A sealing gasket leakage rate testing system and testing method under high temperature and high pressure environment

Abstract

The present invention relates to the technical field of sealing gasket testing, and in particular to a sealing gasket leakage rate testing system and testing method under high temperature and high pressure environment. The present invention comprises an upper pressure plate and a lower pressure plate, and the space enclosed by the tested gasket, the upper pressure plate and the lower pressure plate forms a sealed cavity, and the sealed cavity is connected to the high pressure gas source through a sealing side pipeline and a switch valve; a hollow cavity-shaped balancing cavity is arranged at the upper pressure plate or the lower pressure plate, and the balancing cavity is connected to the high pressure gas source through a balancing side pipeline and a switch valve; a differential pressure sensor for measuring the pressure difference between the two pipelines is bridged between the balancing side pipeline and the sealing side pipeline; a pressure sensor for measuring the current pipeline is arranged on the balancing side pipeline and / or the sealing side pipeline; a temperature sensor is arranged at the upper pressure plate or the lower pressure plate. The present invention can realize the accurate measurement of the leakage rate of the sealing gasket under high temperature and high pressure environment, so as to evaluate the sealing performance of the sealing gasket under high temperature and high pressure.

Description

Technical Field

[0001] The present invention relates to the technical field of sealing gasket testing, and in particular to a sealing gasket leakage rate testing system and testing method under a high temperature and high pressure environment. Background Art

[0002] Sealing gaskets are a kind of static seal widely used in petrochemical, nuclear power and other fields. Their sealing performance is crucial to the long-term safe operation of the device. As the service temperature and pressure of devices and equipment become higher and higher, higher requirements are put forward for the quality of sealing gaskets in extreme environments, especially the sealing performance. Accurately measuring the leakage rate of sealing gaskets in high temperature and high pressure environments is a prerequisite for conducting sealing gasket quality evaluation, sealing failure mechanism research and sealing structure design. At present, although there are some tests on the leakage rate of sealing gaskets in high temperature and high pressure environments, there are still various problems: such as how to solve the problem of uneven temperature of the leak detection cavity when the test temperature is high; some equipment needs to set up a leak detection cavity in the low pressure area of ​​the device, and the sealing of the leak detection cavity is also more troublesome when the temperature is high; the medium gas standards of some equipment cannot be unified, and there is no clear leakage rate measurement test method. So far, how to provide a sealing gasket leakage rate test system and test method under high temperature and high pressure environment, in the hope of realizing the accurate measurement of the leakage rate of sealing gaskets under high temperature and high pressure environment, so as to effectively and accurately evaluate the sealing performance of sealing gaskets under high temperature and high pressure while standardizing the device and unifying the process, has become a technical problem that needs to be solved in recent years in this field. Summary of the invention

[0003] The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art and to provide a sealing gasket leakage rate testing system under high temperature and high pressure environment which has a reasonable structure and is easy to implement, and which can realize accurate measurement of the sealing gasket leakage rate under high temperature and high pressure environment, so as to evaluate the sealing performance of the sealing gasket under high temperature and high pressure.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] A sealing gasket leakage rate testing system under high temperature and high pressure environment is characterized by: comprising an upper pressure plate and a lower pressure plate that cooperate with each other to clamp the gasket to be tested with a specified clamping load, the space enclosed by the gasket to be tested, the upper pressure plate and the lower pressure plate forms a sealed cavity, and the sealed cavity is connected to the high-pressure gas source through a sealing side pipeline and a switch valve; a hollow cavity-shaped balancing cavity is arranged at the upper pressure plate or the lower pressure plate, and the balancing cavity is connected to the high-pressure gas source through a balancing side pipeline and a switch valve; a differential pressure sensor for measuring the pressure difference between the two pipelines is bridged between the balancing side pipeline and the sealing side pipeline; a pressure sensor for measuring the current pipeline is arranged on the balancing side pipeline and / or the sealing side pipeline; a temperature sensor is arranged on the upper pressure plate or the lower pressure plate.

