Pressure testing system and method for pressure vessel

Abstract

The present invention relates to the field of pressure testing technology, and in particular to a pressure testing system and method for pressure vessels. After a test container is tested, the present invention places a subsequent test container to be tested, repeats the above steps, and the gas in the gas storage tank is repeatedly used, the economy of the test is improved, and the use of inert gas as a pressurized medium solves the key problem that the pressure vessel packaging material cannot be tested with water. Therefore, this solution can economically and reasonably use inert gas as a pressurized medium for testing test containers.

Description

Technical Field

[0001] The present invention relates to the technical field of pressure testing, and in particular to a pressure testing system and method for a pressure vessel. Background Art

[0002] Pressure vessels that contain pressurized media need to bear a certain pressure in a confined space. In order to detect the pressure-bearing reliability of pressure vessels, relevant pressure vessels need to be inspected regularly. Generally speaking, water pressure testing is the basis for regular inspections to ultimately determine whether the vessel is usable. Water pressure testing is to use pressurized water as the pressurizing medium for the pressure vessel under test (hereinafter referred to as the test vessel) to simulate actual use.

[0003] In the related art, the test container is usually placed in a closed water tank filled with water, and then the test container is pressurized. The test container is deformed under the pressure, thereby squeezing out part of the water in the water tank, and the safety of the test container is judged by measuring the amount of squeezed water. However, due to the limitations of materials, structures and usage requirements of some test containers, water cannot be used as the pressurizing medium, but inert gas is required as the pressurizing medium. Therefore, how to economically and reasonably use inert gas as the pressurizing medium for the test container inspection is a problem to be solved in the pressure inspection of pressure vessels. Summary of the invention

[0004] The present invention provides a pressure inspection system and method for a pressure vessel, which can economically and reasonably use an inert gas as a pressurized medium for inspecting the test vessel.

[0005] In one embodiment, the present invention provides a pressure inspection system for a pressure vessel, comprising a gas storage tank, a test vessel, and direct gas inlet and outlet pipelines, a pressure boosting pipeline, and a pressure relief pipeline respectively connected to the gas storage tank and the test vessel, wherein the gas storage tank stores inert gas, the test vessel is placed in a sealed water tank, water is stored in the sealed water tank, and a metering water pipe is connected to the upper part of the sealed water tank, and the pressure inspection process of the test vessel includes a pressure charging stage, a pressure boosting stage, a first pressure relief stage, and a second pressure relief stage, wherein:

[0006] During the pressurization stage, the gas storage tank, the direct gas inlet and outlet pipelines and the test container are connected, the booster pipeline and the pressure relief pipeline are closed, and the inert gas in the gas storage tank enters the test container through the direct gas inlet and outlet pipeline until the gas pressures in the gas storage tank and the test container are balanced;

[0007] During the pressure-increasing stage, the gas storage tank, the pressure-increasing pipeline and the test container are connected, and the direct air inlet and outlet pipeline and the pressure-relief pipeline are closed. At this time, the inert gas in the gas storage tank enters the test container after being pressurized by the pressure-increasing pipeline, until the gas pressure in the test container reaches a first preset pressure and is maintained for a preset time. At the same time, the metering water pipe is used to measure the amount of water discharged from the closed water tank due to the expansion and deformation of the test container;

[0008] In the first pressure relief stage, the gas storage tank, the direct gas inlet and outlet pipeline and the test container are connected, the booster pipeline and the pressure relief pipeline are closed, and the inert gas in the test container enters the gas storage tank through the direct gas inlet and outlet pipeline until the gas pressures in the gas storage tank and the test container are balanced;

[0009] During the second pressure relief stage, the gas storage tank, the pressure relief pipeline and the test container are connected, the direct inlet and outlet gas pipelines and the boost pipeline are closed, and the inert gas in the test container enters the gas storage tank after the pressure is relieved through the pressure relief pipeline until the gas pressure in the test container reaches a second preset pressure, and the first preset pressure is greater than the second preset pressure.

