A method for testing the fatigue life of static seals under high pressure and low temperature conditions

Abstract

This invention relates to the field of materials analysis and testing technology, particularly to the field of IPC G01N3 / 08, and more specifically, to a method for testing the fatigue life of static seals under high pressure and low temperature conditions. The method includes the following steps: Step 1: Performing pressure relief tests on the seal under different temperatures and pressures; Step 2: Performing a variable temperature pressure resistance test; Step 3: Replacing the seal and performing a first heating pulse pressure resistance test; Step 4: Performing a cooling pulse pressure resistance test; Step 5: Performing a second heating pulse pressure resistance test; Step 6: Performing a low-temperature pulse pressure resistance test; Step 7: Measuring the low-temperature performance of the seal before and after the experiment; Steps 1 to 6 all include continuous monitoring of pressure relief, simultaneously monitoring the ambient temperature and the actual temperature of the pulsed liquid. If pressure relief occurs at any step during the monitoring period, the test ends, and no further steps are performed. This method can evaluate the fatigue life of seals under low-temperature conditions, thereby meeting the reliability requirements of large-scale equipment.

Description

Technical Field

[0001] This invention relates to the field of materials analysis and testing technology, particularly to the field of IPC G01N3 / 08, and more specifically, to a method for testing the fatigue life of static seals under high pressure and low temperature conditions. Background Technology

[0002] Large-scale mining machinery operates in complex environments, requiring normal operation in extremely cold conditions (down to -50°C) while also meeting the requirements of high-temperature conditions during peak seasons and after continuous operation. To ensure leak-free sealing at low temperatures and a specific lifespan after high-temperature operation, a testing method needs to be developed based on actual working conditions, ensuring that the static seal fatigue life under high pressure and low temperature conditions meets the overall machine's operating requirements.

[0003] For rubber seals, aging performance studies are typically conducted based on the aging properties of the rubber material. For example, GB / T20028-2005 specifies a 50% change in physical properties after aging as the critical value for seal failure. CN201611174320 proposes a compression set ≥ 40% as the critical standard for seal failure. Chinese invention patents CN110765692A and CN113295400A, based on the Arrhenius equation and aging kinetics equation, obtain the aging laws of rubber materials and propose a life prediction method based on aging indices. However, the evaluation indices used in these methods are often not directly related to long-term sealing performance and are all empirical. The methods for determining the relevant life critical values ​​are not clearly defined and lack universality. Summary of the Invention

[0004] The first aspect of this invention provides a method for testing the fatigue life of static seals under high pressure and low temperature conditions, comprising the following steps:

[0005] Step 1: Conduct pressure relief tests on the seals under different temperatures and pressures;

[0006] Step 2: Conduct a variable temperature and pressure withstand test;

[0007] Step 3: Replace the seals and perform the first temperature-increasing pulse pressure test;

[0008] Step 4: Perform a cooling pulse withstand voltage test;

[0009] Step 5: Perform the second heating pulse withstand voltage test;

[0010] Step 6: Perform a low-temperature pulse withstand voltage test;

[0011] Step 7: Determine the low-temperature performance of the seals before and after the experiment;

[0012] Each of steps 1 to 6 includes a step of continuously monitoring the pressure relief, while simultaneously monitoring the ambient temperature and the actual temperature of the pulsed liquid. If pressure relief occurs at any step during the monitoring period, the test ends and no further steps are performed.

[0013] The low-temperature performance can be characterized by at least one of the following parameters: TR 10 Low-temperature brittleness temperature and glass transition temperature.

[0014] The TR 10 The test was conducted in accordance with GB / T7758 "Determination of Low-Temperature Properties of Vulcanized Rubber - Temperature Retraction Method (TR Test)".

[0015] In step 1, the seals are from the same batch, and the number of seals tested is no less than 4, and the tests are conducted simultaneously.

[0016] The applicant's research found that by first conducting pressure relief tests on the seals at different temperatures and pressures, and then conducting variable temperature pressure tests, the seals that have not reached their fatigue life can be identified more quickly, shortening the testing process and reducing testing costs. This may be because the seals are first placed in a high-pressure environment for a long time, so that the overall airtightness and mechanical strength of the seals are subjected to the dual impact of pressure and temperature, and then the variable temperature pressure tests are conducted, which can further verify the life under extreme fatigue conditions.