[0006] Preferably, the sealing cavity and the balancing cavity are close to each other and have the same volume.

[0007] Preferably, the outlet of the high-pressure gas source is connected to the balance chamber via a pressure reducing valve RV, a switch valve 1 V1, a switch valve 2 V2 and a pressure sensor; one end of the sealing side pipeline is connected to the sealing chamber, and a forked branch is provided at the other end, one end of the forked branch is connected to the high-pressure gas source via a switch valve 1 V1, and the other end of the forked branch is connected to the atmospheric environment or a gas collection device via a vent valve V3.

[0008] Preferably, the system also includes a standard container for calibrating the volume of the sealed chamber or the balancer, and the standard container is connected to a section of the pipeline between the switch valve 1 V1 and the switch valve 2 V2 via the switch valve 4 V4.

[0009] Preferably, the pressure sensor is an absolute pressure sensor.

[0010] Preferably, each switch valve is a diaphragm valve.

[0011] Preferably, a testing method using the sealing gasket leakage rate testing system under high temperature and high pressure environment is characterized by comprising the following steps:

[0012] S1. Place the gasket to be tested between the upper pressing plate and the lower pressing plate, and apply the required compression load to the gasket to be tested;

[0013] S2. Open the switch valve V4 to calibrate the volume v of the sealed chamber using a standard container (unit: m) 3 ;

[0014] S3. Open the switch valve 1 V1 and the switch valve 2 V2, and introduce the medium gas of a predetermined pressure into the balance chamber and the sealing chamber through the pressure reducing valve RV, and read the indications of the temperature sensor and the pressure sensor, which are recorded as T0 and P0, where the temperature unit is K and the pressure unit is Pa;

[0015] S4. Close the switch valve 1 V1 and the switch valve 2 V2, heat the upper pressure plate, the lower pressure plate and the gasket to the specified test temperature T, and read the indication of the pressure sensor, which is recorded as P1;

[0016] S5. Calculate the equivalent temperature of the balance chamber and the sealing chamber at the test temperature T:

[0017] At this time, the equivalent temperature of the equilibrium chamber is T' eq1 for:

[0018]

[0019] At this time, the equivalent temperature of the sealing chamber is T eq1 for:

[0020] T eq1 =T′eq1 ;

[0021] S6. Open the switch valve 1 V1 and the switch valve 2 V2, adjust the medium gas pressure to the predetermined test pressure through the pressure reducing valve RV and the vent valve V3, close the switch valve 1 V1, the switch valve 2 V2 and the vent valve V3, keep the readings of the pressure sensor and the differential pressure sensor after the time t, record them as P2 and ΔP, the unit of the time t is s;

[0022] S7. Calculate the equivalent temperature of the equilibrium chamber and the sealing chamber after time t:

[0023] At this time, the equivalent temperature of the equilibrium chamber is T' eq2 for:

[0024]

[0025] At this time, the equivalent temperature of the sealing chamber is T eq2 for:

[0026] T eq2 =T′ eq2 ;

[0027] S8. Calculate the mass leakage rate L of the sealing gasket within time t according to the ideal gas state equation m :

[0028]

[0029] in:

[0030] M is the molecular weight of the medium gas, in g / mol;

[0031] R is the ideal gas constant, and its unit is J / (mol·K).

[0032] Preferably, in step S3, the predetermined pressure is the ratio of the ambient temperature to the test temperature multiplied by the predetermined test pressure.

[0033] The beneficial effects of the present invention are:

[0034] 1) Through the above scheme, the present invention relies on setting a balance chamber on the two pressure plates near the sealing chamber, and uses a pressure sensor to measure the change in gas pressure in the balance chamber before and after heating, and indirectly calculates the equivalent temperature of the sealing chamber at the test temperature; then, the differential pressure sensor is used to measure the pressure difference between the balance chamber and the sealing chamber within a certain period of time, and according to the ideal gas state equation, the mass leakage rate of the sealing gasket under high temperature and high pressure environment can be calculated.

