A measurement method for online detection of breather valves through manual metering orifices in atmospheric pressure storage tanks.

Abstract

This invention belongs to the field of air valve detection, specifically relating to a measurement method for online detection of breather valves through a manual gauging orifice in an atmospheric pressure storage tank. The measurement method includes steps such as preliminary preparation, breather valve investigation, gauging orifice inspection and tooling installation, selection of detection method, and detection. By installing a dedicated inspection tooling at the manual gauging orifice, positive or negative pressure is applied to the gas phase space of the storage tank using the large breathing effect or an external air source, and pressure changes are monitored to obtain the opening pressure value of the breather valve. This invention eliminates the need to disassemble the breather valve, is simple to operate, and has low risk. It can inspect the positive and negative opening pressure values ​​of the breather valve and the leakage and sealing status of the gas phase space of the storage tank, effectively ensuring the operational safety of hazardous chemical storage tanks.

Description

Technical Field

[0001] This invention belongs to the field of air valve detection, specifically relating to a measurement method for online detection of breather valves through a manual metering orifice in an atmospheric pressure storage tank. Background Technology

[0002] According to the "Safety Management Standard for Atmospheric Pressure Storage Tank Areas of Flammable Liquids in Chemical Enterprises" (AQ3063-2025), breather valves and pressure relief manholes of storage tanks should undergo regular visual inspections (for example, checking for corrosion, foreign object blockage, adhesion, etc.) and start-up function checks, at least once a year. The opening pressure and leakage of breather valves should be periodically calibrated offline, with the calibration cycle determined in conjunction with the periodic inspection of the storage tank, and should not exceed 5 years; for those that cannot be calibrated offline, online calibration should be performed. According to the "Integrity Management of Atmospheric Pressure Storage Tanks" (GB / T37327-2019), breather valves for atmospheric pressure storage tanks should be inspected at least once a year; the inspection includes visual inspection, opening pressure, ventilation volume, and leakage testing; the breather valve should be free of abnormal corrosion, leakage, and foreign object blockage; the opening pressure, ventilation volume, and leakage of the breather valve should meet the design requirements. The Technical Specification for Inspection of Safety Accessories of In-Service Vertical Cylindrical Steel Welded Storage Tanks (T / CASEI026-2023) stipulates that the inspection cycle of breather valves, emergency relief valves, hydraulic safety valves, and nitrogen sealing valves should be determined according to different media characteristics and operating conditions. If there are clear regulations from regulatory agencies or users, those regulations shall be followed. If there are no regulations, the cycle should not exceed one year, but may be adjusted according to the risk assessment results.

[0003] Inspecting the breather valve on an atmospheric pressure storage tank seems like a simple task; it could be completed by simply removing the valve from the tank and transporting it to the calibration site—theoretically, this is called offline calibration. However, in reality, removing the breather valve from an atmospheric pressure storage tank and hoisting it to the calibration site is a complex and dangerous task, especially for tanks storing flammable, explosive, or toxic hazardous chemicals and those with large-diameter breather valves (DN300 and above). The risks are significant: First, removing large and heavy breather valves in an explosion-hazardous area is difficult using explosion-proof tools and requires special disassembly methods, thus posing a high risk. Second, transporting the valve from the tank, which is several meters high, to the ground requires hoisting machinery, and whether using a crane or a simple hoist, the risks remain high. Third, the entry of hoisting machinery into the tank area storing hazardous chemicals, or the transport to the top of the tank, are special operations, and the risks remain high. Because the inspection of breather valves is a recommended rather than a mandatory standard in the existing national and industry standards, very few companies, including large state-owned enterprises, can inspect the breather valves on atmospheric pressure storage tanks once a year according to the recommended standards.