[0017] This study found that replacing the seal before testing in step 3 and then performing subsequent tests in steps 3-6 can improve the accuracy of the test. It is possible that after the test in step 2, the seal is close to the edge of its extreme lifespan, and performing the pulse withstand voltage test may cause the experiment to end prematurely, thus making it impossible to test whether the whole machine can meet the specific lifespan during the test process.

[0018] The number of seals that pass the test is not less than 75%, and TR 10 A temperature below 10℃ is considered a pass for the test.

[0019] In step 1, the temperature points are selected from -60℃ to 130℃, and the number of temperature points is 6 to 12. The pressure points are selected from 5 to 50 MPa, and the number of pressure points is 1 to 7.

[0020] Preferably, the temperature points in step 1 are selected from -50℃ to 120℃, and the number of temperature points is 6 to 12; the pressure points are selected from 5 to 50 MPa, and the number of pressure points is 1 to 7.

[0021] Preferably, the temperature point in step 1 is selected from the following values: -50℃, -40℃, -30℃, -20℃, 25℃, 95℃, 100℃, 110℃, 120℃, -45℃, -35℃, -25℃, -15℃, 20℃, 30℃, 35℃, 90℃, 105℃, 115℃, 125℃, 130℃.

[0022] More preferably, the temperature points in step 1 are: -50℃, -40℃, -30℃, -20℃, 25℃, 95℃, 100℃, 110℃, and 120℃.

[0023] Preferably, the pressure point includes at least one between 30-40 MPa, and more preferably, the pressure point includes at least 35 MPa.

[0024] The pressure points also include at least one of the following values: 10MPa, 15MPa, 20MPa, 25MPa, and 28MPa.

[0025] More preferably, the pressure points are 10MPa, 15MPa, 20MPa, 25MPa, and 35MPa.

[0026] Step 2 includes: first cooling from 5-35℃ to -40-60℃, then pressurizing to 20-50MPa, and then heating to 80-110℃ during the pressure holding process.

[0027] Preferably, step 2 includes: first cooling from 15-35°C to -45-60°C, then pressurizing to 30-50 MPa, and then heating to 90-110°C during the pressure holding process.

[0028] In a further preferred embodiment, the temperature is first lowered from 15-35℃ to -45-55℃, then pressurized to 30-40MPa, and the temperature is raised to 90-100℃ during the pressure holding process.

[0029] More preferably, step 2 includes: first cooling from 25°C to -50°C, then pressurizing to 35MPa, and then heating to 95°C during the pressure holding process.

[0030] Each pulse in steps 3 to 6 includes: first, increasing the pressure from 1 to 5 MPa to 20 to 50 MPa within 0.1 to 1 second, and then decreasing the pressure from 20 to 50 MPa to 1 to 5 MPa within 0.1 to 1 second, thus completing one pulse.

[0031] Preferably, the pulses in steps 3 to 6 each include: first increasing the pressure from 1.5 to 5 MPa to 30 to 50 MPa within 0.3 to 1 s, and then decreasing the pressure from 30 to 50 MPa to 1.5 to 5 MPa within 0.3 to 1 s.

[0032] More preferably, the pulses in steps 3 to 6 each include: first increasing the pressure from 1.5 to 3 MPa to 30 to 40 MPa within 0.3 to 0.8 seconds, and then decreasing the pressure from 30 to 40 MPa to 1.5 to 3 MPa within 0.3 to 0.8 seconds.

[0033] More preferably, the pulses in steps 3 to 6 each include: first increasing the pressure from 2MPa to 35MPa within 0.5s, and then decreasing the pressure from 35MPa to 2MPa within 0.5s.

[0034] Step 3 includes: first cooling from 5-35℃ to -40-60℃, then heating up to 80-110℃ and holding the temperature; during the heating and holding process, pulses are applied, and the number of pulses applied is 60,000-120,000.

[0035] Preferably, step 3 includes: first cooling from 15-35°C to -45-60°C, then heating to 90-110°C and holding the temperature; during the heating and holding process, pulses are applied, and the number of pulses applied is 80,000-120,000.

[0036] More preferably, step 3 includes: first cooling from 15-30°C to -45-55°C, then heating to 90-100°C and holding the temperature; during the heating and holding process, pulses are applied, and the number of pulses applied is 80,000-105,000.

[0037] More preferably, step 3 includes: first cooling from 25°C to -50°C, then heating to 95°C and holding the temperature; during the heating and holding process, pulses are applied, and the number of pulses applied is 93,700.