[0035] At this point, the present invention provides a theoretical platform for accurately measuring the leakage rate of sealing gaskets under high temperature and high pressure environments. Combined with the testing method, it can more conveniently evaluate the sealing performance of sealing gaskets under high temperature and high pressure. It has the advantages of simple structure, easy implementation, and accurate measurement.

[0036] Furthermore, the present invention uses a pressure drop method to measure the leakage rate, and there is no need to set up a leakage collection chamber to collect the leaked gas, thus avoiding the problem of sealing the leakage collection chamber at high temperature. By setting up a balance chamber and using a differential pressure sensor to measure the pressure difference between the balance chamber and the sealing chamber, the change in pressure in the sealing chamber before and after leak detection is obtained, which solves the problem of low accuracy of the pressure method for measuring leakage rate under high temperature and high pressure environment. At the same time, by measuring the change in pressure in the balance chamber before and after heating and before and after leak detection, the equivalent temperature of the sealing chamber is indirectly calculated using the gas state equation, which solves the problem of inaccurate measurement due to uneven temperature of the sealing chamber at high temperature, and ensures the accuracy of leakage rate measurement at high temperature, with significant results. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a structural schematic diagram of the present invention.

[0038] The actual correspondence between the reference numerals and component names of the present invention is as follows:

[0039] a-gasket under test b-sealing cavity c-balance cavity

[0040] 11-Upper pressure plate 12-Lower pressure plate

[0041] 20- High pressure gas source 31- Differential pressure sensor 32- Pressure sensor 33- Temperature sensor

[0042] 40-Standard Container DETAILED DESCRIPTION

[0043] For ease of understanding, the specific structure and working mode of the present invention are further described below:

[0044] like Figure 1 As shown, a sealing gasket leakage rate test system under high temperature and high pressure environment includes a high pressure gas cylinder as a high pressure gas source 20, a pressure reducing valve RV, a switch valve 1 V1, a switch valve 4 V4, a standard container 40, a switch valve 2 V2, a differential pressure sensor 31, a pressure sensor 32, an upper pressure plate 11, a temperature sensor 33, a gasket a to be tested, a lower pressure plate 12, and a vent valve V3. Figure 1In the structure shown, a balancing chamber c is arranged at the upper pressure plate 11; during the test, the gasket a to be tested is pressed by the upper pressure plate 11 and the lower pressure plate 12, and a sealed chamber b is naturally formed between the upper pressure plate 11, the lower pressure plate 12 and the gasket a to be tested. The sealed chamber b is connected to the low-pressure side of the differential pressure sensor 31, the switch valve 1 V1, the switch valve 2 V2 and the vent valve V3 through the sealing side pipeline. A balancing chamber c is arranged on the upper pressure plate 11, and the balancing chamber c is connected to the high-pressure side of the differential pressure sensor 31 and the switch valve 2 V2 through the balancing side pipeline. A pressure sensor 32 is arranged on the connecting pipeline between the balancing chamber c and the differential pressure sensor 31, and the pressure sensor 32 is an absolute pressure type pressure sensor. At the same time, the switch valve 4 V4 and the standard container 40 are connected to the pipeline between the switch valve 1 V1 and the switch valve 2 V2. A temperature sensor 33 is also arranged on the upper pressure plate 11.

[0045] During design, the volume of the balance chamber c should be equal to that of the sealing chamber b, and the position of the balance chamber c should be as close as possible to the sealing chamber b. In addition, the switch valve 1 V1, the switch valve 2 V2, the vent valve V3 and the switch valve 4 V4 all use diaphragm valves with good sealing performance.

