A butterfly check valve sealing detection device and method for an important nuclear power plant water system

Abstract

The present invention relates to the field of mechanical maintenance technology, and specifically discloses a sealing detection device and method for butterfly check valves in an important plant water system of a nuclear power plant, wherein the butterfly check valve is placed at the center of the upper circular ring of a sealing detection stand, a combined pressure plate is placed above the contact surface of the nuclear-grade butterfly check valve, and the combined pressure plate and the sealing detection stand are assembled and fastened to ensure that the combined pressure plate and the nuclear-grade butterfly check valve fit tightly; a pressure test pump pressure pipe is connected to a pressure test pipe seat, and the butterfly check valve is filled with a test medium and exhaust is exhausted through a water injection and exhaust pipe. The present invention can inspect and identify the assembly quality and sealing performance of nuclear-grade butterfly check valves in important plant water systems of nuclear power plants in advance, verify the maintenance quality, and avoid repeated valve maintenance that affects the safe operation of nuclear power plant units.

Description

Technical Field

[0001] The present invention belongs to the technical field of mechanical maintenance, and in particular relates to a sealing detection device and method for butterfly check valves in an important plant water system of a nuclear power plant. Background Art

[0002] In the M310 nuclear power unit, each unit in the nuclear tertiary critical service water system has four critical service water pumps. Each critical service water pump is isolated by a nuclear-grade manual butterfly valve at the inlet and outlet. Two critical service water pumps form a train of critical service water system supply pipelines, and each unit has two trains of nuclear safety-related circuits. Each pump outlet within a train is equipped with a nuclear tertiary butterfly check valve to prevent backflow of media and reverse rotation of the pump when another critical service water pump in the train is operating.

[0003] In accordance with scheduled equipment maintenance requirements, nuclear power plant units regularly undergo comprehensive disassembly and inspection of their pump outlet nuclear-grade butterfly check valves during routine operation to replace internal wearing parts and verify component quality. Traditionally, large-diameter butterfly check valves undergo a light-through inspection after disassembly and reassembly to verify the sealing of the butterfly plate. This inspection method differs from the actual operating state of the valve. When the valve is actually installed in the system piping, internal leakage may still occur. This necessitates draining the critical plant water system for isolation and inspection, which involves lifting operations and shielding the fire protection system. Because a second I0 (I0) occurs during the maintenance of nuclear-grade butterfly check valves, further valve inspection threatens the safe operation of the unit's critical cooling source in the nuclear island. If the valve cannot be repaired within the I0 deadline, the unit will need to transition from stable operation to shutdown mode, severely impacting the power generation and economic benefits of the nuclear power plant. If such valves in nuclear power plants of the same industry need to undergo sealing tests, they need to entrust equipment manufacturers with nuclear-grade equipment manufacturing qualifications to use large-scale special testing equipment to conduct the test. The valves need to be transported back and forth, which is time-consuming and costly.

[0004] In order to inspect and identify the assembly quality and sealing performance of nuclear-grade check valves in important plant water systems of nuclear power plants in advance, it is urgent to design a nuclear-grade check valve sealing detection device and method for important plant water systems of nuclear power plants to verify the maintenance quality and avoid repeated valve maintenance that affects the safe operation of nuclear power plant units. Summary of the Invention

[0005] The purpose of the present invention is to provide a butterfly check valve sealing detection device and method for an important plant water system of a nuclear power plant, which can inspect and identify the assembly quality and sealing performance of nuclear-grade butterfly check valves in advance.

[0006] The technical solutions of the present invention are as follows:

[0007] A butterfly check valve sealing detection device for an important plant water system of a nuclear power plant, comprising a sealing detection stand, a combined pressure plate, studs, nuts, gaskets, a water injection exhaust pipe, an exhaust ball valve, a pressure test pipe seat, and a pressure test pump;

[0008] The sealing test stand is a two-layer circular ring connection structure, wherein the upper circular ring structure is a flat flange used to horizontally support the entire butterfly check valve, and the lower circular ring serves as a base;

[0009] The upper and lower rings of the sealing test stand are supported and connected by round steel bars, and visual leakage inspection is performed through the gaps between the round steel bars during the sealing inspection of the butterfly check valve;

[0010] Opening bolt holes on the upper circular ring of the sealing detection stand;

[0011] The combined pressure plate is a flange plate, the inner surface of which is the sealing surface of the clamping butterfly check valve;

[0012] A pressure pipe seat and a water injection and exhaust pipe are welded on the combined pressure plate, and an exhaust ball valve is connected in series in the middle of the water injection and exhaust pipe;

[0013] The upper interface of the pressure-testing pipe seat is connected to the interface of the pressure test pump;

[0014] Bolt holes are arranged around the outer side of the combined pressure plate to ensure that the combined pressure plate and the sealing detection bracket are connected and fastened through studs, nuts and gaskets.