[0004] On November 20, 2023, my country issued the "Technical Specification for Inspection of Safety Accessories of In-Service Vertical Cylindrical Steel Welded Storage Tanks" (T / CASEI026-2023), and on September 24, 2024, it issued the "Inspection and Suitability Evaluation of In-Service Atmospheric Pressure Storage Tanks" (NB / T11662-2024). The two standards describe the same online inspection method for breather valves, which is also the currently available inspection standard for breather valves in my country. One of the two online inspection methods for breather valves described in this standard is called the pressure method (e.g., Figure 1 As shown), another method is called the reverse differential pressure method (e.g. Figure 2 (as shown), but both methods have obvious drawbacks, specifically:

[0005] Figure 1 This diagram illustrates the principle of online pressure testing. It involves isolating the medium inside the tank from the valve under test using a testing interface or specialized testing fixture. Positive and negative pressures are applied to the valve via an external test gas source to test its opening pressure and leakage rate. The biggest challenge of this method lies in installing the specialized testing fixture between the breather valve and the storage tank. Each breather valve diameter requires one fixture, and the larger the nominal diameter, the greater the risk during disassembly and assembly. In other words, this method still requires disassembling the breather valve and installing a specialized base online to isolate it from the storage tank, thus retaining the operational risks associated with disassembling and assembling breather valves on hazardous chemical storage tanks.

[0006] Figure 2 This diagram illustrates the principle of online testing using the reverse differential pressure method. It involves maintaining the valve under test in operation and applying negative or positive pressure to the valve's pressure or vacuum end cavity (connected to the atmosphere) via an external test air source to test the opening pressure and leakage. The biggest challenge of this method lies in installing the test interface at the inlet and outlet of the breather valve while ensuring its airtightness. In other words, although the method maintains the breather valve's operational state, applying negative or positive pressure to the valve's pressure or vacuum end cavity via an external test air source necessitates sealing the breather valve's inlet and outlet. Since the geometry of the breather valve's inlet and outlet is not uniform or regularly smooth, implementing this operation is extremely difficult.

[0007] Therefore, based on this, the technical solution of the present invention is proposed. Summary of the Invention

[0008] To address the problems existing in the prior art, the present invention provides a measurement method for online detection of a breather valve through a manual metering orifice in an atmospheric pressure storage tank. The measurement method includes the following steps: (1) Preliminary preparation: Determine the capacity of the storage tank to be inspected and the physical and chemical properties of the stored medium, and formulate a safe operation guidance process; (2) Investigation of breathing valves: Investigate the type, structure and design opening pressure value of the breathing valve to be tested. If the storage tank is equipped with multiple breathing valves, intervene in the breathing valves not under test to make their valve body weight greater than the value of the breathing valve under test. (3) Inspection of the gauging hole and installation of the tooling: Inspect the manual gauging hole on the storage tank, select a matching special inspection tooling according to its model and size, and install the special inspection tooling on the manual gauging hole to ensure that the special inspection tooling is effectively equipotentially connected to the tank body; (4) Selection of detection method: Select the large breathing effect method or the external air source method according to the test plan, and connect the test device; (5) Conduct testing: Apply positive or negative pressure to the gas phase space of the storage tank through the testing device, monitor the pressure change until the breather valve opens or reaches a stable state, and record the data to obtain the opening pressure value of the breather valve.

[0009] Preferably, in step (2), the breathing valve is a mechanical breathing valve or a liquid-sealed breathing valve; wherein: The mechanical breathing valve is a gravity-type breathing valve, a spring-type breathing valve, or a pilot-operated breathing valve. The gravity-type breather valve has a parallel or coaxial structure.

[0010] Preferably, in step (3), the special inspection tooling is adapted to a detachable rotary gauging hole, a detachable foot-operated gauging hole, or a non-detachable gauging hole.

[0011] Preferably, in step (4), when the large breathing effect mode is selected, the external air source quick interface in the special inspection tool is blocked, and then the inspection quick interface is connected to the quick connector of the inspection device.

[0012] Preferably, in step (4), when an external gas source is selected, the quick-connect interface of the external gas source in the special inspection tool is connected to the electrostatic discharge hose on the storage tank to be inspected, and the other end is connected to the external gas source on the ground.

[0013] Preferably, in step (4), the external air source is an intelligent, digital remote transmission one-stop explosion-proof air compressor and vacuum pump.

[0014] Preferably, in step (4), the testing device includes a recording digital pressure gauge, a recording digital vacuum gauge, a shut-off valve, and a drain valve.

[0015] Preferably, in step (4), the detection device adopts a dual-gauge structure design, including pressure gauges with different ranges and accuracies: When the test pressure is less than 1 kPa, a pressure gauge with an accuracy of 0.2 or 0.5 should be selected. When the test pressure is greater than 1 kPa, a pressure gauge with an accuracy of 0.4 or 1.0 should be selected.