[0046] Based on the above system, the present invention also provides the following testing method, comprising the following steps:

[0047] S1. The gasket a to be tested is placed between the upper platen 11 and the lower platen 12, and the required clamping load is applied to the gasket a to be tested;

[0048] S2. Open the switch valve V4 to calibrate the volume v of the sealed chamber b using the standard container 40, in m 3 ;

[0049] S3. Open the switch valve 1 V1 and the switch valve 2 V2, and introduce the medium gas of the predetermined pressure into the balance chamber c and the sealing chamber b through the pressure reducing valve RV, and read the indications of the temperature sensor 33 and the pressure sensor 32, which are recorded as T0 and P0, where the temperature unit is K and the pressure unit is Pa; the predetermined pressure is the ratio of the ambient temperature to the test temperature multiplied by the predetermined test pressure;

[0050] S4. Close the switch valve V1 and the switch valve V2, heat the upper platen 11, the lower platen 12 and the gasket a to be tested to the specified test temperature T, and read the indication of the pressure sensor 32, recorded as P1;

[0051] S5. Calculate the equivalent temperature of the balance chamber c and the sealing chamber b at the test temperature T:

[0052] At this time, the equivalent temperature of the equilibrium cavity c is T' eq1 for:

[0053]

[0054] At this time, the equivalent temperature of the sealing chamber b is T eq1 for:

[0055] T eq1 =T′ eq1 ;

[0056] S6. Open the switch valve 1 V1 and the switch valve 2 V2, adjust the medium gas pressure to the predetermined test pressure through the pressure reducing valve RV and the vent valve V3, close the switch valve 1 V1, the switch valve 2 V2 and the vent valve V3, and read the indications of the pressure sensor 32 and the differential pressure sensor 31 after holding for a time t, which are recorded as P2 and ΔP, and the unit of the time t is s;

[0057] S7. Calculate the equivalent temperature of the equilibrium chamber c and the sealing chamber b after time t:

[0058] At this time, the equivalent temperature of the equilibrium cavity c is T' eq2 for:

[0059]

[0060] At this time, the equivalent temperature of the sealing chamber b is T eq2 for:

[0061] T eq2 =T′ eq2 ;

[0062] S8. Calculate the mass leakage rate L of the sealing gasket within time t according to the ideal gas state equation m :

[0063]

[0064] in:

[0065] M is the molecular weight of the medium gas, in g / mol;

[0066] R is the ideal gas constant, and its unit is J / (mol·K).

[0067] In the above, the indicating units of the differential pressure sensor 31 and the pressure sensor 32 are both Pa, and the indicating unit of the temperature sensor 33 is Kelvin; the volume unit is cubic meter; and the unit of time t is second.

[0068] Embodiment 1:

[0069] To facilitate further understanding of the present invention, the high temperature and high pressure sealing gasket leakage rate measurement system and method in the present invention are described in detail below in conjunction with specific embodiments:

[0070] The embodiment uses the test system and method to measure the leakage rate of a DN80 pipe flange using a vermiculite-wrapped gasket a.

[0071] The compressive stress of the gasket a under test is 70MPa, the test temperature is 673K, the medium gas pressure is 10MPa, and the medium gas is nitrogen; the differential pressure sensor 31 of the test system has a range of 100KPa and an accuracy of ±0.1%; the pressure sensor 32 has a range of 15MPa and an accuracy of ±0.1%; the temperature sensor 33 is a PT100 thermal resistor; the outer diameters of the upper pressure plate 11 and the lower pressure plate 12 used in the test are both 200mm.