[0010] Preferably, the direct air inlet and outlet pipeline is provided with a first switch valve and a throttle valve, and the throttle valve is used to adjust the flow rate of the inert gas passing through the direct air inlet and outlet pipeline.

[0011] Preferably, along the direction in which the inert gas is transported from the gas storage tank to the test container, the boosting pipeline is provided with a second switch valve, a first compressor and a first check valve.

[0012] Preferably, along the direction in which the inert gas is transported from the test container to the gas storage tank, the pressure relief pipeline is provided with a third switch valve, a second compressor and a second one-way valve.

[0013] Preferably, the gas tank is connected to a first pipeline, which is respectively connected to the direct inlet and outlet gas pipelines, the boost pipeline and the pressure relief pipeline, and the first pipeline is provided with a fourth switch valve, a first pressure tester and a fifth switch valve, the fourth switch valve is located at an end of the first pipeline close to the gas tank, the fifth switch valve is located at an end of the first pipeline away from the gas tank, and the first pressure tester is located between the fourth switch valve and the fifth switch valve.

[0014] Preferably, the test container is connected to a second pipeline, which is respectively connected to the direct air inlet and outlet pipelines, the boost pipeline and the pressure relief pipeline. The second pipeline is provided with a second pressure tester and a sixth switch valve. The second pressure tester is located at one end of the second pipeline close to the test container, and the sixth switch valve is located at one end of the second pipeline away from the test container.

[0015] Preferably, the second pipeline is further provided with a safety valve, and the safety valve is located between the second pressure tester and the sixth switch valve.

[0016] Preferably, the first preset pressure ranges from 12 to 20 MPa, and the second preset pressure ranges from 0.1 to 0.2 MPa.

[0017] Preferably, the opening of the throttle valve is determined by the following formula:

[0018]

[0019] In the formula, A is the opening of the throttle valve, ΔP is the pressure difference before and after the throttle valve, α is the sensitivity of the opening to the pressure difference, Q is the flow rate of the inert gas passing through the throttle valve, and n is a preset index related to the flow rate.

[0020] In another embodiment, the present invention provides a pressure inspection method for a pressure vessel, based on the pressure inspection system for a pressure vessel described in the above embodiment, the method comprises:

[0021] S1. Fill the gas storage tank with an inert gas at a pressure of 10 MPa, and place the test container in the closed water tank;

[0022] S2, performing the operation of the pressurization stage: opening the fourth switch valve and the first switch valve, closing the second switch valve, the third switch valve, the fifth switch valve and the sixth switch valve, and pressurizing the inert gas in the gas storage tank into the test container until the pressure value displayed by the second pressure tester is stable;

[0023] S3, performing the operation of the pressure boosting stage: opening the fourth switch valve and the second switch valve, closing the first switch valve, the third switch valve, the fifth switch valve and the sixth switch valve, starting the first compressor, and pressing the inert gas in the gas storage tank into the test container after the pressure is boosted by the first compressor, until the pressure value displayed by the second pressure tester reaches a first preset pressure and the pressure is maintained for a preset time, and at the same time, using the measuring water pipe to measure the amount of water discharged from the closed water tank due to the expansion and deformation of the test container;

[0024] S4, performing the operation of the first pressure relief stage: opening the fourth switch valve and the first switch valve, closing the second switch valve, the third switch valve, the fifth switch valve and the sixth switch valve, and filling the inert gas in the test container into the gas storage tank until the pressure value displayed by the first pressure tester is stable;

[0025] S5. Execute the operation of the second pressure relief stage: open the fourth switch valve and the third switch valve, close the first switch valve, the second switch valve, the fifth switch valve and the sixth switch valve, start the second compressor, and continue to fill the inert gas in the test container into the gas storage tank until the pressure value displayed by the second pressure tester reaches the second preset pressure.

