JB/T 7046-1993 Verification method for rated fatigue pressure and rated static pressure of hydraulic accumulator pressure chamber
Some standard content:
Mechanical Industry Standard of the People's Republic of China
JB/T 7046-1993
Verification method of rated fatigue pressure and rated static pressure of hydraulic accumulator pressure chamber
Published on September 23, 1993
Ministry of Machinery Industry of the People's Republic of China
Implementation on July 1, 1994
Mechanical Industry Standard of the People's Republic of China
Verification method of rated fatigue pressure and rated static pressure of hydraulic accumulator pressure chamber
1 Subject content and scope of application
JB/T7046-1993
This standard specifies the verification method of rated fatigue pressure and rated static pressure of hydraulic accumulator pressure chamber. This standard applies to gas-liquid accumulator pressure chamber made of metal materials. This standard also applies to hydraulic transmitters made of metal materials used to separate two liquids and gas cylinders connected to the gas storage chamber of the accumulator.
This standard does not apply to accumulators, hydraulic transmitters and gas cylinders made of non-metallic materials, nor to non-gas-liquid accumulators (such as heavy hammer type or spring type).
This standard does not apply to verification after the material strength decreases due to chemical reaction or metal corrosion. 2 Reference standards
JB/T5924 Verification method for rated fatigue pressure and rated static pressure of hydraulic component pressure chamber 3 Terms and symbols
3.1 Pressure chamber
The component containing pressurized oil or gas in the hydraulic accumulator. 3.2 Rated fatigue pressure
The pressure that the accumulator pressure chamber can withstand 10° impacts without failure, represented by the symbol RFP 3.3 Rated static pressure
The static pressure that the accumulator pressure chamber can withstand without failure, represented by the symbol RSP. 3.4 Cyclic test pressure
The amplitude of the impact pressure applied in the cyclic test to verify the rated fatigue pressure is denoted by the symbol CTP. 3.5 Static test pressure
The static pressure applied in the static test to verify the rated static pressure is denoted by the symbol STP. 3.6 Acceleration factor
When calculating the cyclic test pressure using the rated fatigue pressure, the factor used to shorten the number of test cycles from 10° to 10° is denoted by the symbol K.
3.7 Coefficient of variation
When calculating the cyclic test pressure using the rated fatigue pressure, the factor used to take into account the variation of the fatigue strength of the metal is denoted by the symbol Kv. It is also applicable to the calculation of the static test pressure using the rated static pressure. 3.8 Assurance level
Approved by the Ministry of Machinery Industry on September 23, 1993
Implemented on July 1, 1994
JB/T 70461993
The minimum percentage of the verified accumulator pressure chambers that can withstand the rated fatigue pressure 10 times. 3.9 Confidence level
The degree of confirmation by the manufacturer that the expected assurance level has been achieved. 3.10 Failure of the pressure chamber
Structural fracture, crack, deformation causing excessive leakage, and deformation that affects the function of the accumulator 4 Test conditions and test equipment
4.1 General
4.1.1 Test oil: suitable non-corrosive liquid. 4.1.2 Before the test, the air in the test circuit and the pressure chamber to be tested should be removed. The same accumulator sample is used to complete the cyclic test for verifying the rated fatigue pressure first, and then the static test for verifying the rated static pressure. The test results are considered valid only after both tests are passed, otherwise the above tests should be repeated on another new sample. For any sample of the accumulator, static test is not allowed before passing the cyclic test. 4.1.4 Before the test, the gas-liquid conversion isolator of the accumulator should be removed, unless the pressure cannot be maintained after the isolator is removed, the accumulator is allowed to retain the isolator and test in accordance with the provisions of Articles 4.1.5 and 4.1.6. 4.1.5 For accumulators that are allowed to retain the gas-liquid conversion isolator, they must pass the production static pressure test described in Chapter 7 before conducting the rated fatigue pressure verification test or the rated static pressure verification test. 4.1.6 For accumulators that are allowed to retain the gas-liquid conversion isolator, the gas storage chamber and the oil storage chamber should be filled with liquid at the same time before the test to minimize the contact between the isolator and the inner wall of the pressure chamber. 4.1.7 If the accumulator under test is equipped with a charging valve, it shall be installed before the test. 4.1.8 Remove all pressure relief devices of the accumulator under test and plug the interfaces with appropriate joints. 4.1.9 Under the condition that the bearing capacity of the pressure container is not affected, certain structural changes to the pressure container are allowed to facilitate the verification test.
