and recording the detection signal.

6. The method for ultrasonic non-destructive testing of valve seal welds by water coupling according to claim 1, characterized in that, the characteristic pulses of the detection signals of each measuring point include the probe end reflected echo F1, the water reflected echo F2, the slit end reflected echo F3 of the weld, and the weld bottom reflected echo F4.

7. The method for ultrasonic non-destructive testing of valve seal welds by water coupling according to claim 1, characterized in that, by comparing with the measurement results of the metallographic method, the longitudinal wave sound velocity c in the weld is corrected.

8. An ultrasonic non-destructive testing system for valve seal welds by water coupling, characterized in that, it includes: a detection unit for detecting each measuring point on the circumference of the weld; a control unit for adjusting the position and direction of the water immersion focusing probe of the special detection probe device so that the central axis of the water immersion focusing probe is perpendicular to the weld reinforcement surface; Computing unit, which extracts the detection signals of each measuring point and measures the weld thickness and internal defects at the measuring point according to the detection signals of each measuring point; wherein, the measuring of the weld thickness and internal defects at the measuring point according to the detection signals of each measuring point includes: according to the echo reflected from the slit end of the weld , the weld thickness T = ; wherein, c is the longitudinal wave sound velocity in the weld, is the peak time of the echo reflected from the slit end , is the peak time of the echo reflected from the water ; to ensure that the weld thickness and internal defects meet the requirements, the final evaluation value of the weld thickness is determined as = T - 0.06.

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