[0026] Beneficial effects:

[0027] The pressure inspection system and method for pressure vessels provided by the present invention, after the test of a test vessel is completed, the subsequent test vessel to be tested is placed, and the above steps are repeated, so that the gas in the gas storage tank can be repeatedly used, the economy of the test is improved, and the use of inert gas as a pressurizing medium solves the key problem that the packaging materials of the pressure vessel cannot be tested with water. Therefore, this scheme can economically and reasonably use inert gas as a pressurizing medium for testing test containers. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 A schematic structural diagram of a pressure inspection system for a pressure vessel according to an embodiment is shown. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0031] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0033] In the description of the present invention, it should be noted that if the terms "upper", "lower", "inside", "outside", "middle" and the like appear to indicate directions or positional relationships, they are based on the directions or positional relationships shown in the accompanying drawings, or are the directions or positional relationships in which the product of the invention is usually placed when in use. These are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0034] like Figure 1 As shown, the present invention provides a pressure inspection system for a pressure vessel, comprising a gas storage tank 1, a test vessel 2, and a direct gas inlet and outlet pipeline 3, a booster pipeline 4, and a pressure relief pipeline 5 respectively connected to the gas storage tank 1 and the test vessel 2. The gas storage tank 1 stores inert gas, and the test vessel 2 is placed in a closed water tank 21. The closed water tank 21 stores water. A metering water pipe 22 is connected to the upper part of the closed water tank 21. The pressure inspection process of the test vessel 2 includes a pressure charging stage, a pressure boosting stage, a first pressure relief stage, and a second pressure relief stage, wherein:

[0035] During the pressurization stage, the gas storage tank 1, the direct gas inlet and outlet pipeline 3 and the test container 2 are connected, and the booster pipeline 4 and the pressure relief pipeline 5 are closed. At this time, the inert gas in the gas storage tank 1 enters the test container 2 through the direct gas inlet and outlet pipeline 3 until the gas pressure in the gas storage tank 1 and the test container 2 is balanced;

[0036] In the pressure-increasing stage, the gas storage tank 1, the pressure-increasing pipeline 4 and the test container 2 are connected, and the direct air inlet and outlet pipeline 3 and the pressure-relief pipeline 5 are closed. At this time, the inert gas in the gas storage tank 1 enters the test container 2 after being pressurized by the pressure-increasing pipeline 4, until the gas pressure in the test container 2 reaches the first preset pressure and is maintained for a preset time. At the same time, the metering water pipe 22 is used to measure the amount of water discharged from the closed water tank 21 due to the expansion and deformation of the test container 2;

[0037] In the first pressure relief stage, the gas storage tank 1, the direct gas inlet and outlet pipeline 3 and the test container 2 are connected, and the booster pipeline 4 and the pressure relief pipeline 5 are closed. At this time, the inert gas in the test container 2 enters the gas storage tank 1 through the direct gas inlet and outlet pipeline 3 until the gas pressure in the gas storage tank 1 and the test container 2 is balanced;

[0038] In the second pressure relief stage, the gas storage tank 1, the pressure relief pipeline 5 and the test container 2 are connected, and the direct inlet and outlet gas pipelines 3 and the booster pipeline 4 are closed. At this time, the inert gas in the test container 2 enters the gas storage tank 1 after the pressure is relieved through the pressure relief pipeline 5 until the gas pressure in the test container 2 reaches the second preset pressure, and the first preset pressure is greater than the second preset pressure.

[0039] In this embodiment, after the test of a test container is completed, the subsequent test container to be tested is placed in, and the above steps are repeated, so that the gas in the gas storage tank can be reused repeatedly, the economy of the test is improved, and the use of inert gas as a pressurizing medium solves the key problem that the pressure vessel packaging material cannot be tested with water. Therefore, this solution can economically and reasonably use inert gas as a pressurizing medium for testing test containers.

[0040] In one embodiment, the direct inlet and outlet gas pipeline 3 is provided with a first switch valve 31 and a throttle valve 32, and the throttle valve 32 is used to adjust the flow rate of the inert gas passing through the direct inlet and outlet gas pipeline 3. In this arrangement, the flow rate adjustment characteristic of the throttle valve 32 can be used to ensure the stability of the gas delivery process.