[0016] Preferably, in step (4), the detection device further includes a drain valve for replacing the air in the detection pipeline before testing; when the test medium is nitrogen, the air in the pipeline is discharged through the drain valve before pressurization or vacuuming; when the test medium is air, the drain valve is in the closed state.

[0017] To facilitate understanding of this invention, the principles of this invention are explained as follows: like Figure 3 The diagram illustrates the principle of online inspection of the breather valve via the manual gauging port of an atmospheric pressure storage tank, as described in this invention. The method involves installing a specialized fixture with an inspection interface on the manual gauging port of the breather valve to be inspected. This fixture effectively seals with the manual gauging port and can withstand the operating pressure of the storage tank and the pressure of the external air source applied for inspection, ensuring normal inspection of the breather valve. In other words, after installing the specialized fixture with the inspection interface on the manual gauging port of the storage tank, the function of the breather valve can be inspected through normal liquid inflow and outflow from the storage tank; it can also be inspected using an external air source.

[0018] and Figure 4 These are two common types and structures of manual gauging orifices used on storage tanks in China: rotary gauging orifices and foot-operated gauging orifices. They are relatively simple in structure and generally come in four sizes: DN100, DN150, DN200, and DN250. DN150 and DN200 are the most commonly used. Their main function is to manually measure oil and sample media in atmospheric pressure storage tanks, forming a closed system with the tank under normal conditions.

[0019] The inspection method of this invention involves disassembling the gauging port caps of these two models and replacing them with matching dedicated gauging port caps with inspection interfaces to inspect the breather valve. See [link / reference]. Figure 5 , Figure 6 and Figure 7 .

[0020] Figure 5 It is mainly used for storage tanks with detachable rotating gauging ports. Simply remove one bolt from the rotating end of the detachable rotating gauging port cover to install the special tooling with the inspection interface shown in the figure above.

[0021] Figure 6 It is mainly used for foot-operated gauging ports. According to the investigation, the foot-operated gauging port cover can be removed. There are two bolts. After removing it, you can install the special tool with the inspection interface shown in the figure above.

[0022] Figure 7This solution is mainly used for non-removable (riveted) gauging holes produced by a small number of manufacturers, or gauging holes that cannot be used with the two special tooling methods mentioned above. The solution involves fully opening the gauging hole cover (without any disassembly), then installing the special tooling with the inspection interface shown in the diagram into the gauging hole, and finally tightening and sealing it to perform the inspection.

[0023] The beneficial effects of this invention are as follows: 1. No need to disassemble the breather valve: The inspection method of the present invention does not change the structural state of the breather valve of the storage tank or any process facilities in the area, nor does it change the connection state between the breather valve and the storage tank. Only by making a minor modification to the manual gauging port of the storage tank (setting an inspection interface on the gauging port cover), the pressure of the gas phase space of the storage tank can be applied and the inspection signal can be transmitted, avoiding the high-risk operation caused by disassembling the breather valve in the traditional inspection method.

[0024] 2. Comprehensive inspection of tank airtightness: Unlike the current inspection method (which only checks the positive and negative opening pressure of the breather valve and the leakage of the valve core and valve seat), this invention can effectively inspect the leakage of the entire gas phase space of the tank and the airtight working status. From the perspective of occupational health, safety management and environmental protection (HSE), it comprehensively assesses the safety status of the tank, which is far more significant than the leakage inspection of a single component.

[0025] 3. Simple operation and low risk: Only one nut or screw no larger than M14 needs to be removed from the gauging port to connect the external test air source and transmit test data, making the operation simple and easy. For storage tanks with multiple breather valves, only weight intervention is needed on the non-tested breather valve (making its valve body weight greater than that of the breather valve being tested), and the inlet and outlet flame arresters or protective covers need to be removed to complete the inspection.

[0026] 4. Data accuracy and reliability: Maintain the original working state of the breathing valve, and verify that the data accurately reflects the actual working condition of the breathing valve, avoiding changes in opening pressure and leakage caused by disassembly and installation. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram illustrating the principle of online pressure testing.

[0029] Figure 2 This is a schematic diagram of the online inspection principle using the reverse differential pressure method.

[0030] Figure 3 This is a schematic diagram illustrating the principle of the breather valve for online inspection of the oil gauging orifice in this invention.

[0031] Figure 4 This is a schematic diagram of a commonly used manual oil gauging hole.