Under the condition that the bearing capacity of the pressure container is not affected, gaskets, seals, etc. that fail due to wear can be replaced. 4.1.10
4.2 Accuracy of test device
The accuracy of the test device shall meet the following requirements: Cyclic test pressure: ±3%
Static test pressure: 2%
Temperature:
4.3 Test device
±3℃
4.3.1 Cyclic test device
4.3.1.1 The cyclic test device shall be able to provide a stable test pressure. The frequency of the test pressure should be lower than 30Hz. The minimum value of the test pressure shall not be greater than 5% of CTP: The maximum value of the test pressure is equal to the sum of its minimum value and CTP: The test pressure should not contain superimposed oscillations with a range greater than 0.6CTP.
: The pressure measurement point should be directly connected to the pressure chamber to be tested, or set on the pressure oil port near it. This pressure oil port should not be used as an oil supply port during the test as much as possible. When pressure measurement must be carried out on the oil supply pressure pipeline, the fluid resistance between the pressure measurement point and the pressure chamber to be tested should be as small as possible. When conditions permit, it should be verified whether the actual pressure in the pressure chamber during the rated fatigue pressure verification test meets its set value.
JB/T70461993
4.3.1.3 When conducting a high-frequency cyclic test, several small metal balls or loose-fitting metal parts can be placed in the pressure chamber to be tested to reduce the volume of the pressurized oil.
4.3.1.4 The frequency response of the pressure measurement system and instrumentation should be high enough to truly reproduce the cyclic pressure waveform. Otherwise, the actual cyclic test pressure will be higher than the measured value, causing the accumulator to be subjected to excessive load during the test. 4.3.1.5 Install strain gauges at any convenient position of the pressure chamber to verify whether the ratio of the pressure on the accumulator to the resulting stress is consistent with the theoretical value under static pressure loading. 4.3.2 Static test device
The static test device should be able to provide a stable and controllable oil static pressure. 4.3.3 Provide appropriate personal and equipment safety measures. 5
Verification steps for rated fatigue pressure
5.1 Preliminary setting of the rated fatigue pressure of the accumulator5.1.1 Based on stress analysis, calculate the maximum allowable working pressure of the accumulator under internal pressurization conditions as the initial setting value of the rated fatigue pressure (RFP). The maximum design stress used in the calculation is one-fourth of the minimum tensile strength of the material. Unless otherwise specified by the user, the effects of factors such as changes in gas volume with temperature and impact on internal parts are generally not considered. 5.1.2 For accumulators composed of several parts, the RFP of each part should be calculated separately, and the minimum value should be taken as the initial setting value of the RFP of the assembly.
5.2 Determine the material of the pressure vessel body, select the assurance level and the number of samples. 5.3 Select the acceleration factor K value from Table 1 based on the minimum number of test cycles. Table 1 Acceleration factor KN
Pressure vessel body material
Minimum number of test cycles
Ferrous metals
Non-ferrous metals
Based on the required number of test samples, select the coefficient of variation Kv value from Table 2. Table 2 Coefficient of variation Kv
Number of samples
Material composition
Aluminum alloy, magnesium alloy, steel
Copper alloy
Stainless steel
Ferrous metal + non-ferrous metal
Note: ① For pressure vessels composed of multiple materials, when selecting the coefficient of variation K, take the maximum value of the coefficient of variation corresponding to each material. ②The coefficient of variation K listed in the table has a 99.9% assurance level and a 99% confidence level. 5.5 Calculate the cyclic test pressure CTP=KKv RFP according to formula (1).