[0041] In one embodiment, along the direction in which the inert gas is transported from the gas storage tank 1 to the test container 2, the boosting pipeline 4 is provided with a second switch valve 41, a first compressor 42 and a first check valve 43. In this configuration, the first compressor 42 can be used to increase the pressure of the inert gas, and the first check valve 43 can be used to prevent the backflow of the inert gas.

[0042] In one embodiment, along the direction in which the inert gas is transported from the test container 2 to the gas storage tank 1, the pressure relief pipeline 5 is provided with a third switch valve 51, a second compressor 52 and a second check valve 53. In this arrangement, the second compressor 52 can be used to achieve the second pressure relief of the inert gas, and the second check valve 53 can be used to prevent the backflow of the inert gas.

[0043] In one embodiment, the gas storage tank 1 is connected to a first pipeline 6, which is respectively connected to the direct inlet and outlet gas pipeline 3, the booster pipeline 4 and the pressure relief pipeline 5. The first pipeline 6 is provided with a fourth switch valve 61, a first pressure tester 62 and a fifth switch valve 63. The fourth switch valve 61 is located at one end of the first pipeline 6 close to the gas storage tank 1, the fifth switch valve 63 is located at one end of the first pipeline 6 away from the gas storage tank 1, and the first pressure tester 62 is located between the fourth switch valve 61 and the fifth switch valve 63. In this arrangement, the air pressure of the first pipeline 6, that is, the air pressure of the gas storage tank 1, can be monitored in real time by using the first pressure tester 62.

[0044] In one embodiment, the test container 2 is connected to a second pipeline 7, which is respectively connected to the direct inlet and outlet gas pipeline 3, the booster pipeline 4 and the pressure relief pipeline 5. The second pipeline 7 is provided with a second pressure tester 71 and a sixth switch valve 72. The second pressure tester 71 is located at one end of the second pipeline 7 close to the test container 2, and the sixth switch valve 72 is located at one end of the second pipeline 7 away from the test container 2. With such a configuration, the air pressure of the second pipeline 7, i.e., the air pressure of the test container 2, can be monitored in real time by using the second pressure tester 72.

[0045] In one embodiment, the second pipeline 7 is further provided with a safety valve 73, and the safety valve 73 is located between the second pressure tester 71 and the sixth switch valve 72. In this way, the safety during the pressure increase process can be ensured by using the safety valve 73. Once the partial pressure of the second pipeline 7 exceeds the set pressure of the safety valve 73, the gas can be discharged to the outside through the safety valve 73.

[0046] In one embodiment, the first preset pressure ranges from 12 to 20 MPa, and the second preset pressure ranges from 0.1 to 0.2 MPa.

[0047] In one embodiment, the opening of the throttle valve 32 is determined by the following formula:

[0048]

[0049] Wherein, A is the opening of the throttle valve 32, ΔP is the pressure difference before and after the throttle valve 32, α is the sensitivity of the opening to the pressure difference, Q is the flow rate of the inert gas passing through the throttle valve 32, and n is a preset index related to the flow rate.

[0050] In a pressure testing system, the direct formula relationship between the opening of the throttle valve and the pipeline pressure is usually not linear and depends on many variables, such as the physical properties of the fluid, the geometry of the throttle valve, the pipeline size, and the operating conditions of the system. Therefore, the opening of the throttle valve 32 can be accurately adjusted by the above formula.