[0032] Figure 5 This is a schematic diagram of a special inspection fixture with a detachable rotating gauging orifice.

[0033] Figure 6 This is a schematic diagram of a foot-operated gauging hole inspection fixture.

[0034] Figure 7 This is a schematic diagram of a special inspection fixture for non-removable (e.g., riveted) gauging holes.

[0035] Figure 8 This is a schematic diagram of the testing device in an embodiment of the present invention.

[0036] Figure 9 It is the result of the process calculation of the detection system.

[0037] Figure label: Figure 1 The attached diagrams are labeled as follows: 1-Control valve, 2-Inspection device, 3-Inspection interface / dedicated inspection tooling, 4-Valve to be inspected, 5-Storage tank, 6-Data processing system.

[0038] Figure 2 The attached diagrams are labeled as follows: 1-Regulating valve, 2-Inspection device, 3-Pressure and vacuum gauge, 4-Inspection fixture, 5-Valve to be inspected, 6-Storage tank, 7-Pressure and vacuum gauge, 8-Data processing system.

[0039] Figure 3 The attached diagrams are labeled as follows: 1-Storage tank, 2-Breathe valve, 3-Data acquisition system, 4-Inspection device, 5-Special tooling for manual oil gauging, 6-Manual oil gauging, 7-Regulating valve, 8-Flow meter, 9-Vacuum gauge, 10-Vacuum pump, 11-Regulating valve, 12-Flow meter, 13-Pressure gauge, 14-Gas cylinder, 15-Air compressor, 16-Equipotential grounding body, 17-Conductive hose.

[0040] Figure 5 The attached diagrams are labeled as follows: 1-Gas metering guide tube, 2-Gas-liquid balance orifice, 3-Connecting flange, 4-Flange gasket, 5-Rotating gaussing body, 6-Column, 7-Bolt, 8-Sealing gasket, 9-Rotating gaussing inspection cover, 10-External air source quick-connect interface, 11-Inspection interface, 12-Locking handle, 13-Adjustable thread.

[0041] Figure 6The attached diagrams are labeled as follows: 1-Inspection quick-connect interface, 2-Bolt, 3-Gas metering guide tube, 4-Gas-liquid balance orifice, 5-Connecting flange, 6-Flange gasket, 7-Foot-operated gauging orifice body, 8-Support, 9-Adjustable clamping bracket, 10-Sealing gasket, 11-Foot-operated gauging orifice inspection cover, 12-Adjustable screw, 13-Locking handwheel, 14-External air source quick-connect interface.

[0042] Figure 7 The attached diagrams are labeled as follows: 1-Removable clamping head, 2-Retractable bracket, 3-Moving nut, 4-Multi-purpose oil gauging hole inspection cover, 5-Large diameter inspection cover, 6-External air source interface, 7-Screw, 8-Anti-fall hole, 9-Inspection interface.

[0043] Figure 8 The attached diagram shows the following valve references: 1-Negative pressure shut-off valve (less than 1 kPa), 2-Quick connector, 3-Temperature gauge shut-off valve, 4-Balancing valve, 5-Regulating valve, 6-Temperature gauge, 7-Positive pressure shut-off valve (less than 1 kPa), 8-Recording digital pressure gauge (0.2 grade), 9-Release valve, 10-Recording digital pressure gauge (0.4 grade), 11-Release valve, 12-Positive pressure shut-off valve (greater than 1 kPa), 13-Recording digital vacuum gauge (0.4 grade), 14-Release valve, 15-Negative pressure shut-off valve (greater than -0.5 kPa), 16-Release valve, 17-Recording digital vacuum gauge (less than -0.5 kPa, 0.2 grade), 18-Negative pressure shut-off valve (less than -0.5 kPa). Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0045] Example This embodiment provides a measurement method for online detection of a breather valve through a manual metering orifice in an atmospheric pressure storage tank. Figure 3 For example, the measurement method includes the following steps: (1) Before carrying out the breathing valve inspection work, it is necessary to clarify Figure 3 The total capacity of the intermediate storage tank 1 and the physical and chemical properties of its stored medium were determined, and a risk analysis was conducted throughout the inspection process. Comprehensive occupational health, safety management and environmental protection measures and safe operation guidelines were developed.