JB/T7046—1993
5.6 According to the requirements of Article 4.3.1.1, the sample shall be verified and the number of test cycles shall not be less than the minimum number of test cycles. 5.7 Verify the rated fatigue pressure of the pressure container under test according to the verification criteria in Chapter 8. Note: All accumulators that have undergone the rated fatigue pressure verification test shall be scrapped and shall not be selected for use in equipment again. 6
Verification steps for rated static pressure
6.1 Determine the static test pressure (STP) according to formula (2): STPmax=2.5RFP..
Note: The manufacturer may choose an STP smaller than the above calculated value, but the RSP shall be reduced accordingly according to Article 6.4. 6.2 Select the coefficient of variation Kv value according to Article 5.4. (2)
6.3 Use the static test device in Article 4.3.2 to conduct a verification test on the accumulator sample, slowly increase the pressure to STP, and the pressure holding time shall be greater than 1 minute.
6.4 According to the verification criteria in Chapter 8 and using formula (2), verify the rated static pressure (RSP) of the pressure chamber under test: STP
Note: All accumulators that have undergone the rated static pressure verification test shall be scrapped and shall not be selected for use in equipment again. 7 Production static pressure test
Each accumulator product shall be subjected to a production static pressure test after processing. The test steps are shown in Appendix A (Supplement). 8 Verification criteria for rated fatigue pressure and rated static pressure The pressure chamber under test shall be deemed to have failed if any of the following conditions occur during the test: 8.1 Structural fracture.
8.2 Cracks in the pressure chamber.
8.3 Excessive leakage at the seal due to deformation. 9
Expression of verification test results
9.1 The verification test results shall include: assurance level, confidence level, rated fatigue pressure, and rated static pressure. .....(3)
9.2 The rated fatigue pressure and rated static pressure verified in accordance with this standard have an assurance level of 99.9% and a confidence level of 99%, and the code is 3/99.
9.3 The rated fatigue pressure and rated static pressure of the accumulator verified in accordance with this standard are expressed as follows: Example 1: RFP (3/99) = 30MPa
indicates that the rated fatigue pressure is 30MPa.
Example 2: RSP (3/99) = 32MPa
indicates that the rated static pressure is 32MPa.
9.4 The verification test conditions (including oil temperature and environmental conditions), sample changes and replacement of accessories during the verification process shall be recorded or explained in detail in the verification report.
Accumulator production static pressure test steps
JB/T7046-1993
Accumulator production static pressure test steps
(Supplement)
a. Remove all pressure relief devices from the accumulator and plug them with appropriate joints; b. Fill the gas storage chamber and oil storage chamber of the accumulator with oil at atmospheric pressure at the same time (without removing the gas-liquid conversion isolation piece); c. Plug the gas storage chamber with the charging valve or appropriate joint used in actual work; d. Expel the air in the test circuit;
e. Slowly pressurize the oil storage chamber of the accumulator until the pressure reaches 1.5 times the rated fatigue pressure; maintain the pressure for more than 1 minute and observe whether the accumulator leaks or breaks. If there is no external leakage or detectable cracks during the pressure maintenance period, the test is considered to have passed.
JB/T7046-1993
Appendix B
SN curve method for estimating life expectancy (reference)
Figure B1 shows the SN curve of a certain metal material. Its ordinate is the stress S to which the material is subjected; for a pressure container made of the material with a certain shape and size, the stress S can be converted into pressure. Its abscissa is the number of cyclic stresses N that the material can withstand (arranged in logarithmic values), that is, the life of the corresponding pressure container. The life represented at the origin is one time, which is equivalent to the static pressure.
The actual SN curve is represented by a thick solid line in Figure B1; the estimated SN curve is represented by a dotted line. The latter is formed by connecting the rated fatigue pressure and the rated static pressure obtained from the test with a straight line. According to the safety principle, the rated fatigue pressure is plotted at the position corresponding to 10° times. The estimated SN curve shown in the figure is suitable for steel materials; the SN curve of non-ferrous metals does not have a horizontal line segment at the right end.