[0051] In addition, an embodiment of the present invention further provides a pressure inspection method for a pressure vessel. Based on the pressure inspection system for a pressure vessel mentioned in the above embodiment, the method includes:

[0052] S1, fill the gas storage tank 1 with an inert gas at a pressure of 10 MPa, and place the test container 2 in a closed water tank 21;

[0053] S2, perform the operation of the pressure charging stage: open the fourth switch valve 61 and the first switch valve 31, close the second switch valve 41, the third switch valve 51, the fifth switch valve 63 and the sixth switch valve 72, and pressurize the inert gas in the gas storage tank 1 into the test container 2 until the pressure value displayed by the second pressure tester 71 is stable;

[0054] S3, perform the operation of the pressure boosting stage: open the fourth switch valve 61 and the second switch valve 41, close the first switch valve 31, the third switch valve 51, the fifth switch valve 63 and the sixth switch valve 72, start the first compressor 42, and press the inert gas in the gas storage tank 1 into the test container 2 after the pressure is boosted by the first compressor 42, until the pressure value displayed by the second pressure tester 71 reaches the first preset pressure and the pressure is maintained for a preset time, and at the same time, the metering water pipe 22 is used to measure the amount of water discharged from the closed water tank 21 due to the expansion and deformation of the test container 2;

[0055] S4, perform the operation of the first pressure relief stage: open the fourth switch valve 61 and the first switch valve 31, close the second switch valve 41, the third switch valve 51, the fifth switch valve 63 and the sixth switch valve 72, and fill the inert gas in the test container 2 into the gas storage tank 1 until the pressure value displayed by the first pressure tester 62 is stable;

[0056] S5. Execute the operation of the second pressure relief stage: open the fourth switch valve 61 and the third switch valve 51, close the first switch valve 31, the second switch valve 41, the fifth switch valve 63 and the sixth switch valve 72, start the second compressor 52, and continue to fill the inert gas in the test container 2 into the gas storage tank 1 until the pressure value displayed by the second pressure tester 71 reaches the second preset pressure.

[0057] It can be understood that the pressure inspection method for the pressure vessel provided in this embodiment and the pressure inspection system for the pressure vessel provided in the above-mentioned embodiment are based on the same inventive concept, and therefore both have the same beneficial effects, which will not be elaborated herein.

[0058] It should be noted that, in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A pressure inspection system for a pressure vessel, characterized in that: It includes a gas storage tank, a test container, and direct gas inlet and outlet pipelines, a booster pipeline, and a pressure relief pipeline respectively connected to the gas storage tank and the test container. The gas storage tank stores inert gas. The test container is placed in a closed water tank. Water is stored in the closed water tank. A metering water pipe is connected to the upper part of the closed water tank. The pressure test process of the test container includes a pressure charging stage, a pressure boosting stage, a first pressure relief stage, and a second pressure relief stage, wherein: During the pressurization stage, the gas storage tank, the direct gas inlet and outlet pipelines and the test container are connected, the booster pipeline and the pressure relief pipeline are closed, and the inert gas in the gas storage tank enters the test container through the direct gas inlet and outlet pipeline until the gas pressures in the gas storage tank and the test container are balanced; During the pressure-increasing stage, the gas storage tank, the pressure-increasing pipeline and the test container are connected, and the direct air inlet and outlet pipeline and the pressure-relief pipeline are closed. At this time, the inert gas in the gas storage tank enters the test container after being pressurized by the pressure-increasing pipeline, until the gas pressure in the test container reaches a first preset pressure and is maintained for a preset time. At the same time, the metering water pipe is used to measure the amount of water discharged from the closed water tank due to the expansion and deformation of the test container; In the first pressure relief stage, the gas storage tank, the direct gas inlet and outlet pipeline and the test container are connected, the booster pipeline and the pressure relief pipeline are closed, and the inert gas in the test container enters the gas storage tank through the direct gas inlet and outlet pipeline until the gas pressures in the gas storage tank and the test container are balanced; During the second pressure relief stage, the gas storage tank, the pressure relief pipeline and the test container are connected, the direct inlet and outlet gas pipelines and the boost pipeline are closed, and the inert gas in the test container enters the gas storage tank after the pressure is relieved through the pressure relief pipeline until the gas pressure in the test container reaches a second preset pressure, and the first preset pressure is greater than the second preset pressure.