[0015] The outer diameter of the upper circular ring of the sealing detection stand is larger than the outer diameter of the butterfly check valve, and the inner diameter of the upper circular ring is smaller than the inner diameter of the butterfly check valve.

[0016] A sealing gasket is provided between the inner surface of the combined pressure plate and the contact surface of the butterfly check valve for sealing the medium during the test.

[0017] The sealing gasket is made of tetrafluoroethylene.

[0018] A pressing pipe seat is welded at the center of the combined pressing plate, and a water injection exhaust pipe is welded at the center point of the single-side radius of the combined pressing plate.

[0019] The water injection exhaust pipe and the pressure pipe seat are both short stainless steel cylindrical pipes.

[0020] The upper interface of the pressure pipe seat is a threaded interface.

[0021] A method for detecting the sealing of butterfly check valves in an important plant water system of a nuclear power plant based on the detection device includes the following steps:

[0022] Step 1: Check whether the parts of the detection device are damaged;

[0023] Step 2: Place the nuclear-grade butterfly check valve to be tested in the center of the upper ring of the seal test stand;

[0024] Step 3: Install the sealing gasket on the contact surface of the nuclear-grade butterfly check valve, place the combined pressure plate on the contact surface of the nuclear-grade butterfly check valve, and ensure that the bolt holes of the combined pressure plate are aligned with the bolt holes of the sealing test bench;

[0025] Step 4: Assemble and tighten the combined pressure plate and the sealing test bench with studs, nuts, and gaskets to ensure that the combined pressure plate fits tightly with the nuclear-grade butterfly check valve;

[0026] Step 5: Check that the zero position of the pressure gauge of the pressure test pump is normal, and connect the pressure test pump pressure pipe to the pressure test pipe seat;

[0027] Step 6: Open the exhaust ball valve and fill the nuclear-grade butterfly check valve with the test medium through the water injection exhaust pipe;

[0028] Step 7: Slowly operate the pressure test pump to exhaust the air in the nuclear-grade butterfly check valve through the water injection exhaust pipe;

[0029] Step 8: Close the exhaust ball valve, continue to slowly increase the pressure of the pressure test pump, and check to ensure that there is no leakage in the exhaust ball valve and the pressure test pipe seat;

[0030] Step 9: Slowly increase the pressure of the pressure test pump until the pressure test pressure reaches the sealing test pressure value, maintain the pressure and observe whether the pressure display number decreases;

[0031] If there is a decrease, it means there is a problem with the sealing. It is necessary to re-check the valve sealing surface or disassemble the valve for inspection, repair the defect or replace the new valve and then start step 1 again; if the pressure display number does not change, it means the sealing is good;

[0032] Step 10: Continue to increase the pressure of the pressure test pump until the pressure test pressure reaches the high-pressure seal test pressure value, maintain the pressure and observe whether the pressure display number decreases;

[0033] If the pressure indication number does not change, it means that the sealing is good and the test is qualified; if the pressure indication number drops significantly, check the leakage area of ​​the tested nuclear-grade butterfly check valve through the gap between the round steel of the sealing test bench and mark it;

[0034] Step 11: Drain the test medium inside the nuclear-grade butterfly check valve;

[0035] Step 12: Remove the test device in the reverse order of assembly, repair the leaking valve and repeat the sealing test steps.

[0036] In step 1, check the exhaust ball valve, water injection exhaust pipe, and pressure pipe seat on the combined pressure plate to ensure there are no cracks or leaks. Check the smoothness of the flange sealing surface of the combined pressure plate to ensure that the flange surface is not damaged and no debris remains.

[0037] In step 8, if the exhaust ball valve is leaking, it is repaired or replaced. If there is leakage between the exhaust ball valve and the pressure pipe seat, the thread seal at the connection is resealed.