When the rated fatigue pressure and rated static pressure of a hydraulic component pressure chamber are known, the user can estimate its expected life value from the actual pressure value according to the estimated SN curve; or determine the pressure value to be used from the expected life value. When making the above judgment, the user should also consider the impact of factors such as impact, thermal effect and improper use. Pressure
Additional instructions:
-Failure pressure point
Rated static pressure
Life value
Unverified safety zone
Verified safety zone
Surface
Actual S--N is calculated by
Calculated SN curve
Check the labor data
Determine the labor force
SN curve used to estimate the expected life value
This standard is proposed by the National Hydraulic and Pneumatic Standardization Technical Committee. This standard is under the jurisdiction of the Beijing Institute of Automation of the Machinery Industry of the Ministry of Machinery Industry. This standard was drafted by Shanghai Jiaotong University and Beijing Institute of Automation of Mechanical Industry of the Ministry of Machinery Industry. The main drafters of this standard are Lu Yuanzhang, Huang Mingshen, Yin Guohui and Yu Jinghong. 6
Life (times)
People's Republic of China
Mechanical Industry Standard||tt| ... |Postal code 100044)
Format 880×1230
5 sheets 5/8
Word count 12,000
First edition in May 1994
First printing in May 1994
Print run 1-500
Price 6.00 yuan
Mechanical Industry Standard Service Network: http://www.JB.ac.cn661_904 The verification test conditions (including oil temperature and environmental conditions), sample changes and replacement of accessories during the verification process shall be recorded or explained in detail in the verification report.
Accumulator production static pressure test stepsbzxz.net
JB/T7046-1993
Accumulator production static pressure test steps
(Supplement)
a. Remove all pressure relief devices from the accumulator and plug them with appropriate joints; b. Fill the gas storage chamber and oil storage chamber of the accumulator with oil at atmospheric pressure at the same time (without removing the gas-liquid conversion isolation parts); c. Plug the gas storage chamber with the charging valve or appropriate joint used in actual work; d. Expel air from the test circuit;
e. Slowly pressurize the oil storage chamber of the accumulator until the pressure reaches 1.5 times the rated fatigue pressure; maintain the pressure for more than 1 minute and observe whether the accumulator leaks or ruptures. If there is no external leakage or perceptible cracks during the pressure holding period, the test is considered to have passed.
JB/T7046-1993
Appendix B
SN curve method for estimating life expectancy (reference)
Figure B1 shows the SN curve of a certain metal material. Its ordinate is the stress S to which the material is subjected; for a pressure container made of the material with a certain shape and size, the stress S can be converted into pressure. Its abscissa is the number of cyclic stresses N that the material can withstand (arranged in logarithmic values), that is, the life of the corresponding pressure container. The life represented at the origin is one time, which is equivalent to being subjected to static pressure.
The actual SN curve is represented by the thick solid line in Figure B1; the estimated SN curve is represented by the dotted line. The latter is formed by connecting the rated fatigue pressure and the rated static pressure obtained from the test with a straight line. According to the safety principle, the rated fatigue pressure is plotted at the position corresponding to 10°. The estimated SN curve shown in the figure is suitable for steel materials; the SN curve of non-ferrous metals does not have a horizontal line segment on the right end.