2. The pressure testing system according to claim 1, characterized in that: The direct air inlet and outlet pipeline is provided with a first switch valve and a throttle valve, and the throttle valve is used to adjust the flow rate of the inert gas passing through the direct air inlet and outlet pipeline.

3. The pressure testing system according to claim 2, characterized in that: Along the direction in which the inert gas is transported from the gas storage tank to the test container, the booster pipeline is provided with a second switch valve, a first compressor and a first check valve.

4. The pressure testing system according to claim 3, characterized in that: Along the direction in which the inert gas is transported from the test container to the gas storage tank, the pressure relief pipeline is provided with a third switch valve, a second compressor and a second one-way valve.

5. The pressure testing system according to claim 4, characterized in that: The gas tank is connected to a first pipeline, which is respectively connected to the direct inlet and outlet gas pipelines, the boost pipeline and the pressure relief pipeline. The first pipeline is provided with a fourth switch valve, a first pressure tester and a fifth switch valve. The fourth switch valve is located at an end of the first pipeline close to the gas tank, the fifth switch valve is located at an end of the first pipeline away from the gas tank, and the first pressure tester is located between the fourth switch valve and the fifth switch valve.

6. The pressure testing system according to claim 5, characterized in that: The test container is connected to a second pipeline, which is respectively connected to the direct air inlet and outlet pipelines, the boost pipeline and the pressure relief pipeline. The second pipeline is provided with a second pressure tester and a sixth switch valve. The second pressure tester is located at one end of the second pipeline close to the test container, and the sixth switch valve is located at one end of the second pipeline away from the test container.

7. The pressure testing system according to claim 6, characterized in that: The second pipeline is also provided with a safety valve, and the safety valve is located between the second pressure tester and the sixth switch valve.

8. The pressure testing system according to claim 7, characterized in that: The first preset pressure ranges from 12 to 20 MPa, and the second preset pressure ranges from 0.1 to 0.2 MPa.

9. The pressure testing system according to claim 8, characterized in that: The opening of the throttle valve is determined by the following formula: In the formula, A is the opening of the throttle valve, ΔP is the pressure difference before and after the throttle valve, α is the sensitivity of the opening to the pressure difference, Q is the flow rate of the inert gas passing through the throttle valve, and n is a preset index related to the flow rate.

10. A pressure testing method for a pressure vessel, characterized in that: Based on the pressure inspection system of claim 9, the method comprises: S1. Fill the gas storage tank with an inert gas at a pressure of 10 MPa, and place the test container in the closed water tank; S2, performing the operation of the pressurization stage: opening the fourth switch valve and the first switch valve, closing the second switch valve, the third switch valve, the fifth switch valve and the sixth switch valve, and pressurizing the inert gas in the gas storage tank into the test container until the pressure value displayed by the second pressure tester is stable; S3, performing the operation of the pressure boosting stage: opening the fourth switch valve and the second switch valve, closing the first switch valve, the third switch valve, the fifth switch valve and the sixth switch valve, starting the first compressor, and pressing the inert gas in the gas storage tank into the test container after the pressure is boosted by the first compressor, until the pressure value displayed by the second pressure tester reaches a first preset pressure and the pressure is maintained for a preset time, and at the same time, using the measuring water pipe to measure the amount of water discharged from the closed water tank due to the expansion and deformation of the test container; S4, performing the operation of the first pressure relief stage: opening the fourth switch valve and the first switch valve, closing the second switch valve, the third switch valve, the fifth switch valve and the sixth switch valve, and filling the inert gas in the test container into the gas storage tank until the pressure value displayed by the first pressure tester is stable; S5. Execute the operation of the second pressure relief stage: open the fourth switch valve and the third switch valve, close the first switch valve, the second switch valve, the fifth switch valve and the sixth switch valve, start the second compressor, and continue to fill the inert gas in the test container into the gas storage tank until the pressure value displayed by the second pressure tester reaches the second preset pressure.

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