[0046] (2) For the tested Figure 3The investigation of breather valve 2 in the tank requires determining whether it is a mechanical or liquid-sealed type. Mechanical breather valves are classified into three types: gravity-operated, spring-operated, and pilot-operated. Gravity-operated breather valves include parallel and coaxial structures. The correct positive and negative opening pressure values ​​and allowable leakage of the tested breather valve must be determined based on the manufacturer's instructions or the physicochemical properties of the medium in the tank. The number of breather valves on the tested tank also needs to be determined. If there are more than two breather valves, the opening pressure of the non-tested breather valves needs to be adjusted so that their valve body weight exceeds the value of the tested breather valve. The specific method depends on the structure of the breather valves, and the valves should be tested sequentially.

[0047] (3) To Figure 3 Inspect and measure the manual gauging port 6 on intermediate storage tank 1. First, open the manual gauging port cover according to the operating procedures to determine whether there is a gas-liquid balance hole on the gauging port guide tube (or refer to the drawings). Then, determine the model and size of the gauging port. If it is a detachable rotary or foot-operated gauging port, it is necessary to determine... Figure 3 Can the special tooling 5 with inspection function for manual gauging holes be reliably and tightly installed on the gauging hole? If it can be installed effectively, then... Figure 5 or Figure 6 Specialized tooling is required; if effective installation is not possible, then specialized tools are needed. Figure 7 Specialized tooling is required. It is particularly important to ensure that, regardless of the type of inspection tooling used, every part of the tooling is effectively equipotentially bonded to the commonly used storage tank body.

[0048] (4) In Figure 3 After the installation of the manual gauging port 6 and the completion of the inspection fixture 5, the online inspection should be determined according to the breather valve inspection contract. This will determine whether the inspection will utilize the large breathing effect created by the tank's inlet and outlet flow, or an external air source. If the tank inlet and outlet flow is used, it is necessary to... Figure 5 External gas source quick interface 10 Figure 6 External gas source quick interface 14 or Figure 7 The external air supply quick-connect interface 6 is effectively sealed to ensure no leakage, and then an anti-static hose is used to... Figure 5 Quick Interface for Verification 11 Figure 6 The quick interface for verification 1 or Figure 7 The other end connects to the quick-access interface 9 in the middle, and is connected to... Figure 8 The quick connector 2 in the middle can be used for sealed connection to carry out the inspection of the breather valve; if an external air source is used, it needs to be connected while the storage tank is running normally. Figure 5 External gas source quick interface 10 Figure 6 External gas source quick interface 14 or Figure 7 External gas source quick interface 6 and Figure 3The static-dissipating hose 17 is connected to the tank, and the other end is connected to an external air source on the ground. When the external air source pressurizes the tank according to certain requirements, the positive pressure opening value and leakage of the breather valve can be tested; when the external air source evacuates the tank, the negative pressure opening value and leakage of the breather valve can be tested.

[0049] (5) External air source can be selected from the market as an intelligent, digital remote transmission one-stop explosion-proof air compressor and vacuum pump. Points to note: First, the core issue of external air source is controlling the flow rate of compressed air to prevent static electricity from being generated in the pipeline; second, the selected hoses need to have static discharge function; third, if the external air source device is placed inside the fire dike of the storage tank, it is considered an explosion hazard area for the tank area of ​​hazardous chemicals, and the equipment needs to have explosion-proof performance. If it is placed outside the fire dike of the storage tank, a non-explosion-proof type can be selected; fourth, the external air source device must be reliably and independently grounded, or equipotentially connected to the storage tank; fifth, the larger the gas phase space of the storage tank, the longer the pressurization time. According to preliminary calculations, a tank with a 1000m... 3 For a gas-phase space storage tank, the pressure needs to be increased from 0 to 1 kPa. A 50-meter-long, 16mm inner diameter conductive hose is used. The air velocity within the hose must not exceed 10 m / s. The air compressor outlet flow rate is adjusted to 116 L / min, and the compressor outlet pressure is between 0.3 and 0.4 MPa. Assuming minimal gas temperature change during inflation and ignoring pipeline pressure drop (the air compressor outlet pressure is sufficient to overcome resistance), the estimated inflation time is 1.42 hours (calculated flow velocity 9.6 m / s). Fifthly, regarding the use of nitrogen and air, theoretically, for storage tanks with a large gas phase space, the process is the same. Regardless of whether nitrogen or air is used, static electricity will be generated if the flow velocity in the pipeline exceeds a certain value. Therefore, controlling the gas velocity in the conductive hose to not exceed 10 m / s is crucial. It should be emphasized that for nitrogen-sealed storage tanks and those required by local policies and regulatory authorities to use nitrogen, nitrogen must also be used as the test gas source.