[0038] Step 4 includes: first cooling from 80-110℃ to -40-60℃, and then maintaining the temperature; during the heat preservation process, pulses are applied, and the number of pulses applied in step 4 is 1800-5400 times.

[0039] Preferably, step 4 includes: first cooling from 90-110℃ to -45-60℃, and then maintaining the temperature; during the heat preservation process, pulses are applied, and the number of pulses applied in step 4 is 2500-5400 times.

[0040] More preferably, step 4 includes: first cooling from 90-100℃ to -45-55℃, and then maintaining the temperature; during the heat preservation process, pulses are applied, and the number of pulses applied in step 4 is 2500-4000 times.

[0041] More preferably, step 4 includes: first cooling from 95°C to -50°C, and then maintaining the temperature; during the temperature maintenance process, pulses are applied, and the number of pulses applied in step 4 is 3600.

[0042] Step 5 includes: first raising the temperature from -40 to -60°C to 80 to 110°C, and then holding the temperature; during the raising and holding process, pulses are applied, and the number of pulses applied in step 5 is 1800-5400 times.

[0043] Preferably, step 5 includes: first heating from -45 to -60°C to 90 to 110°C, and then holding the temperature; during the heating and holding process, pulses are applied, and the number of pulses applied in step 5 is 2500-5400 times.

[0044] More preferably, step 5 includes: first heating from -45 to -55°C to 90 to 100°C, and then holding the temperature; during the heating and holding process, pulses are applied, and the number of pulses applied in step 5 is 2500-4000 times.

[0045] More preferably, step 5 includes: first heating from -50°C to 95°C, and then holding the temperature; during the heating and holding process, pulses are applied, and the number of pulses applied in step 5 is 3600.

[0046] Step 6 includes: first cooling from 5 to 35°C to -40 to -60°C, and then maintaining the temperature; during the heat preservation process, pulses are applied, and the number of pulses applied in step 6 is 5400-9600 times.

[0047] Preferably, step 6 includes: first cooling from 15-35°C to -45-60°C, and then maintaining the temperature; during the temperature maintenance process, pulses are applied, and the number of pulses applied in step 6 is 6000-9600 times.

[0048] More preferably, step 6 includes: first cooling from 15-30℃ to -45-55℃, and then maintaining the temperature; during the heat preservation process, pulses are applied, and the number of pulses applied in step 6 is 6000-8000 times.

[0049] More preferably, step 6 includes: first cooling from 25°C to -50°C, and then maintaining the temperature; during the temperature maintenance process, pulses are applied, and the number of pulses applied in step 6 is 7200.

[0050] This application research found that the number of pulses applied in step 3 is 80,000-120,000, the number of pulses applied in step 4 is 1,800-5,400, the number of pulses applied in step 5 is 1,800-5,400, and the number of pulses applied in step 6 is 5,400-9,600. This can accurately verify that the working life can reach 15,000 hours. At the same time, the end of the test caused by any step can also provide targeted improvement solutions for the seal. This may involve the calculation method of converting the equilibrium temperature into the ambient temperature. The operating equilibrium temperature can be calculated based on the ambient temperature. If the ambient temperature decreases, the corresponding thermal equilibrium temperature also decreases. Temperature has a great impact on life. The lower the temperature, the smaller the impact. Therefore, specific ambient temperatures and pulses are selected to determine the thermal equilibrium temperature and pulses for testing. At the same time, specific pulses will not cause the seal to be at its performance limit for a long time, but will also ensure long-term durability, so as to ensure the accuracy of the test.

[0051] The cooling or heating rate in steps 3-6 is 0.5 to 5 °C / min.

[0052] Preferably, the cooling or heating rate in steps 3-6 is 0.5 to 3 °C / min.

[0053] More preferably, the cooling or heating rate in steps 3-6 is 1-3°C / min.

[0054] More preferably, the cooling or heating rate in steps 3-6 is 2°C / min.

[0055] The applicant's research found that a cooling or heating rate of 0.5–5 °C / min in steps 3–6 can shorten the testing time; too rapid a heating / cooling rate can damage the machine, while too slow a rate results in low efficiency. Further research revealed that a cooling or heating rate of 0.5–3 °C / min in steps 3–6 can better simulate the temperature change rate under actual working conditions, maintain thermal equilibrium temperature, and more accurately detect the fatigue performance of the seals.