[0038] The remarkable effects of the present invention are:

[0039] (1) The present invention can inspect and identify the assembly quality and sealing performance of nuclear-grade butterfly check valves in important plant water systems of nuclear power plants in advance, verify the maintenance quality, and avoid repeated valve maintenance that affects the safe operation of nuclear power plant units.

[0040] (2) The present invention was tested and applied in the sealing performance inspection of nuclear-grade butterfly check valves in the important plant water systems of multiple M310 units, and the results were good. After application, it was ensured that no leakage of the butterfly valve sealing surface would occur during normal operation after the valve sealing inspection. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a partial cross-sectional diagram of the nuclear-grade butterfly check valve sealing detection device for important plant water systems.

[0042] In the figure: 1. Sealing test bench; 2. Combined pressure plate; 3. Stud; 4. Nut; 5. Gasket; 6. Exhaust ball valve; 7. Water injection exhaust pipe; 8. Pressure pipe seat. DETAILED DESCRIPTION

[0043] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0044] like Figure 1 The device for detecting the sealing of butterfly check valves in an important plant water system of a nuclear power plant shown in the figure includes a sealing detection stand 1, a combined pressure plate 2, a sealing gasket, a stud 3, a nut 4, a gasket 5, a water injection exhaust pipe 7, an exhaust ball valve 6, a pressure pipe seat 8, and a pressure test pump.

[0045] The seal test stand 1 comprises a two-tiered, circular ring structure. The upper ring is a flat flange that horizontally supports the entire butterfly check valve, while the lower ring serves as a base. The upper and lower rings of the seal test stand 1 are supported and connected by 12 evenly spaced round steel bars. During butterfly check valve seal testing, visual leak detection can be performed through the gaps between the steel bars.

[0046] The outer diameter of the upper circular ring of the sealing detection stand 1 is larger than the outer diameter of the butterfly check valve, and the inner diameter is smaller than the inner diameter of the butterfly check valve.

[0047] 28 bolt holes are evenly arranged on the upper circular ring of the sealing detection stand 1 .

[0048] The combined pressure plate 2 is a stainless steel flange plate, the inner surface of which is the sealing surface for clamping the butterfly check valve. A sealing gasket is provided between the inner surface of the combined pressure plate 2 and the contact surface of the butterfly check valve for sealing the medium during the test.

[0049] The sealing gasket is made of tetrafluoroethylene.

[0050] A pressure pipe seat 8 is welded at the center of the combined pressure plate 2 , a water injection and exhaust pipe 7 is welded at the center point of the single-side radius of the combined pressure plate 2 , and an exhaust ball valve 6 is connected in series in the middle of the water injection and exhaust pipe 7 .

[0051] The pressure-testing pipe seat 8 is a short stainless steel cylindrical tube, and the top of the pressure-testing pipe seat 8 is a threaded interface, which is connected to the interface of the pressure test pump.

[0052] The water injection and exhaust pipe 7 is a short stainless steel cylindrical pipe.

[0053] The exhaust ball valve 6 is opened before the test for injection of sealing medium and is closed for sealing during the test.

[0054] A circle of 28 bolt holes is evenly opened on the outer side of the combined pressure plate 2 to ensure that the combined pressure plate 2 can be connected and fastened to the sealing detection bracket 1 through studs 3, nuts 4 and gaskets 5.

[0055] The combined pressing plate 2 is a 304 stainless steel plate, and its thickness meets the mechanical strength load requirements during the sealing test.

[0056] The studs 3, nuts 4 and gaskets 5, of which there are 328 studs, 56 nuts 4 and 56 gaskets 5, are used to connect the combined pressure plate 2 and the sealing test bench 1 during the sealing test of the butterfly check valve, ensuring that the combined pressure plate 2 fits tightly with the sealing surface of the butterfly check valve without leakage, and is assembled as a whole with the sealing test bench 1 to form a sealing test device.

[0057] A method for detecting the sealing of butterfly check valves in an important plant water system of a nuclear power plant comprises the following steps:

[0058] Step 1: Check the exhaust ball valve 6, water injection exhaust pipe 7, and pressure pipe seat 8 on the combined pressure plate 2 for cracks and leaks. Check the smoothness of the flange sealing surface of the combined pressure plate 2 to ensure that the flange surface is not damaged and no debris remains.