[0050] (6) After completing the above five steps, the breather valve inspection can be carried out. First, based on the positive and negative opening pressure values ​​of the breather valve, set up the calibration procedure for the inspection device. Figure 8 In the process, the set pressure of the mechanical breather valve that needs to be calibrated is +0.665 kPa for positive pressure and -0.3 kPa for negative pressure, with a pressure rating of Class B. During positive pressure calibration, the set pressure should be... Figure 8With valves 1 and 18 closed, valves 7 and 9 opened. When the atmospheric pressure tank pressure rises and airflow is discharged from the valves, drain valve 9 is closed. At this point, the recording digital pressure gauge 8 starts counting from 0 and continues until it reaches a certain value that stops rising. This value is the positive pressure opening value of the breather valve (e.g., if it rises to +0.663 kPa and then stops rising, it indicates that the opening pressure is this value; since the test may involve a range, an average value is needed). According to Appendix B of the "Technical Specification for Inspection of Safety Accessories of In-Service Vertical Cylindrical Steel Welded Storage Tanks" (T / CASEI026-2023), the test should be repeated 9 times and the average value taken. According to the "Breather Valve Type Test Rules" (T / CASEI056-2025), at least 3 measurements should be taken for each operating condition (in-situ, 90°, and 180°), and the average value should be taken. The purpose of using dual gauges in this testing device is to verify the accuracy of the data. When the readings are inconsistent, the gauges should be calibrated or verified. For breather valves with a test pressure less than 1 kPa, the accuracy of pressure gauge 8 should be 0.2 or 0.5 class. When the test pressure is greater than 1 kPa, the accuracy of pressure gauge 10 should be 0.4 or 1.0 class. During negative pressure calibration, valves 7, 16, and 18 should be closed, and shut-off valve 1 should be opened. When the vacuum pump is working, observe the value of the recording digital vacuum gauge 17 as it decreases from 0 until it reaches a certain value that no longer changes. This value is the negative pressure opening value of the breather valve (for example, if the value drops to -0.298 kPa and then stops decreasing, this indicates that the opening pressure value is this value).

[0051] Similarly, assuming the set pressure of the spring-loaded breather valve to be calibrated is +6.9 kPa for positive pressure and -4.3 kPa for negative pressure; during positive pressure calibration, the valve should be... Figure 8 With valves 1, 7, and 15 closed, and valves 18, 12, and 11 opened, when the tank pressure rises and airflow is released from the valves, drain valve 11 is closed. At this point, the recording digital pressure gauge 10 starts counting from 0 until it reaches a certain value and stops rising; this is the positive pressure opening value of the breather valve (e.g., if it rises to +6.8 kPa and the value stops rising, this indicates the opening pressure value is this value). For negative pressure calibration, valves 1, 7, 12, and 14 should be closed, and valves 18 and 15 opened. When the vacuum pump is working, observe the value on the recording digital vacuum gauge 17 as it decreases from 0 until it reaches a certain value and stops changing; this is the negative pressure opening value of the breather valve (e.g., if it drops to -4.2 kPa and the value stops decreasing, this indicates the opening pressure value is this value).

[0052] It should be noted that the purpose of designing drain valves 9, 11, 14, and 16 is that the gas phase space of some storage tanks is not air but nitrogen, i.e., the breather valve of a nitrogen-sealed storage tank, whose external gas source needs to be pressurized with nitrogen. Furthermore, some local standards or regulatory departments require the use of nitrogen as the test gas source when inspecting breather valves, and this design is intended to replace the air in the hoses of the testing device. When using air, all of the above drain valves can be in the closed state.