[0056] Beneficial effects

[0057] 1. First, conduct pressure relief tests on the seals under different temperatures and pressures, and then conduct variable temperature pressure resistance tests. This test sequence allows for fatigue life evaluation of the seals in low-temperature environments, which can quickly identify seals that have not reached their fatigue life, shorten the testing process, reduce testing costs, and meet the reliability requirements of large-scale equipment.

[0058] 2. Replacing the seal before testing in step 3 and then performing subsequent tests in steps 3-6 can improve the accuracy of the test.

[0059] 3. The number of pulses applied in step 3 is 80,000-120,000, the number of pulses applied in step 4 is 1,800-5,400, the number of pulses applied in step 5 is 1,800-5,400, and the number of pulses applied in step 6 is 5,400-9,600. This can accurately verify that the working life can reach 15,000 hours.

[0060] 4. The cooling or heating rate in steps 3-6 is 0.5-5℃ / min, which can shorten the test time.

[0061] 5. The testing method of this application is simple. In the 6-step testing process, by analyzing the test results, a reference basis can be provided for targeted improvement schemes for sealing components.

[0062] 6. This application sets pressure relief values ​​and TR. 10 The dual judgment criteria can effectively improve the accuracy of the test. Detailed Implementation

[0063] Example 1

[0064] A method for testing the fatigue life of static seals under high pressure and low temperature conditions. The seal type is NBR90. The test is conducted according to the following steps:

[0065] Step 1: Install the four seals on the four test heads respectively and connect them to the pulse test bench. Perform a 10-minute pressure holding test on each of the following temperatures in sequence: (-50℃, 35MPa), (-40℃, 35MPa), (-30℃, 35MPa), (-20℃, 35MPa), (25℃, 35MPa), (95℃, 35MPa), (100℃, 35MPa), (110℃, 35MPa), and (120℃, 35MPa). There should be no pressure release.

[0066] Step 2: The seal was first cooled from 25℃ to -50℃, then pressurized to 35MPa. During the pressure holding process, the temperature was raised to 95℃. During the test, one seal experienced pressure relief when the temperature was raised to -27.3℃.

[0067] Step 3: Replace 3 seals, first cool down from 25℃ to -50℃, then heat up to 95℃ and keep warm; pulses are applied during the heating and holding process, and the number of pulses applied is 93,700. There is no pressure loss during the test.

[0068] Step 4: Cool the seal from 95℃ to -50℃ and then keep it warm; apply pulses during the warming process, and apply pulses 3600 times in step 4. There was no pressure loss during the test.

[0069] Step 5: First heat the seal from -50℃ to 95℃, and then keep it at that temperature; during the heating and holding process, pulses are applied. The number of pulses applied in Step 5 is 3600 times, and there is no pressure loss during the test.

[0070] Step 6: Cool the seal from 25°C to -50°C, then keep it warm; apply pulses during the warming process, and apply 7200 pulses in step 6. There was no pressure loss during the test.

[0071] Step 7: Measure the TR of the seal before and after the experiment. 10 (The temperature corresponding to a 10% shrinkage rate) is less than 10℃, indicating the product is qualified.

[0072] Example 2

[0073] A method for testing the fatigue life of static seals under high pressure and low temperature conditions. The seal type is NBR90. The test is conducted according to the following steps:

[0074] Step 1: Install the four seals on the four test heads respectively and connect them to the pulse test bench. Perform a 10-minute pressure holding test on each of the following temperatures in sequence: (-50℃, 35MPa), (-40℃, 35MPa), (-30℃, 35MPa), (-20℃, 35MPa), (25℃, 35MPa), (95℃, 35MPa), (100℃, 35MPa), (110℃, 35MPa), and (120℃, 35MPa). There should be no pressure release.

[0075] Step 2: First, cool the seal from 25℃ to -50℃, then pressurize it to 35MPa. During the pressure holding process, raise the temperature to 95℃. During the test, one seal experienced pressure relief when the temperature reached 95℃.

[0076] Step 3: Replace 3 seals, first cool down from 25℃ to -50℃, then heat up to 95℃ and keep warm; pulses are applied during the heating and holding process, and the number of pulses applied is 93,700. There is no pressure loss during the test.

[0077] Step 4: Cool the seal from 95℃ to -50℃ and then keep it warm; apply pulses during the warming process, and apply pulses 3600 times in step 4. There was no pressure loss during the test.