[0072] The testing process is as follows:

[0073] S1. Wipe the corresponding sealing surfaces of the two pressure plates with acetone, place the gasket a to be tested between the upper pressure plate 11 and the lower pressure plate 12, place the pressure plates and the gasket a to be tested on the hydraulic testing machine, apply the required clamping load, and ensure that the gasket compressive stress on the gasket a to be tested is 70MPa;

[0074] S2. Use standard container 40 to calibrate the volume of sealed chamber b, and obtain the volume v of sealed chamber b as 6.48×10 -5 m 3 ;

[0075] S3. Open the switch valve 1 V1 and the switch valve 2 V2, and introduce 4.43×10 6 Pa of nitrogen, at this time, the indicated value T0 of the temperature sensor 33 is 298.8K, and the indicated value P0 of the pressure sensor 32 is 4.43×10 6 Pa;

[0076] S4. Close the switch valve 1 V1 and the switch valve 2 V2, and heat the upper platen 11, the lower platen 12 and the gasket a to be tested to the specified test temperature of 673K ​​through the heating equipment. When the temperature fluctuation does not exceed ±3K, that is, when the temperature is stable, the indication of the pressure sensor 32 is 9.28×10 6 Pa;

[0077] S5. Calculate the equivalent temperature of the balance chamber c and the sealing chamber b at the test temperature T:

[0078] At this time, the equivalent temperature of the equilibrium cavity c is T' eq1 for:

[0079]

[0080] At this time, the equivalent temperature of the sealing chamber b is T eq1 for:

[0081] T eq1 =T′ eq1 =625.9K;

[0082] S6. Open the switch valve 2 V2 and the switch valve 1 V1, and adjust the pressure reducing valve RV so that the medium gas pressure is the test pressure 1.0×10 7 Pa, close the switch valve 1 V1 and the switch valve 2 V2, and start leak detection. The time is t = 600s. After 600s, the reading value P2 of the pressure sensor 32 is 1.002×10 7 Pa, the indicated value ΔP of the differential pressure sensor 31 is 3.56×10 4 Pa;

[0083] S7. Calculate the equivalent temperature of the balance chamber c and the sealing chamber b at the end of the leak detection:

[0084] At this time, the equivalent temperature of the equilibrium cavity c is T' eq2 for:

[0085]

[0086] At this time, the equivalent temperature of the sealing chamber b is T eq2 for:

[0087] T eq2 =T′ eq2 =627.2K;

[0088] S8. Given that the molecular weight of nitrogen is M = 28.01 g / mol and the ideal gas constant is R = 8.314 J / (mol·K), calculate the mass leakage rate of the sealing gasket within 600 s according to the ideal gas state equation:

[0089]

[0090] In summary, the testing system and testing method of the present invention can conveniently and accurately measure the leakage rate of the sealing gasket under high temperature and high pressure environment, so as to evaluate the sealing performance of the sealing gasket under high temperature and high pressure; it has the advantages of simple structure, convenient implementation, and precise measurement, and can ultimately provide relevant data support for conducting sealing gasket quality evaluation, sealing failure mechanism research and sealing structure design under high temperature and high pressure environment.

[0091] Of course, it will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0092] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

[0093] The techniques, shapes, and structural parts not described in detail in the present invention are all well-known techniques.