[0053] Regarding the inspection of breather valve leakage, there are no mandatory national requirements, and the regulations vary among different industry and group standards. The "Breather Valve Type Test Rules" (T / CASEI 056-2025) and "Accessories for Vertical Cylindrical Steel Welded Storage Tanks" (SY / T0511-2024) issued by the China Special Equipment Inspection Association stipulate that for breather valves with a diameter DN≤150, the allowable leakage is ≤0.01 Nm. 3 / h; For breather valves with a diameter between DN200-300, the permissible leakage is ≤0.03Nm. 3 / h. The "Safety, Environmental Protection and Energy Saving Technical Specifications for Breathing Valves, Flame Arrestor Breathing Valves and Flame Arrestors" (T / CIECCPA 088-2025) issued by the China Industrial Energy Conservation and Cleaner Production Association stipulates that for breathing valves with a diameter DN≤150, the permissible leakage is ≤0.0017m³. 3 / h; For breather valves with a diameter of DN200-300, the permissible leakage is ≤0.003m³. 3 / h (the leakage test should be conducted under standard conditions of 20℃±5℃ and 50%±10% relative humidity, and at 85% of the set pressure), the difference between the two is an order of magnitude. International standards, ISO 28300-2008 and API STD 2000-2014, are consistent, both stipulating that for breather valves with a diameter DN≤150, the permissible leakage is ≤0.014m³. 3 For breather valves with a diameter between DN200 and 350, the permissible leakage rate is ≤0.142 m³ / h. 3 / h.

[0054] Verifying the leakage of a breather valve can only be done during offline testing, and even then, it's not very meaningful because the valve's opening value and leakage rate can change during installation. Even the online reverse differential pressure testing method mentioned in the "Technical Specification for Inspection of Safety Accessories of In-Service Vertical Cylindrical Welded Steel Storage Tanks" (T / CASEI026-2023) and "Inspection and Suitability Evaluation of In-Service Atmospheric Pressure Storage Tanks" (NB / T11662-2024) does not verify the leakage of the breather valve, but rather the leakage of the entire gas phase space of the tank (including breather valves, gauging holes, level gauges, manhole covers, and other potentially leaking accessories). In fact, from an occupational health, safety management, and environmental protection (HSE) perspective, what's needed for storage tanks is the overall leakage status of the entire tank, not just the leakage of a single component.

[0055] Additionally, it should be noted that, in Figure 5 In this context, because the industry standard for rotary gauging orifices only specifies the flange interface standard and nominal diameter, while other dimensions are left to the manufacturers to define, this specification is specifically designed to be applicable to the needs of various manufacturers' products. Figure 5 The bolt connection hole of the adjustable screw hole 13 is designed to be adjustable. Figure 6 The adjustable screw 12 in the foot-operated gauging port is designed in this way. Figure 7 It is specifically designed for some manufacturers who use rivet structures to make the gauging hole caps non-removable, or for some non-standard gauging holes. It is suitable for gauging holes of any diameter. Before use, it is necessary to determine the equipotential conductivity between the rods.

[0056] Finally, to facilitate understanding of the present invention, the calculations for the air flow rate and pressurization time in the conductive tubing are explained: (a) Calculation of air velocity in the hose The air compressor's flow rate is 116 L / min. Convert this to standard units: (1) Flow rate: Q = 116 L / min = 0.116 m 3 / min=0.0019333m 3 / s; (2) Calculation of the cross-sectional area of ​​the hose: Inner diameter: d = 16 mm = 0.016 m; Cross-sectional area: A = π (d / 2) 2 =π(0.008) 2 ≈0.000201m 2 ; (3) The air velocity v in the conductive tubing is: v=Q / A=0.008 / 0.000201≈9.62m / s.

[0057] The calculated flow velocity is 9.62 m / s (flow velocity is generally controlled between 7 and 10 m / s).

[0058] (II) Calculation of boost time Based on the isothermal inflation model, the pressurization time is calculated as follows: (1) Required air volume (under standard atmospheric conditions):

[0059] (2) Air compressor flow rate Q = 0.48 m³ / h 3 / min

[0060] The process calculation results of the detection system are as follows Figure 9 As shown, it is basically consistent with the above calculation results, and the compressor outlet pressure can be taken as 0.3~0.4MPa.

[0061] In summary, using an air compressor with a flow rate of 116 L / min to process 1000 m³ of air is effective. 3 It takes approximately 1.42 hours (about 1 hour and 25 minutes) to raise the pressure in the gas phase space of the storage tank from 0 kPa to 1 kPa. If a compressor with a capacity of 40 L / min is used, it will take approximately 4 hours and a half.

[0062] Note: (1) Safe flow rate verification: When the compressor discharge rate of 116L / min is used for inflation, the flow rate of compressed air through the 16mm inner diameter electrostatic conductive hose is about 9.6m / s. This flow rate is within the safe range of 7~10m / s and meets the requirements for safe operation.