When the rated fatigue pressure and rated static pressure of the pressure chamber of a hydraulic component are known, the user can estimate its life expectancy based on the actual pressure value used according to the estimated SN curve; or determine the pressure value to be used based on the life expectancy. When making the above judgments, the user should also consider the impact of factors such as impact, thermal effects and improper use. Pressure
Additional instructions:
-Failure pressure point
Rated static pressure
Life value
Unverified safety zone
Verified safety zone
Surface map
Actual S--N calculated by
SN curve
Check the labor number
Determine the labor force
SN curve used to estimate the expected value of life
This standard is proposed by the National Hydraulic and Pneumatic Standardization Technical Committee. This standard is under the jurisdiction of the Beijing Institute of Automation of the Machinery Industry of the Ministry of Machinery Industry. This standard was drafted by Shanghai Jiaotong University and the Beijing Institute of Automation of the Machinery Industry of the Ministry of Machinery Industry. The main drafters of this standard are Lu Yuanzhang, Huang Mingshen, Yin Guohui, and Yu Jinghong. 6
Life (times)
People's Republic of China
Mechanical Industry Standard||tt| ... |Postal code 100044)
Format 880×1230
5 sheets 5/8
Word count 12,000
First edition in May 1994
First printing in May 1994
Print run 1-500
Price 6.00 yuan
Mechanical Industry Standard Service Network: http://www.JB.ac.cn661_904 The verification test conditions (including oil temperature and environmental conditions), sample changes and replacement of accessories during the verification process shall be recorded or explained in detail in the verification report.
Accumulator production static pressure test steps
JB/T7046-1993
Accumulator production static pressure test steps
(Supplement)
a. Remove all pressure relief devices from the accumulator and plug them with appropriate joints; b. Fill the gas storage chamber and oil storage chamber of the accumulator with oil at atmospheric pressure at the same time (without removing the gas-liquid conversion isolation parts); c. Plug the gas storage chamber with the charging valve or appropriate joint used in actual work; d. Expel air from the test circuit;
e. Slowly pressurize the oil storage chamber of the accumulator until the pressure reaches 1.5 times the rated fatigue pressure; maintain the pressure for more than 1 minute and observe whether the accumulator leaks or ruptures. If there is no external leakage or perceptible cracks during the pressure holding period, the test is considered to have passed.
JB/T7046-1993
Appendix B
SN curve method for estimating life expectancy (reference)
Figure B1 shows the SN curve of a certain metal material. Its ordinate is the stress S to which the material is subjected; for a pressure container made of the material with a certain shape and size, the stress S can be converted into pressure. Its abscissa is the number of cyclic stresses N that the material can withstand (arranged in logarithmic values), that is, the life of the corresponding pressure container. The life represented at the origin is one time, which is equivalent to being subjected to static pressure.
The actual SN curve is represented by the thick solid line in Figure B1; the estimated SN curve is represented by the dotted line. The latter is formed by connecting the rated fatigue pressure and the rated static pressure obtained from the test with a straight line. According to the safety principle, the rated fatigue pressure is plotted at the position corresponding to 10°. The estimated SN curve shown in the figure is suitable for steel materials; the SN curve of non-ferrous metals does not have a horizontal line segment on the right end.
When the rated fatigue pressure and rated static pressure of the pressure chamber of a hydraulic component are known, the user can estimate its life expectancy based on the actual pressure value used according to the estimated SN curve; or determine the pressure value to be used based on the life expectancy. When making the above judgments, the user should also consider the impact of factors such as impact, thermal effects and improper use. Pressure
Additional instructions:
-Failure pressure point
Rated static pressure
Life value
Unverified safety zone
Verified safety zone
Surface map
Actual S--N calculated by
SN curve
Check the labor number
Determine the labor force
SN curve used to estimate the expected value of life
This standard is proposed by the National Hydraulic and Pneumatic Standardization Technical Committee. This standard is under the jurisdiction of the Beijing Institute of Automation of the Machinery Industry of the Ministry of Machinery Industry. This standard was drafted by Shanghai Jiaotong University and the Beijing Institute of Automation of the Machinery Industry of the Ministry of Machinery Industry. The main drafters of this standard are Lu Yuanzhang, Huang Mingshen, Yin Guohui, and Yu Jinghong. 6
Life (times)
People's Republic of China
Mechanical Industry Standard||tt| ... |Postal code 100044)
Format 880×1230
5 sheets 5/8
Word count 12,000
First edition in May 1994
First printing in May 1994
Print run 1-500
Price 6.00 yuan
Mechanical Industry Standard Service Network: http://www.JB.ac.cn661_90
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