[0078] Step 5: First heat the seal from -50℃ to 95℃, and then keep it at that temperature; during the heating and holding process, pulses are applied. The number of pulses applied in Step 5 is 3600 times, and there is no pressure loss during the test.

[0079] Step 6: Cool the seal from 25°C to -50°C, then keep it warm; apply pulses during the warming process, and apply 7200 pulses in step 6. There was no pressure loss during the test.

[0080] Step 7: Measure the TR of the seal before and after the experiment. 10 (The temperature corresponding to a 10% shrinkage rate) is less than 10℃, indicating the product is qualified.

[0081] Example 3

[0082] A method for testing the fatigue life of static seals under high pressure and low temperature conditions. The seal type is NBR90. The test is conducted according to the following steps:

[0083] Step 1: Install the four seals on the four test heads respectively and connect them to the pulse test bench. Perform a 10-minute pressure holding test on each of the following temperatures in sequence: (-50℃, 35MPa), (-40℃, 35MPa), (-30℃, 35MPa), (-20℃, 35MPa), (25℃, 35MPa), (95℃, 35MPa), (100℃, 35MPa), (110℃, 35MPa), and (120℃, 35MPa). There should be no pressure release.

[0084] Step 2: First, cool the seal from 25℃ to -50℃, then pressurize it to 35MPa. During the pressure holding process, raise the temperature to 95℃. During the test, the four seals will successively depressurize as the temperature rises to -40℃ to -30℃. The test ends and the product is judged to be unqualified.

[0085] Example 4

[0086] A method for testing the fatigue life of static seals under high pressure and low temperature conditions. The seal type is NBR90. The test is conducted according to the following steps:

[0087] Step 1: Install the four seals on the four test heads respectively and connect them to the pulse test bench. Perform a 10-minute pressure holding test on each of the following temperatures in sequence: (-50℃, 35MPa), (-40℃, 35MPa), (-30℃, 35MPa), (-20℃, 35MPa), (25℃, 35MPa), (95℃, 35MPa), (100℃, 35MPa), (110℃, 35MPa), and (120℃, 35MPa). There should be no pressure release.

[0088] Step 2: Cool the seal from 25℃ to -50℃, then pressurize it to 35MPa. During the pressure holding process, raise the temperature to 95℃. During the test, the three seals successively depressurized when the temperature was raised to 20.6℃, 27.8℃, and 95.1℃ respectively. The test ends and the product is judged to be unqualified.

[0089] Example 5

[0090] A method for testing the fatigue life of a static seal under high pressure and low temperature conditions. The seal model is HNBR90. The test is conducted according to the following steps:

[0091] Step 1: Install the four seals on the four test heads respectively and connect them to the pulse test bench. All four seals will release pressure during the pressure holding process at (-50℃, 35MPa). The test is then completed, and the product is judged to be unqualified.

[0092] Example 6

[0093] A method for testing the fatigue life of static seals under high pressure and low temperature conditions. The seal type is NBR90. The test is conducted according to the following steps:

[0094] Step 1: Install the four seals on the four test heads respectively and connect them to the pulse test bench. Perform a 10-minute pressure holding test on each of the following temperatures in sequence: (-50℃, 35MPa), (-40℃, 35MPa), (-30℃, 35MPa), (-20℃, 35MPa), (25℃, 35MPa), (95℃, 35MPa), (100℃, 35MPa), (110℃, 35MPa), and (120℃, 35MPa). There should be no pressure release.

[0095] Step 2: First, cool the seal from 25℃ to -50℃, then pressurize it to 35MPa. During the pressure holding process, raise the temperature to 95℃. During the test, the four seals depressurized when the temperature reached 86.3℃, 32.3℃, 91.3℃, and 89.2℃ respectively. The test ends, and the product is judged to be unqualified.

[0096] Example 7

[0097] A method for testing the fatigue life of static seals under high pressure and low temperature conditions. The seal model is NBR80. The test is conducted according to the following steps:

[0098] Step 1: Install the four seals on the four test heads respectively and connect them to the pulse test bench. Perform a 10-minute pressure holding test on each of the following temperatures in sequence: (-50℃, 35MPa), (-40℃, 35MPa), (-30℃, 35MPa), (-20℃, 35MPa), (25℃, 35MPa), (95℃, 35MPa), (100℃, 35MPa), (110℃, 35MPa), and (120℃, 35MPa). There should be no pressure release.