[0059] Step 2: Place the nuclear-grade butterfly check valve to be tested at the center of the upper ring of the sealing test bench 1.

[0060] Step 3: Install the sealing gasket on the contact surface of the nuclear-grade butterfly check valve, and gently place the combined pressure plate 2 on the contact surface of the nuclear-grade butterfly check valve, ensuring that the flange bolt holes of the combined pressure plate 2 are aligned with the flange bolt holes of the sealing test bench 1.

[0061] Step 4: Assemble and tighten the combined pressure plate 2 and the sealing test bench 1 through the matching studs 3, nuts 4, and gaskets 5 to ensure that the combined pressure plate 2 fits tightly with the nuclear-grade butterfly check valve;

[0062] Step 5: Check that the zero position of the pressure gauge of the pressure test pump is normal, and connect the pressure test pump pressure pipe to the pressure test pipe seat 8;

[0063] Step 6: Open the exhaust ball valve 6 and fill the nuclear-grade butterfly check valve with the test medium through the water injection exhaust pipe 7;

[0064] Step 7: Slowly operate the pressure test pump to exhaust the air in the nuclear-grade butterfly check valve through the water injection exhaust pipe 7;

[0065] Step 8: Close the exhaust ball valve 6, continue to slowly increase the pressure of the pressure test pump, and check whether the exhaust ball valve 6 and the pressure test pipe seat 8 are leaking;

[0066] If the exhaust ball valve 6 leaks, repair or replace it. If there is leakage between the exhaust ball valve 6 and the pressure pipe seat 8, reseal the thread seal at the connection.

[0067] Step 9: Slowly increase the pressure of the pressure test pump until the pressure test reaches the sealing test pressure value of 0.3Mpa, maintain the pressure for 15 minutes, and observe whether the pressure display number decreases;

[0068] If there is a decrease, it means there is a problem with the sealing. It is necessary to re-check the valve sealing surface or disassemble the valve for inspection, repair the defect or replace the new valve and then start step 1 again; if the pressure display number does not change, it means the sealing is good;

[0069] Step 10: Continue to increase the pressure of the pressure test pump until the test pressure reaches the high-pressure seal test pressure value of 2.2Mpa, maintain the pressure for 15 minutes, and observe whether the pressure display number decreases;

[0070] If the pressure indication number does not change, it means that the sealing is good and the test is qualified; if the pressure indication number drops significantly, check the leakage area of ​​the tested nuclear-grade butterfly check valve through the gap between the round steels of the sealing test bench 1 and mark it;

[0071] Step 11: Drain the test medium inside the nuclear-grade butterfly check valve;

[0072] Step 12: Remove the test device in the reverse order of assembly, repair the leaking valve and repeat the sealing test steps.

Claims

1. A butterfly check valve sealing detection device for an important nuclear power plant water system, characterized by: It comprises a sealing test stand (1), a combined pressure plate (2), a stud (3), a nut (4), a gasket (5), a water injection exhaust pipe (7), an exhaust ball valve (6), a pressure pipe seat (8), and a pressure test pump; The sealing test stand (1) is a two-layer circular ring connection structure, wherein the upper circular ring structure is a flat flange for horizontally supporting the entire butterfly check valve, and the lower circular ring serves as a base; The upper and lower circular rings of the sealing test stand (1) are supported and connected by round steel bars, and visual leakage inspection is performed through the gaps between the round steel bars during the sealing inspection of the butterfly check valve; Bolt holes are provided on the upper circular ring of the sealing detection stand (1); The combined pressure plate (2) is a flange plate, the inner surface of which is a sealing surface for clamping the butterfly check valve; A pressure pipe seat (8) is welded at the center of the combined pressure plate (2), a water injection and exhaust pipe (7) is welded at the center point of a single radius of the combined pressure plate (2), and an exhaust ball valve (6) is connected in series in the middle of the water injection and exhaust pipe (7); The upper interface of the pressure-testing pipe seat (8) is connected to the interface of the pressure test pump; Bolt holes are provided around the outer side of the combined pressure plate (2) to ensure that the combined pressure plate (2) and the sealing test stand (1) are connected and fastened via studs (3), nuts (4) and gaskets (5); The outer diameter of the upper circular ring of the sealing detection stand (1) is larger than the outer diameter of the butterfly check valve, and the inner diameter of the upper circular ring is smaller than the inner diameter of the butterfly check valve.