[0063] (2) Calculation premise: This calculation is based on an isothermal process (the gas temperature does not change much during the inflation process) and ignores the pipeline pressure drop (the air compressor outlet pressure is sufficient to overcome the resistance). These are reasonable simplifications in engineering calculations.

[0064] (3) Summary: The estimated inflation time is 1.42 hours.

[0065] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A measurement method for online detection of a breather valve through a manual metering orifice in an atmospheric pressure storage tank, characterized in that, The measurement method includes the following steps: (1) Preliminary preparation: Determine the capacity of the storage tank to be inspected and the physical and chemical properties of the stored medium, and formulate a safe operation guidance process; (2) Investigation of breathing valves: Investigate the type, structure and design opening pressure value of the breathing valve to be tested. If the storage tank is equipped with multiple breathing valves, intervene in the breathing valves not under test to make their valve body weight greater than the value of the breathing valve under test. (3) Inspection of the gauging hole and installation of the tooling: Inspect the manual gauging hole on the storage tank, select a matching special inspection tooling according to its model and size, and install the special inspection tooling on the manual gauging hole to ensure that the special inspection tooling is effectively equipotentially connected to the tank body; (4) Selection of detection method: Select the large breathing effect method or the external air source method according to the test plan, and connect the test device; (5) Conduct testing: Apply positive or negative pressure to the gas phase space of the storage tank through the testing device, monitor the pressure change until the breather valve opens or reaches a stable state, and record the data to obtain the opening pressure value of the breather valve.

2. The measurement method for online detection of the breather valve through a manual metering orifice in an atmospheric pressure storage tank according to claim 1, characterized in that, In step (2), the breathing valve is a mechanical breathing valve or a liquid-sealed breathing valve; wherein: The mechanical breathing valve is a gravity-type breathing valve, a spring-type breathing valve, or a pilot-operated breathing valve. The gravity-type breather valve has a parallel or coaxial structure.

3. The measurement method for online detection of the breather valve through a manual metering orifice in an atmospheric pressure storage tank according to claim 1, characterized in that, In step (3), the special inspection tool is adapted to a detachable rotating gauging hole, a detachable foot-operated gauging hole, or a non-detachable gauging hole.

4. The measurement method for online detection of the breather valve through a manual metering orifice in an atmospheric pressure storage tank according to claim 1, characterized in that, In step (4), when the large breathing effect mode is selected, the external air source quick interface in the special inspection tool is blocked, and then the inspection quick interface is connected to the quick connector of the inspection device.

5. The measurement method for online detection of the breather valve through a manual metering orifice in an atmospheric pressure storage tank according to claim 1, characterized in that, In step (4), when the external air source method is selected, the external air source quick interface in the special inspection tool is connected to the static electricity conductive hose on the storage tank to be inspected, and the other end is connected to the external air source on the ground.

6. The measurement method for online detection of the breather valve through a manual metering orifice in an atmospheric pressure storage tank according to claim 1, characterized in that, In step (4), the external air source is an intelligent, digital remote transmission one-stop explosion-proof air compressor and vacuum pump.

7. The measurement method for online detection of the breather valve through a manual metering orifice in an atmospheric pressure storage tank according to claim 1, characterized in that, In step (4), the testing device includes a recording digital pressure gauge, a recording digital vacuum gauge, a shut-off valve, and a drain valve.

8. The measurement method for online detection of the breather valve through a manual metering orifice in an atmospheric pressure storage tank according to claim 1, characterized in that, In step (4), the detection device adopts a dual-gauge structure design, including pressure gauges with different ranges and accuracies: When the test pressure is less than 1 kPa, a pressure gauge with an accuracy of 0.2 or 0.5 should be selected. When the test pressure is greater than 1 kPa, a pressure gauge with an accuracy of 0.4 or 1.0 should be selected.

9. The measurement method for online detection of the breather valve through a manual metering orifice in an atmospheric pressure storage tank according to claim 1, characterized in that, In step (4), the detection device also includes a drain valve, which is used to replace the air in the detection pipeline before testing; when the test medium is nitrogen, the air in the pipeline is discharged through the drain valve before pressurization or vacuuming is performed; when the test medium is air, the drain valve is in the closed state.

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