[0099] Step 2: Cool the seal from 25℃ to -50℃, then pressurize it to 35MPa. During the pressure holding process, raise the temperature to 95℃. During the test, the two seals depressurized when the temperature reached 86.2℃ and 64.2℃ respectively. The test is then completed, and the product is deemed unqualified.

[0100] Performance testing methods

[0101] Record the test results in Table 1. Then, select the same model and batch of seals from the examples and use them on the machine. Record the usage time. If it reaches 15,000 hours, it is qualified; otherwise, it is unqualified. Record the results in Table 1.

[0102] Performance test data

[0103] Table 1

[0104] Example Is the test qualified? Is it qualified for use on the machine? Example 1 Unqualified Unqualified Example 2 Unqualified Unqualified Example 3 Unqualified Unqualified Example 4 qualified qualified Example 5 Unqualified Unqualified Example 6 qualified qualified Example 7 qualified qualified

Claims

1. A method for testing the fatigue life of static seals under high pressure and low temperature conditions, characterized in that, It includes the following steps: Step 1: Conduct pressure relief tests on the seals at different temperatures and pressures; Step 2: Conduct variable temperature pressure resistance tests; Step 3: Replace the seal and conduct the first heating pulse pressure resistance test; Step 4: Conduct a cooling pulse pressure resistance test; Step 5: Conduct the second heating pulse pressure resistance test; Step 6: Conduct a low temperature pulse pressure resistance test; Step 7: Determine the low temperature performance of the seal before and after the experiment; In Steps 1 to 6, there is a step of continuously monitoring pressure relief. If pressure relief occurs in any step during the monitoring period, the test ends and no subsequent steps are carried out; In Steps 3 to 6, each pulse includes one boost and one depressurization as one pulse; In Step 1, the seals are of the same batch, the number of tested seals is not less than 4, and they are tested simultaneously. The test is judged to be qualified if the number of seals passing the test is not less than 75% and the low temperature performance meets the requirements.

2. The fatigue life test method for static seals under high pressure and low temperature environment according to claim 1, characterized in that, The pressure points in Step 1 are selected from between 5 and 50 MPa, and the number of pressure points is 1 to 7.

3. The fatigue life test method for static seals under high pressure and low temperature conditions according to claim 2, characterized in that, The temperature points in Step 1 are selected from between -60°C and 130°C, and the number of temperature points is 6 to 12.

4. The fatigue life test method for static seals under high pressure and low temperature environment according to claim 3, characterized in that, Step 2 includes: first cooling from 5 to 35°C to -40 to -60°C, then pressurizing to 20 to 50 MPa, and heating to 80 to 110°C during the pressure holding process.

5. The fatigue life test method for static seals under high pressure and low temperature environment according to claim 4, characterized in that, In Steps 3 to 6, each pulse includes: first boosting from 1 to 5 MPa to 20 to 50 MPa within 0.1 to 1 s, and then depressurizing from 20 to 50 MPa to 1 to 5 MPa within 0.1 to 1 s. Completing one boost and one depressurization is one pulse.

6. The fatigue life test method for static seals under high pressure and low temperature conditions according to claim 5, characterized in that, Step 3 includes: first cooling from 5 to 35°C to -40 to -60°C, then heating to 80 to 110°C for heat preservation; pulses are applied during the heating and heat preservation processes, and the number of applied pulses is 60,000 - 120,000 times.

7. The fatigue life test method for static seals under high pressure and low temperature environment according to claim 6, characterized in that, Step 4 includes: first cooling from 80 to 110°C to -40 to -60°C, and then conducting heat preservation; pulses are applied during the heat preservation process, and the number of applied pulses in Step 4 is 1,800 - 5,400 times.

8. The fatigue life test method for static seals under high pressure and low temperature environment according to claim 7, characterized in that, Step 5 includes: first heating from -40 to -60°C to 80 to 110°C, and then conducting heat preservation; pulses are applied during the heating and heat preservation processes, and the number of applied pulses in Step 5 is 1,800 - 5,400 times.

9. The fatigue life test method for static seals under high pressure and low temperature conditions according to claim 8, characterized in that, Step 6 includes: first cooling from 5 to 35°C to -40 to -60°C, and then conducting heat preservation; pulses are applied during the heat preservation process, and the number of applied pulses in Step 6 is 5,400 - 9,600 times.

10. The method for testing the fatigue life of static seals under high pressure and low temperature conditions according to any one of claims 5-9, characterized in that, The rate of cooling or heating is 0.5 to 5°C / min.