Claims

1. A testing method for a sealing gasket leakage rate testing system under high temperature and high pressure environment, characterized in that: A sealing gasket leakage rate testing system under high temperature and high pressure environment comprises an upper pressure plate (11) and a lower pressure plate (12) which cooperate with each other to clamp a gasket (a) to be tested with a specified clamping load, a space enclosed by the gasket (a) to be tested, the upper pressure plate (11) and the lower pressure plate (12) form a sealing cavity (b), and the sealing cavity (b) is connected to a high-pressure gas source (20) through a sealing side pipeline and a switch valve; a hollow cavity-shaped balancing cavity (c) is arranged at the upper pressure plate (11) or the lower pressure plate (12), and the balancing cavity (c) is connected to the high-pressure gas source (20) through a balancing side pipeline and a switch valve; a differential pressure sensor (31) for measuring the pressure difference between the two pipelines is bridged between the balancing side pipeline and the sealing side pipeline; a pressure sensor (32) for measuring the current pipeline is arranged on the balancing side pipeline and / or the sealing side pipeline; a temperature sensor (33) is arranged on the upper pressure plate (11) or the lower pressure plate (12); The following steps are involved: S1. The gasket (a) to be tested is placed centered between the upper pressing plate (11) and the lower pressing plate (12), and a required clamping load is applied to the gasket (a) to be tested; S2. Open the switch valve V4 to calibrate the volume v of the sealed chamber (b) using a standard container (40), in m 3 ; S3. Open the switch valve 1 V1 and the switch valve 2 V2, and introduce the medium gas of a predetermined pressure into the balance chamber (c) and the sealing chamber (b) through the pressure reducing valve RV, and read the indications of the temperature sensor (33) and the pressure sensor (32), which are recorded as T0 and P0, where the temperature unit is K and the pressure unit is Pa; S4. Close the switch valve V1 and the switch valve V2, heat the upper pressure plate (11), the lower pressure plate (12) and the gasket (a) to the specified test temperature T, and read the indication of the pressure sensor (32), which is recorded as P1; S5. Calculate the equivalent temperature of the balance chamber (c) and the sealing chamber (b) at the test temperature T: The equivalent temperature T of the equilibrium chamber (c) e ' q1 for: The equivalent temperature T of the sealed cavity (b) eq1 for: T eq1 =T e ′ q1 ; S6. Open the switch valve 1 V1 and the switch valve 2 V2, adjust the medium gas pressure to the predetermined test pressure P through the pressure reducing valve RV and the vent valve V3, close the switch valve 1 V1, the switch valve 2 V2 and the vent valve V3, and read the indications of the pressure sensor (32) and the differential pressure sensor (31) after holding for a time t, which are recorded as P2 and ΔP, and the unit of the time t is s; S7. Calculate the equivalent temperature of the equilibrium chamber (c) and the sealing chamber (b) after time t: The equivalent temperature T of the equilibrium chamber (c) e ' q2 for: The equivalent temperature T of the sealed cavity (b) eq2 for: T eq2 =T e ′ q2 ; S8. Calculate the mass leakage rate L of the sealing gasket within time t according to the ideal gas state equation m : in: M is the molecular weight of the medium gas, in g / mol; R is the ideal gas constant, and its unit is J / (mol·K).

2. The method for testing a sealing gasket leakage rate test system under a high temperature and high pressure environment according to claim 1, characterized in that: The sealing chamber (b) and the balancing chamber (c) are close to each other and have the same volume.

3. The testing method of a sealing gasket leakage rate testing system under high temperature and high pressure environment according to claim 2, characterized in that: The outlet of the high-pressure gas source (20) is connected to the balance chamber (c) via a pressure reducing valve RV, a switch valve 1 V1, a switch valve 2 V2 and a pressure sensor (32); one end of the sealing side pipeline is connected to the sealing chamber (b), and a forked branch is provided at the other end, one end of the forked branch is connected to the high-pressure gas source (20) via a switch valve 1 V1, and the other end of the forked branch is connected to the atmospheric environment or a gas collection device via a vent valve V3.

4. The method for testing a sealing gasket leakage rate test system under a high temperature and high pressure environment according to claim 3, characterized in that: The system also includes a standard container (40) for calibrating the volume of the sealing chamber (b) or the balancing chamber (c), and the standard container (40) is connected to a section of the pipeline between the switch valve 1 V1 and the switch valve 2 V2 via the switch valve 4 V4.

5. The testing method of a sealing gasket leakage rate testing system under high temperature and high pressure environment according to claim 1, 2, 3 or 4, characterized in that: The pressure sensor (32) is an absolute pressure sensor.

6. The method for testing a sealing gasket leakage rate test system under high temperature and high pressure environment according to claim 3 or 4, characterized in that: Each switch valve is a diaphragm valve.

7. The method for testing a sealing gasket leakage rate testing system under high temperature and high pressure environment according to claim 1, characterized in that: In step S3, the predetermined pressure is the ratio of the ambient temperature to the test temperature multiplied by the predetermined test pressure.

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