2. A butterfly check valve sealing detection device for an important nuclear power plant water system according to claim 1, characterized in that: A sealing gasket is provided between the inner surface of the combined pressure plate (2) and the contact surface of the butterfly check valve, for sealing the medium during the test.

3. A butterfly check valve sealing detection device for an important nuclear power plant water system according to claim 2, characterized in that: The sealing gasket is made of tetrafluoroethylene.

4. A butterfly check valve sealing detection device for an important nuclear power plant water system according to claim 1, characterized in that: The water injection and exhaust pipe (7) and the pressure pipe seat (8) are both short stainless steel cylindrical pipes.

5. The butterfly check valve sealing detection device for an important nuclear power plant water system according to claim 1, characterized in that: The upper interface of the pressure pipe seat (8) is a threaded interface.

6. A method for detecting the sealing of butterfly check valves in important plant water systems of nuclear power plants based on the detection device of claim 1, characterized in that: The following steps are involved: Step 1: Check whether the parts of the detection device are damaged; Step 2: Place the nuclear-grade butterfly check valve to be tested at the center of the upper ring of the sealing test stand (1); Step 3: Install the sealing gasket on the contact surface of the nuclear-grade butterfly check valve, place the combined pressure plate (2) above the contact surface of the nuclear-grade butterfly check valve, and ensure that the bolt holes of the combined pressure plate (2) are aligned with the bolt holes of the sealing test bench (1); Step 4: Assemble and tighten the combined pressure plate (2) and the sealing test bench (1) through the studs (3), nuts (4) and gaskets (5) to ensure that the combined pressure plate (2) and the nuclear-grade butterfly check valve fit tightly; Step 5: Check that the zero position of the pressure gauge of the pressure test pump is normal, and connect the pressure test pump pressure pipe to the pressure test pipe seat (8); Step 6: Open the exhaust ball valve (6) and fill the nuclear-grade butterfly check valve with the test medium through the water injection exhaust pipe (7); Step 7: Slowly operate the pressure test pump to exhaust the air in the nuclear-grade butterfly check valve through the water injection exhaust pipe (7); Step 8: Close the exhaust ball valve (6), continue to slowly increase the pressure of the pressure test pump, and check to ensure that there is no leakage in the exhaust ball valve (6) and the pressure test pipe seat (8); Step 9: Slowly increase the pressure of the pressure test pump until the pressure test pressure reaches the sealing test pressure value, maintain the pressure and observe whether the pressure display number decreases; If there is a decrease, it means there is a problem with the sealing. It is necessary to re-check the valve sealing surface or disassemble the valve for inspection, repair the defect or replace the new valve and then start step 1 again; if the pressure display number does not change, it means the sealing is good; Step 10: Continue to increase the pressure of the pressure test pump until the pressure test pressure reaches the high-pressure seal test pressure value, maintain the pressure and observe whether the pressure indication number decreases; If the pressure indication number does not change, it means that the sealing is good and the test is qualified; if the pressure indication number drops significantly, the leakage area of ​​the tested nuclear-grade butterfly check valve is checked through the gap between the round steels of the sealing test bench (1) and marked; Step 11: Drain the test medium inside the nuclear-grade butterfly check valve; Step 12: Remove the test device in the reverse order of assembly, repair the leaking valve and repeat the seal test steps.

7. A method for detecting the sealing of butterfly check valves in an important nuclear power plant water system according to claim 6, characterized in that: In step 1, check that the exhaust ball valve (6), water injection exhaust pipe (7), and pressure pipe seat (8) on the combined pressure plate (2) have no cracks or leaks, and check the smoothness of the flange sealing surface of the combined pressure plate (2) to ensure that the flange surface is not damaged and no debris remains.

8. A method for detecting the sealing of butterfly check valves in an important nuclear power plant water system according to claim 6, characterized in that: In step 8, if the exhaust ball valve (6) leaks, it is repaired or replaced. If there is leakage between the exhaust ball valve (6) and the pressure pipe seat (8), the thread seal at the connection is resealed.

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